diff --git a/README.md b/README.md
index 338295d..77ea786 100644
--- a/README.md
+++ b/README.md
@@ -58,16 +58,24 @@ $template = Handlebars::compile('Hi {{first}} {{last}}!', new Options(
 echo $template(['first' => 'John']); // Error: Runtime: last does not exist
 ```
 
-**Available Options:**
+### Available Options
+
+* `knownHelpers`: Associative array (`helperName => bool`) of helpers known to exist at template execution time.
+  Passing this allows the compiler to optimize a number of cases.
+  Builtin helpers are automatically included in this list and may be omitted by setting that value to `false`.
 * `knownHelpersOnly`: Enable to allow further optimizations based on the known helpers list.
 * `noEscape`: Enable to not HTML escape any content.
 * `strict`: Run in strict mode. In this mode, templates will throw rather than silently ignore missing fields.
-* `assumeObjects`: Removes object existence checks when traversing paths. This is a subset of strict mode that generates optimized templates when the data inputs are known to be safe.
+  This has the side effect of disabling inverse operations such as `{{^foo}}{{/foo}}`
+  unless fields are explicitly included in the source object.
+* `assumeObjects`: Removes object existence checks when traversing paths.
+  This is a subset of strict mode that generates optimized templates when the data inputs are known to be safe.
 * `preventIndent`: Prevent indented partial-call from indenting the entire partial output by the same amount.
-* `ignoreStandalone`: Disables standalone tag removal. When set, blocks and partials that are on their own line will not remove the whitespace on that line.
-* `explicitPartialContext`: Disables implicit context for partials. When enabled, partials that are not passed a context value will execute against an empty object.
-* `helpers`: Provide a key => value array of custom helper functions.
-* `partials`: Provide a key => value array of custom partial templates.
+* `ignoreStandalone`: Disables standalone tag removal.
+  When set, blocks and partials that are on their own line will not remove the whitespace on that line.
+* `explicitPartialContext`: Disables implicit context for partials.
+  When enabled, partials that are not passed a context value will execute against an empty object.
+* `partials`: Provide a `name => value` array of custom partial templates.
 * `partialResolver`: A closure which will be called for any partial not in the `partials` array to return a template for it.
 
 ## Custom Helpers
@@ -80,28 +88,30 @@ This object contains properties for accessing `hash` arguments, `data`, and the
 For example, a custom `#equals` helper with JS equality semantics could be implemented as follows:
 
 ```php
-use DevTheorem\Handlebars\{Handlebars, HelperOptions, Options};
+use DevTheorem\Handlebars\{Handlebars, HelperOptions};
 
-$template = Handlebars::compile('{{#equals my_var false}}Equal to false{{else}}Not equal{{/equals}}', new Options(
-    helpers: [
+$template = Handlebars::compile('{{#equals my_var false}}Equal to false{{else}}Not equal{{/equals}}');
+$options = [
+    'helpers' => [
         'equals' => function (mixed $a, mixed $b, HelperOptions $options) {
             $jsEquals = function (mixed $a, mixed $b): bool {
-                if ($a === null || $b === null) {
-                    // in JS, null is not equal to blank string or false or zero
+                if ($a === null || $b === null || is_string($a) && is_string($b)) {
+                    // In JS, null is not equal to blank string or false or zero,
+                    // and when both operands are strings no coercion is performed.
                     return $a === $b;
                 }
-
+    
                 return $a == $b;
             };
-
+    
             return $jsEquals($a, $b) ? $options->fn() : $options->inverse();
         },
     ],
-));
+];
 
-echo $template(['my_var' => 0]); // Equal to false
-echo $template(['my_var' => 1]); // Not equal
-echo $template(['my_var' => null]); // Not equal
+echo $template(['my_var' => 0], $options); // Equal to false
+echo $template(['my_var' => 1], $options); // Not equal
+echo $template(['my_var' => null], $options); // Not equal
 ```
 
 ## Hooks
@@ -115,13 +125,13 @@ a helper that is not registered, even when the name matches a property in the cu
 For example:
 
 ```php
-use DevTheorem\Handlebars\{Handlebars, HelperOptions, Options};
+use DevTheorem\Handlebars\{Handlebars, HelperOptions};
 
-$templateStr = '{{foo 2 "value"}}
-{{#person}}{{firstName}} {{lastName}}{{/person}}';
+$template = Handlebars::compile('{{foo 2 "value"}}
+{{#person}}{{firstName}} {{lastName}}{{/person}}');
 
-$template = Handlebars::compile($templateStr, new Options(
-    helpers: [
+$options = [
+    'helpers' => [
         'helperMissing' => function (...$args) {
             $options = array_pop($args);
             return "Missing {$options->name}(" . implode(',', $args) . ')';
@@ -130,9 +140,9 @@ $template = Handlebars::compile($templateStr, new Options(
             return "'{$options->name}' not found. Printing block: {$options->fn($context)}";
         },
     ],
-));
+];
 
-echo $template(['person' => ['firstName' => 'John', 'lastName' => 'Doe']]);
+echo $template(['person' => ['firstName' => 'John', 'lastName' => 'Doe']], $options);
 ```
 Output:
 > Missing foo(2,value)  
@@ -147,7 +157,10 @@ Helpers may return a `DevTheorem\Handlebars\SafeString` instance to prevent esca
 When constructing the string that will be marked as safe, any external content should be properly escaped
 using the `Handlebars::escapeExpression()` method to avoid potential security concerns.
 
-## Missing features
+## Missing Features
+
+All syntax and language features from Handlebars.js 4.7.8 should work the same in PHP Handlebars,
+with the following exceptions:
 
-All syntax from Handlebars.js 4.7.8 should work the same in this implementation, with the following exception:
-* Decorators ([deprecated in Handlebars.js](https://github.com/handlebars-lang/handlebars.js/blob/master/docs/decorators-api.md)) have not been implemented.
+* Custom Decorators have not been implemented, as they are [deprecated in Handlebars.js](https://github.com/handlebars-lang/handlebars.js/blob/master/docs/decorators-api.md).
+* The `data` and `compat` compilation options have not been implemented.
diff --git a/composer.json b/composer.json
index b2eb9a8..509d047 100644
--- a/composer.json
+++ b/composer.json
@@ -24,7 +24,7 @@
     "require-dev": {
         "friendsofphp/php-cs-fixer": "^3.94",
         "jbboehr/handlebars-spec": "dev-master",
-        "phpstan/phpstan": "^2.1.40",
+        "phpstan/phpstan": "^2.1.42",
         "phpunit/phpunit": "^11.5"
     },
     "autoload": {
diff --git a/composer.lock b/composer.lock
index 6665a1f..77736f8 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "9f7050f83541f2ec84f18a1920b5498d",
+    "content-hash": "bae8f70488ae219aa647854db7c16bde",
     "packages": [
         {
             "name": "devtheorem/php-handlebars-parser",
@@ -836,11 +836,11 @@
         },
         {
             "name": "phpstan/phpstan",
-            "version": "2.1.40",
+            "version": "2.1.42",
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpstan/phpstan/zipball/9b2c7aeb83a75d8680ea5e7c9b7fca88052b766b",
-                "reference": "9b2c7aeb83a75d8680ea5e7c9b7fca88052b766b",
+                "url": "https://api.github.com/repos/phpstan/phpstan/zipball/1279e1ce86ba768f0780c9d889852b4e02ff40d0",
+                "reference": "1279e1ce86ba768f0780c9d889852b4e02ff40d0",
                 "shasum": ""
             },
             "require": {
@@ -885,7 +885,7 @@
                     "type": "github"
                 }
             ],
-            "time": "2026-02-23T15:04:35+00:00"
+            "time": "2026-03-17T14:58:32+00:00"
         },
         {
             "name": "phpunit/php-code-coverage",
@@ -3063,16 +3063,16 @@
         },
         {
             "name": "symfony/console",
-            "version": "v7.4.4",
+            "version": "v7.4.7",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/console.git",
-                "reference": "41e38717ac1dd7a46b6bda7d6a82af2d98a78894"
+                "reference": "e1e6770440fb9c9b0cf725f81d1361ad1835329d"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/console/zipball/41e38717ac1dd7a46b6bda7d6a82af2d98a78894",
-                "reference": "41e38717ac1dd7a46b6bda7d6a82af2d98a78894",
+                "url": "https://api.github.com/repos/symfony/console/zipball/e1e6770440fb9c9b0cf725f81d1361ad1835329d",
+                "reference": "e1e6770440fb9c9b0cf725f81d1361ad1835329d",
                 "shasum": ""
             },
             "require": {
@@ -3137,7 +3137,7 @@
                 "terminal"
             ],
             "support": {
-                "source": "https://github.com/symfony/console/tree/v7.4.4"
+                "source": "https://github.com/symfony/console/tree/v7.4.7"
             },
             "funding": [
                 {
@@ -3157,7 +3157,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2026-01-13T11:36:38+00:00"
+            "time": "2026-03-06T14:06:20+00:00"
         },
         {
             "name": "symfony/deprecation-contracts",
@@ -3389,16 +3389,16 @@
         },
         {
             "name": "symfony/filesystem",
-            "version": "v7.4.0",
+            "version": "v7.4.6",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/filesystem.git",
-                "reference": "d551b38811096d0be9c4691d406991b47c0c630a"
+                "reference": "3ebc794fa5315e59fd122561623c2e2e4280538e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/filesystem/zipball/d551b38811096d0be9c4691d406991b47c0c630a",
-                "reference": "d551b38811096d0be9c4691d406991b47c0c630a",
+                "url": "https://api.github.com/repos/symfony/filesystem/zipball/3ebc794fa5315e59fd122561623c2e2e4280538e",
+                "reference": "3ebc794fa5315e59fd122561623c2e2e4280538e",
                 "shasum": ""
             },
             "require": {
@@ -3435,7 +3435,7 @@
             "description": "Provides basic utilities for the filesystem",
             "homepage": "https://symfony.com",
             "support": {
-                "source": "https://github.com/symfony/filesystem/tree/v7.4.0"
+                "source": "https://github.com/symfony/filesystem/tree/v7.4.6"
             },
             "funding": [
                 {
@@ -3455,20 +3455,20 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2025-11-27T13:27:24+00:00"
+            "time": "2026-02-25T16:50:00+00:00"
         },
         {
             "name": "symfony/finder",
-            "version": "v7.4.5",
+            "version": "v7.4.6",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/finder.git",
-                "reference": "ad4daa7c38668dcb031e63bc99ea9bd42196a2cb"
+                "reference": "8655bf1076b7a3a346cb11413ffdabff50c7ffcf"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/finder/zipball/ad4daa7c38668dcb031e63bc99ea9bd42196a2cb",
-                "reference": "ad4daa7c38668dcb031e63bc99ea9bd42196a2cb",
+                "url": "https://api.github.com/repos/symfony/finder/zipball/8655bf1076b7a3a346cb11413ffdabff50c7ffcf",
+                "reference": "8655bf1076b7a3a346cb11413ffdabff50c7ffcf",
                 "shasum": ""
             },
             "require": {
@@ -3503,7 +3503,7 @@
             "description": "Finds files and directories via an intuitive fluent interface",
             "homepage": "https://symfony.com",
             "support": {
-                "source": "https://github.com/symfony/finder/tree/v7.4.5"
+                "source": "https://github.com/symfony/finder/tree/v7.4.6"
             },
             "funding": [
                 {
@@ -3523,7 +3523,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2026-01-26T15:07:59+00:00"
+            "time": "2026-01-29T09:40:50+00:00"
         },
         {
             "name": "symfony/options-resolver",
@@ -4395,16 +4395,16 @@
         },
         {
             "name": "symfony/string",
-            "version": "v7.4.4",
+            "version": "v7.4.6",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/string.git",
-                "reference": "1c4b10461bf2ec27537b5f36105337262f5f5d6f"
+                "reference": "9f209231affa85aa930a5e46e6eb03381424b30b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/string/zipball/1c4b10461bf2ec27537b5f36105337262f5f5d6f",
-                "reference": "1c4b10461bf2ec27537b5f36105337262f5f5d6f",
+                "url": "https://api.github.com/repos/symfony/string/zipball/9f209231affa85aa930a5e46e6eb03381424b30b",
+                "reference": "9f209231affa85aa930a5e46e6eb03381424b30b",
                 "shasum": ""
             },
             "require": {
@@ -4462,7 +4462,7 @@
                 "utf8"
             ],
             "support": {
-                "source": "https://github.com/symfony/string/tree/v7.4.4"
+                "source": "https://github.com/symfony/string/tree/v7.4.6"
             },
             "funding": [
                 {
@@ -4482,7 +4482,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2026-01-12T10:54:30+00:00"
+            "time": "2026-02-09T09:33:46+00:00"
         },
         {
             "name": "theseer/tokenizer",
diff --git a/src/Compiler.php b/src/Compiler.php
index 14262d6..57b17cf 100644
--- a/src/Compiler.php
+++ b/src/Compiler.php
@@ -32,11 +32,26 @@ final class Compiler
 
     /**
      * Compile-time stack of block param name arrays, innermost first.
-     * Only populated for constructs that push to $cx->blParam at runtime (currently #each).
+     * Populated for any block that declares block params (e.g. {{#each items as |item i|}}).
      * @var list<string[]>
      */
     private array $blockParamValues = [];
 
+    /**
+     * Stack of booleans, one per active compileProgram() call.
+     * Each entry is set to true if that invocation directly emitted a $blockParams reference.
+     * Used to distinguish direct references from nested closure declarations that merely contain
+     * '$blockParams' as a parameter name in the generated string.
+     * @var bool[]
+     */
+    private array $bpRefStack = [];
+
+    /**
+     * Set when compiling a program to reflect whether that compilation directly
+     * referenced $blockParams (as opposed to nesting a closure that does).
+     */
+    private bool $lastCompileProgramHadDirectBpRef = false;
+
     /**
      * True while compiling helper params/hash values.
      * In strict mode, helper arguments may be undefined without throwing.
@@ -51,16 +66,9 @@ public function compile(Program $program, Context $context): string
     {
         $this->context = $context;
         $this->blockParamValues = [];
-        return $this->compileBody($program);
-    }
-
-    private function compileBody(Program $program): string
-    {
-        $code = '';
-        foreach ($program->body as $statement) {
-            $code .= $this->accept($statement);
-        }
-        return $code;
+        $this->bpRefStack = [];
+        $this->lastCompileProgramHadDirectBpRef = false;
+        return $this->compileProgram($program);
     }
 
     /**
@@ -71,40 +79,41 @@ private function compileBody(Program $program): string
     public function composePHPRender(string $code): string
     {
         $runtime = Runtime::class;
-        $helperOptions = HelperOptions::class;
-        $safeStringClass = SafeString::class;
-        $runtimeContext = RuntimeContext::class;
-        $helpers = Exporter::helpers($this->context);
         $partials = implode(",\n", $this->context->partialCode);
+        $closure = self::templateClosure($code, $partials, "\n \$in = &\$cx->data['root'];");
+        return "use {$runtime} as LR;\nreturn $closure;";
+    }
 
-        // Return generated PHP code string.
-        return <<<VAREND
-            use {$runtime} as LR;
-            use {$safeStringClass};
-            use {$helperOptions};
-            use {$runtimeContext};
-            return function (mixed \$in = null, array \$options = []) {
-                \$helpers = $helpers;
-                \$partials = [$partials];
-                \$partials = array_replace(\$partials, \$options['_partials'] ?? []);
-                foreach (\$options['partials'] ?? [] as \$name => \$p) {
-                    \$partials[\$name] = fn(RuntimeContext \$cx, mixed \$in) => \$p(\$in, ['_partials' => \$cx->partials, 'helpers' => \$cx->helpers, 'partialId' => \$cx->partialId]);
-                }
-                \$cx = new RuntimeContext(
-                    helpers: isset(\$options['helpers']) ? array_merge(\$helpers, \$options['helpers']) : \$helpers,
-                    partials: \$partials,
-                    data: isset(\$options['data']) ? array_merge(['root' => \$in], \$options['data']) : ['root' => \$in],
-                    partialId: \$options['partialId'] ?? 0,
-                );
-                \$in = &\$cx->data['root'];
-                return '$code';
-            };
-            VAREND;
+    /**
+     * Build a partial closure string: a Template-format closure that calls createContext
+     * with empty compiled partials, inheriting context from $partialContext.
+     * @param string $code PHP expression to return (e.g. the result of compileProgram())
+     * @param string $useVars comma-separated variables to capture (e.g. '$blockParams'), or '' for none
+     */
+    private static function templateClosure(string $code, string $partials = '', string $stmts = '', string $useVars = ''): string
+    {
+        $use = $useVars !== '' ? " use ($useVars)" : '';
+        return <<<PHP
+            function (mixed \$in = null, array \$options = [])$use {
+             \$cx = LR::createContext(\$in, \$options, [$partials]);
+             \$cx->frame['root'] = &\$cx->data['root'];$stmts
+             return $code;
+            }
+            PHP;
     }
 
     private function compileProgram(Program $program): string
     {
-        return "'" . $this->compileBody($program) . "'";
+        $this->bpRefStack[] = false;
+        $parts = [];
+        foreach ($program->body as $statement) {
+            $part = $this->accept($statement);
+            if ($part !== '' && $part !== "''") {
+                $parts[] = $part;
+            }
+        }
+        $this->lastCompileProgramHadDirectBpRef = array_pop($this->bpRefStack);
+        return $parts ? implode('.', $parts) : "''";
     }
 
     private function accept(Node $node): string
@@ -144,28 +153,15 @@ private function BlockStatement(BlockStatement $block): string
         $helperName = $this->getSimpleHelperName($block->path);
 
         if ($helperName !== null) {
-            // Custom block helper takes priority
-            if ($this->resolveHelper($helperName)) {
+            if ($this->isKnownHelper($helperName)) {
                 return $this->compileBlockHelper($block, $helperName);
             }
 
-            // Built-in block helpers
-            switch ($helperName) {
-                case 'if':
-                    return $this->compileIf($block, false);
-                case 'unless':
-                    return $this->compileIf($block, true);
-                case 'each':
-                    return $this->compileEach($block);
-                case 'with':
-                    return $this->compileWith($block);
-            }
-
-            if ($block->params) {
-                if ($this->resolveHelper('helperMissing')) {
-                    return $this->compileBlockHelper($block, 'helperMissing', $helperName);
+            if ($block->params || $block->hash !== null) {
+                if ($this->context->options->knownHelpersOnly) {
+                    $this->throwKnownHelpersOnly($helperName);
                 }
-                throw new \Exception('Missing helper: "' . $helperName . '"');
+                return $this->compileDynamicBlockHelper($block, $helperName);
             }
         }
 
@@ -173,171 +169,200 @@ private function BlockStatement(BlockStatement $block): string
         if ($block->path instanceof Literal) {
             $literalKey = $this->getLiteralKeyName($block->path);
 
-            if ($this->resolveHelper($literalKey)) {
+            if ($this->isKnownHelper($literalKey)) {
                 return $this->compileBlockHelper($block, $literalKey);
             }
 
             $escapedKey = self::quote($literalKey);
-            $miss = $this->missValue($literalKey);
-            $var = "\$in[$escapedKey] ?? $miss";
+            $var = "\$in[$escapedKey] ?? " . $this->missValue($literalKey);
 
             if ($block->program === null) {
-                // Inverted section: {{^"foo"}}...{{/"foo"}}
-                $body = $this->compileProgramOrEmpty($block->inverse);
-                return "'.(" . self::getRuntimeFunc('isec', $var) . " ? $body : '').'";
+                return $this->compileInvertedSection($block, $var, null);
             }
 
-            // Regular section: {{#"foo"}}...{{/"foo"}}
-            $body = $this->compileProgram($block->program);
-            $else = $this->compileElseClause($block);
-            return "'." . self::getRuntimeFunc('sec', "\$cx, $var, [], \$in, false, function(\$cx, \$in) {return $body;}$else") . ".'";
+            return $this->compileSection($block, $var, $escapedKey);
         }
 
+        $var = $this->compileExpression($block->path);
+
         // Inverted section: {{^var}}...{{/var}}
         if ($block->program === null) {
-            return $this->compileInvertedSection($block);
+            $escapedName = $helperName !== null ? self::quote($helperName) : null;
+            return $this->compileInvertedSection($block, $var, $escapedName);
         }
 
         // Non-simple path with params: invoke as a dynamic block helper call
         if ($block->params) {
-            return $this->compileDynamicBlockHelper($block);
-        }
-
-        // Block with hash but no positional params → helperMissing
-        if ($block->hash !== null && $this->resolveHelper('helperMissing')) {
-            return $this->compileBlockHelper($block, 'helperMissing', $block->path->original);
+            return $this->compileDynamicBlockHelper($block, (string) $block->path->original, $var);
         }
 
         // Regular section: {{#var}}...{{/var}}
-        return $this->compileSection($block);
+        return $this->compileSection($block, $var, self::quote($block->path->original));
     }
 
-    private function compileDynamicBlockHelper(BlockStatement $block): string
+    private function isKnownHelper(string $helperName): bool
     {
-        if (!$block->program) {
-            throw new \Exception('Dynamic block program must not be empty');
-        }
-        $varPath = $this->compileExpression($block->path);
-        $bp = $block->program->blockParams;
-        $params = $this->compileParams($block->params, $block->hash, $bp ?: null);
-        $body = $this->compileProgramWithBlockParams($block->program, $bp);
-        $else = $this->compileElseClause($block);
-        $name = self::quote((string) $block->path->original);
-        return "'." . self::getRuntimeFunc('dynhbbch', "\$cx, $name, $varPath, $params, \$in, function(\$cx, \$in) {return $body;}$else") . ".'";
+        return $this->context->options->knownHelpers[$helperName] ?? false;
     }
 
-    private function resolveHelper(string $helperName): bool
+    private function compileSection(BlockStatement $block, string $var, string $escapedName): string
     {
-        if (isset($this->context->helpers[$helperName])) {
-            $this->context->usedHelpers[$helperName] = true;
-            return true;
-        }
+        assert($block->program !== null);
 
-        return false;
-    }
+        $blockFn = $this->compileProgramWithBlockParams($block->program);
+        $else = $this->compileElseClause($block);
 
-    private function compileIf(BlockStatement $block, bool $unless): string
-    {
-        if (count($block->params) !== 1) {
-            $helper = $unless ? '#unless' : '#if';
-            throw new \Exception("$helper requires exactly one argument");
+        if ($this->context->options->knownHelpersOnly) {
+            return self::getRuntimeFunc('sec', "\$cx, $var, \$in, $blockFn, $else");
         }
 
-        $savedHelperArgs = $this->compilingHelperArgs;
-        $this->compilingHelperArgs = true;
-        $var = $this->compileExpression($block->params[0]);
-        $includeZero = $this->getIncludeZero($block->hash);
-        $this->compilingHelperArgs = $savedHelperArgs;
-
-        $then = $this->compileProgramOrEmpty($block->program);
-
-        if ($block->inverse && $block->inverse->chained) {
-            // {{else if ...}} chain — compile the inner block directly
-            $elseCode = '';
-            foreach ($block->inverse->body as $stmt) {
-                $elseCode .= $this->accept($stmt);
-            }
-            $else = "'" . $elseCode . "'";
-        } else {
-            $else = $this->compileProgramOrEmpty($block->inverse);
+        $bp = $block->program->blockParams;
+        if ($block->hash !== null || $bp) {
+            $params = $this->compileParams([], $block->hash);
+            $outerBp = $this->outerBlockParamsExpr();
+            return self::getRuntimeFunc('dynhbbch', "\$cx, $escapedName, $var, $params, \$in, $blockFn, $else, " . count($bp) . ", $outerBp");
         }
 
-        $negate = $unless ? '!' : '';
-        $dv = self::getRuntimeFunc('dv', "$var, \$in");
-        return "'.({$negate}" . self::getRuntimeFunc('ifvar', "$dv, $includeZero") . " ? $then : $else).'";
+        return self::getRuntimeFunc('sec', "\$cx, $var, \$in, $blockFn, $else, $escapedName");
     }
 
-    private function compileEach(BlockStatement $block): string
+    private function compileInvertedSection(BlockStatement $block, string $var, ?string $escapedName): string
     {
-        if (count($block->params) !== 1) {
-            throw new \Exception('Must pass iterator to #each');
-        }
+        $body = $this->compileProgramOrEmpty($block->inverse);
 
-        $var = $this->compileExpression($block->params[0]);
-        [$bp, $bs] = $this->getProgramBlockParams($block->program);
+        if ($escapedName !== null) {
+            $blockFn = self::blockClosure($body, inheritsBp: $this->lastCompileProgramHadDirectBpRef);
+            return self::getRuntimeFunc('isech', "\$cx, $var, \$in, $blockFn, $escapedName");
+        }
 
-        $body = $block->program ? $this->compileProgramWithBlockParams($block->program, $bp) : "''";
-        $else = $this->compileElseClause($block);
+        return "(" . self::getRuntimeFunc('isec', $var) . " ? $body : '')";
+    }
 
-        $dv = self::getRuntimeFunc('dv', "$var, \$in");
-        return "'." . self::getRuntimeFunc('sec', "\$cx, $dv, $bs, \$in, true, function(\$cx, \$in) {return $body;}$else") . ".'";
+    /** Returns '$blockParams' when inside a block-param scope (for use() capture), '' otherwise. */
+    private function blockParamsUseVars(): string
+    {
+        return $this->blockParamValues ? '$blockParams' : '';
     }
 
-    private function compileWith(BlockStatement $block): string
+    /**
+     * Returns the PHP expression for the outer block param stack at the current compile-time scope.
+     * '$blockParams' when inside a bp-declaring block; '[]' otherwise (top-level for this each/helper).
+     * When returning '$blockParams', marks the current bpRefStack frame so the enclosing closure
+     * captures $blockParams via use(), even if it doesn't directly access block param values.
+     */
+    private function outerBlockParamsExpr(): string
     {
-        if (count($block->params) !== 1) {
-            throw new \Exception('#with requires exactly one argument');
+        if (!$this->blockParamValues) {
+            return '[]';
         }
-
-        $var = $this->compileExpression($block->params[0]);
-        [$bp, $bs] = $this->getProgramBlockParams($block->program);
-
-        $body = $this->compileProgramOrEmpty($block->program);
-        $else = $this->compileElseClause($block);
-
-        $dv = self::getRuntimeFunc('dv', "$var, \$in");
-        return "'." . self::getRuntimeFunc('wi', "\$cx, $dv, $bs, \$in, function(\$cx, \$in) {return $body;}$else") . ".'";
+        if ($this->bpRefStack) {
+            $this->bpRefStack[array_key_last($this->bpRefStack)] = true;
+        }
+        return '$blockParams';
     }
 
-    private function compileSection(BlockStatement $block): string
+    /**
+     * Compile a block program, pushing/popping its block params around the compilation.
+     */
+    private function compileProgramWithBlockParams(Program $program): string
     {
-        $var = $this->compileExpression($block->path);
-        $escapedName = $block->path instanceof PathExpression ? self::quote($block->path->original) : 'null';
+        $bp = $program->blockParams;
+        if ($bp) {
+            array_unshift($this->blockParamValues, $bp);
+        }
+        $body = $this->compileProgram($program);
+        if ($bp) {
+            array_shift($this->blockParamValues);
+        }
+        return self::blockClosure($body, (bool) $program->blockParams, $this->lastCompileProgramHadDirectBpRef);
+    }
 
-        $body = $this->compileProgramOrEmpty($block->program);
-        $else = $this->compileElseClause($block);
+    private function compileBlockHelper(BlockStatement $block, string $name): string
+    {
+        $inverted = $block->program === null;
+        if ($inverted) {
+            assert($block->inverse !== null);
+        }
+        // For inverted blocks the fn body comes from the inverse program; for normal blocks, the program.
+        $fnProgram = $inverted ? $block->inverse : $block->program;
 
-        if ($this->resolveHelper('blockHelperMissing')) {
-            return "'." . self::getRuntimeFunc('hbbch', "\$cx, 'blockHelperMissing', [[$var],[]], \$in, false, function(\$cx, \$in) {return $body;}$else, $escapedName") . ".'";
+        // Inline if/unless as ternary — eliminates hbbch dispatch and HelperOptions allocation.
+        // Safe because if/unless don't change scope, so $cx and $in are already correct.
+        // Negate for 'unless' in a normal block, or 'if' in an inverted block (swapped semantics).
+        if ($this->canInlineConditional($block, $name, $fnProgram->blockParams)) {
+            $cond = $this->compileConditionalExpr($block->params[0], $name === ($inverted ? 'if' : 'unless'));
+            $body = $this->compileProgram($fnProgram);
+            $elseBody = $inverted ? "''" : $this->compileProgramOrEmpty($block->inverse);
+            return "($cond ? $body : $elseBody)";
         }
 
-        return "'." . self::getRuntimeFunc('sec', "\$cx, $var, [], \$in, false, function(\$cx, \$in) {return $body;}$else") . ".'";
-    }
+        $blockFn = $this->compileProgramWithBlockParams($fnProgram);
+        [$fn, $else] = $inverted
+            ? ['null', $blockFn]
+            : [$blockFn, $this->compileElseClause($block)];
 
-    private function compileInvertedSection(BlockStatement $block): string
-    {
-        $var = $this->compileExpression($block->path);
-        $body = $this->compileProgramOrEmpty($block->inverse);
+        $outerBp = $this->outerBlockParamsExpr();
+        $params = $this->compileParams($block->params, $block->hash);
+        $helperName = self::quote($name);
+        $bpCount = count($fnProgram->blockParams);
 
-        return "'.(" . self::getRuntimeFunc('isec', $var) . " ? $body : '').'";
+        $trailingArgs = ($bpCount > 0 || $outerBp !== '[]') ? ", $bpCount, $outerBp" : '';
+        return self::getRuntimeFunc('hbbch', "\$cx, \$cx->helpers[$helperName], $helperName, $params, \$in, $fn, $else$trailingArgs");
     }
 
-    private function compileBlockHelper(BlockStatement $block, string $helperName, ?string $missingName = null): string
+    /**
+     * Returns true when an if/unless block can be safely inlined as a ternary expression.
+     * Requires: no hash options (e.g. includeZero), no block params, exactly one condition param.
+     * @param string[] $bp
+     */
+    private function canInlineConditional(BlockStatement $block, string $helperName, array $bp): bool
     {
-        $bp = $block->program->blockParams ?? $block->inverse->blockParams ?? [];
-        $params = $this->compileParams($block->params, $block->hash, $bp);
-        $escapedName = $missingName === null ? 'null' : self::quote($missingName);
+        return $this->isKnownHelper($helperName)
+            && ($helperName === 'if' || $helperName === 'unless')
+            && count($block->params) === 1
+            && $block->hash === null
+            && !$bp;
+    }
 
-        if ($block->program === null) {
-            // inverted block
-            $body = $this->compileProgramOrEmpty($block->inverse);
-            return "'." . self::getRuntimeFunc('hbbch', "\$cx, '$helperName', $params, \$in, true, function(\$cx, \$in) {return $body;}, null, $escapedName") . ".'";
+    /**
+     * Compile the condition expression for an inlined if/unless ternary.
+     * For simple single-segment paths, routes through cv() which already resolves closures,
+     * so ifvar() suffices. For all other expressions, closures at nested paths are not
+     * invoked (not a real-world or spec concern).
+     * @param bool $negate true for `unless` or inverted `{{^if}}`
+     */
+    private function compileConditionalExpr(Expression $condExpr, bool $negate): string
+    {
+        $part = $condExpr instanceof PathExpression ? ($condExpr->parts[0] ?? null) : null;
+        if ($condExpr instanceof PathExpression
+            && !$condExpr->data
+            && $condExpr->depth === 0
+            && is_string($part)
+            && !self::scopedId($condExpr)
+            && $this->lookupBlockParam($part) === null
+        ) {
+            $val = self::getRuntimeFunc('cv', '$in, ' . self::quote($part));
+        } else {
+            $savedHelperArgs = $this->compilingHelperArgs;
+            $this->compilingHelperArgs = true;
+            $val = $this->compileExpression($condExpr);
+            $this->compilingHelperArgs = $savedHelperArgs;
         }
+        $cond = self::getRuntimeFunc('ifvar', $val);
+        return $negate ? "!$cond" : $cond;
+    }
 
-        $body = $this->compileProgramWithBlockParams($block->program, $bp);
+    private function compileDynamicBlockHelper(BlockStatement $block, string $name, string $varPath = 'null'): string
+    {
+        $bp = $block->program->blockParams ?? [];
+        $params = $this->compileParams($block->params, $block->hash);
+        $blockFn = $block->program !== null
+            ? $this->compileProgramWithBlockParams($block->program)
+            : self::blockClosure("''");
         $else = $this->compileElseClause($block);
-
-        return "'." . self::getRuntimeFunc('hbbch', "\$cx, '$helperName', $params, \$in, false, function(\$cx, \$in) {return $body;}$else, $escapedName") . ".'";
+        $outerBp = $this->outerBlockParamsExpr();
+        $helperName = self::quote($name);
+        return self::getRuntimeFunc('dynhbbch', "\$cx, $helperName, $varPath, $params, \$in, $blockFn, $else, " . count($bp) . ", $outerBp");
     }
 
     private function DecoratorBlock(BlockStatement $block): string
@@ -362,7 +387,10 @@ private function DecoratorBlock(BlockStatement $block): string
         // Do NOT add to partialCode - `in()` handles runtime registration, keeping inline partials block-scoped.
         $this->context->usedPartial[$partialName] = '';
 
-        return "'." . self::getRuntimeFunc('in', "\$cx, " . self::quote($partialName) . ", function(\$cx, \$in) {return $body;}") . ".'";
+        // Capture $blockParams if we're inside a block-param scope so the inline partial body can access them.
+        $useVars = $this->blockParamsUseVars();
+        $escapedName = self::quote($partialName);
+        return self::getRuntimeFunc('in', "\$cx, $escapedName, " . self::templateClosure($body, useVars: $useVars));
     }
 
     private function Decorator(Decorator $decorator): never
@@ -374,16 +402,13 @@ private function PartialStatement(PartialStatement $statement): string
     {
         $name = $statement->name;
 
-        if ($name instanceof PathExpression) {
-            $p = self::quote($name->original);
-            $this->resolveAndCompilePartial($name->original);
-        } elseif ($name instanceof SubExpression) {
+        if ($name instanceof SubExpression) {
             $p = $this->SubExpression($name);
             $this->context->usedDynPartial++;
-        } elseif ($name instanceof NumberLiteral || $name instanceof StringLiteral) {
-            $literalName = $this->getLiteralKeyName($name);
-            $p = self::quote($literalName);
-            $this->resolveAndCompilePartial($literalName);
+        } elseif ($name instanceof PathExpression || $name instanceof StringLiteral || $name instanceof NumberLiteral) {
+            $partialName = $name instanceof PathExpression ? $name->original : $this->getLiteralKeyName($name);
+            $p = self::quote($partialName);
+            $this->resolveAndCompilePartial($partialName);
         } else {
             $p = $this->compileExpression($name);
         }
@@ -395,10 +420,10 @@ private function PartialStatement(PartialStatement $statement): string
         // appendContent opcode) and invoke the partial with an empty indent so its lines are
         // not additionally indented.
         if ($this->context->options->preventIndent && $statement->indent !== '') {
-            return "'.$indent." . self::getRuntimeFunc('p', "\$cx, $p, $vars, 0, ''") . ".'";
+            return "$indent." . self::getRuntimeFunc('p', "\$cx, $p, $vars, 0, ''");
         }
 
-        return "'." . self::getRuntimeFunc('p', "\$cx, $p, $vars, 0, $indent") . ".'";
+        return self::getRuntimeFunc('p', "\$cx, $p, $vars, 0, $indent");
     }
 
     private function PartialBlockStatement(PartialBlockStatement $statement): string
@@ -409,21 +434,18 @@ private function PartialBlockStatement(PartialBlockStatement $statement): string
         // Hoist inline partial registrations so they run before the partial is called.
         // Without this, inline partials defined in the block would only be registered when
         // {{> @partial-block}} is invoked, too late for partials that call them directly.
-        $hoisted = '';
+        $hoistedParts = [];
         foreach ($statement->program->body as $stmt) {
             if ($stmt instanceof BlockStatement && $stmt->type === 'DecoratorBlock') {
-                $hoisted .= $this->accept($stmt);
+                $hoistedParts[] = $this->accept($stmt);
             }
         }
 
         $name = $statement->name;
         $body = $this->compileProgram($statement->program);
 
-        if ($name instanceof PathExpression) {
-            $partialName = $name->original;
-            $p = self::quote($partialName);
-        } elseif ($name instanceof StringLiteral || $name instanceof NumberLiteral) {
-            $partialName = $this->getLiteralKeyName($name);
+        if ($name instanceof PathExpression || $name instanceof StringLiteral || $name instanceof NumberLiteral) {
+            $partialName = $name instanceof PathExpression ? $name->original : $this->getLiteralKeyName($name);
             $p = self::quote($partialName);
         } else {
             $p = $this->compileExpression($name);
@@ -444,19 +466,25 @@ private function PartialBlockStatement(PartialBlockStatement $statement): string
             }
 
             if (!$found) {
-                // Register fallback body as the partial
-                $func = "function (\$cx, \$in) {return $body;}";
+                // Mark as known so LR::p() can resolve it at runtime.
                 $this->context->usedPartial[$partialName] = '';
-                $this->context->partialCode[$partialName] = self::quote($partialName) . " => $func";
+                // Don't add to partialCode — register via LR::in() at runtime so $blockParams
+                // is captured from the enclosing scope when block params are in use.
             }
         }
 
         $vars = $this->compilePartialParams($statement->params, $statement->hash);
 
-        return $hoisted
-            . "'."
-            . self::getRuntimeFunc('in', "\$cx, '@partial-block$pid', function(\$cx, \$in) {return $body;}") . "."
-            . self::getRuntimeFunc('p', "\$cx, $p, $vars, $pid, ''") . ".'";
+        // Capture $blockParams if we're inside a block-param scope so the partial block body can access them.
+        $useVars = $this->blockParamsUseVars();
+        $fallbackParts = ($partialName !== null && !$found)
+            ? [self::getRuntimeFunc('inFallback', "\$cx, " . self::quote($partialName) . ', ' . self::templateClosure($body, useVars: $useVars))]
+            : [];
+        $parts = [...$hoistedParts, ...$fallbackParts,
+            self::getRuntimeFunc('in', "\$cx, '@partial-block$pid', " . self::templateClosure($body, useVars: $useVars)),
+            self::getRuntimeFunc('p', "\$cx, $p, $vars, $pid, ''"),
+        ];
+        return implode('.', $parts);
     }
 
     private function MustacheStatement(MustacheStatement $mustache): string
@@ -468,79 +496,61 @@ private function MustacheStatement(MustacheStatement $mustache): string
         if ($path instanceof PathExpression) {
             $helperName = $this->getSimpleHelperName($path);
 
-            // Registered helper
-            if ($helperName !== null && $this->resolveHelper($helperName)) {
-                $params = $this->compileParams($mustache->params, $mustache->hash);
-                $call = self::getRuntimeFunc('hbch', "\$cx, '$helperName', $params, \$in");
-                return "'." . self::getRuntimeFunc($fn, $call) . ".'";
+            if ($helperName !== null && ($this->isKnownHelper($helperName) || $mustache->params || $mustache->hash !== null)) {
+                $call = $this->buildInlineHelperCall($helperName, $mustache->params, $mustache->hash);
+                return self::getRuntimeFunc($fn, $call);
             }
 
-            // Built-in: lookup
-            if ($helperName === 'lookup') {
-                return $this->compileLookup($mustache, $raw);
-            }
-
-            // Built-in: log
-            if ($helperName === 'log') {
-                return $this->compileLog($mustache);
-            }
-
-            if ($mustache->params) {
+            if ($mustache->params || $mustache->hash !== null) {
                 // Non-simple path with params (data var or pathed expression): invoke via dv()
-                if ($helperName === null) {
-                    $varPath = $this->PathExpression($path);
-                    $args = array_map(fn($p) => $this->compileExpression($p), $mustache->params);
-                    $call = self::getRuntimeFunc('dv', "$varPath, " . implode(', ', $args));
-                    return "'." . self::getRuntimeFunc($fn, $call) . ".'";
-                }
-                if (!$this->context->options->strict && $this->resolveHelper('helperMissing')) {
-                    $params = $this->compileParams($mustache->params, $mustache->hash);
-                    $escapedName = self::quote($helperName);
-                    $call = self::getRuntimeFunc('hbch', "\$cx, 'helperMissing', $params, \$in, $escapedName");
-                    return "'." . self::getRuntimeFunc($fn, $call) . ".'";
-                }
-                throw new \Exception('Missing helper: "' . $helperName . '"');
+                $varPath = $this->PathExpression($path);
+                $args = array_map(fn($p) => $this->compileExpression($p), $mustache->params);
+                $call = self::getRuntimeFunc('dv', "$varPath, " . implode(', ', $args));
+                return self::getRuntimeFunc($fn, $call);
             }
 
-            // Plain variable — if helperMissing is registered, route missing identifiers to it
-            if ($helperName !== null && !$this->context->options->strict && $this->resolveHelper('helperMissing')) {
-                $bpIdx = $this->lookupBlockParam($helperName);
-                if ($bpIdx === null) {
-                    $escapedKey = self::quote($helperName);
-                    $hbch = self::getRuntimeFunc('hbch', "\$cx, 'helperMissing', [[],[]], \$in, $escapedKey");
-                    $val = "(is_array(\$in) && array_key_exists($escapedKey, \$in) ? \$in[$escapedKey] : $hbch)";
-                    return "'." . self::getRuntimeFunc($fn, $val) . ".'";
+            // When not strict/assumeObjects, check runtime helpers for bare identifiers.
+            if ($helperName !== null && !$this->context->options->strict && !$this->context->options->assumeObjects
+                && $this->lookupBlockParam($helperName) === null) {
+                $escapedKey = self::quote($helperName);
+                if ($this->context->options->knownHelpersOnly) {
+                    return self::getRuntimeFunc($fn, self::getRuntimeFunc('cv', "\$in, $escapedKey"));
                 }
+                return self::getRuntimeFunc($fn, self::getRuntimeFunc('hv', "\$cx, $escapedKey, \$in"));
             }
 
-            // Plain variable; wrap in dv() to support lambda context values
+            // Plain variable. Data variables (@foo) may be closures, so wrap in dv() to invoke
+            // them. Context variables (e.g. user.name) are never closures per the spec — all
+            // lambda tests use single-segment identifiers which go through hv()/cv() — and
+            // dv() doesn't pass context to them anyway, so skip it.
             $varPath = $this->PathExpression($path);
-            return "'." . self::getRuntimeFunc($fn, self::getRuntimeFunc('dv', $varPath)) . ".'";
+            if (!$path->data) {
+                return self::getRuntimeFunc($fn, $varPath);
+            }
+            return self::getRuntimeFunc($fn, self::getRuntimeFunc('dv', $varPath));
         }
 
         // Literal path — treat as named context lookup or helper call
         $literalKey = $this->getLiteralKeyName($path);
 
-        if ($this->resolveHelper($literalKey)) {
-            $params = $this->compileParams($mustache->params, $mustache->hash);
-            $escapedKey = self::quote($literalKey);
-            $call = self::getRuntimeFunc('hbch', "\$cx, $escapedKey, $params, \$in");
-            return "'." . self::getRuntimeFunc($fn, $call) . ".'";
+        if ($this->isKnownHelper($literalKey) || $mustache->params || $mustache->hash !== null) {
+            $call = $this->buildInlineHelperCall($literalKey, $mustache->params, $mustache->hash);
+            return self::getRuntimeFunc($fn, $call);
         }
 
-        if ($mustache->params) {
-            throw new \Exception('Missing helper: "' . $literalKey . '"');
+        $escapedKey = self::quote($literalKey);
+
+        if (!$this->context->options->strict && !$this->context->options->knownHelpersOnly) {
+            return self::getRuntimeFunc($fn, self::getRuntimeFunc('hv', "\$cx, $escapedKey, \$in"));
         }
 
-        $escapedKey = self::quote($literalKey);
         $miss = $this->missValue($literalKey);
-        $val = "\$in[$escapedKey] ?? $miss";
-        return "'." . self::getRuntimeFunc($fn, $val) . ".'";
+        return self::getRuntimeFunc($fn, "\$in[$escapedKey] ?? $miss");
     }
 
     private function ContentStatement(ContentStatement $statement): string
     {
-        return self::escape($statement->value);
+        return self::quote($statement->value);
     }
 
     private function CommentStatement(CommentStatement $statement): string
@@ -553,31 +563,17 @@ private function CommentStatement(CommentStatement $statement): string
     private function SubExpression(SubExpression $expression): string
     {
         $path = $expression->path;
-        $helperName = null;
-
-        if ($path instanceof PathExpression) {
-            $helperName = $this->getSimpleHelperName($path);
-        } elseif ($path instanceof Literal) {
-            $helperName = $this->getLiteralKeyName($path);
-        }
-
-        // Registered helper
-        if ($helperName !== null && $this->resolveHelper($helperName)) {
-            $params = $this->compileParams($expression->params, $expression->hash);
-            $escapedName = self::quote($helperName);
-            return self::getRuntimeFunc('hbch', "\$cx, $escapedName, $params, \$in");
-        }
-
-        // Built-in: lookup (as subexpression)
-        if ($helperName === 'lookup') {
-            return $this->getWithLookup($expression->params[0], $expression->params[1]);
-        }
+        $helperName = match (true) {
+            $path instanceof Literal => $this->getLiteralKeyName($path),
+            $path instanceof PathExpression => $this->getSimpleHelperName($path),
+            default => null,
+        };
 
-        if ($helperName !== null) {
-            throw new \Exception('Missing helper: "' . $helperName . '"');
+        if ($helperName === null) {
+            throw new \Exception('Sub-expression must be a helper call');
         }
 
-        throw new \Exception('Sub-expression must be a helper call');
+        return $this->buildInlineHelperCall($helperName, $expression->params, $expression->hash);
     }
 
     private function PathExpression(PathExpression $expression): string
@@ -605,11 +601,15 @@ private function PathExpression(PathExpression $expression): string
 
         // Check block params (depth-0, non-data, non-scoped paths only)
         if (!$data && $depth === 0 && !self::scopedId($expression)) {
-            $bpIdx = $this->lookupBlockParam($stringParts[0]);
-            if ($bpIdx !== null) {
-                $escapedName = self::quote($stringParts[0]);
-                $bpBase = "\$cx->blParam[$bpIdx][$escapedName]";
+            $bp = $this->lookupBlockParam($stringParts[0]);
+            if ($bp !== null) {
+                [$bpDepth, $bpIndex] = $bp;
+                $bpBase = "\$blockParams[$bpDepth][$bpIndex]";
                 $remaining = self::buildKeyAccess(array_slice($stringParts, 1));
+                // Mark the current compileProgram() level as having a direct $blockParams reference.
+                if ($this->bpRefStack) {
+                    $this->bpRefStack[array_key_last($this->bpRefStack)] = true;
+                }
                 return "$bpBase$remaining ?? $miss";
             }
         }
@@ -659,7 +659,8 @@ private function PathExpression(PathExpression $expression): string
             $escapedOriginal = self::quote($expression->original);
             $expr = $base;
             foreach ($stringParts as $part) {
-                $expr = self::getRuntimeFunc('strictLookup', "$expr, " . self::quote($part) . ", $escapedOriginal");
+                $escapedKey = self::quote($part);
+                $expr = self::getRuntimeFunc('strictLookup', "$expr, $escapedKey, $escapedOriginal");
             }
             return $expr;
         }
@@ -709,19 +710,17 @@ private function getLiteralKeyName(Literal $literal): string
     }
 
     /**
-     * Find the $cx->blParam index for a block param name, or null if not a block param.
-     * Iterates blockParamValues from innermost to outermost; only non-empty levels
-     * increment the runtime blParam index.
+     * Return [$depth, $index] if $name is a block param in any enclosing scope, null otherwise.
+     * $depth=0 is the innermost scope; each outer scope increments $depth.
+     * @return array{int,int}|null
      */
-    private function lookupBlockParam(string $name): ?int
+    private function lookupBlockParam(string $name): ?array
     {
-        $blParamIndex = 0;
-        foreach ($this->blockParamValues as $levelParams) {
-            if (in_array($name, $levelParams, true)) {
-                return $blParamIndex;
-            }
-            if ($levelParams) {
-                $blParamIndex++;
+        foreach ($this->blockParamValues as $depth => $levelParams) {
+            $index = array_search($name, $levelParams, true);
+            if ($index !== false) {
+                assert(is_int($index));
+                return [$depth, $index];
             }
         }
         return null;
@@ -769,8 +768,8 @@ private function resolvePartial(string &$name): ?string
         if (isset($this->context->partials[$name])) {
             return $this->context->partials[$name];
         }
-        if ($this->context->partialResolver) {
-            return ($this->context->partialResolver)($this->context, $name);
+        if ($this->context->options->partialResolver) {
+            return ($this->context->options->partialResolver)($name);
         }
         return null;
     }
@@ -789,8 +788,7 @@ private function compilePartialTemplate(string $name, string $template): void
         $code = (new Compiler($this->parser))->compile($program, $tmpContext);
         $this->context->merge($tmpContext);
 
-        $func = "function (\$cx, \$in) {return '$code';}";
-        $this->context->partialCode[$name] = self::quote($name) . " => $func";
+        $this->context->partialCode[$name] = self::quote($name) . ' => ' . self::templateClosure($code);
     }
 
     public function handleDynamicPartials(): void
@@ -807,12 +805,12 @@ public function handleDynamicPartials(): void
     // ── Helpers ──────────────────────────────────────────────────────
 
     /**
-     * Build the [[positional],[named]] or [[positional],[named],[blockParams]] param format.
+     * Build the positional and named param components as separate arguments.
+     * Returns '[$a,$b], [hash]'.
      *
      * @param Expression[] $params
-     * @param string[]|null $blockParams
      */
-    private function compileParams(array $params, ?Hash $hash, ?array $blockParams = null): string
+    private function compileParams(array $params, ?Hash $hash): string
     {
         $savedHelperArgs = $this->compilingHelperArgs;
         $this->compilingHelperArgs = true;
@@ -825,12 +823,11 @@ private function compileParams(array $params, ?Hash $hash, ?array $blockParams =
         $named = $hash ? $this->Hash($hash) : '';
         $this->compilingHelperArgs = $savedHelperArgs;
 
-        $bp = $blockParams ? ',' . self::listString($blockParams) : '';
-        return '[[' . implode(',', $positional) . '],[' . $named . "]$bp]";
+        return '[' . implode(',', $positional) . '], [' . $named . ']';
     }
 
     /**
-     * Build params for partial calls: [[$context],[named]].
+     * Build context and hash arguments for partial calls: "$context, [named]".
      *
      * @param Expression[] $params
      */
@@ -844,7 +841,7 @@ private function compilePartialParams(array $params, ?Hash $hash): string
 
         $named = $hash ? $this->Hash($hash) : '';
 
-        return "[[$contextVar],[$named]]";
+        return "$contextVar, [$named]";
     }
 
     /**
@@ -876,29 +873,15 @@ private function getSimpleHelperName(PathExpression|Literal $path): ?string
     }
 
     /**
-     * Compile the else/inverse clause of a block as a trailing closure argument, or '' if absent.
+     * Compile the else/inverse clause of a block as a trailing closure argument, or 'null' if absent.
      */
     private function compileElseClause(BlockStatement $block): string
     {
-        return $block->inverse
-            ? ", function(\$cx, \$in) {return " . $this->compileProgram($block->inverse) . ";}"
-            : ', null';
-    }
-
-    /**
-     * Compile a block program, pushing/popping block params around the compilation.
-     * @param string[] $bp
-     */
-    private function compileProgramWithBlockParams(Program $program, array $bp): string
-    {
-        if ($bp) {
-            array_unshift($this->blockParamValues, $bp);
-        }
-        $body = $this->compileProgram($program);
-        if ($bp) {
-            array_shift($this->blockParamValues);
+        if (!$block->inverse) {
+            $this->lastCompileProgramHadDirectBpRef = false;
+            return 'null';
         }
-        return $body;
+        return $this->compileProgramWithBlockParams($block->inverse);
     }
 
     /**
@@ -906,11 +889,11 @@ private function compileProgramWithBlockParams(Program $program, array $bp): str
      */
     private function buildBasePath(bool $data, int $depth): string
     {
-        $base = $data ? '$cx->data' : '$in';
+        $base = $data ? '$cx->frame' : '$in';
         if ($depth > 0) {
             $base = $data
                 ? $base . str_repeat("['_parent']", $depth)
-                : "\$cx->scopes[count(\$cx->scopes)-$depth]";
+                : "\$cx->depths[count(\$cx->depths)-$depth]";
         }
         return $base;
     }
@@ -937,23 +920,30 @@ private static function getRuntimeFunc(string $name, string $args): string
         return "LR::$name($args)";
     }
 
-    private static function escape(string $string): string
+    /**
+     * @param bool $declaresBp  true when this closure receives new block param values as its third argument
+     * @param bool $inheritsBp  true when this closure must capture $blockParams from the enclosing scope
+     */
+    private static function blockClosure(string $body, bool $declaresBp = false, bool $inheritsBp = false): string
     {
-        return addcslashes($string, "'\\");
+        $preamble = '';
+        if (str_contains($body, '$cx->depths[count($cx->depths)-')) {
+            $preamble = '$sc=count($cx->depths);';
+            $body = str_replace('$cx->depths[count($cx->depths)-', '$cx->depths[$sc-', $body);
+        }
+        if ($declaresBp) {
+            return "function(\$cx, \$in, array \$blockParams = []) {{$preamble}return $body;}";
+        }
+        if ($inheritsBp) {
+            // Inherits block params from the enclosing closure's $blockParams variable.
+            return "function(\$cx, \$in) use (\$blockParams) {{$preamble}return $body;}";
+        }
+        return "function(\$cx, \$in) {{$preamble}return $body;}";
     }
 
     private static function quote(string $string): string
     {
-        return "'" . self::escape($string) . "'";
-    }
-
-    /**
-     * Get string presentation for a string list
-     * @param string[] $list
-     */
-    private static function listString(array $list): string
-    {
-        return '[' . implode(',', array_map(self::quote(...), $list)) . ']';
+        return "'" . addcslashes($string, "'\\") . "'";
     }
 
     private function missValue(string $key): string
@@ -963,99 +953,44 @@ private function missValue(string $key): string
             : 'null';
     }
 
-    /** @return array{string[], string} [$bp, $bs] */
-    private function getProgramBlockParams(?Program $program): array
-    {
-        $bp = $program ? $program->blockParams : [];
-        $bs = self::listString($bp);
-        return [$bp, $bs];
-    }
-
     private function compileProgramOrEmpty(?Program $program): string
     {
-        return $program ? $this->compileProgram($program) : "''";
+        if (!$program) {
+            $this->lastCompileProgramHadDirectBpRef = false;
+            return "''";
+        }
+        return $this->compileProgram($program);
     }
 
-    /**
-     * Return only the string parts of a mixed parts array, re-indexed.
-     * @param array<string|SubExpression> $parts
-     * @return list<string>
-     */
-    private static function stringPartsOf(array $parts): array
+    private function throwKnownHelpersOnly(string $helperName): never
     {
-        return array_values(array_filter($parts, fn($p) => is_string($p)));
+        throw new \Exception("You specified knownHelpersOnly, but used the unknown helper $helperName");
     }
 
     /**
-     * Get includeZero value from hash.
+     * Build an hbch (known) or dynhbch (unknown) inline helper call string.
+     * @param Expression[] $params
      */
-    private function getIncludeZero(?Hash $hash): string
+    private function buildInlineHelperCall(string $name, array $params, ?Hash $hash): string
     {
-        if ($hash) {
-            foreach ($hash->pairs as $pair) {
-                if ($pair->key === 'includeZero') {
-                    return $this->compileExpression($pair->value);
-                }
-            }
+        $compiledParams = $this->compileParams($params, $hash);
+        $helperName = self::quote($name);
+        if ($this->isKnownHelper($name)) {
+            return self::getRuntimeFunc('hbch', "\$cx, \$cx->helpers[$helperName], $helperName, $compiledParams, \$in");
         }
-        return 'false';
-    }
-
-    /**
-     * Compile {{lookup items idx}} in mustache context.
-     */
-    private function compileLookup(MustacheStatement $mustache, bool $raw): string
-    {
-        $fn = $raw ? 'raw' : 'encq';
-
-        if (count($mustache->params) !== 2) {
-            throw new \Exception('{{lookup}} requires 2 arguments');
+        if ($this->context->options->knownHelpersOnly) {
+            $this->throwKnownHelpersOnly($name);
         }
-
-        $itemsExpr = $mustache->params[0];
-        $idxExpr = $mustache->params[1];
-        $varCode = $this->getWithLookup($itemsExpr, $idxExpr);
-
-        return "'." . self::getRuntimeFunc($fn, $varCode) . ".'";
+        return self::getRuntimeFunc('dynhbch', "\$cx, $helperName, $compiledParams, \$in");
     }
 
     /**
-     * Compile a path with an additional dynamic lookup segment.
-     */
-    private function compilePathWithLookup(PathExpression $path, string $lookupCode): string
-    {
-        $data = $path->data;
-        $depth = $path->depth;
-        $parts = self::stringPartsOf($path->parts);
-
-        $base = $this->buildBasePath($data, $depth);
-        $n = self::buildKeyAccess($parts);
-
-        $miss = $this->missValue($path->original);
-
-        return $base . $n . "[$lookupCode] ?? $miss";
-    }
-
-    /**
-     * Compile {{log ...}} built-in.
+     * Return only the string parts of a mixed parts array, re-indexed.
+     * @param array<string|SubExpression> $parts
+     * @return list<string>
      */
-    private function compileLog(MustacheStatement $mustache): string
-    {
-        $params = $this->compileParams($mustache->params, $mustache->hash);
-        return "'." . self::getRuntimeFunc('lo', $params) . ".'";
-    }
-
-    private function getWithLookup(Expression $itemsExpr, Expression $idxExpr): string
+    private static function stringPartsOf(array $parts): array
     {
-        $idxCode = $this->compileExpression($idxExpr);
-
-        if ($itemsExpr instanceof PathExpression) {
-            $varCode = $this->compilePathWithLookup($itemsExpr, $idxCode);
-        } else {
-            $itemsCode = $this->compileExpression($itemsExpr);
-            $miss = $this->missValue('lookup');
-            $varCode = $itemsCode . "[$idxCode] ?? $miss";
-        }
-        return $varCode;
+        return array_values(array_filter($parts, fn($p) => is_string($p)));
     }
 }
diff --git a/src/Context.php b/src/Context.php
index f9ba8b1..9b9fd4b 100644
--- a/src/Context.php
+++ b/src/Context.php
@@ -2,8 +2,6 @@
 
 namespace DevTheorem\Handlebars;
 
-use Closure;
-
 /**
  * @internal
  */
@@ -12,12 +10,9 @@ final class Context
     /**
      * @param array<string, string> $usedPartial
      * @param array<string, string> $partialCode
-     * @param array<string, true> $usedHelpers
      * @param array<string, string> $partials
-     * @param null|Closure(Context, string):(string|null) $partialResolver
      * @param array<mixed> $partialBlock
      * @param array<mixed> $inlinePartial
-     * @param array<string, callable> $helpers
      */
     public function __construct(
         public readonly Options $options,
@@ -26,27 +21,20 @@ public function __construct(
         public int $usedDynPartial = 0,
         public int $usedPBlock = 0,
         public int $partialBlockId = 0,
-        public array $usedHelpers = [],
         public array $partials = [],
-        public ?Closure $partialResolver = null,
         public array $partialBlock = [],
         public array $inlinePartial = [],
-        public array $helpers = [],
     ) {
         $this->partials = $options->partials;
-        $this->partialResolver = $options->partialResolver;
-        $this->helpers = $options->helpers;
     }
 
     /**
      * Update from another context.
      */
-    public function merge(Context $context): void
+    public function merge(self $context): void
     {
-        $this->helpers = $context->helpers;
         $this->partials = $context->partials;
         $this->partialCode = $context->partialCode;
-        $this->usedHelpers = $context->usedHelpers;
         $this->usedDynPartial = $context->usedDynPartial;
         $this->usedPBlock = $context->usedPBlock;
         $this->partialBlockId = $context->partialBlockId;
diff --git a/src/Exporter.php b/src/Exporter.php
deleted file mode 100644
index 93acbe1..0000000
--- a/src/Exporter.php
+++ /dev/null
@@ -1,96 +0,0 @@
-<?php
-
-namespace DevTheorem\Handlebars;
-
-/**
- * @internal
- */
-final class Exporter
-{
-    /**
-     * Get PHP code string from a closure of function as string
-     */
-    public static function closure(\Closure $closure): string
-    {
-        $ref = new \ReflectionFunction($closure);
-        return static::getClosureSource($ref);
-    }
-
-    /**
-     * Export required custom helper functions
-     */
-    public static function helpers(Context $context): string
-    {
-        $ret = '';
-        foreach ($context->helpers as $name => $func) {
-            if (!isset($context->usedHelpers[$name])) {
-                continue;
-            }
-            if ($func instanceof \Closure) {
-                $ret .= ("            '$name' => " . static::closure($func) . ",\n");
-                continue;
-            }
-            if (is_string($func)) {
-                $ret .= "            '$name' => '$func',\n";
-            } else {
-                throw new \Exception('Unexpected helper type: ' . gettype($func));
-            }
-        }
-
-        return "[$ret]";
-    }
-
-    public static function getClosureSource(\ReflectionFunction $fn): string
-    {
-        $filename = $fn->getFileName();
-        if ($filename === false) {
-            throw new \Exception("Failed to get file for closure");
-        }
-        $fileContents = file_get_contents($filename);
-        if ($fileContents === false) {
-            throw new \Exception("Unable to read file: $filename");
-        }
-        $startLine = $fn->getStartLine();
-        $endLine = $fn->getEndLine();
-        $enteredFnToken = null;
-        $depth = 0;
-        $code = '';
-
-        foreach (\PhpToken::tokenize($fileContents) as $token) {
-            if ($token->line < $startLine) {
-                continue;
-            } elseif ($token->line > $endLine) {
-                break;
-            } elseif (!$enteredFnToken) {
-                if ($token->id !== T_FUNCTION && $token->id !== T_FN) {
-                    continue;
-                }
-                $enteredFnToken = $token;
-            }
-
-            $name = $token->getTokenName();
-
-            if (in_array($name, ['(', '[', '{', 'T_CURLY_OPEN'])) {
-                $depth++;
-            } elseif (in_array($name, [')', ']', '}'])) {
-                if ($depth === 0 && $enteredFnToken->id === T_FN) {
-                    return rtrim($code);
-                }
-                $depth--;
-            }
-
-            if ($depth === 0) {
-                if ($enteredFnToken->id === T_FUNCTION && $name === '}') {
-                    $code .= $token->text;
-                    return $code;
-                } elseif ($enteredFnToken->id === T_FN && in_array($name, [';', ','])) {
-                    return $code;
-                }
-            }
-
-            $code .= $token->text;
-        }
-
-        return $code;
-    }
-}
diff --git a/src/Handlebars.php b/src/Handlebars.php
index eb2bbcc..38cdc43 100644
--- a/src/Handlebars.php
+++ b/src/Handlebars.php
@@ -4,11 +4,15 @@
 
 use DevTheorem\HandlebarsParser\ParserFactory;
 
+/**
+ * @phpstan-type RenderOptions array{data?: array<mixed>, helpers?: array<string, \Closure>, partials?: array<string, \Closure>}
+ * @phpstan-type Template \Closure(mixed=, RenderOptions=): string
+ */
 final class Handlebars
 {
     /**
      * Compiles a template so it can be executed immediately.
-     * @return \Closure(mixed=, array<mixed>=):string
+     * @return Template
      */
     public static function compile(string $template, Options $options = new Options()): \Closure
     {
@@ -33,6 +37,7 @@ public static function precompile(string $template, Options $options = new Optio
 
     /**
      * Sets up a template that was precompiled with precompile().
+     * @return Template
      */
     public static function template(string $templateSpec): \Closure
     {
diff --git a/src/HelperOptions.php b/src/HelperOptions.php
index 2796ae7..075b6b2 100644
--- a/src/HelperOptions.php
+++ b/src/HelperOptions.php
@@ -2,29 +2,171 @@
 
 namespace DevTheorem\Handlebars;
 
+use Closure;
+
+/** @internal */
+enum Scope
+{
+    /** Sentinel default for fn()/inverse() meaning "use the current scope unchanged". */
+    case Use;
+}
+
 class HelperOptions
 {
     /**
-     * @param array<mixed> $hash
      * @param array<mixed> $data
+     * @param array<mixed> $hash
+     * @param array<mixed> $outerBlockParams outer block param stack, passed as trailing elements of the stack
      */
     public function __construct(
-        public readonly string $name,
-        public readonly array $hash,
-        public readonly \Closure $fn,
-        public readonly \Closure $inverse,
-        public readonly int $blockParams,
         public mixed &$scope,
         public array &$data,
+        public readonly string $name = '',
+        public readonly array $hash = [],
+        public readonly int $blockParams = 0,
+        private readonly ?RuntimeContext $cx = null,
+        private readonly ?Closure $cb = null,
+        private readonly ?Closure $inv = null,
+        private readonly array $outerBlockParams = [],
     ) {}
 
-    public function fn(mixed ...$args): string
+    /**
+     * Allows isset($options->fn) and isset($options->inverse) to check whether the block exists.
+     */
+    public function __isset(string $name): bool
+    {
+        if ($name === 'fn') {
+            return $this->cb !== null;
+        } elseif ($name === 'inverse') {
+            return $this->inv !== null;
+        }
+        return false;
+    }
+
+    public function fn(mixed $context = Scope::Use, mixed $data = null): string
+    {
+        if ($this->cx === null) {
+            throw new \Exception('fn() is not supported for inline helpers');
+        } elseif ($this->cb === null) {
+            return '';
+        }
+        $cx = $this->cx;
+        $scope = $this->scope;
+
+        // Save partials so that any {{#* inline}} partials registered inside the block body
+        // don't leak out after fn() returns. The spec requires inline partials to be
+        // block-scoped. PHP copy-on-write makes this assignment cheap when no inline partials are registered.
+        $savedPartials = $cx->partials;
+
+        // Skip depths push for explicit same-context pass (equivalent to HBS.js options.fn(this))
+        $skipDepths = $context === $scope;
+        $resolvedContext = $skipDepths ? $scope : ($context === Scope::Use ? $scope : $context);
+        $ret = $this->callBlock($this->cb, $resolvedContext, !$skipDepths, $data);
+
+        $cx->partials = $savedPartials;
+        return $ret;
+    }
+
+    public function inverse(mixed $context = null, mixed $data = null): string
     {
-        return ($this->fn)(...$args);
+        if ($this->cx === null) {
+            throw new \Exception('inverse() is not supported for inline helpers');
+        } elseif ($this->inv === null) {
+            return '';
+        }
+        return $this->callBlock($this->inv, $context ?? $this->scope, $context !== null, $data);
     }
 
-    public function inverse(mixed ...$args): string
+    /** @param array<mixed>|null $data */
+    private function callBlock(\Closure $closure, mixed $context, bool $pushDepths, ?array $data): string
     {
-        return ($this->inverse)(...$args);
+        $cx = $this->cx;
+        assert($cx !== null);
+        $savedFrame = null;
+        $bpStack = null;
+
+        if (isset($data['data'])) {
+            $savedFrame = $cx->frame;
+            // Fast path: only root in frame, no user @-data to inherit
+            $newFrame = count($savedFrame) === 1 ? $data['data'] : array_replace($savedFrame, $data['data']);
+            $newFrame['root'] = &$cx->data['root'];
+            $newFrame['_parent'] = $savedFrame;
+            $cx->frame = $newFrame;
+        }
+
+        if (isset($data['blockParams'])) {
+            // Build block params stack: current level prepended to outer stack.
+            $bpStack = [$data['blockParams'], ...$this->outerBlockParams];
+        }
+
+        if ($pushDepths) {
+            // Push the current scope onto depths so that ../ path expressions inside the block
+            // body can traverse back up to the caller's context.
+            $cx->depths[] = $this->scope;
+        }
+        $ret = $closure($cx, $context, $bpStack);
+        if ($pushDepths) {
+            array_pop($cx->depths);
+        }
+        if ($savedFrame !== null) {
+            $cx->frame = $savedFrame;
+        }
+        return $ret;
+    }
+
+    /**
+     * Optimized iteration for each-like helpers: performs depths push and partials save/restore
+     * once around the entire loop rather than once per fn() call.
+     *
+     * HBS.js achieves the same effect by capturing the depths array at sub-program creation time
+     * (before the loop), so all iterations share the same static depths reference.
+     *
+     * @param array<mixed> $items
+     * @internal
+     */
+    public function iterate(array $items): string
+    {
+        if (!$items) {
+            return $this->inverse();
+        }
+        if ($this->cb === null) {
+            return '';
+        }
+        $cx = $this->cx;
+        assert($cx !== null);
+        $cb = $this->cb;
+
+        // Push depths and save partials once for the entire loop.
+        $cx->depths[] = $this->scope;
+        $savedPartials = $cx->partials;
+
+        $last = count($items) - 1;
+        $ret = '';
+        $i = 0;
+        $outerFrame = $cx->frame;
+        // Fast path: when only root is in the frame, skip array_replace.
+        $simpleFrame = count($outerFrame) === 1;
+        // Pre-allocate bpStack once; mutate [0][0] and [0][1] per iteration.
+        // PHP COW ensures the inner array's refcount returns to 1 after $cb() returns,
+        // so the next iteration's assignment is an in-place mutation, not a copy.
+        $bpStack = [[null, null], ...$this->outerBlockParams];
+
+        foreach ($items as $index => $value) {
+            $iterData = ['key' => $index, 'index' => $i, 'first' => $i === 0, 'last' => $i === $last];
+            $newFrame = $simpleFrame ? $iterData : array_replace($outerFrame, $iterData);
+            $newFrame['root'] = &$cx->data['root'];
+            $newFrame['_parent'] = $outerFrame;
+            $cx->frame = $newFrame;
+
+            $bpStack[0][0] = $value;
+            $bpStack[0][1] = $index;
+            $ret .= $cb($cx, $value, $bpStack);
+            $i++;
+        }
+
+        $cx->frame = $outerFrame;
+        array_pop($cx->depths);
+        $cx->partials = $savedPartials;
+        return $ret;
     }
 }
diff --git a/src/Options.php b/src/Options.php
index 317a0ea..e89d428 100644
--- a/src/Options.php
+++ b/src/Options.php
@@ -6,12 +6,16 @@
 
 readonly class Options
 {
+    /** @var array<string, bool> */
+    public array $knownHelpers;
+
     /**
-     * @param array<string, callable> $helpers
+     * @param array<string, bool> $knownHelpers
      * @param array<string, string> $partials
-     * @param null|Closure(Context, string):(string|null) $partialResolver
+     * @param null|Closure(string):(string|null) $partialResolver
      */
     public function __construct(
+        array $knownHelpers = [],
         public bool $knownHelpersOnly = false,
         public bool $noEscape = false,
         public bool $strict = false,
@@ -19,8 +23,10 @@ public function __construct(
         public bool $preventIndent = false,
         public bool $ignoreStandalone = false,
         public bool $explicitPartialContext = false,
-        public array $helpers = [],
         public array $partials = [],
         public ?Closure $partialResolver = null,
-    ) {}
+    ) {
+        $builtIn = ['if' => true, 'unless' => true, 'each' => true, 'with' => true, 'lookup' => true, 'log' => true];
+        $this->knownHelpers = array_replace($builtIn, $knownHelpers);
+    }
 }
diff --git a/src/Runtime.php b/src/Runtime.php
index 18ba789..bb890b9 100644
--- a/src/Runtime.php
+++ b/src/Runtime.php
@@ -6,9 +6,111 @@
 
 /**
  * @internal
+ * @phpstan-import-type RenderOptions from Handlebars
  */
 final class Runtime
 {
+    /** @var array<string, \Closure>|null */
+    private static ?array $defaultHelpers = null;
+    /** Parent RuntimeContext during a user-partial invocation, null at top level. */
+    private static ?RuntimeContext $partialContext = null;
+
+    /**
+     * Default implementations of the built-in Handlebars helpers.
+     * These are pre-registered in every runtime context and can be overridden.
+     *
+     * @return array<string, \Closure>
+     */
+    public static function defaultHelpers(): array
+    {
+        return self::$defaultHelpers ??= [
+            'if' => static function (mixed ...$args): string {
+                if (count($args) !== 2) {
+                    throw new \Exception('#if requires exactly one argument');
+                }
+                /** @var HelperOptions $options */
+                $options = $args[1];
+                $condition = $args[0] instanceof \Closure ? $args[0]($options->scope) : $args[0];
+                return static::ifvar($condition, (bool) ($options->hash['includeZero'] ?? false))
+                    ? $options->fn($options->scope)
+                    : $options->inverse();
+            },
+            'unless' => static function (mixed ...$args): string {
+                if (count($args) !== 2) {
+                    throw new \Exception('#unless requires exactly one argument');
+                }
+                /** @var HelperOptions $options */
+                $options = $args[1];
+                $condition = $args[0] instanceof \Closure ? $args[0]($options->scope) : $args[0];
+                return static::ifvar($condition, (bool) ($options->hash['includeZero'] ?? false))
+                    ? $options->inverse()
+                    : $options->fn($options->scope);
+            },
+            'each' => static function (mixed $context, ?HelperOptions $options = null): string {
+                if (!$options) {
+                    throw new \Exception('Must pass iterator to #each');
+                }
+                if ($context instanceof \Closure) {
+                    $context = $context($options->scope);
+                }
+                if ($context instanceof \Traversable) {
+                    $context = iterator_to_array($context);
+                } elseif (!is_array($context)) {
+                    $context = [];
+                }
+                return $options->iterate($context);
+            },
+            'with' => static function (mixed ...$args): string {
+                if (count($args) !== 2) {
+                    throw new \Exception('#with requires exactly one argument');
+                }
+                /** @var HelperOptions $options */
+                $options = $args[1];
+                $context = $args[0] instanceof \Closure ? $args[0]($options->scope) : $args[0];
+                if (static::ifvar($context)) {
+                    return $options->fn($context, ['blockParams' => [$context]]);
+                }
+                return $options->inverse();
+            },
+            'lookup' => static function (mixed $obj, string|int $key): mixed {
+                if (is_array($obj)) {
+                    return $obj[$key] ?? null;
+                }
+                if (is_object($obj)) {
+                    return $obj->$key ?? null;
+                }
+                return null;
+            },
+            'log' => static function (mixed ...$args): string {
+                array_pop($args); // remove HelperOptions
+                error_log(var_export($args, true));
+                return '';
+            },
+            'helperMissing' => static function (mixed ...$args): mixed {
+                /** @var HelperOptions $options */
+                $options = end($args);
+                if (count($args) === 1 && !isset($options->fn)) {
+                    // Bare variable lookup with no match — return null (mirrors HBS.js undefined).
+                    return null;
+                }
+                throw new \Exception('Missing helper: "' . $options->name . '"');
+            },
+            'blockHelperMissing' => static function (mixed $context, HelperOptions $options): string {
+                if ($context instanceof \Traversable) {
+                    $context = iterator_to_array($context);
+                }
+                if (is_array($context)) {
+                    return array_is_list($context) ? $options->iterate($context) : $options->fn($context);
+                }
+                if ($context === false || $context === null) {
+                    return $options->inverse();
+                }
+                // true renders with the outer scope unchanged; any other truthy value becomes the new scope.
+                return $options->fn($context === true ? $options->scope : $context);
+            },
+        ];
+    }
+
     /**
      * Throw exception for missing expression. Only used in strict mode.
      */
@@ -29,6 +131,41 @@ public static function strictLookup(mixed $base, string $key, string $original):
         return $base[$key];
     }
 
+    /**
+     * Build a RuntimeContext from raw render options and compile-time partial closures.
+     *
+     * @param RenderOptions $options
+     * @param array<string, \Closure> $compiledPartials
+     */
+    public static function createContext(mixed $context, array $options, array $compiledPartials): RuntimeContext
+    {
+        $parentCx = self::$partialContext;
+        $root = ['root' => $context];
+
+        if ($parentCx !== null) {
+            // Partial context: reuse the parent's already-merged helpers and partials directly.
+            // PHP copy-on-write ensures partials is only copied if in() registers a new inline partial.
+            // Inherit the parent's current frame so @index, @key, etc. remain accessible inside partials.
+            // templateClosure will update frame['root'] to reference this partial's own data['root'].
+            return new RuntimeContext(
+                helpers: $parentCx->helpers,
+                partials: $parentCx->partials,
+                depths: $parentCx->depths,
+                data: $root,
+                partialId: $parentCx->partialId,
+                frame: $parentCx->frame,
+            );
+        }
+
+        $data = $options['data'] ?? [];
+        return new RuntimeContext(
+            helpers: array_replace(Runtime::defaultHelpers(), $options['helpers'] ?? []),
+            partials: array_replace($compiledPartials, $options['partials'] ?? []),
+            data: ['root' => $data['root'] ?? $context],
+            frame: $data,
+        );
+    }
+
     /**
      * Invoke $v if it is callable, passing any extra args; otherwise return $v as-is.
      * Used for data variables that may hold functions (e.g. {{@hello}} or {{@hello "arg"}}).
@@ -39,13 +176,34 @@ public static function dv(mixed $v, mixed ...$args): mixed
     }
 
     /**
-     * For {{log}}.
-     * @param array<mixed> $v
+     * Context variable lookup for knownHelpersOnly mode.
+     * Looks up $name in $_this; if the value is a Closure, invokes it with $_this as context.
+     * Skips helper dispatch (the compiler has already ruled out known helpers).
+     *
+     * @param mixed $_this current rendering context
      */
-    public static function lo(array $v): string
+    public static function cv(mixed &$_this, string $name): mixed
     {
-        error_log(var_export($v[0], true));
-        return '';
+        $v = is_array($_this) ? ($_this[$name] ?? null) : null;
+        return $v instanceof \Closure ? $v($_this) : $v;
+    }
+
+    /**
+     * Helper-or-variable lookup for bare {{identifier}} expressions.
+     * Checks runtime helpers first, then context value, then helperMissing fallback.
+     *
+     * @param mixed $_this current rendering context
+     */
+    public static function hv(RuntimeContext $cx, string $name, mixed &$_this): mixed
+    {
+        $helper = $cx->helpers[$name] ?? null;
+        if ($helper !== null) {
+            return static::hbch($cx, $helper, $name, [], [], $_this);
+        }
+        if (is_array($_this) && array_key_exists($name, $_this)) {
+            return static::dv($_this[$name]);
+        }
+        return static::hbch($cx, $cx->helpers['helperMissing'], $name, [], [], $_this);
     }
 
     /**
@@ -67,7 +225,7 @@ public static function ifvar(mixed $v, bool $zero = false): bool
     }
 
     /**
-     * For {{^var}} .
+     * Returns true if an inverse block {{^var}} should be rendered.
      *
      * @param array<array<mixed>|string|int>|string|int|bool|null $v value to be tested
      *
@@ -78,6 +236,17 @@ public static function isec(mixed $v): bool
         return $v === null || $v === false || (is_array($v) && !$v);
     }
 
+    /**
+     * Inverted section with runtime helper check.
+     */
+    public static function isech(RuntimeContext $cx, mixed $v, mixed $in, \Closure $else, string $helperName): string
+    {
+        if (isset($cx->helpers[$helperName])) {
+            return static::hbbch($cx, $cx->helpers[$helperName], $helperName, [], [], $in, null, $else);
+        }
+        return static::hbbch($cx, $cx->helpers['blockHelperMissing'], $helperName, [$v], [], $in, null, $else);
+    }
+
     /**
      * HTML encode {{var}} just like handlebars.js
      *
@@ -97,7 +266,7 @@ public static function encq($var): string
      *
      * @param array<mixed>|string|StringObject|int|bool|null $v value to be output
      */
-    public static function raw(array|string|StringObject|int|bool|null $v): string
+    public static function raw(array|string|StringObject|int|float|bool|null $v): string
     {
         if ($v === true) {
             return 'true';
@@ -123,161 +292,32 @@ public static function raw(array|string|StringObject|int|bool|null $v): string
     }
 
     /**
-     * For {{#var}} or {{#each}} .
+     * For {{#var}} sections.
      *
-     * @param array<array<mixed>|string|int>|string|int|bool|null|\Closure|\Traversable<string, mixed> $v value for the section
-     * @param array<string> $bp block parameters
-     * @param array<array<mixed>|string|int>|string|int|null $in input data with current scope
-     * @param bool $each true when rendering #each
+     * @param mixed $in input data with current scope
      * @param \Closure $cb callback function to render child context
      * @param \Closure|null $else callback function to render child context when {{else}}
      */
-    public static function sec(RuntimeContext $cx, mixed $v, array $bp, mixed $in, bool $each, \Closure $cb, ?\Closure $else = null): string
+    public static function sec(RuntimeContext $cx, mixed $value, mixed $in, \Closure $cb, ?\Closure $else = null, ?string $helperName = null): string
     {
-        if ($else !== null && (is_array($v) || $v instanceof \ArrayObject)) {
-            return $else($cx, $in);
-        }
-
-        $push = $in !== $v || $each;
-        $isAry = is_array($v) || $v instanceof \ArrayObject;
-        $isTrav = $v instanceof \Traversable;
-        $loop = $each || (is_array($v) && array_is_list($v));
-
-        if (($loop && $isAry || $isTrav) && is_iterable($v)) {
-            $last = null;
-            $isObj = false;
-            $isSparseArray = false;
-            if (is_array($v)) {
-                $keys = array_keys($v);
-                $last = count($keys) - 1;
-                $isObj = !array_is_list($v);
-                $isSparseArray = $isObj && !array_filter($keys, is_string(...));
-            }
-            $ret = [];
-            $cx = clone $cx;
-            if ($push) {
-                $cx->scopes[] = $in;
-            }
-            $i = 0;
-            $oldData = $cx->data ?? [];
-            $cx->data = array_merge(['root' => $oldData['root'] ?? null], $oldData, ['_parent' => $oldData]);
-
-            foreach ($v as $index => $raw) {
-                $cx->data['first'] = ($i === 0);
-                $cx->data['last'] = ($i === $last);
-                $cx->data['key'] = $index;
-                $cx->data['index'] = $isSparseArray ? $index : $i;
-                $i++;
-                if ($bp) {
-                    $bpEntry = [];
-                    if (isset($bp[0])) {
-                        $bpEntry[$bp[0]] = $raw;
-                        $raw = static::merge($raw, [$bp[0] => $raw]);
-                    }
-                    if (isset($bp[1])) {
-                        $bpEntry[$bp[1]] = $index;
-                        $raw = static::merge($raw, [$bp[1] => $index]);
-                    }
-                    array_unshift($cx->blParam, $bpEntry);
-                }
-                $ret[] = $cb($cx, $raw);
-                if ($bp) {
-                    array_shift($cx->blParam);
-                }
-            }
-
-            if ($isObj) {
-                unset($cx->data['key']);
-            } else {
-                unset($cx->data['last']);
-            }
-            unset($cx->data['index'], $cx->data['first']);
-
-            if ($push) {
-                array_pop($cx->scopes);
-            }
-            return join('', $ret);
+        if ($helperName !== null && isset($cx->helpers[$helperName])) {
+            return static::hbbch($cx, $cx->helpers[$helperName], $helperName, [], [], $in, $cb, $else);
         }
 
-        if ($each) {
-            return ($else !== null) ? $else($cx, $in) : '';
-        }
-
-        if ($isAry) {
-            if ($push) {
-                $cx->scopes[] = $in;
-            }
-            $ret = $cb($cx, $v);
-            if ($push) {
-                array_pop($cx->scopes);
-            }
-            return $ret;
-        }
-
-        if ($v instanceof \Closure) {
-            $options = new HelperOptions(
-                name: '',
-                hash: [],
-                fn: function ($context = null) use ($cx, $in, $cb) {
-                    if ($context === null || $context === $in) {
-                        return $cb($cx, $in);
-                    }
-                    return static::withScope($cx, $in, $context, $cb);
-                },
-                inverse: function ($context = null) use ($cx, $in, $else) {
-                    if ($else === null) {
-                        return '';
-                    }
-                    if ($context === null || $context === $in) {
-                        return $else($cx, $in);
-                    }
-                    return static::withScope($cx, $in, $context, $else);
-                },
-                blockParams: 0,
+        // Lambda functions in block position receive HelperOptions directly.
+        // This must be checked before blockHelperMissing routing.
+        if ($value instanceof \Closure) {
+            $result = $value(new HelperOptions(
                 scope: $in,
-                data: $cx->data,
-            );
-            $result = $v($options);
-            return static::applyBlockHelperMissing($cx, $result, $in, $cb, $else);
-        }
-
-        if ($v !== null && $v !== false) {
-            return $cb($cx, $v === true ? $in : $v);
+                data: $cx->frame,
+                cx: $cx,
+                cb: $cb,
+                inv: $else,
+            ));
+            return static::resolveBlockResult($cx, $result, $in, $cb, $else);
         }
 
-        return $else !== null ? $else($cx, $in) : '';
-    }
-
-    /**
-     * For {{#with}} .
-     *
-     * @param array<array<mixed>|string|int>|string|int|null $v value to be the new context
-     * @param array<string> $bp block parameters
-     * @param array<array<mixed>|string|int>|\stdClass|null $in input data with current scope
-     * @param \Closure $cb callback function to render child context
-     * @param \Closure|null $else callback function to render child context when {{else}}
-     */
-    public static function wi(RuntimeContext $cx, mixed $v, array $bp, array|\stdClass|null $in, \Closure $cb, ?\Closure $else = null): string
-    {
-        if (isset($bp[0])) {
-            $v = static::merge($v, [$bp[0] => $v]);
-        }
-
-        if ($v === null || is_array($v) && !$v) {
-            return $else ? $else($cx, $in) : '';
-        }
-
-        $savedPartials = $cx->partials;
-
-        if ($v === $in) {
-            $ret = $cb($cx, $v);
-        } else {
-            $ret = static::withScope($cx, $in, $v, $cb);
-        }
-
-        $cx->partials = $savedPartials;
-
-        return $ret;
+        return static::hbbch($cx, $cx->helpers['blockHelperMissing'], $helperName ?? '', [$value], [], $in, $cb, $else);
     }
 
     /**
@@ -310,22 +350,31 @@ public static function merge(mixed $a, mixed $b): mixed
     /**
      * For {{> partial}} .
      *
-     * @param string $p partial name
-     * @param array<array<mixed>> $v value to be the new context
+     * @param string $name partial name
+     * @param mixed $context the partial's context value
+     * @param array<string, mixed> $hash named hash overrides merged into the context
      * @param string $indent whitespace to prepend to each line of the partial's output
      */
-    public static function p(RuntimeContext $cx, string $p, array $v, int $pid, string $indent): string
+    public static function p(RuntimeContext $cx, string $name, mixed $context, array $hash, int $pid, string $indent): string
     {
-        $pp = ($p === '@partial-block') ? $p . ($pid > 0 ? $pid : $cx->partialId) : $p;
+        $pp = ($name === '@partial-block') ? $name . ($pid > 0 ? $pid : $cx->partialId) : $name;
 
-        if (!isset($cx->partials[$pp])) {
-            throw new \Exception("The partial $p could not be found");
+        $fn = $cx->partials[$pp] ?? null;
+        if ($fn === null) {
+            throw new \Exception("The partial $name could not be found");
         }
 
         $savedPartialId = $cx->partialId;
-        $cx->partialId = ($p === '@partial-block') ? ($pid > 0 ? $pid : ($cx->partialId > 0 ? $cx->partialId - 1 : 0)) : $pid;
+        $cx->partialId = ($name === '@partial-block') ? ($pid > 0 ? $pid : ($cx->partialId > 0 ? $cx->partialId - 1 : 0)) : $pid;
 
-        $result = $cx->partials[$pp]($cx, static::merge($v[0][0], $v[1]));
+        $context = $hash ? static::merge($context, $hash) : $context;
+        $prev = self::$partialContext;
+        self::$partialContext = $cx;
+        try {
+            $result = $fn($context);
+        } finally {
+            self::$partialContext = $prev;
+        }
         $cx->partialId = $savedPartialId;
 
         if ($indent !== '') {
@@ -344,217 +393,172 @@ public static function p(RuntimeContext $cx, string $p, array $v, int $pid, stri
         return $result;
     }
 
+    /**
+     * Like in() but only registers the partial if it is not already present in the context.
+     * Used for {{#> partial}}fallback{{/partial}} blocks when the partial was not found at compile time.
+     *
+     * @param string $name partial name
+     * @param \Closure $partial the compiled fallback partial
+     */
+    public static function inFallback(RuntimeContext $cx, string $name, \Closure $partial): string
+    {
+        $cx->partials[$name] ??= $partial;
+        return '';
+    }
+
     /**
      * For {{#* inlinepartial}} .
      *
-     * @param string $p partial name
-     * @param \Closure $code the compiled partial code
+     * @param string $name partial name
+     * @param \Closure $partial the compiled partial
      */
-    public static function in(RuntimeContext $cx, string $p, \Closure $code): void
+    public static function in(RuntimeContext $cx, string $name, \Closure $partial): string
     {
-        if (str_starts_with($p, '@partial-block')) {
+        if (str_starts_with($name, '@partial-block')) {
             // Capture the outer partialId at registration time so that when this
             // block closure runs, any {{>@partial-block}} inside it resolves to
-            // the correct outer partial block (not partialId - 1).
+            // the correct outer partial block rather than following the pid-decrement chain.
             $outerPartialId = $cx->partialId;
-            $cx->partials[$p] = function (RuntimeContext $cx, mixed $in) use ($code, $outerPartialId): string {
-                $cx->partialId = $outerPartialId;
-                return $code($cx, $in);
+            $cx->partials[$name] = function (mixed $context = null, array $options = []) use ($partial, $outerPartialId): string {
+                $callingCx = self::$partialContext;
+                assert($callingCx !== null);
+                $savedId = $callingCx->partialId;
+                $callingCx->partialId = $outerPartialId;
+                $result = $partial($context, $options);
+                $callingCx->partialId = $savedId;
+                return $result;
             };
         } else {
-            $cx->partials[$p] = $code;
+            $cx->partials[$name] = $partial;
         }
+        return '';
     }
 
     /**
-     * For single custom helpers.
-     *
-     * @param string $ch the name of custom helper to be executed
-     * @param array<array<mixed>> $vars variables for the helper
-     * @param array<string,array<mixed>|string|int> $_this current rendering context for the helper
-     * @param string|null $logicalName when set, use as options.name instead of $ch
+     * @param array<mixed> $positional
+     * @param array<string, mixed> $hash
      */
-    public static function hbch(RuntimeContext $cx, string $ch, array $vars, mixed &$_this, ?string $logicalName = null): mixed
+    public static function dynhbch(RuntimeContext $cx, string $name, array $positional, array $hash, mixed &$_this): mixed
     {
-        if (isset($cx->blParam[0][$ch])) {
-            return $cx->blParam[0][$ch];
+        $helper = $cx->helpers[$name] ?? null;
+        if ($helper !== null) {
+            return static::hbch($cx, $helper, $name, $positional, $hash, $_this);
         }
 
-        $options = new HelperOptions(
-            name: $logicalName ?? $ch,
-            hash: $vars[1],
-            fn: fn() => '',
-            inverse: fn() => '',
-            blockParams: 0,
-            scope: $_this,
-            data: $cx->data,
-        );
+        $fn = $_this[$name] ?? null;
+        if ($fn instanceof \Closure) {
+            return static::hbch($cx, $fn, $name, $positional, $hash, $_this);
+        }
+
+        if (!$positional && !$hash) {
+            // No arguments: must be a helper call (e.g. sub-expression), not a property lookup.
+            throw new \Exception('Missing helper: "' . $name . '"');
+        }
 
-        return static::exch($cx, $ch, $vars, $options);
+        return static::hbch($cx, $cx->helpers['helperMissing'], $name, $positional, $hash, $_this);
     }
 
     /**
-     * For block custom helpers.
+     * For single known helpers.
      *
-     * @param string $ch the name of custom helper to be executed
-     * @param array<array<mixed>> $vars variables for the helper
-     * @param array<string,array<mixed>|string|int> $_this current rendering context for the helper
-     * @param bool $inverted the logic will be inverted
-     * @param \Closure $cb callback function to render child context
-     * @param \Closure|null $else callback function to render child context when {{else}}
-     * @param string|null $logicalName when set, use as options.name instead of $ch
+     * @param array<mixed> $positional
+     * @param array<string, mixed> $hash
+     * @param mixed $_this current rendering context for the helper
      */
-    public static function hbbch(RuntimeContext $cx, string $ch, array $vars, mixed &$_this, bool $inverted, \Closure $cb, ?\Closure $else = null, ?string $logicalName = null): mixed
+    public static function hbch(RuntimeContext $cx, \Closure $helper, string $name, array $positional, array $hash, mixed &$_this): mixed
     {
-        $blockParams = isset($vars[2]) ? count($vars[2]) : 0;
-        $data = &$cx->data;
-
-        // invert the logic
-        if ($inverted) {
-            $tmp = $else;
-            $else = $cb;
-            $cb = $tmp;
+        /** @var \WeakMap<\Closure, int>|null $paramCounts */
+        static $paramCounts = null;
+        $paramCounts ??= new \WeakMap();
+
+        $numParams = $paramCounts[$helper] ?? null;
+        if ($numParams === null) {
+            // Cache the number of parameters for the closure so HelperOptions doesn't have to be instantiated
+            // when it isn't used. This can boost runtime performance by 20% for complex templates.
+            $rf = new \ReflectionFunction($helper);
+            $params = $rf->getParameters();
+            $numParams = $params && end($params)->isVariadic() ? 0 : $rf->getNumberOfParameters();
+            $paramCounts[$helper] = $numParams;
+        }
+        if ($numParams === 0 || $numParams > count($positional)) {
+            $positional[] = new HelperOptions(
+                scope: $_this,
+                data: $cx->frame,
+                name: $name,
+                hash: $hash,
+            );
         }
 
-        $options = new HelperOptions(
-            name: $logicalName ?? $ch,
-            hash: $vars[1],
-            fn: static::makeBlockFn($cx, $_this, $cb, $vars),
-            inverse: static::makeInverseFn($cx, $_this, $else),
-            blockParams: $blockParams,
-            scope: $_this,
-            data: $data,
-        );
-
-        return static::applyBlockHelperMissing($cx, static::exch($cx, $ch, $vars, $options), $_this, $cb, $else);
+        return $helper(...$positional);
     }
 
     /**
-     * Like hbbch but for non-registered paths (pathed/depthed/scoped block calls with params).
-     * @param array<array<mixed>> $vars variables for the helper
-     * @param array<string,array<mixed>|string|int> $_this current rendering context for the helper
-     * @param \Closure $cb callback function to render child context
+     * For block custom helpers.
+     *
+     * @param array<mixed> $positional
+     * @param array<string, mixed> $hash
+     * @param mixed $_this current rendering context for the helper
+     * @param \Closure|null $cb callback function to render child context (null for inverted blocks)
      * @param \Closure|null $else callback function to render child context when {{else}}
+     * @param array<mixed> $outerBlockParams outer block param stack for block params declared by the template
      */
-    public static function dynhbbch(RuntimeContext $cx, string $name, mixed $callable, array $vars, mixed &$_this, \Closure $cb, ?\Closure $else = null): mixed
+    public static function hbbch(RuntimeContext $cx, \Closure $helper, string $name, array $positional, array $hash, mixed &$_this, ?\Closure $cb, ?\Closure $else, int $blockParamCount = 0, array $outerBlockParams = []): string
     {
-        if (!$callable instanceof \Closure) {
-            throw new \Exception('"' . $name . '" is not a block helper function');
-        }
-
-        $blockParams = isset($vars[2]) ? count($vars[2]) : 0;
-        $data = &$cx->data;
-
-        $options = new HelperOptions(
-            name: '',
-            hash: $vars[1],
-            fn: static::makeBlockFn($cx, $_this, $cb, $vars),
-            inverse: static::makeInverseFn($cx, $_this, $else),
-            blockParams: $blockParams,
+        $positional[] = new HelperOptions(
             scope: $_this,
-            data: $data,
+            data: $cx->frame,
+            name: $name,
+            hash: $hash,
+            blockParams: $blockParamCount,
+            cx: $cx,
+            cb: $cb,
+            inv: $else,
+            outerBlockParams: $outerBlockParams,
         );
-
-        $args = $vars[0];
-        $args[] = $options;
-        try {
-            $result = $callable(...$args);
-        } catch (\Throwable $e) {
-            throw new \Exception('Runtime: dynamic block helper error: ' . $e->getMessage());
-        }
-
-        return static::applyBlockHelperMissing($cx, $result, $_this, $cb, $else);
+        return static::resolveBlockResult($cx, $helper(...$positional), $_this, $cb, $else);
     }
 
     /**
-     * Build the $fn closure passed to HelperOptions for block helpers.
-     * Handles private variable updates, block-param injection, and context scope pushing.
-     *
-     * @param array<array<mixed>> $vars
+     * Like hbbch but for non-registered paths (pathed/depthed/scoped block calls with params).
+     * @param array<mixed> $positional
+     * @param array<string, mixed> $hash
+     * @param array<string,array<mixed>|string|int> $_this current rendering context for the helper
+     * @param \Closure $cb callback function to render child context
+     * @param \Closure|null $else callback function to render child context when {{else}}
+     * @param array<mixed> $outerBlockParams outer block param stack for block params declared by the template
      */
-    private static function makeBlockFn(RuntimeContext $cx, mixed $_this, ?\Closure $cb, array $vars): \Closure
+    public static function dynhbbch(RuntimeContext $cx, string $name, mixed $callable, array $positional, array $hash, mixed &$_this, \Closure $cb, ?\Closure $else, int $blockParamCount, array $outerBlockParams): mixed
     {
-        if (!$cb) {
-            return fn() => '';
+        $helper = $cx->helpers[$name] ?? null;
+        if ($helper !== null) {
+            return static::hbbch($cx, $helper, $name, $positional, $hash, $_this, $cb, $else, $blockParamCount, $outerBlockParams);
         }
 
-        return function ($context = null, $data = null) use ($cx, $_this, $cb, $vars) {
-            $cx = clone $cx;
-            $oldData = $cx->data;
-            if (isset($data['data'])) {
-                $cx->data = array_merge(['root' => $oldData['root']], $data['data'], ['_parent' => $oldData]);
-            }
-
-            if (isset($data['blockParams'], $vars[2])) {
-                $ex = array_combine($vars[2], array_slice($data['blockParams'], 0, count($vars[2])));
-                array_unshift($cx->blParam, $ex);
-            }
-
-            if ($context === null || $context === $_this) {
-                $ret = $cb($cx, $_this);
-            } else {
-                $ret = static::withScope($cx, $_this, $context, $cb);
-            }
-
-            if (isset($data['data'])) {
-                $cx->data = $oldData;
-            }
-            return $ret;
-        };
-    }
+        if (!$callable instanceof \Closure) {
+            return static::hbbch($cx, $cx->helpers['helperMissing'], $name, $positional, $hash, $_this, $cb, $else, $blockParamCount, $outerBlockParams);
+        }
 
-    /**
-     * Build the $inverse closure passed to HelperOptions for block helpers.
-     */
-    private static function makeInverseFn(RuntimeContext $cx, mixed $_this, ?\Closure $else): \Closure
-    {
-        return $else
-            ? function ($context = null) use ($cx, $_this, $else) {
-                if ($context === null) {
-                    return $else($cx, $_this);
-                }
-                return static::withScope($cx, $_this, $context, $else);
-            }
-        : fn() => '';
+        return static::hbbch($cx, $callable, '', $positional, $hash, $_this, $cb, $else, $blockParamCount, $outerBlockParams);
     }
 
     /**
-     * Apply blockHelperMissing semantics: if the helper returned a string/SafeString,
-     * pass it through; otherwise treat the return value as a section context.
+     * Resolve the return value of a block helper call:
+     * pass through string/SafeString, stringify arrays, or delegate non-string values to blockHelperMissing.
      */
-    private static function applyBlockHelperMissing(RuntimeContext $cx, mixed $result, mixed $_this, ?\Closure $cb, ?\Closure $else): string
+    private static function resolveBlockResult(RuntimeContext $cx, mixed $result, mixed $_this, ?\Closure $cb, ?\Closure $else): string
     {
         if (is_string($result) || $result instanceof SafeString) {
             return (string) $result;
         }
 
-        // $cb may be null (inverted block with no else clause) after the inversion swap in hbbch
-        return static::sec($cx, $result, [], $_this, false, $cb ?? static fn() => '', $else);
-    }
-
-    private static function withScope(RuntimeContext $cx, mixed $scope, mixed $context, \Closure $cb): string
-    {
-        $cx->scopes[] = $scope;
-        $ret = $cb($cx, $context);
-        array_pop($cx->scopes);
-        return $ret;
-    }
-
-    /**
-     * Execute custom helper with prepared options
-     *
-     * @param string $ch the name of custom helper to be executed
-     * @param array<array<mixed>> $vars variables for the helper
-     */
-    public static function exch(RuntimeContext $cx, string $ch, array $vars, HelperOptions $options): mixed
-    {
-        $args = $vars[0];
-        $args[] = $options;
+        // Arrays stringify like JS Array.prototype.toString(), regardless of fn block.
+        if (is_array($result)) {
+            return implode(',', $result);
+        }
 
-        try {
-            return ($cx->helpers[$ch])(...$args);
-        } catch (\Throwable $e) {
-            throw new \Exception("Custom helper '$ch' error: " . $e->getMessage());
+        if ($cb === null) {
+            return ''; // can occur when compiled from an inverted block helper (e.g. {{^helper}}...{{/helper}})
         }
+        return static::hbbch($cx, $cx->helpers['blockHelperMissing'], '', [$result], [], $_this, $cb, $else);
     }
 }
diff --git a/src/RuntimeContext.php b/src/RuntimeContext.php
index 11481e0..bcca385 100644
--- a/src/RuntimeContext.php
+++ b/src/RuntimeContext.php
@@ -5,21 +5,21 @@
 /**
  * @internal
  */
-class RuntimeContext
+final class RuntimeContext
 {
     /**
-     * @param array<string, callable> $helpers
-     * @param array<string, callable> $partials
-     * @param array<mixed> $scopes
+     * @param array<string, \Closure> $helpers
+     * @param array<string, \Closure> $partials
+     * @param array<mixed> $depths
      * @param array<mixed> $data
-     * @param array<mixed> $blParam
+     * @param array<mixed> $frame
      */
     public function __construct(
         public array $helpers = [],
         public array $partials = [],
-        public array $scopes = [],
+        public array $depths = [],
         public array $data = [],
-        public array $blParam = [],
         public int $partialId = 0,
+        public array $frame = [],
     ) {}
 }
diff --git a/tests/ErrorTest.php b/tests/ErrorTest.php
index a82bce5..59ed3af 100644
--- a/tests/ErrorTest.php
+++ b/tests/ErrorTest.php
@@ -8,21 +8,31 @@
 use PHPUnit\Framework\TestCase;
 
 /**
- * @phpstan-type RenderTest array{template: string, options?: Options, data?: array<mixed>, expected: string}
+ * @phpstan-type RenderTest array{
+ *     template: string, options?: Options, helpers?: array<string, \Closure>, data?: array<mixed>, expected: string,
+ * }
  * @phpstan-type ErrorCase array{template: string, options?: Options, expected: string}
  */
 class ErrorTest extends TestCase
 {
     /**
+     * @param array<string, \Closure> $helpers
      * @param array<mixed> $data
      */
     #[DataProvider("renderErrorProvider")]
-    public function testRenderingException(string $template, string $expected, ?Options $options = null, array $data = []): void
-    {
+    public function testRenderingException(
+        string $template,
+        string $expected,
+        ?Options $options = null,
+        array $helpers = [],
+        array $data = [],
+    ): void {
         $php = Handlebars::precompile($template, $options ?? new Options());
         $renderer = Handlebars::template($php);
         try {
-            $renderer($data);
+            $renderer($data, [
+                'helpers' => $helpers,
+            ]);
             $this->fail("Expected to throw exception: {$expected}. CODE: $php");
         } catch (\Exception $e) {
             $this->assertEquals($expected, $e->getMessage(), $php);
@@ -67,19 +77,15 @@ public static function renderErrorProvider(): array
             [
                 // strict mode should override helperMissing
                 'template' => '{{foo}}',
-                'options' => new Options(
-                    strict: true,
-                    helpers: ['helperMissing' => fn() => 'bad'],
-                ),
+                'options' => new Options(strict: true),
+                'helpers' => ['helperMissing' => fn() => 'bad'],
                 'expected' => '"foo" not defined',
             ],
             [
                 // strict mode should override blockHelperMissing
                 'template' => '{{#foo}}OK{{/foo}}',
-                'options' => new Options(
-                    strict: true,
-                    helpers: ['blockHelperMissing' => fn() => 'bad'],
-                ),
+                'options' => new Options(strict: true),
+                'helpers' => ['blockHelperMissing' => fn() => 'bad'],
                 'expected' => '"foo" not defined',
             ],
             [
@@ -94,20 +100,55 @@ public static function renderErrorProvider(): array
             ],
             [
                 'template' => '{{foo}}',
-                'options' => new Options(
-                    helpers: [
-                        'foo' => function () {
-                            throw new \Exception('Expect the unexpected');
-                        },
-                    ],
-                ),
-                'expected' => 'Custom helper \'foo\' error: Expect the unexpected',
+                'helpers' => [
+                    'foo' => function () {
+                        throw new \Exception('Expect the unexpected');
+                    },
+                ],
+                'expected' => 'Expect the unexpected',
             ],
             // ensure that callable strings in data aren't treated as functions
             [
                 'template' => "{{#foo.bar 'arg'}}{{/foo.bar}}",
                 'data' => ['foo' => ['bar' => 'strlen']],
-                'expected' => '"foo.bar" is not a block helper function',
+                'expected' => 'Missing helper: "foo.bar"',
+            ],
+            [
+                'template' => '{{typeof hello}}',
+                'expected' => 'Missing helper: "typeof"',
+            ],
+            [
+                'template' => '{{#test foo}}{{/test}}',
+                'expected' => 'Missing helper: "test"',
+            ],
+            [
+                'template' => '{{test_join (foo bar)}}',
+                'helpers' => [
+                    'test_join' => function ($input) {
+                        return join('.', $input);
+                    },
+                ],
+                'expected' => 'Missing helper: "foo"',
+            ],
+            [
+                'template' => '{{> (foo) bar}}',
+                'expected' => 'Missing helper: "foo"',
+            ],
+            [
+                'template' => '{{#with}}OK!{{/with}}',
+                'expected' => '#with requires exactly one argument',
+            ],
+            [
+                'template' => '{{#if}}OK!{{/if}}',
+                'expected' => '#if requires exactly one argument',
+            ],
+            [
+                'template' => '{{#unless}}OK!{{/unless}}',
+                'expected' => '#unless requires exactly one argument',
+            ],
+            [
+                'template' => '{{#each}}OK!{{/each}}',
+                'expected' => 'Must pass iterator to #each',
             ],
         ];
     }
@@ -131,50 +172,23 @@ public static function errorProvider(): array
         return [
             [
                 'template' => '{{typeof hello}}',
-                'expected' => 'Missing helper: "typeof"',
-            ],
-            [
-                'template' => '{{#with}}OK!{{/with}}',
-                'expected' => '#with requires exactly one argument',
-            ],
-            [
-                'template' => '{{#if}}OK!{{/if}}',
-                'expected' => '#if requires exactly one argument',
-            ],
-            [
-                'template' => '{{#unless}}OK!{{/unless}}',
-                'expected' => '#unless requires exactly one argument',
-            ],
-            [
-                'template' => '{{#each}}OK!{{/each}}',
-                'expected' => 'Must pass iterator to #each',
-            ],
-            [
-                'template' => '{{lookup}}',
-                'expected' => '{{lookup}} requires 2 arguments',
-            ],
-            [
-                'template' => '{{lookup foo}}',
-                'expected' => '{{lookup}} requires 2 arguments',
+                'options' => new Options(knownHelpersOnly: true),
+                'expected' => 'You specified knownHelpersOnly, but used the unknown helper typeof',
             ],
             [
-                'template' => '{{#test foo}}{{/test}}',
-                'expected' => 'Missing helper: "test"',
+                'template' => '{{#test "arg"}}{{/test}}',
+                'options' => new Options(knownHelpersOnly: true),
+                'expected' => 'You specified knownHelpersOnly, but used the unknown helper test',
             ],
             [
-                'template' => '{{test_join (foo bar)}}',
-                'options' => new Options(
-                    helpers: [
-                        'test_join' => function ($input) {
-                            return join('.', $input);
-                        },
-                    ],
-                ),
-                'expected' => 'Missing helper: "foo"',
+                'template' => '{{#list id="nav-bar"}}{{/list}}',
+                'options' => new Options(knownHelpersOnly: true),
+                'expected' => 'You specified knownHelpersOnly, but used the unknown helper list',
             ],
             [
-                'template' => '{{> (foo) bar}}',
-                'expected' => 'Missing helper: "foo"',
+                'template' => '{{#if true}}nope{{/if}}',
+                'options' => new Options(knownHelpers: ['if' => false], knownHelpersOnly: true),
+                'expected' => 'You specified knownHelpersOnly, but used the unknown helper if',
             ],
             [
                 'template' => '{{#*help me}}{{/help}}',
diff --git a/tests/ExporterTest.php b/tests/ExporterTest.php
deleted file mode 100644
index ce084a6..0000000
--- a/tests/ExporterTest.php
+++ /dev/null
@@ -1,26 +0,0 @@
-<?php
-
-namespace DevTheorem\Handlebars\Test;
-
-use DevTheorem\Handlebars\Exporter;
-use PHPUnit\Framework\TestCase;
-
-class ExporterTest extends TestCase
-{
-    public function testClosure(): void
-    {
-        $expected = 'function ($a) {
-                return 1 + $a;
-            }';
-        $this->assertSame($expected, Exporter::closure(
-            function ($a) {
-                return 1 + $a;
-            },
-        ));
-
-        $this->assertSame('fn() => 1 + 1', Exporter::closure(fn() => 1 + 1));
-        $this->assertSame('fn(int $a) => $a * 2', Exporter::closure(
-            fn(int $a) => $a * 2,
-        ));
-    }
-}
diff --git a/tests/HandlebarsSpecTest.php b/tests/HandlebarsSpecTest.php
index e934337..0dad045 100644
--- a/tests/HandlebarsSpecTest.php
+++ b/tests/HandlebarsSpecTest.php
@@ -25,7 +25,7 @@ public static function createFrame(mixed $data): mixed
 
 /**
  * @phpstan-type JsonSpec array{
- *     file: string, no: int, message: string|null, data: null|int|bool|string|array<mixed>,
+ *     file: string, no: int, message: string|null, data: null|int|bool|string|array<mixed>|stdClass,
  *     it: string, description: string, expected: string|null, helpers: array<mixed>,
  *     partials: array<mixed>, compileOptions: array<mixed>, template: string,
  *     exception: string|null, runtimeOptions: array<mixed>, number: string|null,
@@ -33,8 +33,6 @@ public static function createFrame(mixed $data): mixed
  */
 class HandlebarsSpecTest extends TestCase
 {
-    private int $tested = 0;
-
     /**
      * @param JsonSpec $spec
      */
@@ -64,44 +62,35 @@ public function testSpecs(array $spec): void
 
             // this method may be useful in JS, but not in PHP
             || $spec['description'] === 'helpers - the lookupProperty-option'
+
+            // PHP doesn't have the same concept of sparse arrays as JS, so there's no need to skip over holes.
+            || $spec['it'] === 'GH-1065: Sparse arrays'
         ) {
             $this->markTestIncomplete('Not supported case: just skip it');
         }
 
         // FIX SPEC
-        if ($spec['it'] === 'helper block with complex lookup expression' && isset($spec['helpers']['goodbyes']['php'])) {
-            $spec['helpers']['goodbyes']['php'] = str_replace('$options->fn();', '$options->fn([]);', $spec['helpers']['goodbyes']['php']);
-        }
         if ($spec['it'] === 'should take presednece over parent block params') {
-            $spec['helpers']['goodbyes']['php'] = 'function($options) { static $value; if ($value === null) { $value = 1; } return $options->fn(["value" => "bar"], ["blockParams" => $options->blockParams === 1 ? [$value++, $value++] : null]);}';
+            $spec['helpers']['goodbyes']['php'] = str_replace('static $value = 0;', 'static $value = 1;', $spec['helpers']['goodbyes']['php']);
         }
-        if ($spec['it'] === 'Functions are bound to the context in knownHelpers only mode' && is_array($spec['data'])) {
-            $spec['data']['foo']['php'] = 'function($options) { return $options->scope[\'bar\']; }';
-        }
-
-        self::unsetRecursive($spec['data'], '!sparsearray');
         self::addDataHelpers($spec);
 
         // setup helpers
-        $this->tested++;
         $helpers = [];
-        $helpersList = '';
+        $helpersList = '[';
         foreach ($spec['helpers'] as $name => $func) {
             if (!isset($func['php'])) {
-                $this->markTestIncomplete("Skip [{$spec['file']}#{$spec['description']}]#{$spec['no']} , no PHP helper code provided for this case.");
+                $this->markTestIncomplete("No PHP helper code provided for [{$spec['file']}#{$spec['description']}]#{$spec['no']}");
             }
-            $helperName = preg_replace('/[.\\/]/', '_', "custom_helper_{$spec['no']}_{$this->tested}_$name");
-            $helpers[$name] = $helperName;
-            $helper = self::patchSafeString(
-                preg_replace('/function/', "function $helperName", $func['php'], 1),
-            );
+            $helper = self::patchSafeString($func['php']);
             $helper = str_replace('$options[\'name\']', '$options->name', $helper);
             $helper = str_replace('$options[\'data\']', '$options->data', $helper);
             $helper = str_replace('$options[\'hash\']', '$options->hash', $helper);
             $helper = str_replace('$arguments[count($arguments)-1][\'name\'];', '$arguments[count($arguments)-1]->name;', $helper);
-            $helpersList .= "$helper\n";
+            $helpersList .= "\n  '$name' => $helper,\n";
+            eval('$helpers[\'' . $name . '\'] = ' . $helper . ';');
         }
-        eval($helpersList);
+        $helpersList .= ']';
 
         // Convert "!code" partials (callable PHP strings) into actual callables.
         $partials = [];
@@ -123,14 +112,13 @@ public function testSpecs(array $spec): void
             $explicitPartialContext = $spec['compileOptions']['explicitPartialContext'] ?? false;
 
             $php = Handlebars::precompile($spec['template'], new Options(
+                knownHelpers: $spec['compileOptions']['knownHelpers'] ?? [],
                 knownHelpersOnly: $knownHelpersOnly,
                 strict: $strict,
                 assumeObjects: $assumeObjects,
                 preventIndent: $preventIndent,
                 ignoreStandalone: $ignoreStandalone,
                 explicitPartialContext: $explicitPartialContext,
-                /** @phpstan-ignore argument.type */
-                helpers: $helpers,
                 partials: $stringPartials,
             ));
         } catch (\Exception $e) {
@@ -144,6 +132,7 @@ public function testSpecs(array $spec): void
 
         try {
             $ropt = [
+                'helpers' => $helpers,
                 'partials' => $partials,
             ];
             if (is_array($spec['runtimeOptions']['data'] ?? null)) {
@@ -177,7 +166,7 @@ public function testSpecs(array $spec): void
      */
     private static function getSpecDetails(array $spec, string $code, string $helpers): string
     {
-        return "{$spec['file']}#{$spec['description']}]#{$spec['no']}:{$spec['it']}\nHelpers:\n$helpers\nPHP code:\n$code";
+        return "{$spec['file']}#{$spec['description']}]#{$spec['no']}:{$spec['it']}\nHelpers: $helpers\nPHP code:\n$code";
     }
 
     /**
@@ -265,21 +254,6 @@ private static function evalNestedCode(array &$data): void
         }
     }
 
-    private static function unsetRecursive(mixed &$array, string $unwanted_key): void
-    {
-        if (!is_array($array)) {
-            return;
-        }
-        if (isset($array[$unwanted_key])) {
-            unset($array[$unwanted_key]);
-        }
-        foreach ($array as &$value) {
-            if (is_array($value)) {
-                self::unsetRecursive($value, $unwanted_key);
-            }
-        }
-    }
-
     private static function patchSafeString(string $code): string
     {
         $classname = '\\DevTheorem\\Handlebars\\SafeString';
diff --git a/tests/RegressionTest.php b/tests/RegressionTest.php
index 7871626..c5c4d5f 100644
--- a/tests/RegressionTest.php
+++ b/tests/RegressionTest.php
@@ -2,7 +2,6 @@
 
 namespace DevTheorem\Handlebars\Test;
 
-use DevTheorem\Handlebars\Context;
 use DevTheorem\Handlebars\Handlebars;
 use DevTheorem\Handlebars\HelperOptions;
 use DevTheorem\Handlebars\Options;
@@ -11,7 +10,10 @@
 use PHPUnit\Framework\TestCase;
 
 /**
- * @phpstan-type RegIssue array{id?: int, template: string, data?: array<mixed>, options?: Options, expected: string}
+ * @phpstan-type RegIssue array{
+ *     desc?: string, template: string, data?: mixed, options?: Options,
+ *     helpers?: array<string, \Closure>, expected: string,
+ * }
  */
 class RegressionTest extends TestCase
 {
@@ -77,36 +79,31 @@ public function testRuntimePartials(): void
     }
 
     /**
-     * @param RegIssue $issue
+     * @param array<mixed>|null $data
+     * @param array<string, \Closure> $helpers
      */
-    #[DataProvider("issueProvider")]
-    public function testIssues(array $issue): void
+    #[DataProvider("helperProvider")]
+    #[DataProvider("partialProvider")]
+    #[DataProvider("builtInProvider")]
+    #[DataProvider("syntaxProvider")]
+    public function testIssues(string $template, string $expected, mixed $data = null, ?Options $options = null, array $helpers = [], string $desc = ''): void
     {
-        $templateSpec = Handlebars::precompile($issue['template'], $issue['options'] ?? new Options());
+        $templateSpec = Handlebars::precompile($template, $options ?? new Options());
 
         try {
             $template = Handlebars::template($templateSpec);
-            $result = $template($issue['data'] ?? null);
+            $result = $template($data, ['helpers' => $helpers]);
         } catch (\Throwable $e) {
-            $this->fail("Error: {$e->getMessage()}\nPHP code:\n$templateSpec");
+            $this->fail("$desc\nError: {$e->getMessage()}\nPHP code:\n$templateSpec");
         }
-        $this->assertEquals($issue['expected'], $result, "PHP CODE:\n$templateSpec");
+        $this->assertEquals($expected, $result, "$desc\nPHP code:\n$templateSpec");
     }
 
     /**
-     * @return array<array{RegIssue}>
+     * @return list<RegIssue>
      */
-    public static function issueProvider(): array
+    public static function helperProvider(): array
     {
-        $test_helpers = ['ouch' => fn() => 'ok'];
-
-        $test_helpers2 = ['ouch' => fn() => 'wa!'];
-
-        $test_helpers3 = [
-            'ouch' => fn() => 'wa!',
-            'god' => fn() => 'yo',
-        ];
-
         $myIf = function ($conditional, HelperOptions $options) {
             if ($conditional) {
                 return $options->fn();
@@ -136,6 +133,13 @@ public static function issueProvider(): array
         };
 
         $myDash = fn($a, $b) => "$a-$b";
+        $list = fn($arg) => join(',', $arg);
+        $keys = fn($arg) => array_keys($arg);
+        $echo = fn($arg) => "ECHO: $arg";
+        $testArray = fn($input) => is_array($input) ? 'IS_ARRAY' : 'NOT_ARRAY';
+        $returnBlock = fn(HelperOptions $options) => $options->fn();
+        $getThisBar = fn($input, HelperOptions $options) => $input . '-' . $options->scope['bar'];
+        $equal = fn($a, $b) => $a === $b;
 
         $equals = function (mixed $a, mixed $b, HelperOptions $options) {
             $jsEquals = function (mixed $a, mixed $b): bool {
@@ -150,9 +154,21 @@ public static function issueProvider(): array
             return $jsEquals($a, $b) ? $options->fn() : $options->inverse();
         };
 
-        $issues = [
+        $inlineHashProp = function ($arg, HelperOptions $options) {
+            return "$arg-{$options->hash['bar']}";
+        };
+
+        $inlineHashArr = function (HelperOptions $options) {
+            $ret = '';
+            foreach ($options->hash as $k => $v) {
+                $ret .= "$k : $v,";
+            }
+            return $ret;
+        };
+
+        return [
             [
-                'id' => 2,
+                'desc' => 'LNC #2',
                 'template' => <<<_hbs
                     {{#ifEquals @root.item "foo"}}
                         phooey
@@ -170,620 +186,311 @@ public static function issueProvider(): array
                         {{/if}}
                     {{/ifEquals}}
                     _hbs,
-                'options' => new Options(
-                    helpers: ['ifEquals' => $equals],
-                ),
+                'helpers' => ['ifEquals' => $equals],
                 'data' => ['item' => 'buzz'],
                 'expected' => "            buzzy\n",
             ],
 
             [
-                'id' => 7,
-                'template' => "<p>\n  {{> list}}\n</p>",
-                'data' => ['items' => ['Hello', 'World']],
-                'options' => new Options(
-                    partials: ['list' => "{{#each items}}{{this}}\n{{/each}}"],
-                ),
-                'expected' => "<p>\n  Hello\n  World\n</p>",
-            ],
-
-            [
-                'id' => 39,
-                'template' => '{{{tt}}}',
-                'data' => ['tt' => 'bla bla bla'],
-                'expected' => 'bla bla bla',
-            ],
-
-            [
-                'id' => 44,
+                'desc' => 'LNC #44',
                 'template' => '<div class="terms-text"> {{render "artists-terms"}} </div>',
-                'options' => new Options(
-                    helpers: [
-                        'render' => function ($view, $data = []) {
-                            return 'OK!';
-                        },
-                    ],
-                ),
-                'data' => ['tt' => 'bla bla bla'],
-                'expected' => '<div class="terms-text"> OK! </div>',
-            ],
-
-            [
-                'id' => 46,
-                'template' => '{{{this.id}}}, {{a.id}}',
-                'data' => ['id' => 'bla bla bla', 'a' => ['id' => 'OK!']],
-                'expected' => 'bla bla bla, OK!',
+                'helpers' => [
+                    'render' => fn($view) => $view . '.html',
+                ],
+                'expected' => '<div class="terms-text"> artists-terms.html </div>',
             ],
 
             [
-                'id' => 49,
-                'template' => '{{date_format}} 1, {{date_format2}} 2, {{date_format3}} 3, {{date_format4}} 4',
-                'options' => new Options(
-                    helpers: [
-                        'date_format' => function () {
-                            return "OKOK~1";
-                        },
-                        'date_format2' => function () {
-                            return "OKOK~2";
-                        },
-                        'date_format3' => function () {
-                            return "OKOK~3";
-                        },
-                        'date_format4' => function () {
-                            return "OKOK~4";
-                        },
-                    ],
-                ),
-                'expected' => 'OKOK~1 1, OKOK~2 2, OKOK~3 3, OKOK~4 4',
+                'desc' => 'LNC #49',
+                'template' => '{{date_format}} 1, {{date_format2}} 2',
+                'helpers' => [
+                    'date_format' => fn() => "OKOK~1",
+                    'date_format2' => fn() => "OKOK~2",
+                ],
+                'expected' => 'OKOK~1 1, OKOK~2 2',
             ],
 
             [
-                'id' => 52,
+                'desc' => 'LNC #52',
                 'template' => '{{{test_array tmp}}} should be happy!',
-                'options' => new Options(
-                    helpers: [
-                        'test_array' => function ($input) {
-                            return is_array($input) ? 'IS_ARRAY' : 'NOT_ARRAY';
-                        },
-                    ],
-                ),
+                'helpers' => ['test_array' => $testArray],
                 'data' => ['tmp' => ['A', 'B', 'C']],
                 'expected' => 'IS_ARRAY should be happy!',
             ],
 
             [
-                'id' => 62,
+                'desc' => 'LNC #62',
                 'template' => '{{{test_join @root.foo.bar}}} should be happy!',
-                'options' => new Options(
-                    helpers: [
-                        'test_join' => fn($input) => join('.', $input),
-                    ],
-                ),
+                'helpers' => ['test_join' => $list],
                 'data' => ['foo' => ['A', 'B', 'bar' => ['C', 'D']]],
-                'expected' => 'C.D should be happy!',
-            ],
-
-            [
-                'id' => 64,
-                'template' => '{{#each foo}} Test! {{this}} {{/each}}{{> test1}} ! >>> {{>recursive}}',
-                'options' => new Options(
-                    partials: [
-                        'test1' => "123\n",
-                        'recursive' => "{{#if foo}}{{bar}} -> {{#with foo}}{{>recursive}}{{/with}}{{else}}END!{{/if}}\n",
-                    ],
-                ),
-                'data' => [
-                    'bar' => 1,
-                    'foo' => [
-                        'bar' => 3,
-                        'foo' => [
-                            'bar' => 5,
-                            'foo' => [
-                                'bar' => 7,
-                                'foo' => [
-                                    'bar' => 11,
-                                    'foo' => [
-                                        'no foo here',
-                                    ],
-                                ],
-                            ],
-                        ],
-                    ],
-                ],
-                'expected' => " Test! 3  Test! [object Object] 123\n ! >>> 1 -> 3 -> 5 -> 7 -> 11 -> END!\n\n\n\n\n\n",
-            ],
-
-            [
-                'id' => 66,
-                'template' => '{{&foo}} , {{foo}}, {{{foo}}}',
-                'data' => ['foo' => 'Test & " \' :)'],
-                'expected' => 'Test & " \' :) , Test &amp; &quot; &#x27; :), Test & " \' :)',
+                'expected' => 'C,D should be happy!',
             ],
 
             [
-                'id' => 68,
+                'desc' => 'LNC #68',
                 'template' => '{{#myeach foo}} Test! {{this}} {{/myeach}}',
-                'options' => new Options(
-                    helpers: ['myeach' => $myEach],
-                ),
+                'helpers' => ['myeach' => $myEach],
                 'data' => ['foo' => ['A', 'B', 'bar' => ['C', 'D', 'E']]],
                 'expected' => ' Test! A  Test! B  Test! C,D,E ',
             ],
 
             [
-                'id' => 81,
-                'template' => '{{#with ../person}} {{^name}} Unknown {{/name}} {{/with}}?!',
-                'data' => ['parent?!' => ['A', 'B', 'bar' => ['C', 'D', 'E']]],
-                'expected' => '?!',
-            ],
-
-            [
-                'id' => 83,
-                'template' => '{{> tests/test1}}',
-                'options' => new Options(
-                    partials: [
-                        'tests/test1' => "123\n",
-                    ],
-                ),
-                'expected' => "123\n",
-            ],
-
-            [
-                'id' => 85,
+                'desc' => 'LNC #85',
                 'template' => '{{helper 1 foo bar="q"}}',
-                'options' => new Options(
-                    helpers: [
-                        'helper' => function ($arg1, $arg2, HelperOptions $options) {
-                            return "ARG1:$arg1, ARG2:$arg2, HASH:{$options->hash['bar']}";
-                        },
-                    ],
-                ),
+                'helpers' => [
+                    'helper' => function ($arg1, $arg2, HelperOptions $options) {
+                        return "ARG1:$arg1, ARG2:$arg2, HASH:{$options->hash['bar']}";
+                    },
+                ],
                 'data' => ['foo' => 'BAR'],
                 'expected' => 'ARG1:1, ARG2:BAR, HASH:q',
             ],
 
             [
-                'id' => 88,
-                'template' => '{{>test2}}',
-                'options' => new Options(
-                    partials: [
-                        'test2' => "a{{> test1}}b\n",
-                        'test1' => "123\n",
-                    ],
-                ),
-                'expected' => "a123\nb\n",
-            ],
-
-            [
-                'id' => 90,
-                'template' => '{{#items}}{{#value}}{{.}}{{/value}}{{/items}}',
-                'data' => ['items' => [['value' => '123']]],
-                'expected' => '123',
-            ],
-
-            [
-                'id' => 109,
-                'template' => '{{#if "OK"}}it\'s great!{{/if}}',
-                'options' => new Options(noEscape: true),
-                'expected' => 'it\'s great!',
-            ],
-
-            [
-                'id' => 110,
-                'template' => 'ABC{{#block "YES!"}}DEF{{foo}}GHI{{/block}}JKL',
-                'options' => new Options(
-                    helpers: [
-                        'block' => function ($name, HelperOptions $options) {
-                            return "1-$name-2-" . $options->fn() . '-3';
-                        },
-                    ],
-                ),
+                'desc' => 'LNC #110',
+                'template' => 'ABC{{#block "YES!"}}DEF{{foo}}GHI{{else}}NO~{{/block}}JKL',
+                'helpers' => [
+                    'block' => function ($name, HelperOptions $options) {
+                        return "1-$name-2-" . $options->fn() . '-3';
+                    },
+                ],
                 'data' => ['foo' => 'bar'],
                 'expected' => 'ABC1-YES!-2-DEFbarGHI-3JKL',
             ],
-
             [
-                'id' => 109,
-                'template' => '{{foo}} {{> test}}',
-                'options' => new Options(
-                    noEscape: true,
-                    partials: ['test' => '{{foo}}'],
-                ),
-                'data' => ['foo' => '<'],
-                'expected' => '< <',
+                'template' => 'ABC{{#block "YES!"}}TRUE{{else}}DEF{{foo}}GHI{{/block}}JKL',
+                'helpers' => [
+                    'block' => function ($name, HelperOptions $options) {
+                        return "1-$name-2-" . $options->inverse() . '-3';
+                    },
+                ],
+                'data' => ['foo' => 'bar'],
+                'expected' => 'ABC1-YES!-2-DEFbarGHI-3JKL',
             ],
 
             [
-                'id' => 114,
+                'desc' => 'LNC #114',
                 'template' => '{{^myeach .}}OK:{{.}},{{else}}NOT GOOD{{/myeach}}',
-                'options' => new Options(
-                    helpers: ['myeach' => $myEach],
-                ),
+                'helpers' => ['myeach' => $myEach],
                 'data' => [1, 'foo', 3, 'bar'],
                 'expected' => 'NOT GOODNOT GOODNOT GOODNOT GOOD',
             ],
 
             [
-                'id' => 124,
+                'desc' => 'LNC #124',
                 'template' => '{{list foo bar abc=(lt 10 3) def=(lt 3 10)}}',
-                'options' => new Options(
-                    helpers: [
-                        'lt' => function ($a, $b) {
-                            return ($a > $b) ? new SafeString("$a>$b") : '';
-                        },
-                        'list' => function (...$args) {
-                            $out = 'List:';
-                            /** @var HelperOptions $opts */
-                            $opts = array_pop($args);
-
-                            foreach ($args as $v) {
-                                if ($v) {
-                                    $out .= ")$v , ";
-                                }
+                'helpers' => [
+                    'lt' => function ($a, $b) {
+                        return ($a > $b) ? new SafeString("$a>$b") : '';
+                    },
+                    'list' => function (...$args) {
+                        $out = 'List:';
+                        /** @var HelperOptions $opts */
+                        $opts = array_pop($args);
+
+                        foreach ($args as $v) {
+                            if ($v) {
+                                $out .= ")$v , ";
                             }
+                        }
 
-                            foreach ($opts->hash as $k => $v) {
-                                if ($v) {
-                                    $out .= "]$k=$v , ";
-                                }
+                        foreach ($opts->hash as $k => $v) {
+                            if ($v) {
+                                $out .= "]$k=$v , ";
                             }
-                            return new SafeString($out);
-                        },
-                    ],
-                ),
+                        }
+                        return new SafeString($out);
+                    },
+                ],
                 'data' => ['foo' => 'OK!', 'bar' => 'OK2', 'abc' => false, 'def' => 123],
                 'expected' => 'List:)OK! , )OK2 , ]abc=10>3 , ',
             ],
-
             [
-                'id' => 124,
+                'desc' => 'LNC #124',
                 'template' => '{{#if (equal \'OK\' cde)}}YES!{{/if}}',
-                'options' => new Options(
-                    helpers: [
-                        'equal' => fn($a, $b) => $a === $b,
-                    ],
-                ),
+                'helpers' => ['equal' => $equal],
                 'data' => ['cde' => 'OK'],
                 'expected' => 'YES!',
             ],
-
             [
-                'id' => 124,
+                'desc' => 'LNC #124',
                 'template' => '{{#if (equal true (equal \'OK\' cde))}}YES!{{/if}}',
-                'options' => new Options(
-                    helpers: [
-                        'equal' => fn($a, $b) => $a === $b,
-                    ],
-                ),
+                'helpers' => ['equal' => $equal],
                 'data' => ['cde' => 'OK'],
                 'expected' => 'YES!',
             ],
 
             [
-                'id' => 125,
+                'desc' => 'LNC #125',
                 'template' => '{{#if (equal true ( equal \'OK\' cde))}}YES!{{/if}}',
-                'options' => new Options(
-                    helpers: [
-                        'equal' => fn($a, $b) => $a === $b,
-                    ],
-                ),
+                'helpers' => ['equal' => $equal],
                 'data' => ['cde' => 'OK'],
                 'expected' => 'YES!',
             ],
-
             [
-                'id' => 125,
+                'desc' => 'LNC #125',
                 'template' => '{{#if (equal true (equal \' OK\' cde))}}YES!{{/if}}',
-                'options' => new Options(
-                    helpers: [
-                        'equal' => fn($a, $b) => $a === $b,
-                    ],
-                ),
+                'helpers' => ['equal' => $equal],
                 'data' => ['cde' => ' OK'],
                 'expected' => 'YES!',
             ],
-
             [
-                'id' => 125,
+                'desc' => 'LNC #125',
                 'template' => '{{#if (equal true (equal \' ==\' cde))}}YES!{{/if}}',
-                'options' => new Options(
-                    helpers: [
-                        'equal' => fn($a, $b) => $a === $b,
-                    ],
-                ),
+                'helpers' => ['equal' => $equal],
                 'data' => ['cde' => ' =='],
                 'expected' => 'YES!',
             ],
-
             [
-                'id' => 125,
+                'desc' => 'LNC #125',
                 'template' => '{{#if (equal true (equal " ==" cde))}}YES!{{/if}}',
-                'options' => new Options(
-                    helpers: [
-                        'equal' => fn($a, $b) => $a === $b,
-                    ],
-                ),
+                'helpers' => ['equal' => $equal],
                 'data' => ['cde' => ' =='],
                 'expected' => 'YES!',
             ],
-
-            [
-                'id' => 125,
-                'template' => '{{[ abc]}}',
-                'data' => [' abc' => 'YES!'],
-                'expected' => 'YES!',
-            ],
-
             [
-                'id' => 125,
+                'desc' => 'LNC #125',
                 'template' => '{{list [ abc] " xyz" \' def\' "==" \'==\' "OK"}}',
-                'options' => new Options(
-                    helpers: [
-                        'list' => function ($a, $b) {
-                            $out = 'List:';
-                            $args = func_get_args();
-                            array_pop($args);
-                            foreach ($args as $v) {
-                                if ($v) {
-                                    $out .= ")$v , ";
-                                }
+                'helpers' => [
+                    'list' => function (...$args) {
+                        $out = 'List:';
+                        array_pop($args);
+                        foreach ($args as $v) {
+                            if ($v) {
+                                $out .= ")$v , ";
                             }
-                            return $out;
-                        },
-                    ],
-                ),
+                        }
+                        return $out;
+                    },
+                ],
                 'data' => [' abc' => 'YES!'],
                 'expected' => 'List:)YES! , ) xyz , ) def , )&#x3D;&#x3D; , )&#x3D;&#x3D; , )OK , ',
             ],
 
             [
-                'id' => 127,
+                'desc' => 'LNC #127',
                 'template' => '{{#each array}}#{{#if true}}{{name}}-{{../name}}-{{../../name}}-{{../../../name}}{{/if}}##{{#myif true}}{{name}}={{../name}}={{../../name}}={{../../../name}}{{/myif}}###{{#mywith true}}{{name}}~{{../name}}~{{../../name}}~{{../../../name}}{{/mywith}}{{/each}}',
                 'data' => ['name' => 'john', 'array' => [1, 2, 3]],
-                'options' => new Options(
-                    helpers: ['myif' => $myIf, 'mywith' => $myWith],
-                ),
-                // PENDING ISSUE, check for https://github.com/wycats/handlebars.js/issues/1135
-                // 'expected' => '#--john-##==john=###~~john~#--john-##==john=###~~john~#--john-##==john=###~~john~',
-                'expected' => '#-john--##=john==###~~john~#-john--##=john==###~~john~#-john--##=john==###~~john~',
-            ],
-
-            [
-                'id' => 128,
-                'template' => 'foo: {{foo}} , parent foo: {{../foo}}',
-                'data' => ['foo' => 'OK'],
-                'expected' => 'foo: OK , parent foo: ',
+                'helpers' => ['myif' => $myIf, 'mywith' => $myWith],
+                // HBS.js output is different due to context coercion (https://github.com/handlebars-lang/handlebars.js/issues/1135):
+                // 'expected' => '#-john--##==john=###~john~~#-john--##==john=###~~john~#-john--##==john=###~~john~'
+                'expected' => '#-john--##==john=###~~john~#-john--##==john=###~~john~#-john--##==john=###~~john~',
             ],
 
             [
-                'id' => 132,
+                'desc' => 'LNC #132',
                 'template' => '{{list (keys .)}}',
                 'data' => ['foo' => 'bar', 'test' => 'ok'],
-                'options' => new Options(
-                    helpers: [
-                        'keys' => function ($arg) {
-                            return array_keys($arg);
-                        },
-                        'list' => function ($arg) {
-                            return join(',', $arg);
-                        },
-                    ],
-                ),
+                'helpers' => ['keys' => $keys, 'list' => $list],
                 'expected' => 'foo,test',
             ],
 
             [
-                'id' => 133,
+                'desc' => 'LNC #133',
                 'template' => "{{list (keys\n .\n ) \n}}",
                 'data' => ['foo' => 'bar', 'test' => 'ok'],
-                'options' => new Options(
-                    helpers: [
-                        'keys' => function ($arg) {
-                            return array_keys($arg);
-                        },
-                        'list' => function ($arg) {
-                            return join(',', $arg);
-                        },
-                    ],
-                ),
+                'helpers' => ['keys' => $keys, 'list' => $list],
                 'expected' => 'foo,test',
             ],
-
             [
-                'id' => 133,
+                'desc' => 'LNC #133',
                 'template' => "{{list\n .\n \n \n}}",
                 'data' => ['foo', 'bar', 'test'],
-                'options' => new Options(
-                    helpers: [
-                        'list' => fn($arg) => join(',', $arg),
-                    ],
-                ),
+                'helpers' => ['list' => $list],
                 'expected' => 'foo,bar,test',
             ],
 
             [
-                'id' => 134,
+                'desc' => 'LNC #134',
                 'template' => "{{#if 1}}{{list (keys names)}}{{/if}}",
                 'data' => ['names' => ['foo' => 'bar', 'test' => 'ok']],
-                'options' => new Options(
-                    helpers: [
-                        'keys' => fn($arg) => array_keys($arg),
-                        'list' => fn($arg) => join(',', $arg),
-                    ],
-                ),
+                'helpers' => ['keys' => $keys, 'list' => $list],
                 'expected' => 'foo,test',
             ],
 
             [
-                'id' => 138,
+                'desc' => 'LNC #138',
                 'template' => "{{#each (keys .)}}={{.}}{{/each}}",
                 'data' => ['foo' => 'bar', 'test' => 'ok', 'Haha'],
-                'options' => new Options(
-                    helpers: [
-                        'keys' => fn($arg) => array_keys($arg),
-                    ],
-                ),
+                'helpers' => ['keys' => $keys],
                 'expected' => '=foo=test=0',
             ],
 
             [
-                'id' => 140,
+                'desc' => 'LNC #140',
                 'template' => "{{[a.good.helper] .}}",
                 'data' => ['ha', 'hey', 'ho'],
-                'options' => new Options(
-                    helpers: [
-                        'a.good.helper' => fn($arg) => join(',', $arg),
-                    ],
-                ),
+                'helpers' => [
+                    'a.good.helper' => fn($arg) => join(',', $arg),
+                ],
                 'expected' => 'ha,hey,ho',
             ],
 
             [
-                'id' => 141,
+                'desc' => 'LNC #141',
                 'template' => "{{#with foo}}{{#getThis bar}}{{/getThis}}{{/with}}",
                 'data' => ['foo' => ['bar' => 'Good!']],
-                'options' => new Options(
-                    helpers: [
-                        'getThis' => function ($input, HelperOptions $options) {
-                            return $input . '-' . $options->scope['bar'];
-                        },
-                    ],
-                ),
+                'helpers' => ['getThis' => $getThisBar],
                 'expected' => 'Good!-Good!',
             ],
-
             [
-                'id' => 141,
+                'desc' => 'LNC #141',
                 'template' => "{{#with foo}}{{getThis bar}}{{/with}}",
                 'data' => ['foo' => ['bar' => 'Good!']],
-                'options' => new Options(
-                    helpers: [
-                        'getThis' => function ($input, HelperOptions $options) {
-                            return $input . '-' . $options->scope['bar'];
-                        },
-                    ],
-                ),
+                'helpers' => ['getThis' => $getThisBar],
                 'expected' => 'Good!-Good!',
             ],
 
             [
-                'id' => 143,
+                'desc' => 'LNC #143',
                 'template' => "{{testString foo bar=\" \"}}",
                 'data' => ['foo' => 'good!'],
-                'options' => new Options(
-                    helpers: [
-                        'testString' => function ($arg, HelperOptions $options) {
-                            return $arg . '-' . $options->hash['bar'];
-                        },
-                    ],
-                ),
+                'helpers' => ['testString' => $inlineHashProp],
                 'expected' => 'good!- ',
             ],
-
             [
-                'id' => 143,
+                'desc' => 'LNC #143',
                 'template' => "{{testString foo bar=\"\"}}",
                 'data' => ['foo' => 'good!'],
-                'options' => new Options(
-                    helpers: [
-                        'testString' => function ($arg, HelperOptions $options) {
-                            return $arg . '-' . $options->hash['bar'];
-                        },
-                    ],
-                ),
+                'helpers' => ['testString' => $inlineHashProp],
                 'expected' => 'good!-',
             ],
-
             [
-                'id' => 143,
+                'desc' => 'LNC #143',
                 'template' => "{{testString foo bar=' '}}",
                 'data' => ['foo' => 'good!'],
-                'options' => new Options(
-                    helpers: [
-                        'testString' => function ($arg, HelperOptions $options) {
-                            return $arg . '-' . $options->hash['bar'];
-                        },
-                    ],
-                ),
+                'helpers' => ['testString' => $inlineHashProp],
                 'expected' => 'good!- ',
             ],
-
             [
-                'id' => 143,
+                'desc' => 'LNC #143',
                 'template' => "{{testString foo bar=''}}",
                 'data' => ['foo' => 'good!'],
-                'options' => new Options(
-                    helpers: [
-                        'testString' => function ($arg, HelperOptions $options) {
-                            return $arg . '-' . $options->hash['bar'];
-                        },
-                    ],
-                ),
+                'helpers' => ['testString' => $inlineHashProp],
                 'expected' => 'good!-',
             ],
 
             [
-                'id' => 143,
-                'template' => "{{testString foo bar=\" \"}}",
-                'data' => ['foo' => 'good!'],
-                'options' => new Options(
-                    helpers: [
-                        'testString' => function ($arg1, HelperOptions $options) {
-                            return $arg1 . '-' . $options->hash['bar'];
-                        },
-                    ],
-                ),
-                'expected' => 'good!- ',
+                'desc' => 'LNC #153',
+                'template' => '{{echo "test[]"}}',
+                'helpers' => ['echo' => $echo],
+                'expected' => "ECHO: test[]",
             ],
-
             [
-                'id' => 147,
-                'template' => '{{> test/test3 foo="bar"}}',
-                'data' => ['test' => 'OK!', 'foo' => 'error'],
-                'options' => new Options(
-                    partials: ['test/test3' => '{{test}}, {{foo}}'],
-                ),
-                'expected' => 'OK!, bar',
+                'desc' => 'LNC #153',
+                'template' => '{{echo \'test[]\'}}',
+                'helpers' => ['echo' => $echo],
+                'expected' => "ECHO: test[]",
             ],
 
             [
-                'id' => 153,
-                'template' => '{{echo "test[]"}}',
-                'options' => new Options(
-                    helpers: [
-                        'echo' => fn($in) => "-$in-",
-                    ],
-                ),
-                'expected' => "-test[]-",
-            ],
-
-            [
-                'id' => 153,
-                'template' => '{{echo \'test[]\'}}',
-                'options' => new Options(
-                    helpers: [
-                        'echo' => fn($in) => "-$in-",
-                    ],
-                ),
-                'expected' => "-test[]-",
-            ],
-
-            [
-                'id' => 154,
-                'template' => 'O{{! this is comment ! ... }}K!',
-                'expected' => "OK!",
-            ],
-
-            [
-                'id' => 157,
+                'desc' => 'LNC #157',
                 'template' => '{{{du_mp text=(du_mp "123")}}}',
-                'options' => new Options(
-                    helpers: [
-                        'du_mp' => function (HelperOptions|string $a) {
-                            return '>' . print_r($a->hash ?? $a, true);
-                        },
-                    ],
-                ),
+                'helpers' => [
+                    'du_mp' => function (HelperOptions|string $a) {
+                        return '>' . print_r($a->hash ?? $a, true);
+                    },
+                ],
                 'expected' => <<<VAREND
                     >Array
                     (
@@ -794,136 +501,25 @@ public static function issueProvider(): array
             ],
 
             [
-                'id' => 157,
-                'template' => '{{>test_js_partial}}',
-                'options' => new Options(
-                    partials: [
-                        'test_js_partial' => <<<VAREND
-                            Test GA....
-                            <script>
-                            (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){console.log('works!')};})();
-                            </script>
-                            VAREND,
-                    ],
-                ),
-                'expected' => <<<VAREND
-                    Test GA....
-                    <script>
-                    (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){console.log('works!')};})();
-                    </script>
-                    VAREND,
-            ],
-
-            [
-                'id' => 159,
-                'template' => '{{#.}}true{{else}}false{{/.}}',
-                'data' => new \ArrayObject(),
-                'expected' => "false",
-            ],
-
-            [
-                'id' => 169,
-                'template' => '{{{{a}}}}true{{else}}false{{{{/a}}}}',
-                'data' => ['a' => true],
-                'expected' => "true{{else}}false",
-            ],
-
-            [
-                'id' => 171,
+                'desc' => 'LNC #171',
                 'template' => '{{#my_private_each .}}{{@index}}:{{.}},{{/my_private_each}}',
                 'data' => ['a', 'b', 'c'],
-                'options' => new Options(
-                    helpers: [
-                        'my_private_each' => function ($context, HelperOptions $options) {
-                            $data = $options->data;
-                            $out = '';
-                            foreach ($context as $idx => $cx) {
-                                $data['index'] = $idx;
-                                $out .= $options->fn($cx, ['data' => $data]);
-                            }
-                            return $out;
-                        },
-                    ],
-                ),
+                'helpers' => [
+                    'my_private_each' => function ($context, HelperOptions $options) {
+                        $data = $options->data;
+                        $out = '';
+                        foreach ($context as $idx => $cx) {
+                            $data['index'] = $idx;
+                            $out .= $options->fn($cx, ['data' => $data]);
+                        }
+                        return $out;
+                    },
+                ],
                 'expected' => '0:a,1:b,2:c,',
             ],
 
             [
-                'id' => 175,
-                'template' => 'a{{!-- {{each}} haha {{/each}} --}}b',
-                'expected' => 'ab',
-            ],
-
-            [
-                'id' => 175,
-                'template' => 'c{{>test}}d',
-                'options' => new Options(
-                    partials: [
-                        'test' => 'a{{!-- {{each}} haha {{/each}} --}}b',
-                    ],
-                ),
-                'expected' => 'cabd',
-            ],
-
-            [
-                'id' => 177,
-                'template' => '{{{{a}}}} {{{{b}}}} {{{{/b}}}} {{{{/a}}}}',
-                'data' => ['a' => true],
-                'expected' => ' {{{{b}}}} {{{{/b}}}} ',
-            ],
-
-            [
-                'id' => 177,
-                'template' => '{{{{a}}}} {{{{b}}}} {{{{/b}}}} {{{{/a}}}}',
-                'data' => ['a' => true],
-                'options' => new Options(
-                    helpers: [
-                        'a' => fn(HelperOptions $options) => $options->fn(),
-                    ],
-                ),
-                'expected' => ' {{{{b}}}} {{{{/b}}}} ',
-            ],
-
-            [
-                'id' => 177,
-                'template' => '{{{{a}}}} {{{{b}}}} {{{{/b}}}} {{{{/a}}}}',
-                'expected' => '',
-            ],
-
-            [
-                'id' => 199,
-                'template' => '{{#if foo}}1{{else if bar}}2{{else}}3{{/if}}',
-                'expected' => '3',
-            ],
-
-            [
-                'id' => 199,
-                'template' => '{{#if foo}}1{{else if bar}}2{{/if}}',
-                'data' => ['bar' => true],
-                'expected' => '2',
-            ],
-
-            [
-                'id' => 200,
-                'template' => '{{#unless 0}}1{{else if foo}}2{{else}}3{{/unless}}',
-                'data' => ['foo' => false],
-                'expected' => '1',
-            ],
-            [
-                'id' => 201,
-                'template' => '{{#unless 0 includeZero=true}}1{{else if foo}}2{{else}}3{{/unless}}',
-                'data' => ['foo' => true],
-                'expected' => '2',
-            ],
-            [
-                'id' => 202,
-                'template' => '{{#unless 0 includeZero=true}}1{{else if foo}}2{{else}}3{{/unless}}',
-                'data' => ['foo' => false],
-                'expected' => '3',
-            ],
-
-            [
-                // based on examples at https://handlebarsjs.com/guide/hooks.html
+                'desc' => 'Hooks (https://handlebarsjs.com/guide/hooks.html)',
                 'template' => <<<_hbs
                     {{foo}}
                     {{foo "value"}}
@@ -933,18 +529,16 @@ public static function issueProvider(): array
                     {{#person}}{{firstName}} {{lastName}}{{/person}}
                     _hbs,
                 'data' => ['person' => ['firstName' => 'Yehuda', 'lastName' => 'Katz']],
-                'options' => new Options(
-                    helpers: [
-                        'helperMissing' => function (...$args) {
-                            $options = array_pop($args);
-                            $argVals = array_map(fn($arg) => is_bool($arg) ? ($arg ? 'true' : 'false') : $arg, $args);
-                            return "Missing {$options->name}(" . implode(',', $argVals) . ')';
-                        },
-                        'blockHelperMissing' => function (mixed $context, HelperOptions $options) {
-                            return "Helper '{$options->name}' not found. Printing block: {$options->fn($context)}";
-                        },
-                    ],
-                ),
+                'helpers' => [
+                    'helperMissing' => function (...$args) {
+                        $options = array_pop($args);
+                        $argVals = array_map(fn($arg) => is_bool($arg) ? ($arg ? 'true' : 'false') : $arg, $args);
+                        return "Missing {$options->name}(" . implode(',', $argVals) . ')';
+                    },
+                    'blockHelperMissing' => function (mixed $context, HelperOptions $options) {
+                        return "Helper '{$options->name}' not found. Printing block: {$options->fn($context)}";
+                    },
+                ],
                 'expected' => <<<_result
                     Missing foo()
                     Missing foo(value)
@@ -955,170 +549,630 @@ public static function issueProvider(): array
                     _result,
             ],
             [
-                'id' => 201,
+                'desc' => 'LNC #201',
                 'template' => '{{#foo "test"}}World{{/foo}}',
-                'options' => new Options(
-                    helpers: [
-                        'helperMissing' => fn(string $name, HelperOptions $options) => "$name = {$options->fn()}",
-                    ],
-                ),
+                'helpers' => [
+                    'helperMissing' => fn(string $name, HelperOptions $options) => "$name = {$options->fn()}",
+                ],
                 'expected' => 'test = World',
             ],
 
             [
-                'id' => 204,
-                'template' => '{{#> test name="A"}}B{{/test}}{{#> test name="C"}}D{{/test}}',
-                'data' => ['bar' => true],
-                'options' => new Options(
-                    partials: [
-                        'test' => '{{name}}:{{> @partial-block}},',
-                    ],
-                ),
-                'expected' => 'A:B,C:D,',
-            ],
-
-            [
-                'id' => 206,
-                'template' => '{{#with bar}}{{#../foo}}YES!{{/../foo}}{{/with}}',
-                'data' => ['foo' => 999, 'bar' => true],
-                'expected' => 'YES!',
-            ],
-
-            [
-                'id' => 213,
+                'desc' => 'LNC #213',
                 'template' => '{{#if foo}}foo{{else if bar}}{{#moo moo}}moo{{/moo}}{{/if}}',
                 'data' => ['foo' => true],
-                'options' => new Options(
-                    helpers: [
-                        'moo' => fn($arg1) => $arg1 === null,
-                    ],
-                ),
+                'helpers' => ['moo' => fn($arg1) => $arg1 === null],
                 'expected' => 'foo',
             ],
 
             [
-                'id' => 213,
-                'template' => '{{#with .}}bad{{else}}Good!{{/with}}',
-                'data' => [],
-                'expected' => 'Good!',
+                'desc' => 'LNC #227',
+                'template' => '{{#if moo}}A{{else if bar}}B{{else foo}}C{{/if}}',
+                'helpers' => ['foo' => $returnBlock],
+                'expected' => 'C',
             ],
 
             [
-                'id' => 216,
-                'template' => '{{foo.length}}',
-                'data' => ['foo' => []],
-                'expected' => '0',
+                'desc' => 'LNC #233',
+                'template' => '{{#if foo}}FOO{{else}}BAR{{/if}}',
+                // Opt out of compile-time inlining so the custom runtime helper is dispatched
+                'options' => new Options(knownHelpers: ['if' => false]),
+                'helpers' => [
+                    'if' => fn($arg, HelperOptions $options) => $options->fn(),
+                ],
+                'expected' => 'FOO',
             ],
 
             [
-                'id' => 221,
-                'template' => 'a{{ouch}}b',
-                'options' => new Options(
-                    helpers: $test_helpers,
-                ),
-                'expected' => 'aokb',
+                'desc' => 'LNC #252',
+                'template' => '{{foo (lookup bar 1)}}',
+                'data' => [
+                    'bar' => ['nil', [3, 5]],
+                ],
+                'helpers' => ['foo' => $testArray],
+                'expected' => 'IS_ARRAY',
             ],
 
             [
-                'id' => 221,
-                'template' => 'a{{ouch}}b',
-                'options' => new Options(
-                    helpers: $test_helpers2,
-                ),
-                'expected' => 'awa!b',
+                'desc' => 'LNC #253',
+                'template' => '{{foo.bar}}',
+                'data' => ['foo' => ['bar' => 'OK!']],
+                'helpers' => ['foo' => fn() => 'bad'],
+                'expected' => 'OK!',
             ],
 
             [
-                'id' => 221,
-                'template' => 'a{{ouch}}b',
-                'options' => new Options(
-                    helpers: $test_helpers3,
-                ),
-                'expected' => 'awa!b',
+                'desc' => 'LNC #257',
+                'template' => '{{foo a=(foo a=(foo a="ok"))}}',
+                'helpers' => [
+                    'foo' => fn(HelperOptions $opt) => $opt->hash['a'],
+                ],
+                'expected' => 'ok',
             ],
 
             [
-                'id' => 224,
-                'template' => '{{#> foo bar}}a,b,{{.}},{{!-- comment --}},d{{/foo}}',
-                'data' => ['bar' => 'BA!'],
-                'options' => new Options(
-                    partials: ['foo' => 'hello, {{> @partial-block}}'],
-                ),
-                'expected' => 'hello, a,b,BA!,,d',
+                'desc' => 'LNC #268',
+                'template' => '{{foo}}{{bar}}',
+                'helpers' => [
+                    'foo' => function (HelperOptions $opt) {
+                        $opt->scope['change'] = true;
+                    },
+                    'bar' => fn(HelperOptions $opt) => $opt->scope['change'] ? 'ok' : 'bad',
+                ],
+                'expected' => 'ok',
             ],
 
             [
-                'id' => 224,
-                'template' => '{{#> foo bar}}{{#if .}}OK! {{.}}{{else}}no bar{{/if}}{{/foo}}',
-                'data' => ['bar' => 'BA!'],
-                'options' => new Options(
-                    partials: ['foo' => 'hello, {{> @partial-block}}'],
-                ),
-                'expected' => 'hello, OK! BA!',
+                'desc' => 'LNC #281',
+                'template' => '{{echo (echo "foo bar (moo).")}}',
+                'helpers' => ['echo' => $echo],
+                'expected' => 'ECHO: ECHO: foo bar (moo).',
             ],
 
             [
-                'id' => 227,
-                'template' => '{{#if moo}}A{{else if bar}}B{{else foo}}C{{/if}}',
-                'options' => new Options(
-                    helpers: [
-                        'foo' => fn(HelperOptions $options) => $options->fn(),
-                    ],
-                ),
-                'expected' => 'C',
+                'desc' => 'LNC #281',
+                'template' => "{{test 'foo bar' (toRegex '^(foo|bar|baz)')}}",
+                'helpers' => [
+                    'toRegex' => fn($regex) => "/$regex/",
+                    'test' => fn(string $str, string $regex) => (bool) preg_match($regex, $str),
+                ],
+                'expected' => 'true',
             ],
 
             [
-                'id' => 227,
-                'template' => '{{#if moo}}A{{else if bar}}B{{else with foo}}C{{.}}{{/if}}',
-                'data' => ['foo' => 'D'],
-                'expected' => 'CD',
+                'desc' => 'LNC #297',
+                'template' => '{{test "foo" bar="\" "}}',
+                'helpers' => ['test' => $inlineHashProp],
+                'expected' => 'foo-&quot; ',
             ],
 
             [
-                'id' => 227,
-                'template' => '{{#if moo}}A{{else if bar}}B{{else each foo}}C{{.}}{{/if}}',
-                'data' => ['foo' => [1, 3, 5]],
-                'expected' => 'C1C3C5',
+                'desc' => 'LNC #298',
+                'template' => '{{test "\"\"\"" bar="\"\"\""}}',
+                'helpers' => ['test' => $inlineHashProp],
+                'expected' => '&quot;&quot;&quot;-&quot;&quot;&quot;',
+            ],
+            [
+                'template' => "{{test '\'\'\'' bar='\'\'\''}}",
+                'helpers' => ['test' => $inlineHashProp],
+                'expected' => '&#x27;&#x27;&#x27;-&#x27;&#x27;&#x27;',
             ],
 
             [
-                'id' => 229,
-                'template' => '{{#if foo.bar.moo}}TRUE{{else}}FALSE{{/if}}',
-                'data' => [],
-                'expected' => 'FALSE',
+                'desc' => 'LNC #310',
+                'template' => <<<_tpl
+                    {{#custom-block 'some-text' data=(custom-helper
+                      opt_a='foo'
+                      opt_b='bar'
+                    )}}...{{/custom-block}}
+                    _tpl,
+                'helpers' => [
+                    'custom-block' => function ($string, HelperOptions $opts) {
+                        return strtoupper($string) . '-' . $opts->hash['data'] . $opts->fn();
+                    },
+                    'custom-helper' => function (HelperOptions $options) {
+                        return $options->hash['opt_a'] . $options->hash['opt_b'];
+                    },
+                ],
+                'expected' => 'SOME-TEXT-foobar...',
             ],
 
             [
-                'id' => 233,
-                'template' => '{{#if foo}}FOO{{else}}BAR{{/if}}',
-                'data' => [],
-                'options' => new Options(
-                    helpers: [
-                        'if' => function ($arg, HelperOptions $options) {
-                            return $options->fn();
-                        },
+                'desc' => 'LNC #315',
+                'template' => '{{#each foo}}#{{@key}}({{@index}})={{.}}-{{moo}}-{{@irr}}{{/each}}',
+                'helpers' => [
+                    'moo' => function (HelperOptions $opts) {
+                        $opts->data['irr'] = '123';
+                        return '321';
+                    },
+                ],
+                'data' => [
+                    'foo' => [
+                        'a' => 'b',
+                        'c' => 'd',
+                        'e' => 'f',
                     ],
-                ),
-                'expected' => 'FOO',
+                ],
+                'expected' => '#a(0)=b-321-123#c(1)=d-321-123#e(2)=f-321-123',
             ],
 
             [
-                'id' => 234,
-                'template' => '{{> (lookup foo 2)}}',
-                'data' => ['foo' => ['a', 'b', 'c']],
-                'options' => new Options(
-                    partials: [
-                        'a' => '1st',
-                        'b' => '2nd',
-                        'c' => '3rd',
-                    ],
-                ),
-                'expected' => '3rd',
+                'desc' => 'LNC #350',
+                'template' => <<<_hbs
+                    Before: {{var}}
+                    (Setting Variable) {{setvar "var" "Foo"}}
+                    After: {{var}}
+                    _hbs,
+                'data' => ['var' => 'value'],
+                'helpers' => [
+                    'setvar' => function ($name, $value, HelperOptions $options) {
+                        $options->data['root'][$name] = $value;
+                    },
+                ],
+                'expected' => "Before: value\n(Setting Variable) \nAfter: Foo",
             ],
 
             [
-                'id' => 235,
+                'desc' => 'LNC #357',
+                'template' => '{{echo (echo "foobar(moo).")}}',
+                'helpers' => ['echo' => $echo],
+                'expected' => 'ECHO: ECHO: foobar(moo).',
+            ],
+            [
+                'desc' => 'LNC #357',
+                'template' => "{{{debug (debug 'foobar(moo).')}}}",
+                'helpers' => ['debug' => $echo],
+                'expected' => 'ECHO: ECHO: foobar(moo).',
+            ],
+            [
+                'desc' => 'LNC #357',
+                'template' => '{{echo (echo "foobar(moo)." (echo "moobar(foo)"))}}',
+                'helpers' => ['echo' => $echo],
+                'expected' => 'ECHO: ECHO: foobar(moo).',
+            ],
+
+            [
+                'desc' => 'LNC #367',
+                'template' => "{{#each (myfunc 'foo(bar)' ) }}{{.}},{{/each}}",
+                'helpers' => [
+                    'myfunc' => fn($arg) => explode('(', $arg),
+                ],
+                'expected' => 'foo,bar),',
+            ],
+
+            [
+                'desc' => 'LNC #371',
+                'template' => <<<_tpl
+                    {{#myeach '[{"a":"ayy", "b":"bee"},{"a":"zzz", "b":"ccc"}]' as | newContext index | }}
+                    Foo {{newContext.a}} {{index}}
+                    {{/myeach}}
+                    _tpl,
+                'helpers' => [
+                    'myeach' => function ($context, HelperOptions $options) {
+                        $theArray = json_decode($context, true);
+                        $ret = '';
+                        foreach ($theArray as $i => $value) {
+                            $ret .= $options->fn([], ['blockParams' => [$value, $i]]);
+                        }
+                        return $ret;
+                    },
+                ],
+                'expected' => "Foo ayy 0\nFoo zzz 1\n",
+            ],
+
+            [
+                'template' => '{{testNull null undefined 1}}',
+                'data' => 'test',
+                'helpers' => [
+                    'testNull' => function ($arg1, $arg2) {
+                        return ($arg1 === null && $arg2 === null) ? 'YES!' : 'no';
+                    },
+                ],
+                'expected' => 'YES!',
+            ],
+
+            [
+                'template' => '{{[helper]}}',
+                'helpers' => ['helper' => fn() => 'DEF'],
+                'expected' => 'DEF',
+            ],
+
+            [
+                'template' => '{{#[helper3]}}ABC{{/[helper3]}}',
+                'helpers' => ['helper3' => fn() => 'DEF'],
+                'expected' => 'DEF',
+            ],
+
+            [
+                'template' => '{{hash abc=["def=123"]}}',
+                'helpers' => ['hash' => $inlineHashArr],
+                'data' => ['"def=123"' => 'La!'],
+                'expected' => 'abc : La!,',
+            ],
+
+            [
+                'template' => '{{hash abc=[\'def=123\']}}',
+                'helpers' => ['hash' => $inlineHashArr],
+                'data' => ["'def=123'" => 'La!'],
+                'expected' => 'abc : La!,',
+            ],
+
+            [
+                'template' => '-{{getroot}}=',
+                'helpers' => [
+                    'getroot' => fn(HelperOptions $options) => $options->data['root'],
+                ],
+                'data' => 'ROOT!',
+                'expected' => '-ROOT!=',
+            ],
+
+            [
+                'desc' => 'inverted helpers should support hash arguments',
+                'template' => '{{^helper fizz="buzz"}}{{/helper}}',
+                'helpers' => [
+                    'helper' => fn(HelperOptions $options) => $options->hash['fizz'],
+                ],
+                'expected' => 'buzz',
+            ],
+            [
+                'template' => '{{#myif foo}}YES{{else}}NO{{/myif}}',
+                'helpers' => ['myif' => $myIf],
+                'expected' => 'NO',
+            ],
+
+            [
+                'template' => '{{#myif foo}}YES{{else}}NO{{/myif}}',
+                'data' => ['foo' => 1],
+                'helpers' => ['myif' => $myIf],
+                'expected' => 'YES',
+            ],
+
+            [
+                'template' => '{{#mylogic 0 foo bar}}YES:{{.}}{{else}}NO:{{.}}{{/mylogic}}',
+                'data' => ['foo' => 'FOO', 'bar' => 'BAR'],
+                'helpers' => ['mylogic' => $myLogic],
+                'expected' => 'NO:BAR',
+            ],
+
+            [
+                'template' => '{{#mylogic true foo bar}}YES:{{.}}{{else}}NO:{{.}}{{/mylogic}}',
+                'data' => ['foo' => 'FOO', 'bar' => 'BAR'],
+                'helpers' => ['mylogic' => $myLogic],
+                'expected' => 'YES:FOO',
+            ],
+
+            [
+                'template' => '{{#mywith foo}}YA: {{name}}{{/mywith}}',
+                'data' => ['name' => 'OK?', 'foo' => ['name' => 'OK!']],
+                'helpers' => ['mywith' => $myWith],
+                'expected' => 'YA: OK!',
+            ],
+
+            [
+                'template' => '{{mydash \'abc\' "dev"}}',
+                'data' => ['a' => 'a', 'b' => 'b', 'c' => ['c' => 'c'], 'd' => 'd', 'e' => 'e'],
+                'helpers' => ['mydash' => $myDash],
+                'expected' => 'abc-dev',
+            ],
+
+            [
+                'template' => '{{mydash \'a b c\' "d e f"}}',
+                'data' => ['a' => 'a', 'b' => 'b', 'c' => ['c' => 'c'], 'd' => 'd', 'e' => 'e'],
+                'helpers' => ['mydash' => $myDash],
+                'expected' => 'a b c-d e f',
+            ],
+
+            [
+                'template' => '{{mydash "abc" (test_array 1)}}',
+                'data' => ['a' => 'a', 'b' => 'b', 'c' => ['c' => 'c'], 'd' => 'd', 'e' => 'e'],
+                'helpers' => [
+                    'mydash' => $myDash,
+                    'test_array' => $testArray,
+                ],
+                'expected' => 'abc-NOT_ARRAY',
+            ],
+
+            [
+                'template' => '{{mydash "abc" (mydash a b)}}',
+                'data' => ['a' => 'a', 'b' => 'b', 'c' => ['c' => 'c'], 'd' => 'd', 'e' => 'e'],
+                'helpers' => ['mydash' => $myDash],
+                'expected' => 'abc-a-b',
+            ],
+
+            [
+                'template' => '{{#equals my_var false}}Equal to false{{else}}Not equal{{/equals}}',
+                'data' => ['my_var' => 0],
+                'helpers' => ['equals' => $equals],
+                'expected' => 'Equal to false',
+            ],
+            [
+                'template' => '{{#equals my_var false}}Equal to false{{else}}Not equal{{/equals}}',
+                'data' => ['my_var' => 1],
+                'helpers' => ['equals' => $equals],
+                'expected' => 'Not equal',
+            ],
+            [
+                'template' => '{{#equals my_var false}}Equal to false{{else}}Not equal{{/equals}}',
+                'helpers' => ['equals' => $equals],
+                'expected' => 'Not equal',
+            ],
+
+            [
+                'template' => <<<VAREND
+                    <ul>
+                     <li>1. {{helper1 name}}</li>
+                     <li>2. {{helper1 value}}</li>
+                     <li>3. {{helper2 name}}</li>
+                     <li>4. {{helper2 value}}</li>
+                     <li>9. {{link name}}</li>
+                     <li>10. {{link value}}</li>
+                     <li>11. {{alink url text}}</li>
+                     <li>12. {{{alink url text}}}</li>
+                    </ul>
+                    VAREND
+                ,
+                'data' => ['name' => 'John', 'value' => 10000, 'url' => 'http://yahoo.com', 'text' => 'You&Me!'],
+                'helpers' => [
+                    'helper1' => fn($arg) => is_array($arg) ? '-Array-' : "-$arg-",
+                    'helper2' => fn($arg) => is_array($arg) ? '=Array=' : "=$arg=",
+                    'link' => function ($arg) {
+                        if (is_array($arg)) {
+                            $arg = 'Array';
+                        }
+                        return "<a href=\"{$arg}\">click here</a>";
+                    },
+                    'alink' => function ($u, $t) {
+                        $u = is_array($u) ? 'Array' : $u;
+                        $t = is_array($t) ? 'Array' : $t;
+                        return "<a href=\"$u\">$t</a>";
+                    },
+                ],
+                'expected' => <<<VAREND
+                    <ul>
+                     <li>1. -John-</li>
+                     <li>2. -10000-</li>
+                     <li>3. &#x3D;John&#x3D;</li>
+                     <li>4. &#x3D;10000&#x3D;</li>
+                     <li>9. &lt;a href&#x3D;&quot;John&quot;&gt;click here&lt;/a&gt;</li>
+                     <li>10. &lt;a href&#x3D;&quot;10000&quot;&gt;click here&lt;/a&gt;</li>
+                     <li>11. &lt;a href&#x3D;&quot;http://yahoo.com&quot;&gt;You&amp;Me!&lt;/a&gt;</li>
+                     <li>12. <a href="http://yahoo.com">You&Me!</a></li>
+                    </ul>
+                    VAREND,
+            ],
+
+            [
+                'template' => ">{{helper1 \"===\"}}<",
+                'helpers' => [
+                    'helper1' => fn($arg) => is_array($arg) ? '-Array-' : "-$arg-",
+                ],
+                'expected' => ">-&#x3D;&#x3D;&#x3D;-<",
+            ],
+
+            [
+                'desc' => 'inverted block helper with block params',
+                'template' => '{{^helper items as |foo bar baz|}}{{foo}}{{bar}}{{baz}}{{/helper}}',
+                'helpers' => [
+                    'helper' => function (array $items, HelperOptions $options) {
+                        return $options->inverse(null, ['blockParams' => [1, 2, 3]]);
+                    },
+                ],
+                'data' => ['items' => []],
+                'expected' => '123',
+            ],
+            [
+                'desc' => 'inverted block helper returning truthy non-string: stringified like JS',
+                'template' => '{{^helper}}block{{/helper}}',
+                'helpers' => ['helper' => fn() => ['truthy', 'array']],
+                'expected' => 'truthy,array',
+            ],
+            [
+                'desc' => 'block helper returning truthy non-string: stringified like JS',
+                'template' => '{{#helper}}block{{/helper}}',
+                'helpers' => ['helper' => fn() => ['truthy', 'array']],
+                'expected' => 'truthy,array',
+            ],
+            [
+                'template' => '{{^helper}}block{{/helper}}',
+                'options' => new Options(knownHelpers: ['helper' => true]),
+                'helpers' => ['helper' => fn() => ['truthy', 'array']],
+                'expected' => 'truthy,array',
+            ],
+            [
+                'desc' => 'block helper returning truthy non-string: stringified like JS',
+                'template' => '{{#helper}}block{{/helper}}',
+                'options' => new Options(knownHelpers: ['helper' => true]),
+                'helpers' => ['helper' => fn() => ['truthy', 'array']],
+                'expected' => 'truthy,array',
+            ],
+
+            [
+                'desc' => 'ensure that literal block path helper names are correctly escaped',
+                'template' => '{{#"it\'s"}}YES{{/"it\'s"}}',
+                'options' => new Options(knownHelpers: ["it's" => true]),
+                'helpers' => ["it's" => fn(HelperOptions $options) => $options->fn()],
+                'expected' => 'YES',
+            ],
+
+            [
+                'desc' => 'closures in data can be used like helpers',
+                'template' => '{{test "Hello"}}',
+                'data' => ['test' => fn(string $arg) => "$arg runtime data"],
+                'expected' => 'Hello runtime data',
+            ],
+            [
+                'desc' => 'helpers always take precedence over data closures',
+                'template' => '{{test "Hello"}}',
+                'data' => ['test' => fn(string $arg) => "$arg runtime data"],
+                'helpers' => ['test' => fn(string $arg) => "$arg runtime helper"],
+                'expected' => 'Hello runtime helper',
+            ],
+        ];
+    }
+
+    /**
+     * @return list<RegIssue>
+     */
+    public static function partialProvider(): array
+    {
+        return [
+            [
+                'desc' => 'LNC #7',
+                'template' => "<p>\n  {{> list}}\n</p>",
+                'data' => ['items' => ['Hello', 'World']],
+                'options' => new Options(
+                    partials: ['list' => "{{#each items}}{{this}}\n{{/each}}"],
+                ),
+                'expected' => "<p>\n  Hello\n  World\n</p>",
+            ],
+
+            [
+                'desc' => 'LNC #64',
+                'template' => '{{#each foo}} Test! {{this}} {{/each}}{{> test1}} ! >>> {{>recursive}}',
+                'options' => new Options(
+                    partials: [
+                        'test1' => "123\n",
+                        'recursive' => "{{#if foo}}{{bar}} -> {{#with foo}}{{>recursive}}{{/with}}{{else}}END!{{/if}}\n",
+                    ],
+                ),
+                'data' => [
+                    'bar' => 1,
+                    'foo' => [
+                        'bar' => 3,
+                        'foo' => [
+                            'bar' => 5,
+                            'foo' => [
+                                'bar' => 7,
+                                'foo' => [
+                                    'bar' => 11,
+                                    'foo' => [
+                                        'no foo here',
+                                    ],
+                                ],
+                            ],
+                        ],
+                    ],
+                ],
+                'expected' => " Test! 3  Test! [object Object] 123\n ! >>> 1 -> 3 -> 5 -> 7 -> 11 -> END!\n\n\n\n\n\n",
+            ],
+
+            [
+                'desc' => 'LNC #83',
+                'template' => '{{> tests/test1}}',
+                'options' => new Options(
+                    partials: ['tests/test1' => "123\n"],
+                ),
+                'expected' => "123\n",
+            ],
+
+            [
+                'desc' => 'LNC #88',
+                'template' => '{{>test2}}',
+                'options' => new Options(
+                    partials: [
+                        'test2' => "a{{> test1}}b\n",
+                        'test1' => "123\n",
+                    ],
+                ),
+                'expected' => "a123\nb\n",
+            ],
+
+            [
+                'desc' => 'LNC #109',
+                'template' => '{{foo}} {{> test}}',
+                'options' => new Options(
+                    noEscape: true,
+                    partials: ['test' => '{{foo}}'],
+                ),
+                'data' => ['foo' => '<'],
+                'expected' => '< <',
+            ],
+
+            [
+                'desc' => 'LNC #147',
+                'template' => '{{> test/test3 foo="bar"}}',
+                'data' => ['test' => 'OK!', 'foo' => 'error'],
+                'options' => new Options(
+                    partials: ['test/test3' => '{{test}}, {{foo}}'],
+                ),
+                'expected' => 'OK!, bar',
+            ],
+
+            [
+                'desc' => 'LNC #157',
+                'template' => '{{>test_js_partial}}',
+                'options' => new Options(
+                    partials: [
+                        'test_js_partial' => <<<VAREND
+                            Test GA....
+                            <script>
+                            (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){console.log('works!')};})();
+                            </script>
+                            VAREND,
+                    ],
+                ),
+                'expected' => <<<VAREND
+                    Test GA....
+                    <script>
+                    (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){console.log('works!')};})();
+                    </script>
+                    VAREND,
+            ],
+
+            [
+                'desc' => 'LNC #175',
+                'template' => 'c{{>test}}d',
+                'options' => new Options(
+                    partials: ['test' => 'a{{!-- {{each}} haha {{/each}} --}}b'],
+                ),
+                'expected' => 'cabd',
+            ],
+
+            [
+                'desc' => 'LNC #204',
+                'template' => '{{#> test name="A"}}B{{/test}}{{#> test name="C"}}D{{/test}}',
+                'data' => ['bar' => true],
+                'options' => new Options(
+                    partials: ['test' => '{{name}}:{{> @partial-block}},'],
+                ),
+                'expected' => 'A:B,C:D,',
+            ],
+
+            [
+                'desc' => 'LNC #224',
+                'template' => '{{#> foo bar}}a,b,{{.}},{{!-- comment --}},d{{/foo}}',
+                'data' => ['bar' => 'BA!'],
+                'options' => new Options(
+                    partials: ['foo' => 'hello, {{> @partial-block}}'],
+                ),
+                'expected' => 'hello, a,b,BA!,,d',
+            ],
+            [
+                'desc' => 'LNC #224',
+                'template' => '{{#> foo bar}}{{#if .}}OK! {{.}}{{else}}no bar{{/if}}{{/foo}}',
+                'data' => ['bar' => 'BA!'],
+                'options' => new Options(
+                    partials: ['foo' => 'hello, {{> @partial-block}}'],
+                ),
+                'expected' => 'hello, OK! BA!',
+            ],
+
+            [
+                'desc' => 'LNC #234',
+                'template' => '{{> (lookup foo 2)}}',
+                'data' => ['foo' => ['a', 'b', 'c']],
+                'options' => new Options(
+                    partials: [
+                        'a' => '1st',
+                        'b' => '2nd',
+                        'c' => '3rd',
+                    ],
+                ),
+                'expected' => '3rd',
+            ],
+
+            [
+                'desc' => 'LNC #235',
                 'template' => '{{#> "myPartial"}}{{#> myOtherPartial}}{{ @root.foo}}{{/myOtherPartial}}{{/"myPartial"}}',
                 'data' => ['foo' => 'hello!'],
                 'options' => new Options(
@@ -1131,7 +1185,7 @@ public static function issueProvider(): array
             ],
 
             [
-                'id' => 236,
+                'desc' => 'LNC #236',
                 'template' => 'A{{#> foo}}B{{#> bar}}C{{>moo}}D{{/bar}}E{{/foo}}F',
                 'options' => new Options(
                     partials: [
@@ -1144,7 +1198,7 @@ public static function issueProvider(): array
             ],
 
             [
-                'id' => 241,
+                'desc' => 'LNC #241',
                 'template' => '{{#>foo}}{{#*inline "bar"}}GOOD!{{#each .}}>{{.}}{{/each}}{{/inline}}{{/foo}}',
                 'data' => ['1', '3', '5'],
                 'options' => new Options(
@@ -1157,21 +1211,7 @@ public static function issueProvider(): array
             ],
 
             [
-                'id' => 243,
-                'template' => '{{lookup . 3}}',
-                'data' => ['3' => 'OK'],
-                'expected' => 'OK',
-            ],
-
-            [
-                'id' => 243,
-                'template' => '{{lookup . "test"}}',
-                'data' => ['test' => 'OK'],
-                'expected' => 'OK',
-            ],
-
-            [
-                'id' => 244,
+                'desc' => 'LNC #244',
                 'template' => '{{#>outer}}content{{/outer}}',
                 'data' => ['test' => 'OK'],
                 'options' => new Options(
@@ -1184,647 +1224,432 @@ public static function issueProvider(): array
             ],
 
             [
-                'id' => 245,
-                'template' => '{{#each foo}}{{#with .}}{{bar}}-{{../../name}}{{/with}}{{/each}}',
-                'data' => ['name' => 'bad', 'foo' => [
-                    ['bar' => 1],
-                    ['bar' => 2],
-                ]],
-                'expected' => '1-2-',
+                'desc' => 'LNC #284',
+                'template' => '{{> foo}}',
+                'options' => new Options(
+                    partials: ['foo' => "12'34"],
+                ),
+                'expected' => "12'34",
             ],
-
             [
-                'id' => 252,
-                'template' => '{{foo (lookup bar 1)}}',
-                'data' => ['bar' => [
-                    'nil',
-                    [3, 5],
-                ]],
+                'desc' => 'LNC #284',
+                'template' => '{{> (lookup foo 2)}}',
+                'data' => ['foo' => ['a', 'b', 'c']],
                 'options' => new Options(
-                    helpers: [
-                        'foo' => fn($arg1) => is_array($arg1) ? 'OK' : 'bad',
+                    partials: [
+                        'a' => '1st',
+                        'b' => '2nd',
+                        'c' => "3'r'd",
                     ],
                 ),
-                'expected' => 'OK',
+                'expected' => "3'r'd",
             ],
 
             [
-                'id' => 253,
-                'template' => '{{foo.bar}}',
-                'data' => ['foo' => ['bar' => 'OK!']],
+                'desc' => 'LNC #292',
+                'template' => '{ {{#>outer}} {{#>innerBlock}} Hello {{/innerBlock}} {{>simple}} {{/outer}} }',
                 'options' => new Options(
-                    helpers: [
-                        'foo' => fn() => 'bad',
+                    partials: [
+                        'outer' => '( {{#>nested}} « {{>@partial-block}} » {{/nested}} )',
+                        'nested' => '[ {{>@partial-block}} ]',
+                        'innerBlock' => '< {{>@partial-block}} >',
+                        'simple' => 'World!',
                     ],
                 ),
-                'expected' => 'OK!',
+                'expected' => '{ ( [  «  <  Hello  > World!  »  ] ) }',
             ],
 
             [
-                'id' => 254,
-                'template' => '{{#if a}}a{{else if b}}b{{else}}c{{/if}}{{#if a}}a{{else if b}}b{{/if}}',
-                'data' => ['b' => 1],
-                'expected' => 'bb',
+                'desc' => 'LNC #295',
+                'template' => '{{> MyPartial (newObject name="John Doe") message=(echo message=(echo message="Hello World!"))}}',
+                'options' => new Options(
+                    partials: ['MyPartial' => '{{name}} says: "{{message}}"'],
+                ),
+                'helpers' => [
+                    'newObject' => fn(HelperOptions $options) => $options->hash,
+                    'echo' => fn(HelperOptions $options) => $options->hash['message'],
+                ],
+                'expected' => 'John Doe says: "Hello World!"',
             ],
 
             [
-                'id' => 255,
-                'template' => '{{foo.length}}',
-                'data' => ['foo' => [1, 2]],
-                'expected' => '2',
+                'desc' => 'LNC #302',
+                'template' => "{{#*inline \"t1\"}}{{#if imageUrl}}<span />{{else}}<div />{{/if}}{{/inline}}{{#*inline \"t2\"}}{{#if imageUrl}}<span />{{else}}<div />{{/if}}{{/inline}}{{#*inline \"t3\"}}{{#if imageUrl}}<span />{{else}}<div />{{/if}}{{/inline}}",
+                'expected' => '',
             ],
 
             [
-                'id' => 3,
-                'template' => 'ok{{{lookup . "missing"}}}',
-                'expected' => 'ok',
+                'desc' => 'LNC #303',
+                'template' => '{{#*inline "t1"}} {{#if url}} <a /> {{else if imageUrl}} <img /> {{else}} <span /> {{/if}} {{/inline}}',
+                'expected' => '',
             ],
 
             [
-                'id' => 257,
-                'template' => '{{foo a=(foo a=(foo a="ok"))}}',
+                'desc' => 'LNC #316',
+                'template' => '{{> StrongPartial text="Use the syntax: {{varName}}."}}',
                 'options' => new Options(
-                    helpers: [
-                        'foo' => fn(HelperOptions $opt) => $opt->hash['a'],
-                    ],
+                    partials: ['StrongPartial' => '<strong>{{text}}</strong>'],
                 ),
-                'expected' => 'ok',
-            ],
-
-            [
-                'id' => 261,
-                'template' => '{{#each foo as |bar|}}?{{bar.[0]}}{{/each}}',
-                'data' => ['foo' => [['a'], ['b']]],
-                'expected' => '?a?b',
-            ],
-
-            [
-                'id' => 267,
-                'template' => '{{#each . as |v k|}}#{{k}}>{{v}}|{{.}}{{/each}}',
-                'data' => ['a' => 'b', 'c' => 'd'],
-                'expected' => '#a>b|b#c>d|d',
+                'data' => ['varName' => 'unused'],
+                'expected' => '<strong>Use the syntax: {{varName}}.</strong>',
             ],
 
             [
-                'id' => 268,
-                'template' => '{{foo}}{{bar}}',
+                'template' => '{{> (pname foo) bar}}',
+                'data' => ['bar' => 'OK! SUBEXP+PARTIAL!', 'foo' => 'test/test3'],
                 'options' => new Options(
-                    helpers: [
-                        'foo' => function (HelperOptions $opt) {
-                            $opt->scope['change'] = true;
-                        },
-                        'bar' => function (HelperOptions $opt) {
-                            return $opt->scope['change'] ? 'ok' : 'bad';
-                        },
-                    ],
+                    partials: ['test/test3' => '{{.}}'],
                 ),
-                'expected' => 'ok',
+                'helpers' => ['pname' => fn($arg) => $arg],
+                'expected' => 'OK! SUBEXP+PARTIAL!',
             ],
 
             [
-                'id' => 278,
-                'template' => '{{#foo}}-{{#bar}}={{moo}}{{/bar}}{{/foo}}',
+                'template' => '{{> (partial_name_helper type)}}',
                 'data' => [
-                    'foo' => [
-                        ['bar' => 0, 'moo' => 'A'],
-                        ['bar' => 1, 'moo' => 'B'],
-                        ['bar' => false, 'moo' => 'C'],
-                        ['bar' => true, 'moo' => 'D'],
+                    'type' => 'dog',
+                    'name' => 'Lucky',
+                    'age' => 5,
+                ],
+                'options' => new Options(
+                    partials: [
+                        'people' => 'This is {{name}}, he is {{age}} years old.',
+                        'animal' => 'This is {{name}}, it is {{age}} years old.',
+                        'default' => 'This is {{name}}.',
                     ],
+                ),
+                'helpers' => [
+                    'partial_name_helper' => function (string $type) {
+                        return match ($type) {
+                            'man', 'woman' => 'people',
+                            'dog', 'cat' => 'animal',
+                            default => 'default',
+                        };
+                    },
                 ],
-                'expected' => '-=-=--=D',
+                'expected' => 'This is Lucky, it is 5 years old.',
             ],
 
             [
-                'id' => 281,
-                'template' => '{{echo (echo "foo bar (moo).")}}',
+                'template' => '{{> testpartial newcontext mixed=foo}}',
+                'data' => ['foo' => 'OK!', 'newcontext' => ['bar' => 'test']],
                 'options' => new Options(
-                    helpers: [
-                        'echo' => fn($arg1) => "ECHO: $arg1",
-                    ],
+                    partials: ['testpartial' => '{{bar}}-{{mixed}}'],
                 ),
-                'expected' => 'ECHO: ECHO: foo bar (moo).',
+                'expected' => 'test-OK!',
             ],
 
             [
-                'id' => 281,
-                'template' => "{{test 'foo bar' (toRegex '^(foo|bar|baz)')}}",
+                'desc' => 'ensure that partial names are correctly escaped',
+                'template' => '{{> "foo\button\'"}} {{> "bar\\\link"}}',
                 'options' => new Options(
-                    helpers: [
-                        'toRegex' => fn($regex) => "/$regex/",
-                        'test' => fn(string $str, string $regex) => (bool) preg_match($regex, $str),
+                    partials: [
+                        'foo\button\'' => 'Button!',
+                        'bar\\\link' => 'Link!',
                     ],
                 ),
-                'expected' => 'true',
+                'expected' => 'Button! Link!',
             ],
 
             [
-                'id' => 284,
-                'template' => '{{> foo}}',
+                'template' => '{{#each .}}->{{>tests/test3}}{{/each}}',
+                'data' => ['a', 'b', 'c'],
                 'options' => new Options(
-                    partials: ['foo' => "12'34"],
+                    partials: ['tests/test3' => 'New context:{{.}}'],
                 ),
-                'expected' => "12'34",
+                'expected' => "->New context:a->New context:b->New context:c",
             ],
-
             [
-                'id' => 284,
-                'template' => '{{> (lookup foo 2)}}',
-                'data' => ['foo' => ['a', 'b', 'c']],
+                'template' => '{{#each .}}->{{>tests/test3 ../foo}}{{/each}}',
+                'data' => ['a', 'foo' => ['d', 'e', 'f']],
                 'options' => new Options(
-                    partials: [
-                        'a' => '1st',
-                        'b' => '2nd',
-                        'c' => "3'r'd",
-                    ],
+                    partials: ['tests/test3' => 'New context:{{.}}'],
                 ),
-                'expected' => "3'r'd",
-            ],
-
-            [
-                'id' => 289,
-                'template' => "1\n2\n{{~foo~}}\n3",
-                'data' => ['foo' => 'OK'],
-                'expected' => "1\n2OK3",
-            ],
-
-            [
-                'id' => 289,
-                'template' => "1\n2\n{{#test}}\n3TEST\n{{/test}}\n4",
-                'data' => ['test' => 1],
-                'expected' => "1\n2\n3TEST\n4",
-            ],
-
-            [
-                'id' => 289,
-                'template' => "1\n2\n{{~#test}}\n3TEST\n{{/test}}\n4",
-                'data' => ['test' => 1],
-                'expected' => "1\n23TEST\n4",
-            ],
-
-            [
-                'id' => 289,
-                'template' => "1\n2\n{{#>test}}\n3TEST\n{{/test}}\n4",
-                'expected' => "1\n2\n3TEST\n4",
-            ],
-
-            [
-                'id' => 289,
-                'template' => "1\n2\n\n{{#>test}}\n3TEST\n{{/test}}\n4",
-                'expected' => "1\n2\n\n3TEST\n4",
-            ],
-
-            [
-                'id' => 289,
-                'template' => "1\n2\n\n{{#>test~}}\n\n3TEST\n{{/test}}\n4",
-                'expected' => "1\n2\n\n3TEST\n4",
-            ],
-
-            [
-                'id' => 290,
-                'template' => '{{foo}} }} OK',
-                'data' => [
-                    'foo' => 'YES',
-                ],
-                'expected' => 'YES }} OK',
-            ],
-
-            [
-                'id' => 290,
-                'template' => '{{foo}}{{#with "}"}}{{.}}{{/with}}OK',
-                'data' => [
-                    'foo' => 'YES',
-                ],
-                'expected' => 'YES}OK',
-            ],
-
-            [
-                'id' => 290,
-                'template' => '{ {{foo}}',
-                'data' => [
-                    'foo' => 'YES',
-                ],
-                'expected' => '{ YES',
+                'expected' => "->New context:d,e,f->New context:d,e,f",
             ],
 
             [
-                'id' => 290,
-                'template' => '{{#with "{{"}}{{.}}{{/with}}{{foo}}{{#with "{{"}}{{.}}{{/with}}',
-                'data' => [
-                    'foo' => 'YES',
-                ],
-                'expected' => '{{YES{{',
+                'template' => '{{#*inline}}{{/inline}}',
+                'expected' => '',
             ],
 
             [
-                'id' => 292,
-                'template' => '{ {{#>outer}} {{#>innerBlock}} Hello {{/innerBlock}} {{>simple}} {{/outer}} }',
+                'template' => <<<_tpl
+                    <div>
+                      {{> partialA}}
+                      {{> partialB}}
+                    </div>
+                    _tpl,
                 'options' => new Options(
                     partials: [
-                        'outer' => '( {{#>nested}} « {{>@partial-block}} » {{/nested}} )',
-                        'nested' => '[ {{>@partial-block}} ]',
-                        'innerBlock' => '< {{>@partial-block}} >',
-                        'simple' => 'World!',
+                        'partialA' => "<div>\n  Partial A\n  {{> partialB}}\n</div>\n",
+                        'partialB' => "<p>\n  Partial B\n</p>\n",
                     ],
                 ),
-                'expected' => '{ ( [  «  <  Hello  > World!  »  ] ) }',
+                'expected' => <<<_result
+                    <div>
+                      <div>
+                        Partial A
+                        <p>
+                          Partial B
+                        </p>
+                      </div>
+                      <p>
+                        Partial B
+                      </p>
+                    </div>
+                    _result,
             ],
 
             [
-                'id' => 295,
-                'template' => '{{> MyPartial (newObject name="John Doe") message=(echo message=(echo message="Hello World!"))}}',
+                'template' => "{{>test1}}\n  {{>test1}}\nDONE\n",
                 'options' => new Options(
-                    helpers: [
-                        'newObject' => fn(HelperOptions $options) => $options->hash,
-                        'echo' => fn(HelperOptions $options) => $options->hash['message'],
-                    ],
-                    partials: [
-                        'MyPartial' => '{{name}} says: "{{message}}"',
-                    ],
+                    partials: ['test1' => "1:A\n 2:B\n  3:C\n 4:D\n5:E\n"],
                 ),
-                'expected' => 'John Doe says: "Hello World!"',
+                'expected' => "1:A\n 2:B\n  3:C\n 4:D\n5:E\n  1:A\n   2:B\n    3:C\n   4:D\n  5:E\nDONE\n",
             ],
-
             [
-                'id' => 297,
-                'template' => '{{test "foo" prop="\" "}}',
+                'template' => "{{>test1}}\n  {{>test1}}\nDONE\n",
                 'options' => new Options(
-                    helpers: [
-                        'test' => function ($arg1, HelperOptions $options) {
-                            return "{$arg1} {$options->hash['prop']}";
-                        },
-                    ],
+                    preventIndent: true,
+                    partials: ['test1' => "1:A\n 2:B\n  3:C\n 4:D\n5:E\n"],
                 ),
-                'expected' => 'foo &quot; ',
+                'expected' => "1:A\n 2:B\n  3:C\n 4:D\n5:E\n  1:A\n 2:B\n  3:C\n 4:D\n5:E\nDONE\n",
             ],
 
             [
-                'id' => 298,
-                'template' => '{{test "\"\"\"" prop="\"\"\""}}',
+                'template' => "{{>test}}\n",
+                'data' => ['foo' => 'ha', 'bar' => 'hey'],
                 'options' => new Options(
-                    helpers: [
-                        'test' => function ($arg1, HelperOptions $options) {
-                            return "{$arg1} {$options->hash['prop']}";
-                        },
-                    ],
+                    partials: ['test' => "{{foo}}\n  {{bar}}\n"],
                 ),
-                'expected' => '&quot;&quot;&quot; &quot;&quot;&quot;',
+                'expected' => "ha\n  hey\n",
             ],
             [
-                'template' => "{{test '\'\'\'' prop='\'\'\''}}",
+                'template' => " {{>test}}\n",
+                'data' => ['foo' => 'ha', 'bar' => 'hey'],
                 'options' => new Options(
-                    helpers: [
-                        'test' => function ($arg1, HelperOptions $options) {
-                            return "{$arg1} {$options->hash['prop']}";
-                        },
-                    ],
+                    preventIndent: true,
+                    partials: ['test' => "{{foo}}\n  {{bar}}\n"],
                 ),
-                'expected' => '&#x27;&#x27;&#x27; &#x27;&#x27;&#x27;',
+                'expected' => " ha\n  hey\n",
             ],
-
             [
-                'id' => 302,
-                'template' => "{{#*inline \"t1\"}}{{#if imageUrl}}<span />{{else}}<div />{{/if}}{{/inline}}{{#*inline \"t2\"}}{{#if imageUrl}}<span />{{else}}<div />{{/if}}{{/inline}}{{#*inline \"t3\"}}{{#if imageUrl}}<span />{{else}}<div />{{/if}}{{/inline}}",
-                'expected' => '',
+                'template' => "\n {{>test}}\n",
+                'data' => ['foo' => 'ha', 'bar' => 'hey'],
+                'options' => new Options(
+                    preventIndent: true,
+                    partials: ['test' => "{{foo}}\n  {{bar}}\n"],
+                ),
+                'expected' => "\n ha\n  hey\n",
             ],
 
             [
-                'id' => 303,
-                'template' => '{{#*inline "t1"}} {{#if url}} <a /> {{else if imageUrl}} <img /> {{else}} <span /> {{/if}} {{/inline}}',
-                'expected' => '',
+                'template' => "ST:\n{{#foo}}\n {{>test1}}\n{{/foo}}\nOK\n",
+                'data' => ['foo' => [1, 2]],
+                'options' => new Options(
+                    partials: ['test1' => "1:A\n 2:B({{@index}})\n"],
+                ),
+                'expected' => "ST:\n 1:A\n  2:B(0)\n 1:A\n  2:B(1)\nOK\n",
             ],
 
             [
-                'id' => 310,
-                'template' => <<<_tpl
-                    {{#custom-block 'some-text' data=(custom-helper
-                      opt_a='foo'
-                      opt_b='bar'
-                    )}}...{{/custom-block}}
-                    _tpl,
+                'template' => '{{>foo}} and {{>bar}}',
                 'options' => new Options(
-                    helpers: [
-                        'custom-block' => function ($string, HelperOptions $opts) {
-                            return strtoupper($string) . '-' . $opts->hash['data'] . $opts->fn();
-                        },
-                        'custom-helper' => function (HelperOptions $options) {
-                            return $options->hash['opt_a'] . $options->hash['opt_b'];
-                        },
-                    ],
+                    partialResolver: fn(string $name) => "PARTIAL: $name",
                 ),
-                'expected' => 'SOME-TEXT-foobar...',
+                'expected' => 'PARTIAL: foo and PARTIAL: bar',
             ],
 
             [
-                'id' => 313,
-                'template' => <<<_tpl
-                    {{#if conditionA}}
-                      {{#if conditionA1}}
-                        Do something then do more stuff conditionally
-                        {{#if conditionA1.x}}
-                          Do something here
-                        {{else if conditionA1.y}}
-                          Do something else here
-                        {{/if}}
-                      {{/if}}
-                    {{else if conditionB}}
-                      Do something else
-                    {{else}}
-                      Finally, do this last thing if all else fails
-                    {{/if}}
-                    _tpl,
-                'expected' => "  Finally, do this last thing if all else fails\n",
+                'desc' => '{{#* inline}} partials registered inside a block section do not leak out after the block ends',
+                'template' => '{{#* inline "p"}}BEFORE{{/inline}}{{#section}}{{#* inline "p"}}INSIDE{{/inline}}{{> p}}{{/section}}{{> p}}',
+                'options' => new Options(knownHelpersOnly: true),
+                'data' => ['section' => ['x' => 1]],
+                'expected' => 'INSIDEBEFORE',
             ],
 
             [
-                'id' => 315,
-                'template' => '{{#each foo}}#{{@key}}({{@index}})={{.}}-{{moo}}-{{@irr}}{{/each}}',
-                'options' => new Options(
-                    helpers: [
-                        'moo' => function (HelperOptions $opts) {
-                            $opts->data['irr'] = '123';
-                            return '321';
-                        },
-                    ],
-                ),
-                'data' => [
-                    'foo' => [
-                        'a' => 'b',
-                        'c' => 'd',
-                        'e' => 'f',
-                    ],
-                ],
-                'expected' => '#a(0)=b-321-123#c(1)=d-321-123#e(2)=f-321-123',
+                'template' => '{{#>foo}}inline\'partial{{/foo}}',
+                'expected' => 'inline\'partial',
             ],
 
             [
-                'id' => 316,
-                'template' => '{{> StrongPartial text="Use the syntax: {{varName}}."}}',
-                'options' => new Options(
-                    partials: [
-                        'StrongPartial' => '<strong>{{text}}</strong>',
-                    ],
-                ),
-                'data' => [
-                    'varName' => 'unused',
-                ],
-                'expected' => '<strong>Use the syntax: {{varName}}.</strong>',
+                'template' => "{{#> testPartial}}\n before\n  {{#> innerPartial}}\n   inner!\n  {{/innerPartial}}\n after\n {{/testPartial}}",
+                'expected' => " before\n   inner!\n after\n",
             ],
+        ];
+    }
 
+    /**
+     * @return list<RegIssue>
+     */
+    public static function builtInProvider(): array
+    {
+        return [
             [
-                'id' => 344,
-                'template' => '{{{{raw}}}} {{bar}} {{{{/raw}}}} {{bar}}',
-                'data' => [
-                    'raw' => true,
-                    'bar' => 'content',
-                ],
-                'expected' => ' {{bar}}  content',
+                'desc' => 'LNC #81',
+                'template' => '{{#with ../person}} {{^name}} Unknown {{/name}} {{/with}}?!',
+                'data' => ['parent?!' => ['A', 'B', 'bar' => ['C', 'D', 'E']]],
+                'expected' => '?!',
             ],
 
             [
-                'id' => 350,
-                'template' => <<<_hbs
-                    Before: {{var}}
-                    (Setting Variable) {{setvar "var" "Foo"}}
-                    After: {{var}}
-                    _hbs,
-                'data' => ['var' => 'value'],
-                'options' => new Options(
-                    helpers: [
-                        'setvar' => function ($name, $value, HelperOptions $options) {
-                            $options->data['root'][$name] = $value;
-                        },
-                    ],
-                ),
-                'expected' => "Before: value\n(Setting Variable) \nAfter: Foo",
+                'desc' => 'LNC #109',
+                'template' => '{{#if "OK"}}it\'s great!{{/if}}',
+                'options' => new Options(noEscape: true),
+                'expected' => 'it\'s great!',
             ],
 
             [
-                'id' => 357,
-                'template' => '{{echo (echo "foobar(moo).")}}',
-                'options' => new Options(
-                    helpers: [
-                        'echo' => fn($arg1) => "ECHO: $arg1",
-                    ],
-                ),
-                'expected' => 'ECHO: ECHO: foobar(moo).',
+                'desc' => 'LNC #199',
+                'template' => '{{#if foo}}1{{else if bar}}2{{else}}3{{/if}}',
+                'expected' => '3',
             ],
             [
-                'id' => 357,
-                'template' => "{{{debug (debug 'foobar(moo).')}}}",
-                'options' => new Options(
-                    helpers: [
-                        'debug' => fn($arg1) => "ECHO: $arg1",
-                    ],
-                ),
-                'expected' => 'ECHO: ECHO: foobar(moo).',
+                'desc' => 'LNC #199',
+                'template' => '{{#if foo}}1{{else if bar}}2{{/if}}',
+                'data' => ['bar' => true],
+                'expected' => '2',
             ],
             [
-                'id' => 357,
-                'template' => '{{echo (echo "foobar(moo)." (echo "moobar(foo)"))}}',
-                'options' => new Options(
-                    helpers: [
-                        'echo' => fn($arg1) => "ECHO: $arg1",
-                    ],
-                ),
-                'expected' => 'ECHO: ECHO: foobar(moo).',
+                'desc' => 'LNC #200',
+                'template' => '{{#unless 0}}1{{else if foo}}2{{else}}3{{/unless}}',
+                'data' => ['foo' => false],
+                'expected' => '1',
             ],
-
             [
-                'id' => 367,
-                'template' => "{{#each (myfunc 'foo(bar)' ) }}{{.}},{{/each}}",
-                'options' => new Options(
-                    helpers: [
-                        'myfunc' => fn($arg) => explode('(', $arg),
-                    ],
-                ),
-                'expected' => 'foo,bar),',
+                'desc' => 'LNC #201',
+                'template' => '{{#unless 0 includeZero=true}}1{{else if foo}}2{{else}}3{{/unless}}',
+                'data' => ['foo' => true],
+                'expected' => '2',
             ],
-
             [
-                'id' => 369,
-                'template' => '{{#each paragraphs}}<p>{{this}}</p>{{else}}<p class="empty">{{foo}}</p>{{/each}}',
-                'data' => ['foo' => 'bar'],
-                'expected' => '<p class="empty">bar</p>',
+                'desc' => 'LNC #202',
+                'template' => '{{#unless 0 includeZero=true}}1{{else if foo}}2{{else}}3{{/unless}}',
+                'data' => ['foo' => false],
+                'expected' => '3',
             ],
 
             [
-                'id' => 370,
-                'template' => '{{@root.items.length}}',
-                'data' => ['items' => [1, 2, 3]],
-                'expected' => '3',
+                'desc' => 'LNC #206',
+                'template' => '{{#with bar}}{{#../foo}}YES!{{/../foo}}{{/with}}',
+                'data' => ['foo' => 999, 'bar' => true],
+                'expected' => 'YES!',
             ],
 
             [
-                'id' => 371,
-                'template' => <<<_tpl
-                    {{#myeach '[{"a":"ayy", "b":"bee"},{"a":"zzz", "b":"ccc"}]' as | newContext index | }}
-                    Foo {{newContext.a}} {{index}}
-                    {{/myeach}}
-                    _tpl,
-                'options' => new Options(
-                    helpers: [
-                        'myeach' => function ($context, HelperOptions $options) {
-                            $theArray = json_decode($context, true);
-                            if (!is_array($theArray)) {
-                                return '';
-                            }
-
-                            $ret = '';
-                            foreach ($theArray as $i => $value) {
-                                $ret .= $options->fn([], ['blockParams' => [$value, $i]]);
-                            }
-                            return $ret;
-                        },
-                    ],
-                ),
-                'expected' => "Foo ayy 0\nFoo zzz 1\n",
+                'desc' => 'LNC #213',
+                'template' => '{{#with .}}bad{{else}}Good!{{/with}}',
+                'expected' => 'Good!',
             ],
 
             [
-                'template' => '{{#each . as |v k|}}#{{k}}{{/each}}',
-                'data' => ['a' => [], 'c' => []],
-                'expected' => '#a#c',
+                'desc' => 'LNC #227',
+                'template' => '{{#if moo}}A{{else if bar}}B{{else with foo}}C{{.}}{{/if}}',
+                'data' => ['foo' => 'D'],
+                'expected' => 'CD',
+            ],
+            [
+                'desc' => 'LNC #227',
+                'template' => '{{#if moo}}A{{else if bar}}B{{else each foo}}C{{.}}{{/if}}',
+                'data' => ['foo' => [1, 3, 5]],
+                'expected' => 'C1C3C5',
             ],
 
             [
-                'template' => '{{testNull null undefined 1}}',
-                'data' => 'test',
-                'options' => new Options(
-                    helpers: [
-                        'testNull' => function ($arg1, $arg2) {
-                            return ($arg1 === null && $arg2 === null) ? 'YES!' : 'no';
-                        },
-                    ],
-                ),
-                'expected' => 'YES!',
+                'desc' => 'LNC #229',
+                'template' => '{{#if foo.bar.moo}}TRUE{{else}}FALSE{{/if}}',
+                'expected' => 'FALSE',
             ],
 
             [
-                'template' => '{{> (pname foo) bar}}',
-                'data' => ['bar' => 'OK! SUBEXP+PARTIAL!', 'foo' => 'test/test3'],
-                'options' => new Options(
-                    helpers: [
-                        'pname' => fn($arg) => $arg,
-                    ],
-                    partials: ['test/test3' => '{{.}}'],
-                ),
-                'expected' => 'OK! SUBEXP+PARTIAL!',
+                'desc' => 'LNC #243',
+                'template' => '{{lookup . 3}}',
+                'data' => ['3' => 'OK'],
+                'expected' => 'OK',
+            ],
+            [
+                'desc' => 'LNC #243',
+                'template' => '{{lookup . "test"}}',
+                'data' => ['test' => 'OK'],
+                'expected' => 'OK',
             ],
 
             [
-                'template' => '{{> (partial_name_helper type)}}',
+                'desc' => 'LNC #245',
+                'template' => '{{#each foo}}{{#with .}}{{bar}}-{{../../name}}{{/with}}{{/each}}',
                 'data' => [
-                    'type' => 'dog',
-                    'name' => 'Lucky',
-                    'age' => 5,
+                    'name' => 'bad',
+                    'foo' => [['bar' => 1], ['bar' => 2]],
                 ],
-                'options' => new Options(
-                    helpers: [
-                        'partial_name_helper' => function (string $type) {
-                            return match ($type) {
-                                'man', 'woman' => 'people',
-                                'dog', 'cat' => 'animal',
-                                default => 'default',
-                            };
-                        },
-                    ],
-                    partials: [
-                        'people' => 'This is {{name}}, he is {{age}} years old.',
-                        'animal' => 'This is {{name}}, it is {{age}} years old.',
-                        'default' => 'This is {{name}}.',
-                    ],
-                ),
-                'expected' => 'This is Lucky, it is 5 years old.',
+                'expected' => '1-2-',
             ],
 
             [
-                'template' => '{{> testpartial newcontext mixed=foo}}',
-                'data' => ['foo' => 'OK!', 'newcontext' => ['bar' => 'test']],
-                'options' => new Options(
-                    partials: ['testpartial' => '{{bar}}-{{mixed}}'],
-                ),
-                'expected' => 'test-OK!',
+                'desc' => 'LNC #254',
+                'template' => '{{#if a}}a{{else if b}}b{{else}}c{{/if}}{{#if a}}a{{else if b}}b{{/if}}',
+                'data' => ['b' => 1],
+                'expected' => 'bb',
             ],
 
             [
-                'template' => '{{[helper]}}',
-                'options' => new Options(
-                    helpers: [
-                        'helper' => fn() => 'DEF',
-                    ],
-                ),
-                'data' => [],
-                'expected' => 'DEF',
+                'desc' => 'LNC #261',
+                'template' => '{{#each foo as |bar|}}?{{bar.[0]}}{{/each}}',
+                'data' => ['foo' => [['a'], ['b']]],
+                'expected' => '?a?b',
             ],
 
             [
-                'template' => '{{#[helper3]}}ABC{{/[helper3]}}',
-                'options' => new Options(
-                    helpers: [
-                        'helper3' => fn() => 'DEF',
-                    ],
-                ),
-                'data' => [],
-                'expected' => 'DEF',
+                'desc' => 'LNC #267',
+                'template' => '{{#each . as |v k|}}#{{k}}>{{v}}|{{.}}{{/each}}',
+                'data' => ['a' => 'b', 'c' => 'd'],
+                'expected' => '#a>b|b#c>d|d',
             ],
 
             [
-                'template' => '{{hash abc=["def=123"]}}',
-                'options' => new Options(
-                    helpers: [
-                        'hash' => function (HelperOptions $options) {
-                            $ret = '';
-                            foreach ($options->hash as $k => $v) {
-                                $ret .= "$k : $v,";
-                            }
-                            return $ret;
-                        },
-                    ],
-                ),
-                'data' => ['"def=123"' => 'La!'],
-                'expected' => 'abc : La!,',
+                'desc' => 'LNC #313',
+                'template' => <<<_tpl
+                    {{#if conditionA}}
+                      {{#if conditionA1}}
+                        Do something then do more stuff conditionally
+                        {{#if conditionA1.x}}
+                          Do something here
+                        {{else if conditionA1.y}}
+                          Do something else here
+                        {{/if}}
+                      {{/if}}
+                    {{else if conditionB}}
+                      Do something else
+                    {{else}}
+                      Finally, do this last thing if all else fails
+                    {{/if}}
+                    _tpl,
+                'expected' => "  Finally, do this last thing if all else fails\n",
             ],
 
             [
-                'template' => '{{hash abc=[\'def=123\']}}',
-                'options' => new Options(
-                    helpers: [
-                        'hash' => function (HelperOptions $options) {
-                            $ret = '';
-                            foreach ($options->hash as $k => $v) {
-                                $ret .= "$k : $v,";
-                            }
-                            return $ret;
-                        },
-                    ],
-                ),
-                'data' => ["'def=123'" => 'La!'],
-                'expected' => 'abc : La!,',
+                'desc' => 'LNC #369',
+                'template' => '{{#each paragraphs}}<p>{{this}}</p>{{else}}<p class="empty">{{foo}}</p>{{/each}}',
+                'data' => ['foo' => 'bar'],
+                'expected' => '<p class="empty">bar</p>',
             ],
 
             [
-                'template' => 'ABC{{#block "YES!"}}DEF{{foo}}GHI{{else}}NO~{{/block}}JKL',
-                'options' => new Options(
-                    helpers: [
-                        'block' => function ($name, HelperOptions $options) {
-                            return "1-$name-2-" . $options->fn() . '-3';
-                        },
-                    ],
-                ),
-                'data' => ['foo' => 'bar'],
-                'expected' => 'ABC1-YES!-2-DEFbarGHI-3JKL',
+                'desc' => '#3',
+                'template' => 'ok{{{lookup . "missing"}}}',
+                'expected' => 'ok',
             ],
 
             [
-                'template' => '-{{getroot}}=',
-                'options' => new Options(
-                    helpers: [
-                        'getroot' => fn(HelperOptions $options) => $options->data['root'],
-                    ],
-                ),
-                'data' => 'ROOT!',
-                'expected' => '-ROOT!=',
+                'template' => '{{#each . as |v k|}}#{{k}}{{/each}}',
+                'data' => ['a' => [], 'c' => []],
+                'expected' => '#a#c',
+            ],
+            [
+                'template' => '{{#each . as |item|}}{{item.foo}}{{/each}}',
+                'data' => [['foo' => 'bar'], ['foo' => 'baz']],
+                'expected' => 'barbaz',
             ],
 
             [
@@ -1833,19 +1658,6 @@ public static function issueProvider(): array
                 'expected' => 'A-=b,a,0,0~%-=d,c,0,1~%-=f,e,0,2~%B',
             ],
 
-            [
-                'template' => 'ABC{{#block "YES!"}}TRUE{{else}}DEF{{foo}}GHI{{/block}}JKL',
-                'options' => new Options(
-                    helpers: [
-                        'block' => function ($name, HelperOptions $options) {
-                            return "1-$name-2-" . $options->inverse() . '-3';
-                        },
-                    ],
-                ),
-                'data' => ['foo' => 'bar'],
-                'expected' => 'ABC1-YES!-2-DEFbarGHI-3JKL',
-            ],
-
             [
                 'template' => '{{#each .}}{{..}}>{{/each}}',
                 'data' => ['a', 'b', 'c'],
@@ -1853,445 +1665,372 @@ public static function issueProvider(): array
             ],
 
             [
-                // ensure that partial names are correctly escaped
-                'template' => '{{> "foo\button\'"}} {{> "bar\\\link"}}',
-                'options' => new Options(
-                    partials: [
-                        'foo\button\'' => 'Button!',
-                        'bar\\\link' => 'Link!',
-                    ],
-                ),
-                'expected' => 'Button! Link!',
+                'desc' => 'inverted each: non-empty array renders nothing, empty array renders body',
+                'template' => '{{^each items}}EMPTY{{/each}}',
+                'data' => ['items' => ['a', 'b']],
+                'expected' => '',
+            ],
+            [
+                'template' => '{{^each items}}EMPTY{{/each}}',
+                'data' => ['items' => []],
+                'expected' => 'EMPTY',
+            ],
+
+            [
+                'desc' => 'inverted if with else clause',
+                'template' => '{{^if exists}}bad{{else}}OK{{/if}}',
+                'data' => ['exists' => true],
+                'expected' => 'OK',
             ],
 
             [
-                // ensure that block parameters are correctly escaped
+                'desc' => 'ensure that block parameters are correctly escaped',
                 'template' => "{{#each items as |[it\\'s] item|}}{{item}}{{/each}}",
                 'data' => ['items' => ['one', 'two']],
                 'expected' => '01',
             ],
 
             [
-                'template' => '{{#each .}}->{{>tests/test3}}{{/each}}',
-                'data' => ['a', 'b', 'c'],
-                'options' => new Options(
-                    partials: ['tests/test3' => 'New context:{{.}}'],
-                ),
-                'expected' => "->New context:a->New context:b->New context:c",
+                'template' => '{{#with "{{"}}{{.}}{{/with}}',
+                'expected' => '{{',
+            ],
+            [
+                'template' => '{{#with true}}{{.}}{{/with}}',
+                'expected' => 'true',
             ],
 
             [
-                'template' => '{{#each .}}->{{>tests/test3 ../foo}}{{/each}}',
-                'data' => ['a', 'foo' => ['d', 'e', 'f']],
-                'options' => new Options(
-                    partials: ['tests/test3' => 'New context:{{.}}'],
-                ),
-                'expected' => "->New context:d,e,f->New context:d,e,f",
+                'template' => '{{#if .}}YES{{else}}NO{{/if}}',
+                'data' => true,
+                'expected' => 'YES',
             ],
 
             [
-                'template' => '{{{"{{"}}}',
-                'data' => ['{{' => ':D'],
-                'expected' => ':D',
+                'template' => '{{#with items}}OK!{{/with}}',
+                'expected' => '',
+            ],
+            [
+                'template' => '{{log}}',
+                'expected' => '',
             ],
 
             [
-                'template' => '{{{\'{{\'}}}',
-                'data' => ['{{' => ':D'],
-                'expected' => ':D',
+                'template' => '{{#with people}}Yes , {{name}}{{else}}No, {{name}}{{/with}}',
+                'data' => ['people' => ['name' => 'Peter'], 'name' => 'NoOne'],
+                'expected' => 'Yes , Peter',
             ],
 
             [
-                'template' => '{{#with "{{"}}{{.}}{{/with}}',
-                'expected' => '{{',
+                'template' => '{{#with people}}Yes , {{name}}{{else}}No, {{name}}{{/with}}',
+                'data' => ['name' => 'NoOne'],
+                'expected' => 'No, NoOne',
             ],
+
             [
-                'template' => '{{#with true}}{{.}}{{/with}}',
-                'expected' => 'true',
+                'template' => '{{#each foo}}{{@key}}: {{.}},{{/each}}',
+                'data' => ['foo' => [1, 'a' => 'b', 5]],
+                'expected' => '0: 1,a: b,1: 5,',
             ],
 
             [
-                'template' => '{{good_helper}}',
-                'options' => new Options(
-                    helpers: [
-                        'good_helper' => fn() => 'OK!',
-                    ],
-                ),
-                'expected' => 'OK!',
+                'template' => '{{#each foo}}{{@key}}: {{.}},{{/each}}',
+                'data' => ['foo' => new TwoDimensionIterator(2, 3)],
+                'expected' => '0x0: 0,1x0: 0,0x1: 0,1x1: 1,0x2: 0,1x2: 2,',
             ],
 
             [
-                'template' => '-{{.}}-',
-                'data' => 'abc',
-                'expected' => '-abc-',
+                'template' => "   {{#if foo}}\nYES\n{{else}}\nNO\n{{/if}}\n",
+                'expected' => "NO\n",
             ],
 
             [
-                'template' => '-{{this}}-',
-                'data' => 123,
-                'expected' => '-123-',
+                'template' => "  {{#each foo}}\n{{@key}}: {{.}}\n{{/each}}\nDONE",
+                'data' => ['foo' => ['a' => 'A', 'b' => 'BOY!']],
+                'expected' => "a: A\nb: BOY!\nDONE",
             ],
 
             [
-                'template' => '{{#if .}}YES{{else}}NO{{/if}}',
-                'data' => true,
-                'expected' => 'YES',
+                'template' => "\n{{#each foo~}}\n  <li>{{.}}</li>\n{{~/each}}\n\nOK",
+                'data' => ['foo' => ['ha', 'hu']],
+                'expected' => "\n<li>ha</li><li>hu</li>\nOK",
             ],
+        ];
+    }
 
-            // data can contain closures
+    /**
+     * @return list<RegIssue>
+     */
+    public static function syntaxProvider(): array
+    {
+        return [
             [
-                'template' => '{{foo}}',
-                'data' => ['foo' => fn() => 'OK'],
-                'expected' => 'OK',
+                'desc' => 'LNC #39',
+                'template' => '{{{tt}}}',
+                'data' => ['tt' => 'bla bla bla'],
+                'expected' => 'bla bla bla',
             ],
-            // but callable strings or arrays should NOT be treated as functions
+
             [
-                'template' => '{{foo}}',
-                'data' => ['foo' => 'hrtime'],
-                'expected' => 'hrtime',
+                'desc' => 'LNC #46',
+                'template' => '{{{this.id}}}, {{a.id}}',
+                'data' => ['id' => 'bla bla bla', 'a' => ['id' => 'OK!']],
+                'expected' => 'bla bla bla, OK!',
             ],
+
             [
-                'template' => '{{#foo}}OK{{else}}bad{{/foo}}',
-                'data' => ['foo' => 'is_string'],
-                'expected' => 'OK',
+                'desc' => 'LNC #66',
+                'template' => '{{&foo}} , {{foo}}, {{{foo}}}',
+                'data' => ['foo' => 'Test & " \' :)'],
+                'expected' => 'Test & " \' :) , Test &amp; &quot; &#x27; :), Test & " \' :)',
             ],
 
             [
-                'template' => '{{foo}}',
-                'data' => ['foo' => 'OK'],
-                'expected' => 'OK',
+                'desc' => 'LNC #90',
+                'template' => '{{#items}}{{#value}}{{.}}{{/value}}{{/items}}',
+                'data' => ['items' => [['value' => '123']]],
+                'expected' => '123',
             ],
 
             [
-                'template' => '{{foo}}',
-                'expected' => '',
+                'desc' => 'LNC #125',
+                'template' => '{{[ abc]}}',
+                'data' => [' abc' => 'YES!'],
+                'expected' => 'YES!',
             ],
+
             [
-                'template' => '{{foo.bar}}',
-                'expected' => '',
+                'desc' => 'LNC #128',
+                'template' => 'foo: {{foo}} , parent foo: {{../foo}}',
+                'data' => ['foo' => 'OK'],
+                'expected' => 'foo: OK , parent foo: ',
             ],
+
             [
-                'template' => '{{foo.bar}}',
-                'data' => ['foo' => []],
-                'expected' => '',
+                'desc' => 'LNC #154',
+                'template' => 'O{{! this is comment ! ... }}K!',
+                'expected' => "OK!",
             ],
+
             [
-                'template' => '{{#with items}}OK!{{/with}}',
-                'expected' => '',
+                'desc' => 'LNC #159',
+                'template' => '{{#.}}true{{else}}false{{/.}}',
+                'data' => new \ArrayObject(),
+                'expected' => "false",
             ],
+
             [
-                'template' => '{{log}}',
-                'expected' => '',
+                'desc' => 'non-empty list in a section with {{else}} must iterate, not show the else branch',
+                'template' => '{{#items}}{{.}},{{else}}empty{{/items}}',
+                'data' => ['items' => ['a', 'b', 'c']],
+                'expected' => 'a,b,c,',
             ],
             [
-                'template' => '{{#*inline}}{{/inline}}',
-                'expected' => '',
+                'desc' => 'non-empty ArrayObject should also iterate',
+                'template' => '{{#.}}{{@index}}:{{.}},{{else}}empty{{/.}}',
+                'data' => new \ArrayObject(['x', 'y']),
+                'expected' => '0:x,1:y,',
             ],
 
             [
-                'template' => '{{#myif foo}}YES{{else}}NO{{/myif}}',
-                'options' => new Options(
-                    helpers: ['myif' => $myIf],
-                ),
-                'expected' => 'NO',
+                'desc' => 'LNC #169',
+                'template' => '{{{{a}}}}true{{else}}false{{{{/a}}}}',
+                'data' => ['a' => true],
+                'expected' => "true{{else}}false",
             ],
 
             [
-                'template' => '{{#myif foo}}YES{{else}}NO{{/myif}}',
-                'data' => ['foo' => 1],
-                'options' => new Options(
-                    helpers: ['myif' => $myIf],
-                ),
-                'expected' => 'YES',
+                'desc' => 'LNC #175',
+                'template' => 'a{{!-- {{each}} haha {{/each}} --}}b',
+                'expected' => 'ab',
             ],
 
             [
-                'template' => '{{#mylogic 0 foo bar}}YES:{{.}}{{else}}NO:{{.}}{{/mylogic}}',
-                'data' => ['foo' => 'FOO', 'bar' => 'BAR'],
-                'options' => new Options(
-                    helpers: ['mylogic' => $myLogic],
-                ),
-                'expected' => 'NO:BAR',
+                'desc' => 'LNC #177',
+                'template' => '{{{{a}}}} {{{{b}}}} {{{{/b}}}} {{{{/a}}}}',
+                'data' => ['a' => true],
+                'expected' => ' {{{{b}}}} {{{{/b}}}} ',
             ],
-
             [
-                'template' => '{{#mylogic true foo bar}}YES:{{.}}{{else}}NO:{{.}}{{/mylogic}}',
-                'data' => ['foo' => 'FOO', 'bar' => 'BAR'],
-                'options' => new Options(
-                    helpers: ['mylogic' => $myLogic],
-                ),
-                'expected' => 'YES:FOO',
+                'desc' => 'LNC #177',
+                'template' => '{{{{a}}}} {{{{b}}}} {{{{/b}}}} {{{{/a}}}}',
+                'data' => ['a' => true],
+                'helpers' => ['a' => fn(HelperOptions $options) => $options->fn()],
+                'expected' => ' {{{{b}}}} {{{{/b}}}} ',
+            ],
+            [
+                'desc' => 'LNC #177',
+                'template' => '{{{{a}}}} {{{{b}}}} {{{{/b}}}} {{{{/a}}}}',
+                'expected' => '',
             ],
 
             [
-                'template' => '{{#mywith foo}}YA: {{name}}{{/mywith}}',
-                'data' => ['name' => 'OK?', 'foo' => ['name' => 'OK!']],
-                'options' => new Options(
-                    helpers: ['mywith' => $myWith],
-                ),
-                'expected' => 'YA: OK!',
+                'desc' => 'LNC #216',
+                'template' => '{{foo.length}}',
+                'data' => ['foo' => []],
+                'expected' => '0',
+            ],
+            [
+                'desc' => 'LNC #255',
+                'template' => '{{foo.length}}',
+                'data' => ['foo' => [1, 2]],
+                'expected' => '2',
             ],
 
             [
-                'template' => '{{mydash \'abc\' "dev"}}',
-                'data' => ['a' => 'a', 'b' => 'b', 'c' => ['c' => 'c'], 'd' => 'd', 'e' => 'e'],
-                'options' => new Options(
-                    helpers: ['mydash' => $myDash],
-                ),
-                'expected' => 'abc-dev',
+                'desc' => 'LNC #278',
+                'template' => '{{#foo}}-{{#bar}}={{moo}}{{/bar}}{{/foo}}',
+                'data' => [
+                    'foo' => [
+                        ['bar' => 0, 'moo' => 'A'],
+                        ['bar' => 1, 'moo' => 'B'],
+                        ['bar' => false, 'moo' => 'C'],
+                        ['bar' => true, 'moo' => 'D'],
+                    ],
+                ],
+                'expected' => '-=-=--=D',
             ],
 
             [
-                'template' => '{{mydash \'a b c\' "d e f"}}',
-                'data' => ['a' => 'a', 'b' => 'b', 'c' => ['c' => 'c'], 'd' => 'd', 'e' => 'e'],
-                'options' => new Options(
-                    helpers: ['mydash' => $myDash],
-                ),
-                'expected' => 'a b c-d e f',
+                'desc' => 'LNC #289',
+                'template' => "1\n2\n{{~foo~}}\n3",
+                'data' => ['foo' => 'OK'],
+                'expected' => "1\n2OK3",
             ],
-
             [
-                'template' => '{{mydash "abc" (test_array 1)}}',
-                'data' => ['a' => 'a', 'b' => 'b', 'c' => ['c' => 'c'], 'd' => 'd', 'e' => 'e'],
-                'options' => new Options(
-                    helpers: [
-                        'mydash' => $myDash,
-                        'test_array' => function ($input) {
-                            return is_array($input) ? 'IS_ARRAY' : 'NOT_ARRAY';
-                        },
-                    ],
-                ),
-                'expected' => 'abc-NOT_ARRAY',
+                'desc' => 'LNC #289',
+                'template' => <<<'HBS'
+                    1
+                    2
+                    {{#test}}
+                    3TEST
+                    {{/test}}
+                    4
+                    HBS,
+                'data' => ['test' => 1],
+                'expected' => "1\n2\n3TEST\n4",
             ],
-
             [
-                'template' => '{{mydash "abc" (myjoin a b)}}',
-                'data' => ['a' => 'a', 'b' => 'b', 'c' => ['c' => 'c'], 'd' => 'd', 'e' => 'e'],
-                'options' => new Options(
-                    helpers: [
-                        'mydash' => $myDash,
-                        'myjoin' => function ($a, $b) {
-                            return "$a$b";
-                        },
-                    ],
-                ),
-                'expected' => 'abc-ab',
+                'desc' => 'LNC #289',
+                'template' => "1\n2\n{{~#test}}\n3TEST\n{{/test}}\n4",
+                'data' => ['test' => 1],
+                'expected' => "1\n23TEST\n4",
             ],
-
             [
-                'template' => '{{#equals my_var false}}Equal to false{{else}}Not equal{{/equals}}',
-                'data' => ['my_var' => 0],
-                'options' => new Options(
-                    helpers: ['equals' => $equals],
-                ),
-                'expected' => 'Equal to false',
+                'desc' => 'LNC #289',
+                'template' => "1\n2\n{{#>test}}\n3TEST\n{{/test}}\n4",
+                'expected' => "1\n2\n3TEST\n4",
             ],
             [
-                'template' => '{{#equals my_var false}}Equal to false{{else}}Not equal{{/equals}}',
-                'data' => ['my_var' => 1],
-                'options' => new Options(
-                    helpers: ['equals' => $equals],
-                ),
-                'expected' => 'Not equal',
+                'desc' => 'LNC #289',
+                'template' => "1\n2\n\n{{#>test}}\n3TEST\n{{/test}}\n4",
+                'expected' => "1\n2\n\n3TEST\n4",
             ],
             [
-                'template' => '{{#equals my_var false}}Equal to false{{else}}Not equal{{/equals}}',
-                'data' => [],
-                'options' => new Options(
-                    helpers: ['equals' => $equals],
-                ),
-                'expected' => 'Not equal',
+                'desc' => 'LNC #289',
+                'template' => "1\n2\n\n{{#>test~}}\n\n3TEST\n{{/test}}\n4",
+                'expected' => "1\n2\n\n3TEST\n4",
             ],
 
             [
-                'template' => '{{#with people}}Yes , {{name}}{{else}}No, {{name}}{{/with}}',
-                'data' => ['people' => ['name' => 'Peter'], 'name' => 'NoOne'],
-                'expected' => 'Yes , Peter',
+                'desc' => 'LNC #290',
+                'template' => '{{foo}} }} OK',
+                'data' => ['foo' => 'YES'],
+                'expected' => 'YES }} OK',
             ],
-
             [
-                'template' => '{{#with people}}Yes , {{name}}{{else}}No, {{name}}{{/with}}',
-                'data' => ['name' => 'NoOne'],
-                'expected' => 'No, NoOne',
+                'desc' => 'LNC #290',
+                'template' => '{{foo}}{{#with "}"}}{{.}}{{/with}}OK',
+                'data' => ['foo' => 'YES'],
+                'expected' => 'YES}OK',
             ],
-
             [
-                'template' => <<<VAREND
-                    <ul>
-                     <li>1. {{helper1 name}}</li>
-                     <li>2. {{helper1 value}}</li>
-                     <li>3. {{helper2 name}}</li>
-                     <li>4. {{helper2 value}}</li>
-                     <li>9. {{link name}}</li>
-                     <li>10. {{link value}}</li>
-                     <li>11. {{alink url text}}</li>
-                     <li>12. {{{alink url text}}}</li>
-                    </ul>
-                    VAREND
-                ,
-                'data' => ['name' => 'John', 'value' => 10000, 'url' => 'http://yahoo.com', 'text' => 'You&Me!'],
-                'options' => new Options(
-                    helpers: [
-                        'helper1' => function ($arg) {
-                            $arg = is_array($arg) ? 'Array' : $arg;
-                            return "-$arg-";
-                        },
-                        'helper2' => function ($arg) {
-                            return is_array($arg) ? '=Array=' : "=$arg=";
-                        },
-                        'link' => function ($arg) {
-                            if (is_array($arg)) {
-                                $arg = 'Array';
-                            }
-                            return "<a href=\"{$arg}\">click here</a>";
-                        },
-                        'alink' => function ($u, $t) {
-                            $u = is_array($u) ? 'Array' : $u;
-                            $t = is_array($t) ? 'Array' : $t;
-                            return "<a href=\"$u\">$t</a>";
-                        },
-                    ],
-                ),
-                'expected' => <<<VAREND
-                    <ul>
-                     <li>1. -John-</li>
-                     <li>2. -10000-</li>
-                     <li>3. &#x3D;John&#x3D;</li>
-                     <li>4. &#x3D;10000&#x3D;</li>
-                     <li>9. &lt;a href&#x3D;&quot;John&quot;&gt;click here&lt;/a&gt;</li>
-                     <li>10. &lt;a href&#x3D;&quot;10000&quot;&gt;click here&lt;/a&gt;</li>
-                     <li>11. &lt;a href&#x3D;&quot;http://yahoo.com&quot;&gt;You&amp;Me!&lt;/a&gt;</li>
-                     <li>12. <a href="http://yahoo.com">You&Me!</a></li>
-                    </ul>
-                    VAREND,
+                'desc' => 'LNC #290',
+                'template' => '{ {{foo}}',
+                'data' => ['foo' => 'YES'],
+                'expected' => '{ YES',
             ],
-
             [
-                'template' => '{{#each foo}}{{@key}}: {{.}},{{/each}}',
-                'data' => ['foo' => [1, 'a' => 'b', 5]],
-                'expected' => '0: 1,a: b,1: 5,',
+                'desc' => 'LNC #290',
+                'template' => '{{#with "{{"}}{{.}}{{/with}}{{foo}}{{#with "{{"}}{{.}}{{/with}}',
+                'data' => ['foo' => 'YES'],
+                'expected' => '{{YES{{',
             ],
 
             [
-                'template' => '{{#each foo}}{{@key}}: {{.}},{{/each}}',
-                'data' => ['foo' => new TwoDimensionIterator(2, 3)],
-                'expected' => '0x0: 0,1x0: 0,0x1: 0,1x1: 1,0x2: 0,1x2: 2,',
+                'desc' => 'LNC #344',
+                'template' => '{{{{raw}}}} {{bar}} {{{{/raw}}}} {{bar}}',
+                'data' => [
+                    'raw' => true,
+                    'bar' => 'content',
+                ],
+                'expected' => ' {{bar}}  content',
             ],
 
             [
-                'template' => "   {{#if foo}}\nYES\n{{else}}\nNO\n{{/if}}\n",
-                'expected' => "NO\n",
+                'desc' => 'LNC #370',
+                'template' => '{{@root.items.length}}',
+                'data' => ['items' => [1, 2, 3]],
+                'expected' => '3',
             ],
 
             [
-                'template' => "  {{#each foo}}\n{{@key}}: {{.}}\n{{/each}}\nDONE",
-                'data' => ['foo' => ['a' => 'A', 'b' => 'BOY!']],
-                'expected' => "a: A\nb: BOY!\nDONE",
+                'template' => '{{{"{{"}}}',
+                'data' => ['{{' => ':D'],
+                'expected' => ':D',
             ],
-
             [
-                'template' => <<<_tpl
-                    <div>
-                      {{> partialA}}
-                      {{> partialB}}
-                    </div>
-                    _tpl,
-                'options' => new Options(
-                    partials: [
-                        'partialA' => "<div>\n  Partial A\n  {{> partialB}}\n</div>\n",
-                        'partialB' => "<p>\n  Partial B\n</p>\n",
-                    ],
-                ),
-                'expected' => <<<_result
-                    <div>
-                      <div>
-                        Partial A
-                        <p>
-                          Partial B
-                        </p>
-                      </div>
-                      <p>
-                        Partial B
-                      </p>
-                    </div>
-                    _result,
+                'template' => '{{{\'{{\'}}}',
+                'data' => ['{{' => ':D'],
+                'expected' => ':D',
             ],
 
             [
-                'template' => "{{>test1}}\n  {{>test1}}\nDONE\n",
-                'options' => new Options(
-                    partials: ['test1' => "1:A\n 2:B\n  3:C\n 4:D\n5:E\n"],
-                ),
-                'expected' => "1:A\n 2:B\n  3:C\n 4:D\n5:E\n  1:A\n   2:B\n    3:C\n   4:D\n  5:E\nDONE\n",
+                'template' => '-{{.}}-',
+                'data' => 'abc',
+                'expected' => '-abc-',
             ],
-
             [
-                'template' => "{{>test1}}\n  {{>test1}}\nDONE\n",
-                'options' => new Options(
-                    preventIndent: true,
-                    partials: ['test1' => "1:A\n 2:B\n  3:C\n 4:D\n5:E\n"],
-                ),
-                'expected' => "1:A\n 2:B\n  3:C\n 4:D\n5:E\n  1:A\n 2:B\n  3:C\n 4:D\n5:E\nDONE\n",
+                'template' => '-{{this}}-',
+                'data' => 123,
+                'expected' => '-123-',
             ],
 
             [
-                'template' => "{{foo}}\n  {{bar}}\n",
-                'data' => ['foo' => 'ha', 'bar' => 'hey'],
-                'expected' => "ha\n  hey\n",
+                'desc' => 'data can contain closures',
+                'template' => '{{foo}}',
+                'data' => ['foo' => fn() => 'OK'],
+                'expected' => 'OK',
             ],
-
             [
-                'template' => "{{>test}}\n",
-                'data' => ['foo' => 'ha', 'bar' => 'hey'],
-                'options' => new Options(
-                    partials: ['test' => "{{foo}}\n  {{bar}}\n"],
-                ),
-                'expected' => "ha\n  hey\n",
+                'desc' => 'callable strings or arrays should NOT be treated as functions',
+                'template' => '{{foo}}',
+                'data' => ['foo' => 'hrtime'],
+                'expected' => 'hrtime',
             ],
-
             [
-                'template' => " {{>test}}\n",
-                'data' => ['foo' => 'ha', 'bar' => 'hey'],
-                'options' => new Options(
-                    preventIndent: true,
-                    partials: ['test' => "{{foo}}\n  {{bar}}\n"],
-                ),
-                'expected' => " ha\n  hey\n",
+                'template' => '{{#foo}}OK{{else}}bad{{/foo}}',
+                'data' => ['foo' => 'is_string'],
+                'expected' => 'OK',
             ],
 
             [
-                'template' => "\n {{>test}}\n",
-                'data' => ['foo' => 'ha', 'bar' => 'hey'],
-                'options' => new Options(
-                    preventIndent: true,
-                    partials: ['test' => "{{foo}}\n  {{bar}}\n"],
-                ),
-                'expected' => "\n ha\n  hey\n",
+                'template' => '{{foo}}',
+                'expected' => '',
             ],
-
             [
-                'template' => "\n{{#each foo~}}\n  <li>{{.}}</li>\n{{~/each}}\n\nOK",
-                'data' => ['foo' => ['ha', 'hu']],
-                'expected' => "\n<li>ha</li><li>hu</li>\nOK",
+                'template' => '{{foo.bar}}',
+                'expected' => '',
             ],
-
             [
-                'template' => "ST:\n{{#foo}}\n {{>test1}}\n{{/foo}}\nOK\n",
-                'data' => ['foo' => [1, 2]],
-                'options' => new Options(
-                    partials: ['test1' => "1:A\n 2:B({{@index}})\n"],
-                ),
-                'expected' => "ST:\n 1:A\n  2:B(0)\n 1:A\n  2:B(1)\nOK\n",
+                'template' => '{{foo.bar}}',
+                'data' => ['foo' => []],
+                'expected' => '',
             ],
 
             [
-                'template' => ">{{helper1 \"===\"}}<",
-                'options' => new Options(
-                    helpers: [
-                        'helper1' => fn($arg) => is_array($arg) ? '-Array-' : "-$arg-",
-                    ],
-                ),
-                'expected' => ">-&#x3D;&#x3D;&#x3D;-<",
+                'template' => "{{foo}}\n  {{bar}}\n",
+                'data' => ['foo' => 'ha', 'bar' => 'hey'],
+                'expected' => "ha\n  hey\n",
             ],
 
             [
@@ -2314,29 +2053,39 @@ public static function issueProvider(): array
             ],
 
             [
-                'template' => '{{#>foo}}inline\'partial{{/foo}}',
-                'expected' => 'inline\'partial',
+                'desc' => 'knownHelpersOnly: array section values are correctly handled',
+                'template' => '{{#items}}{{name}}{{/items}}',
+                'options' => new Options(knownHelpersOnly: true),
+                'data' => ['items' => ['name' => 'foo']],
+                'expected' => 'foo',
             ],
-
             [
-                'template' => '{{>foo}} and {{>bar}}',
-                'options' => new Options(
-                    partialResolver: function (Context $context, string $name) {
-                        return "PARTIAL: $name";
-                    },
-                ),
-                'expected' => 'PARTIAL: foo and PARTIAL: bar',
+                'desc' => 'empty array renders else block',
+                'template' => '{{#items}}YES{{else}}NO{{/items}}',
+                'options' => new Options(knownHelpersOnly: true),
+                'data' => ['items' => []],
+                'expected' => 'NO',
             ],
-
             [
-                'template' => "{{#> testPartial}}\n ERROR: testPartial is not found!\n  {{#> innerPartial}}\n   ERROR: innerPartial is not found!\n   ERROR: innerPartial is not found!\n  {{/innerPartial}}\n ERROR: testPartial is not found!\n {{/testPartial}}",
-                'expected' => " ERROR: testPartial is not found!\n   ERROR: innerPartial is not found!\n   ERROR: innerPartial is not found!\n ERROR: testPartial is not found!\n",
+                'desc' => 'non-empty array renders fn block even when else is present',
+                'template' => '{{#items}}{{@index}}: {{.}}{{#if @last}}last!{{else}}, {{/if}}{{else}}NO{{/items}}',
+                'options' => new Options(knownHelpersOnly: true),
+                'data' => ['items' => ['a', 'b']],
+                'expected' => '0: a, 1: blast!',
+            ],
+            [
+                'desc' => '../path resolves correctly when array context differs from enclosing context',
+                'template' => '{{#items}}{{name}}/{{../name}}{{/items}}',
+                'options' => new Options(knownHelpersOnly: true),
+                'data' => ['name' => 'outer', 'items' => ['name' => 'inner']],
+                'expected' => 'inner/outer',
+            ],
+            [
+                'desc' => '../path inside a true-valued section is empty (matches HBS.js: no depths push for true)',
+                'template' => '{{#flag}}{{../name}}{{/flag}}',
+                'data' => ['flag' => true, 'name' => 'outer'],
+                'expected' => '',
             ],
-
         ];
-
-        return array_map(function ($i) {
-            return [$i];
-        }, $issues);
     }
 }
diff --git a/tests/RuntimeTest.php b/tests/RuntimeTest.php
index cf9bbe8..7321bac 100644
--- a/tests/RuntimeTest.php
+++ b/tests/RuntimeTest.php
@@ -34,6 +34,16 @@ public function testIsec(): void
         $this->assertFalse(Runtime::isec(['1']));
     }
 
+    public function testRaw(): void
+    {
+        $this->assertEquals('1', Runtime::raw(1));
+        $this->assertEquals('1.1', Runtime::raw(1.1));
+        $this->assertEquals('true', Runtime::raw(true));
+        $this->assertEquals('false', Runtime::raw(false));
+        $this->assertEquals('0,1', Runtime::raw([0, 1]));
+        $this->assertEquals('', Runtime::raw(null));
+    }
+
     private static function createStringable(string $value): \Stringable
     {
         return new class ($value) implements \Stringable {