[pull] main from fern-api:main

generators/go/internal/generator/model.go

@@ -2038,7 +2038,7 @@ func getExtraPropertiesFieldName(extraPropertiesEnabled bool) string {
 
 // unknownToGoType maps the given unknown into its Go-equivalent.
 func unknownToGoType(_ any) string {
-	return "interface{}"
+	return "any"
 }
 
 // literalToUndiscriminatedUnionField maps Fern's literal types to the field name used in an

generators/go/internal/testdata/model/alias/fixtures/imdb.go

@@ -309,6 +309,6 @@ func (u *Union) validate() error {
 	return nil
 }
 
-type Unknown = interface{}
+type Unknown = any
 
 type Uuid = uuid.UUID

generators/go/sdk/versions.yml

@@ -1,4 +1,14 @@
 # yaml-language-server: $schema=../../../fern-versions-yml.schema.json
+- version: 1.30.3
+  changelogEntry:
+    - summary: |
+        Use `any` instead of `interface{}` for unknown type schemas. Since Go 1.18+,
+        `any` is the idiomatic alias for `interface{}`. This is a purely cosmetic
+        modernization with no behavioral change.
+      type: fix
+  createdAt: "2026-03-16"
+  irVersion: 61
+
 - version: 1.30.2
   changelogEntry:
     - summary: |

generators/python/sdk/versions.yml

@@ -1,5 +1,15 @@
 # yaml-language-server: $schema=../../../fern-versions-yml.schema.json
 # For unreleased changes, use unreleased.yml
+- version: 5.0.2
+  changelogEntry:
+    - summary: |
+        Add docstring emission for unknown/any type alias definitions. When a type alias
+        resolves to `typing.Any` and has a description in the API definition, the generated
+        Python code now includes the docstring below the type alias declaration.
+      type: fix
+  createdAt: "2026-03-17"
+  irVersion: 65
+
 - version: 5.0.1
   changelogEntry:
     - summary: |
@@ -52,6 +62,7 @@
       type: fix
   createdAt: "2026-03-12"
   irVersion: 65
+
 - version: 4.63.5
   changelogEntry:
     - summary: |

generators/python/src/fern_python/codegen/ast/nodes/declarations/type_alias/type_alias_declaration.py

@@ -6,10 +6,11 @@
 
 
 class TypeAliasDeclaration(AstNode):
-    def __init__(self, name: str, type_hint: TypeHint, snippet: Optional[str] = None):
+    def __init__(self, name: str, type_hint: TypeHint, snippet: Optional[str] = None, docs: Optional[str] = None):
         self.name = name
         self.type_hint = type_hint
         self.snippet = snippet
+        self.docs = docs
         self.ghost_references: Set[Reference] = set()
 
     def get_metadata(self) -> AstNodeMetadata:
@@ -32,3 +33,9 @@ def write(self, writer: NodeWriter, should_write_as_snippet: Optional[bool] = No
         writer.write(f"{self.name} = ")
         self.type_hint.write(writer=writer)
         writer.write_newline_if_last_line_not()
+
+        if self.docs is not None:
+            writer.write_line('"""')
+            writer.write(self.docs)
+            writer.write_newline_if_last_line_not()
+            writer.write_line('"""')

generators/python/src/fern_python/generators/pydantic_model/type_declaration_handler/pydantic_models/pydantic_model_alias_generator.py

@@ -46,6 +46,7 @@ def generate(
                     name=self._context.get_class_name_for_type_id(self._name.type_id, as_request=False),
                     type_hint=self._type_hint,
                     snippet=self._snippet,
+                    docs=self._docs,
                 ),
                 should_export=True,
             )

generators/python/src/fern_python/generators/pydantic_model/type_declaration_handler/typeddicts/typeddict_alias_generator.py

@@ -38,6 +38,7 @@ def generate(
                 name=self._context.get_class_name_for_type_id(self._name.type_id, as_request=True),
                 type_hint=self._type_hint,
                 snippet=self._snippet,
+                docs=self._docs,
             ),
             should_export=True,
         )

generators/typescript/asIs/tests/mock-server/MockServerPool.ts

@@ -103,4 +103,4 @@ class MockServerPool {
     }
 }
 
-export const mockServerPool = new MockServerPool();
+export const mockServerPool: MockServerPool = new MockServerPool();

generators/typescript/model/type-reference-converters/src/AbstractTypeReferenceToTypeNodeConverter.ts

@@ -368,19 +368,26 @@ export abstract class AbstractTypeReferenceToTypeNodeConverter extends AbstractT
         const keyTypeNode = this.convert({ ...params, typeReference: map.keyType });
         const valueTypeNode = this.convert({ ...params, typeReference: map.valueType });
         return this.generateNonOptionalTypeReferenceNode({
-            typeNode: ts.factory.createTypeReferenceNode("Record", [keyTypeNode.typeNode, valueTypeNode.typeNode]),
+            typeNode: ts.factory.createTypeReferenceNode("Record", [
+                keyTypeNode.typeNode,
+                valueTypeNode.typeNodeWithoutUndefined
+            ]),
             requestTypeNode:
                 keyTypeNode.requestTypeNode || valueTypeNode.requestTypeNode
                     ? ts.factory.createTypeReferenceNode("Record", [
                           keyTypeNode.requestTypeNode ?? keyTypeNode.typeNode,
-                          valueTypeNode.requestTypeNode ?? valueTypeNode.typeNode
+                          valueTypeNode.requestTypeNodeWithoutUndefined ??
+                              valueTypeNode.requestTypeNode ??
+                              valueTypeNode.typeNodeWithoutUndefined
                       ])
                     : undefined,
             responseTypeNode:
                 keyTypeNode.responseTypeNode || valueTypeNode.responseTypeNode
                     ? ts.factory.createTypeReferenceNode("Record", [
                           keyTypeNode.responseTypeNode ?? keyTypeNode.typeNode,
-                          valueTypeNode.responseTypeNode ?? valueTypeNode.typeNode
+                          valueTypeNode.responseTypeNodeWithoutUndefined ??
+                              valueTypeNode.responseTypeNode ??
+                              valueTypeNode.typeNodeWithoutUndefined
                       ])
                     : undefined
         });

generators/typescript/sdk/client-class-generator/src/GeneratedSdkClientClassImpl.ts

@@ -874,16 +874,30 @@ export class GeneratedSdkClientClassImpl implements GeneratedSdkClientClass {
             getAuthHeadersCode = "";
         }
 
-        // For multi-URL environments, this._options.environment is an object (e.g. { ec2: string; s3: string }),
-        // not a single string URL. Only pass `environment` when it resolves to a single base URL string.
-        const isMultiUrlEnvironment =
-            this.intermediateRepresentation.environments?.environments.type === "multipleBaseUrls";
-        const environmentCode = isMultiUrlEnvironment ? "" : "environment: this._options.environment,";
+        // Resolve the base URL from either the explicit baseUrl option or the environment.
+        // For multi-URL environments (e.g. { ec2: string; s3: string }), the environment is an object,
+        // so we project it to a string via its first base URL property to avoid passing an object where a string is expected.
+        // The property name is read from the IR's baseUrls definition rather than hardcoded.
+        // For single-URL or no-IR-defined environments, the environment is already a string, so we fall back to it directly.
+        const envs = this.intermediateRepresentation.environments?.environments;
+        let baseUrlCode: string;
+        if (envs != null && envs.type === "multipleBaseUrls") {
+            const firstBaseUrl = envs.baseUrls[0];
+            if (firstBaseUrl == null) {
+                throw new Error("Multi-URL environment has no base URLs defined");
+            }
+            const firstBaseUrlName = firstBaseUrl.name.camelCase.unsafeName;
+            baseUrlCode = `baseUrl: this._options.baseUrl ?? (async () => {
+        const env = await core.Supplier.get(this._options.environment);
+        return typeof env === "string" ? env : (env as Record<string, string>)?.${firstBaseUrlName};
+    }),`;
+        } else {
+            baseUrlCode = "baseUrl: this._options.baseUrl ?? this._options.environment,";
+        }
 
         const fetchMethodBody = `
 return core.makePassthroughRequest(input, init, {
-    ${environmentCode}
-    baseUrl: this._options.baseUrl,
+    ${baseUrlCode}
     headers: this._options.headers,
     timeoutInSeconds: this._options.timeoutInSeconds,
     maxRetries: this._options.maxRetries,

generators/typescript/sdk/generator/src/test-generator/TestGenerator.ts

@@ -176,6 +176,10 @@ export class TestGenerator {
             import { defineConfig } from "vitest/config";
             export default defineConfig({
                 test: {
+                    typecheck: {
+                        enabled: true,
+                        tsconfig: "./${this.relativeTestPath}/tsconfig.json"
+                    },
                     projects: [
                         {
                             test: {

generators/typescript/sdk/versions.yml

@@ -1,4 +1,40 @@
 # yaml-language-server: $schema=../../../fern-versions-yml.schema.json
+- version: 3.58.0
+  changelogEntry:
+    - summary: |
+        Add explicit type annotation to `mockServerPool` export in generated test
+        mock-server code to satisfy `--isolatedDeclarations`.
+      type: fix
+    - summary: |
+        Enable vitest typechecking in generated vitest config so that type errors
+        in test and source files are caught when running `vitest`.
+      type: feat
+  createdAt: "2026-03-17"
+  irVersion: 65
+
+- version: 3.57.2
+  changelogEntry:
+    - summary: |
+        Fix map types with unknown/any value types to not include spurious `| undefined`.
+        Previously, `map<string, UnknownType>` generated `Record<string, UnknownType | undefined>`
+        instead of `Record<string, UnknownType>`. The `| undefined` is now correctly omitted
+        from map value types.
+      type: fix
+  createdAt: "2026-03-16"
+  irVersion: 65
+
+- version: 3.57.1
+  changelogEntry:
+    - summary: |
+        Fix passthrough `fetch()` method producing 404s when the SDK environment is an
+        object (e.g. `{ base: string; production: string }`) instead of a plain string URL.
+        The generated code now resolves the environment supplier inline and projects object
+        environments to their `.base` property, instead of passing the raw object to
+        `makePassthroughRequest` where it would be stringified as `[object Object]`.
+      type: fix
+  createdAt: "2026-03-16"
+  irVersion: 65
+
 - version: 3.57.0
   changelogEntry:
     - summary: |
@@ -10,7 +46,6 @@
       type: feat
   createdAt: "2026-03-16"
   irVersion: 65
-
 - version: 3.56.4
   changelogEntry:
     - summary: |

packages/cli/api-importers/openapi-to-ir/src/3.1/paths/RequestBodyConverter.ts

@@ -389,9 +389,9 @@ export class RequestBodyConverter extends Converters.AbstractConverters.Abstract
             properties: {
                 ...resolvedMediaTypeSchema.properties,
                 [this.streamingExtension.streamConditionProperty]: {
+                    ...streamConditionProperty,
                     type: "boolean",
-                    const: isStreaming,
-                    ...streamConditionProperty
+                    const: isStreaming
                 } as OpenAPIV3_1.SchemaObject
             },
             required: [...(resolvedMediaTypeSchema.required ?? []), this.streamingExtension.streamConditionProperty]

packages/cli/api-importers/openapi/openapi-ir-parser/src/openapi/v3/converters/operation/convertStreamingOperation.ts

@@ -196,9 +196,9 @@ function getRequestBody({
         properties: {
             ...resolvedRequestBodySchema.properties,
             [streamingExtension.streamConditionProperty]: {
+                ...(streamingProperty ?? {}),
                 type: "boolean",
-                "x-fern-boolean-literal": isStreaming,
-                ...(streamingProperty ?? {})
+                "x-fern-boolean-literal": isStreaming
                 // biome-ignore lint/suspicious/noExplicitAny: allow explicit any
             } as any
         },

packages/cli/api-importers/openapi/openapi-ir-to-fern-tests/src/__test__/fixtures/x-fern-streaming-with-stream-condition/openapi.yml

@@ -49,7 +49,9 @@ components:
           example: How can I use the Vectara platform?
         stream_response:
           description: Indicates whether the response should be streamed or not.
-          type: boolean
+          type:
+            - boolean
+            - "null"
           default: false
       required:
         - query

packages/cli/api-importers/v3-importer-tests/src/__test__/__snapshots__/v3-sdks/x-fern-streaming-with-stream-condition.json

@@ -101,14 +101,20 @@
             "valueType": {
               "container": {
                 "optional": {
-                  "primitive": {
-                    "v1": "BOOLEAN",
-                    "v2": {
-                      "default": false,
-                      "type": "boolean"
-                    }
+                  "container": {
+                    "nullable": {
+                      "primitive": {
+                        "v1": "BOOLEAN",
+                        "v2": {
+                          "default": false,
+                          "type": "boolean"
+                        }
+                      },
+                      "type": "primitive"
+                    },
+                    "type": "nullable"
                   },
-                  "type": "primitive"
+                  "type": "container"
                 },
                 "type": "optional"
               },

packages/cli/api-importers/v3-importer-tests/src/__test__/fixtures/x-fern-streaming-with-stream-condition/openapi.yml

@@ -49,7 +49,9 @@ components:
           example: How can I use the Vectara platform?
         stream_response:
           description: Indicates whether the response should be streamed or not.
-          type: boolean
+          type:
+            - boolean
+            - "null"
           default: false
       required:
         - query

packages/cli/cli/versions.yml

@@ -1,4 +1,15 @@
 # yaml-language-server: $schema=../../../fern-versions-yml.schema.json
+- version: 4.31.1
+  changelogEntry:
+    - summary: |
+        Fix `x-fern-streaming` with `stream-condition` emitting the condition field
+        as an optional boolean instead of a required literal in split request types.
+        When the source property was nullable (`type: [boolean, "null"]`), the spread
+        order allowed the original property to overwrite the literal overrides.
+      type: fix
+  createdAt: "2026-03-17"
+  irVersion: 65
+
 - version: 4.31.0
   changelogEntry:
     - summary: |

packages/cli/fern-definition/ir-to-jsonschema/src/__test__/__snapshots__/csharp-namespace-collision/type_System_Task.json

@@ -6,11 +6,15 @@
     },
     "user": {
       "$ref": "#/definitions/System.User"
+    },
+    "owner": {
+      "$ref": "#/definitions/System.User"
     }
   },
   "required": [
     "name",
-    "user"
+    "user",
+    "owner"
   ],
   "additionalProperties": false,
   "definitions": {

packages/cli/fern-definition/ir-to-jsonschema/src/__test__/__snapshots__/exhaustive/type_types/object_MapOfDocumentedUnknownType.json

@@ -0,0 +1,18 @@
+{
+  "type": "object",
+  "additionalProperties": {
+    "$ref": "#/definitions/types.object.DocumentedUnknownType"
+  },
+  "definitions": {
+    "types.object.DocumentedUnknownType": {
+      "type": [
+        "string",
+        "number",
+        "boolean",
+        "object",
+        "array",
+        "null"
+      ]
+    }
+  }
+}