fix(plan): forward LOCALAPPDATA so Node's compile cache stays outside the workspace (#389)

`DEFAULT_UNTRACKED_ENV` already forwards most Windows env vars to cached tasks, but `LOCALAPPDATA` was missing. Node's compile cache uses it to decide where to put cache files on Windows. Without it, the cache lands inside the workspace, the runner sees the same files both written and read in one run, and refuses to cache anything with `not cached because it modified its input`.

Add `LOCALAPPDATA` to the list, and mirror it in the e2e harness so the accompanying Node compile-cache fixture goes from failing on Windows to passing on every platform.

Author: branchseer

crates/vite_task_bin/tests/e2e_snapshots/fixtures/node_compile_cache_outside_workspace/a.mjs

@@ -0,0 +1 @@
+export const value = 'a';

crates/vite_task_bin/tests/e2e_snapshots/fixtures/node_compile_cache_outside_workspace/b.mjs

@@ -0,0 +1 @@
+export const value = 'b';

crates/vite_task_bin/tests/e2e_snapshots/fixtures/node_compile_cache_outside_workspace/c.mjs

@@ -0,0 +1 @@
+export const value = 'c';

crates/vite_task_bin/tests/e2e_snapshots/fixtures/node_compile_cache_outside_workspace/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "node-compile-cache-outside-workspace-fixture",
+  "private": true,
+  "type": "module"
+}

crates/vite_task_bin/tests/e2e_snapshots/fixtures/node_compile_cache_outside_workspace/run.mjs

@@ -0,0 +1,20 @@
+// Tiny Node script that turns on the v22 compile cache and imports a
+// few sibling modules so the cache directory actually gets some files
+// written to it. On a normally-configured machine the cache lives in
+// the OS temp directory (outside the workspace), so the runner doesn't
+// see those files when it decides whether the run can be cached.
+//
+// If the spawned process doesn't have LOCALAPPDATA (or TMP/TEMP/
+// USERPROFILE) set on Windows, Node ends up putting the cache inside
+// the workspace, the same files are both written and read in this one
+// run, and the runner refuses to cache it. That's the bug this fixture
+// catches.
+import { enableCompileCache } from 'node:module';
+
+enableCompileCache();
+
+await import('./a.mjs');
+await import('./b.mjs');
+await import('./c.mjs');
+
+console.log('done');

crates/vite_task_bin/tests/e2e_snapshots/fixtures/node_compile_cache_outside_workspace/snapshots.toml

@@ -0,0 +1,20 @@
+[[e2e]]
+name = "node_compile_cache_does_not_poison_workspace"
+comment = """
+Runs a small Node script that turns on Node's compile cache. The cache should land in the OS temp directory (outside the workspace), so two `vt run --cache build` calls should be a miss then a hit. On Windows, if the spawned task env doesn't have `LOCALAPPDATA`, Node puts the cache inside the workspace instead, the runner sees the same files both written and read, and refuses to cache the run — so the second call becomes another miss with a "not cached because it modified its input" message.
+"""
+ignore = true
+steps = [
+  { argv = [
+    "vt",
+    "run",
+    "--cache",
+    "build",
+  ], comment = "first run: cache miss" },
+  { argv = [
+    "vt",
+    "run",
+    "--cache",
+    "build",
+  ], comment = "second run: cache hit" },
+]

crates/vite_task_bin/tests/e2e_snapshots/fixtures/node_compile_cache_outside_workspace/snapshots/node_compile_cache_does_not_poison_workspace.md

@@ -0,0 +1,24 @@
+# node_compile_cache_does_not_poison_workspace
+
+Runs a small Node script that turns on Node's compile cache. The cache should land in the OS temp directory (outside the workspace), so two `vt run --cache build` calls should be a miss then a hit. On Windows, if the spawned task env doesn't have `LOCALAPPDATA`, Node puts the cache inside the workspace instead, the runner sees the same files both written and read, and refuses to cache the run — so the second call becomes another miss with a "not cached because it modified its input" message.
+
+## `vt run --cache build`
+
+first run: cache miss
+
+```
+$ node run.mjs
+done
+```
+
+## `vt run --cache build`
+
+second run: cache hit
+
+```
+$ node run.mjs ◉ cache hit, replaying
+done
+
+---
+vt run: cache hit.
+```

crates/vite_task_bin/tests/e2e_snapshots/fixtures/node_compile_cache_outside_workspace/vite-task.json

@@ -0,0 +1,8 @@
+{
+  "tasks": {
+    "build": {
+      "command": "node run.mjs",
+      "cache": true
+    }
+  }
+}

crates/vite_task_bin/tests/e2e_snapshots/main.rs

@@ -392,6 +392,30 @@ fn run_case(
             // On Windows, ensure common executable extensions are included in PATHEXT for command resolution in subprocesses.
             if cfg!(windows) {
                 cmd.env("PATHEXT", ".COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC");
+                // Forward the Windows env vars Node needs to find a real
+                // temp directory. Without these, Node's compile cache and
+                // similar helpers fall back to a workspace-relative path
+                // and break cached runs. Values come from cargo-test's
+                // own env when present.
+                for name in [
+                    "TMP",
+                    "TEMP",
+                    "APPDATA",
+                    "LOCALAPPDATA",
+                    "PROGRAMDATA",
+                    "USERPROFILE",
+                    "HOMEDRIVE",
+                    "HOMEPATH",
+                    "WINDIR",
+                    "SYSTEMROOT",
+                    "SYSTEMDRIVE",
+                    "ProgramFiles",
+                    "ProgramFiles(x86)",
+                ] {
+                    if let Some(value) = env::var_os(name) {
+                        cmd.env(name, value);
+                    }
+                }
             }
             for (k, v) in step.envs() {
                 let resolved = resolve_env_placeholder(v.as_str());

crates/vite_task_graph/src/config/mod.rs

@@ -445,6 +445,11 @@ pub const DEFAULT_UNTRACKED_ENV: &[&str] = &[
     "RUNNER_*",
     // Windows specific
     "APPDATA",
+    // Node's compile cache uses LOCALAPPDATA to pick its cache directory
+    // on Windows. Without it the cache lands inside the workspace and
+    // breaks every cached task that opts into the compile cache. See
+    // the `node_compile_cache_outside_workspace` e2e fixture.
+    "LOCALAPPDATA",
     "PROGRAMDATA",
     "SYSTEMROOT",
     "SYSTEMDRIVE",