[Gourav224]

In build mode, startCompilerPlugin only drops an environment's compiler in that same environment's buildStart. Earlier environments' compilers (a module cache full of Babel ASTs, plus closures over the plugin hook context) therefore stay alive while later environments build. On a large app that is about 1.2 GB.

Fix

Add a buildEnd hook to the per-environment server-fn plugin. When this.environment.mode === 'build', it deletes that environment's compiler, matching the existing buildStart condition. Nothing reads an environment's compiler after its build ends:

• The shared serverFnsById registry lives outside the compiler.
• compilers.get is otherwise only used in dev paths (hotUpdate, watchChange, the serve-only lookup plugin).
• The bundledDev client environment runs in dev mode, so its compiler is kept for watchChange.

Testing

• New regression test tests/vite/start-compiler-plugin-build.test.ts. It drives the plugin's buildStart, transform and buildEnd hooks for a build environment, then asserts through a WeakRef and forced GC that the hook context is released. It fails before the fix and passes after.
• @tanstack/start-plugin-core: test:unit (873 passed), test:types and test:eslint all pass.

Fixes #8794

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Improved cleanup after builds so completed build contexts can be released instead of remaining in memory. This helps avoid retaining unnecessary build resources while preserving the existing build behavior.

[changeset-bot]

🦋 Changeset detected

Latest commit: 67db0df

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@tanstack/start-plugin-core	Patch
@tanstack/react-start-rsc	Patch
@tanstack/react-start	Patch
@tanstack/solid-start	Patch
@tanstack/vue-start	Patch

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ℹ️ Recent review info

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• Source mode: Auto
• Repository: TanStack/router
• Branch: main
• File: .coderabbit.yaml
• Commit: 6b9fe6d
• Layers: Repository YAML
• Review profile: CHILL
• Plan: Advanced
• Run ID: 382d97f3-6f86-4724-afd4-c60ace66e368

📥 Commits

Reviewing files that changed from the base of the PR and between 6b9fe6d and 67db0df.

📒 Files selected for processing: 3

• .changeset/release-start-compiler-after-build.md
• packages/start-plugin-core/src/vite/start-compiler-plugin/plugin.ts
• packages/start-plugin-core/tests/vite/start-compiler-plugin-build.test.ts

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 9 remain after this review.

📝 Walkthrough

In build mode, the plugin now removes the current environment’s server-function compiler when the build ends. A new test checks whether the build context becomes unreachable, and a changeset declares a patch release.

Changes: Server-function compiler build cleanup

Layer / File(s)	Summary
Build-end compiler cleanup and validation packages/start-plugin-core/src/vite/start-compiler-plugin/plugin.ts, packages/start-plugin-core/tests/vite/start-compiler-plugin-build.test.ts, .changeset/release-start-compiler-after-build.md	In build mode, buildEnd removes the current environment’s compiler from compilers. The test runs the build hooks and checks whether the associated context becomes unreachable after garbage collection. The changeset declares a patch release for @tanstack/start-plugin-core.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~12 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 67db0

No concrete merge-blocking risk was identified in the reviewed changes.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 2 files. (1 skipped: 1 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Title check		The title clearly and concisely describes the main change: releasing each environment's server-function compiler after its build.
Description check		The description clearly explains the problem, fix, implementation rationale, regression test, test results, and linked issue. It does not include the template's checklist or release-impact sections, b…
Linked Issues check		Issue #8794 requires deleting each build environment's server-function compiler after that environment finishes. The new buildEnd hook in perEnvServerFnPlugin deletes compilers by `this.environm…
Out of Scope Changes check		The changes stay within issue #8794. The implementation releases the compiler, the test verifies the memory-release behavior, and the changeset records the package patch release. No unrelated source o…

Full details: Description check

Explanation

The description clearly explains the problem, fix, implementation rationale, regression test, test results, and linked issue. It does not include the template's checklist or release-impact sections, but the required change and validation details are present.

Full details: Linked Issues check

Explanation

Issue #8794 requires deleting each build environment's server-function compiler after that environment finishes. The new buildEnd hook in perEnvServerFnPlugin deletes compilers by this.environment.name when the mode is build. The regression test runs buildStart, transform, and buildEnd, then verifies release of the hook context through WeakRef and GC. The patch release changeset documents the fix.

Full details: Out of Scope Changes check

Explanation

The changes stay within issue #8794. The implementation releases the compiler, the test verifies the memory-release behavior, and the changeset records the package patch release. No unrelated source or test changes are present in the reviewed diff.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 2 files. (1 skipped: 1 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

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