perf(desktop): cache compiled JavaScript between launches

[t3dotgg]

Packaged desktop launches recompile the main process and local backend on each start. This change enables V8 code caching for repeat launches.

• A small boot.cjs enables the Node compile cache before loading main.cjs.
• The packaged local backend loads the cache through --require. No cache setting is added to provider or terminal environments.
• The backend flushes its cache after startup. Windows force-kills the backend on quit, so saving only at process exit would lose the cache.
• The production t3code:// scheme enables Chromium's code cache. Electron checks the source hash before reusing bytecode.

Dev launches bypass the cache loader. AppImage launches skip Node caching because their mount paths change on each launch. AppImage still gets renderer caching. WSL, SSH, and standalone server launches do not get the new desktop cache preload.

Linux stores the Node cache under $XDG_CACHE_HOME/t3code/compile-cache, or ~/.cache/t3code/compile-cache. macOS and Windows use the user temp directory. Cache setup and flush failures do not prevent startup. Old runtime cache directories are not pruned by this change.

Validation:

• Focused tests run the generated boot entry and backend preload with caching enabled and disabled.
• A subprocess test verifies that flushed cache files survive forced termination.
• Focused desktop and server tests, changed-file lint, and server typecheck pass.
• The desktop build passes. The generated loader was tested inside ASAR with Electron 44.4.2 in Node mode.
• CI builds desktop and runs the bundle tests. The separate desktop smoke script uses boot.cjs, but CI does not run that script.
• Packaged Windows and macOS quit/relaunch, and renderer timing in a real window, remain unverified.

The original PR reported these measurements on packaged v0.0.42, Linux x64, Electron 44:

Measurement	Before	Cached
Main process bundle compile	~130 ms	~1 ms
Backend startup to --version	1075 ms	924 ms
Renderer boot chunks compiled in Node	~150 ms	~17 ms

These are separate measurements, not an end-to-end window-ready result. The renderer measurement does not establish Chromium's actual saving. Cold launches must create the cache and may take longer.

Original change by Claude Opus 5.5 in Claude Code. Follow-up fixes and validation by GPT-6 Astra through the Codex harness in T3 Code.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Performance
  • Packaged desktop apps now use code caching for the app and Windows backend, which may improve startup times on subsequent runs.
  • Cache data is saved after startup completes. Caching remains disabled for development launches and AppImage builds.
  • Cache setup failures do not prevent the app from starting.

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.5 KiB	13.5 KiB	+28 B (+0.2%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	+6 B (+0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.4 KiB	6.5 KiB	+22 B (+0.3%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.2 KiB	56.3 KiB	+44 B (+0.1%)	66.4 KiB	✅
Codex	Live turn messages	9	10	+1 (+11.1%)	21	✅
Claude	Total thread wire	13.5 KiB	13.5 KiB	+6 B (+0.0%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	+3 B (+0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.4 KiB	6.4 KiB	+3 B (+0.0%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.0 KiB	57.0 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	9	9	0 (0.0%)	21	✅

Baseline: c13f7d9 · PR result: 96a5af1 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 114.0 KiB
• Claude decoded thread snapshot: 114.7 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR changes the default packaged desktop startup path across the main process, backend, renderer, and persistent filesystem caching, rather than making a purely mechanical or test-only change. It also adds a new oxlint suppression directive in production code, so the change warrants human review.

Notes:

• Diff unchanged. Approvability was decided on eligibility alone.

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📝 Walkthrough

Walkthrough

The desktop build adds Node compile-cache setup and routes desktop startup through a bootstrap that loads it before the main bundle. Packaged Windows backend launches preload the cache module. AppImage launches skip Node cache setup, and the production Electron scheme enables Chromium code caching. Server startup also flushes the compile cache after publishing the ready event.

Changes

Desktop Compile Cache

Layer / File(s)	Summary
Compile-cache setup and build apps/desktop/src/compileCache.ts, apps/desktop/src/electron/ElectronProtocol.ts, apps/desktop/vite.config.ts, knip.jsonc	Adds platform-specific selection of the Node compile-cache directory and skips cache setup when APPIMAGE is set. Setup errors are caught. The production scheme enables Chromium code caching. Vite builds the bootstrap and cache modules as CommonJS, and Knip lists them as entry points.
Desktop bootstrap wiring apps/desktop/src/boot.ts, apps/desktop/package.json, scripts/build-desktop-artifact.ts, apps/desktop/scripts/smoke-test.mjs, apps/desktop/scripts/main-process-bundle.test.mjs	Routes the desktop package, staged package, and smoke test through boot.cjs, which loads compileCache.cjs before main.cjs. The bundle test checks cached and uncached execution through the bootstrap and direct preload paths.
Windows backend preload apps/desktop/src/app/DesktopEnvironment.ts, apps/desktop/src/backend/DesktopBackendConfiguration.ts, apps/desktop/src/backend/DesktopBackendConfiguration.test.ts	Adds the compile-cache path to the desktop environment. Packaged Windows backend launches pass the path with Node’s --require option; development launches omit it. Tests assert both behaviors.
Server startup cache flush apps/server/src/compileCache.ts, apps/server/src/serverRuntimeStartup.ts, apps/server/src/compileCache.test.ts	Adds flushCompileCache and calls it after startup completes and the ready event is published. The test checks cache-file behavior when caching is enabled and disabled.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Feature

Suggested reviewers: juliusmarminge

Merge Risk: 🟡 Moderate · up to 96a5a

Server tests can fail on a supported Node version. Fix the subprocess import before merging; the desktop entry-file configuration no longer presents the reported Knip risk.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 13 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the main change: enabling compiled JavaScript caching for repeat desktop launches.
Description check	✅ Passed	The description explains what changed, why it changed, platform-specific behavior, validation, limitations, and performance measurements. It does not use the template headings or include the checklist…

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In `@apps/desktop/vite.config.ts`:
- Line 95: Update the Knip configuration to recognize the Vite entries
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• apps/desktop/package.json
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• apps/desktop/src/app/DesktopEnvironment.ts
• apps/desktop/src/backend/DesktopBackendConfiguration.ts
• apps/desktop/src/boot.ts
• apps/desktop/src/compileCache.ts
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In `@apps/desktop/src/compileCache.ts`:
- Line 9: Add the compileCache TypeScript source to the relevant Knip entry
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In `@apps/server/src/compileCache.test.ts`:
- Line 20: Update the subprocess import of compileCache.ts in the persistence
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