fix(cli): write logger trace output to file by default

[hardfist]

Summary

• write the default logger tracing layer output to .rspack-profile-${timestamp}-${pid}/rspack.log instead of stdout
• keep explicit RSPACK_TRACE_OUTPUT=stdout|stderr support
• update profile tests and sync the English/Chinese tracing docs with the current behavior

Related links

None.

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

Validation

• pnpm install --frozen-lockfile
• pnpm run build:binding:dev
• pnpm run build:js
• pnpm --filter @rspack/cli exec rstest run tests/build/profile/profile.test.ts --testTimeout 60000
• pnpm prettier --check packages/rspack-cli/src/utils/profile.ts packages/rspack-cli/tests/build/profile/profile.test.ts packages/rspack/src/trace/index.ts website/docs/en/contribute/development/tracing.md website/docs/zh/contribute/development/tracing.md website/docs/en/guide/optimization/profile.mdx website/docs/zh/guide/optimization/profile.mdx
• pnpm --dir website run check:spell
• git diff --check

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[github-actions]

📦 Binary Size-limit

Comparing 7fc08c0 to chore: add draft release notes skill (#14028) by neverland

🙈 Size remains the same at 61.93MB

[github-actions]

Rsdoctor Bundle Diff Analysis

Found 6 projects in monorepo, 0 projects with changes.

📊 Quick Summary

Project	Total Size	Change
popular-libs	1.7 MB	0
react-1k	826.3 KB	0
react-5k	2.7 MB	0
react-10k	5.7 MB	0
ui-components	4.8 MB	0
rome	1.6 MB	0

Generated by Rsdoctor GitHub Action

[codspeed-hq]

Merging this PR will improve performance by 30.22%

⚡ 1 improved benchmark
✅ 33 untouched benchmarks
⏩ 25 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	js@Traverse compilation.modules	80.3 µs	61.7 µs	+30.22%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing codex/logger-trace-file-default (7fc08c0) with main (ccdadab)}

Footnotes

1. 25 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR changes Rspack CLI tracing so the default logger layer output is written to a file under the generated profile directory instead of printing to stdout, and updates docs/tests to match.

Changes:

• Default logger trace output now writes to .rspack-profile-${timestamp}-${pid}/rspack.log (with stdout|stderr still supported when explicitly configured).
• Updated profile-related tests to assert file output instead of stdout output.
• Updated English/Chinese tracing and profiling docs to reflect the new default output behavior and output path resolution.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
website/docs/zh/guide/optimization/profile.mdx	Updates zh profiling guide to describe rspack.log default and Perfetto output.
website/docs/zh/contribute/development/tracing.md	Updates zh tracing docs for new default outputs and relative-path resolution behavior.
website/docs/en/guide/optimization/profile.mdx	Updates en profiling guide to describe rspack.log default and Perfetto output.
website/docs/en/contribute/development/tracing.md	Updates en tracing docs for new default outputs and relative-path resolution behavior.
packages/rspack/src/trace/index.ts	Updates comments describing JS tracer behavior/output naming.
packages/rspack-cli/tests/build/profile/profile.test.ts	Updates tests to assert traces go to files by default and refactors cleanup.
packages/rspack-cli/src/utils/profile.ts	Implements new default output paths and avoids directory creation for stdout/stderr.

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