[intellild]

Summary

• Record the source ID returned by the output map and use it for mappings that point directly to a bundled CSS file.
• Register the CSS source when its inline source map cannot be read.
• Cover both cases with Parcel source map regression tests.

Example

If the output map already has existing.css at index 0, Bundler may assign entry.css stylesheet index 0 while the output map assigns it source ID 1. Previously its mappings pointed at existing.css. They now use the output map's ID for entry.css. The same fallback works when the CSS has an unreadable inline map.

Validation

• Both regression cases failed on the previous master and pass with this change.
• cargo test --locked -p rspack-lightningcss --no-default-features --features bundler --test test_parcel_bundler_source_map
• cargo check --locked --workspace --all-features

Stack

1. This PR
2. Use std::fmt::Write for printer output
3. Serialize CSS through PrinterTrait
4. Introduce the custom_sourcemap feature flag
5. Custom source maps through generic PrinterOptions

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by OpenAI Codex

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-04T09:32:01.296218Z	b391f63	PR opened

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[codspeed]

Merging this PR will not alter performance

✅ 8 untouched benchmarks
⏩ 8 skipped benchmarks¹

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_{Comparing codex/rstack-fix-bundler-source-indices (b391f63) with master (ec31b9a)}

Footnotes

1. 8 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. ↩