refactor(loader): separate reusable metadata from execution state

[intellild]

Motivation

Resolved loader metadata should be reusable across runs, while pitch data and execution flags belong to each run. The JavaScript bridge also used to combine both in JsLoaderItem, converting unchanged loader requests, types and cache flags back to Rust on each return.

For example, with JavaScript loader -> builtin:swc-loader -> JavaScript loader, each JavaScript invocation can update dependencies and pitch data and return { loaderData, state } without repeating loader metadata. Each loader retains its own pitch data for its normal stage, while content, source maps and additional data pass along the pipeline as one current value each. A rebuild reuses the resolved native metadata but starts with fresh execution flags and pitch data.

Changes

• Store Loaders directly on the normal module, backed by Vec<ResolvedLoader> and lazily initialized immutable LoaderItem metadata. Access it through LoaderRunnerContext::loaders().
• Create fresh loader_data and LoaderItemState collections for each native run, indexed by loader position. Keep each loader's pitch data separate from execution flags, and mirror the split in the binding with loaderData, JsLoaderMetadata and JsLoaderItemState.
• Pass an owned #[napi(object)] JsLoaderContextState and a separate loaderData array to JavaScript. The existing loader-context getters/setters update them, and the runner returns both through a single #[napi(object)] JsLoaderResult for Rust to merge.
• Adapt parallel-loader payloads, pitch data writeback and loader-cache access to the separated data and state. Preserve the public module loader snapshot shape, existing Buffer/source-map transfers, hook timing and native context ownership.
• Mark finish_called only for loaders whose normal stage has executed. Previously, an unrelated JavaScript return could mark a pending builtin loader as finished and incorrectly preserve its input when it returned no output.
• Cover return conversion without metadata, independent pitch data across builtin loaders, pitch data replacement in a worker, binary/map/additional-data roundtrips and a native loader that returns no output; document the boundary in English and Chinese.

Stack

1. refactor(loader): replace should-yield hooks with execution kind #15592 — execution kind and removal of the should-yield hook (base: main).
2. This PR — reusable metadata and per-run state, including the JavaScript bridge.
3. perf(loader): schedule loader chains as execution units #15401 — LoaderChain scheduling and Rust-side chain caching.

The class/boxed-context ownership protocol, BoxSource transfer and cross-invocation JavaScript wrapper reuse remain separate follow-up work.

Validation

• pnpm run build:cli:dev — passed.
• cargo clippy -p rspack_binding_api -p rspack_loader_runner --all-targets --offline -- -D warnings — passed.
• cargo test -p rspack_loader_runner --offline — 10 passed.
• pnpm --dir tests/rspack-test run test --project base -t loader — 567 passed, including parallel loaders, cache/rebuild cases and the new state regressions.
• pnpm --dir tests/rspack-test run test --project base Config -t source-map — 184 passed.
• Rust formatting, JavaScript lint/format, documentation spelling and git diff --check — passed.
• Binding declarations regenerated from the Rust N-API definitions.

---

by OpenAI Codex

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📦 Binary Size-limit

Comparing b67ed7a to test: use rspack.sources in test cases (#15734) by Jiahan Chen

🎉 Size decreased by 12.00KB from 68.79MB to 68.78MB (⬇️0.02%)

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Rsdoctor Bundle Diff Analysis

Found 5 projects in monorepo, 0 projects with changes.

📊 Quick Summary

Project	Total Size	Gzip Size	Change	Gzip Change
popular-libs	1.7 MB	529.8 KB	0	0
react-10k	5.4 MB	1.3 MB	0	0
react-1k	827.7 KB	226.6 KB	0	0
ui-components	5.0 MB	1.4 MB	0	0
react-5k	2.6 MB	670.9 KB	0	0

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[codspeed]

Merging this PR will degrade performance by 0.03%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
❌ 1 regressed benchmark
✅ 48 untouched benchmarks
⏩ 47 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	rust@create_full_hash	2.3 ms	2.4 ms	-2.18%
⚡	rust@create_module_hashes	7.6 ms	7.4 ms	+2.17%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing codex/loader-metadata (b67ed7a) with main (7163c74)}

Footnotes

1. 47 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. ↩

[intellild]

@codex review

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-16T08:17:44.194816Z	933ff2f	Manual request

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Codex Review: Didn't find any major issues. Breezy!

Reviewed commit: 292af28c37

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[intellild]

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Codex Review: Didn't find any major issues. What shall we delve into next?

Reviewed commit: f1bc6544e9

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[intellild]

@codex review

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Codex Review: Didn't find any major issues. Already looking forward to the next diff.

Reviewed commit: 933ff2fb04

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