Avoid duplicate CommonJS TypeScript transforms (GOL-418)

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Summary

• establish one transform owner for every CommonJS TypeScript entry path
• carry prepared CommonJS graphs through synchronous require transactions while reusing cached child metadata
• classify TypeScript module format from transformed AST semantics, including erased type-only syntax and top-level-await edge cases
• preserve cache rollback, source registration, export metadata, cycles, and ESM interop

Validation

• focused P2 and P3 TypeScript runtime contracts
• P2 and P3 strip and transform-immutability tests
• module-loader architecture suite
• targeted AST classifier unit coverage
• root and changed-source formatting/Clippy checks
• final independent exact-SHA review passed at d107dc6cdaffdbe1f4e069a1a6b4c3d7a16472c6

CI note

All substantive CI lanes passed except one recurring Preview 3 runtime-group-2 transport failure (fetch_with_referrer_policy, Hyper IncompleteMessage / HttpProtocolError). The targeted group-8 rerun passed, and the same group-2 signature is independently reproduced and owned by GOL-420; no GOL-418 source change is indicated.

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Exact-SHA correction review and local verification completed for d107dc6cdaffdbe1f4e069a1a6b4c3d7a16472c6.

The correction establishes one AST-based TypeScript module-format decision for CommonJS preparation, including type-only import/export erasure, .mts/.cts precedence over package type, CommonJS-wrapper lexical bindings and destructuring, erased ambient declarations, import.meta, top-level await, for await, and await using with nested-function exclusions.

Regression coverage now verifies recursive CJS reexport preparation, exact transform ownership/counts, cached child reuse, true ESM avoidance, failure rollback, a type: module package containing .cts, lexical-only ESM markers, and top-level versus nested for await / await using behavior.

Independent delta review: PASS with no remaining findings.

Local exact-SHA verification:

• root and skeleton formatting: PASS
• targeted AST classifier unit: PASS (1 passed, 45 filtered)
• host runtime Clippy with -D warnings: PASS
• focused P2 TypeScript runtime contract: PASS
• focused P3 TypeScript runtime contract: PASS
• targeted skeleton Clippy: no findings in changed internal/typescript.rs; it reproduces the same 39 documented older-branch module_loading.rs diagnostics

The tracked tree is clean, Cargo.toml_ is restored, generated skeleton artifacts are removed, and Cargo.lock is unchanged. CI is now running against this exact SHA.

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Targeted rerun of test-runtime-p3 (2) completed at the reviewed SHA d107dc6cdaffdbe1f4e069a1a6b4c3d7a16472c6 and reproduced the same transport-owned failure a second time.

The failing case is again runtime::fetch::fetch_with_referrer_policy; the host reports Hyper IncompleteMessage, and Preview 3 surfaces ErrorCode::HttpProtocolError. This is the independently reproduced GOL-420 transport lifecycle flake, not a TypeScript transformation failure.

No source changes were made. Every other substantive P2/P3 runtime, node-compat, build, and test lane is green, including the targeted group 8 rerun.