fix(runtime): #5437 — CJS-interop probe on module-default wrapper must not auto-call it (fixes #5546 boot crash)

[proggeramlug]

Why

Follow-up to #5546 (merged). That change auto-calls a registered CJS module-default wrapper closure on a property miss to obtain module.exports. For a CJS module whose module.exports is a function (e.g. debug → createDebug), the wrapper is that function, and the ubiquitous _interop_require_default(require("debug")) reads .__esModule off it → miss → the fallback calls createDebug() with no args → enabled(undefined) → undefined.length → throws at module-init. The server exits at boot (regressed the Next.js #5437 bundle from HTTP 500-serving to HTTP 000-boot-crash, and can break other SWC/Babel-compiled-CJS programs).

This also means #5546's reported "undefined-ctor 1→0" was a measurement artifact — the server crashed at boot before the request render where SharedCacheControls is evaluated. (Completing the actual W6 close — making the auto-call fire for the captured uw — is tracked separately and in progress.)

Fix (runtime-only, +87/-3)

crates/perry-runtime/src/object/field_get_set.rs: on a registered module-default wrapper, short-circuit the two CJS-interop probe keys before the auto-call:

• .__esModule → undefined (a function-export CJS module is not an ES module)
• .default → the wrapper closure itself (interop-default of a non-ESM module is module.exports)

Both added to the auto-call exclusion list. Genuine non-default member reads (the #5437 SharedCacheControls path) are unaffected.

Validation

• Regression test module_default_wrapper_interop_probe_does_not_call_wrapper — wrapper panic!s if invoked; asserts the probe keys resolve without calling it.
• Bundle: the .length boot crash is gone — server boots and serves again (back to HTTP 500; the remaining 1× SharedCacheControls throw is the in-progress real W6 close).
• cargo test -p perry-runtime: 1071 pass incl. the new test.

Refs #5437, #5546.

Summary by CodeRabbit

Bug Fixes

• Fixed a runtime crash during application boot that occurred when the CommonJS module interoperability system probed certain module wrappers. The issue was caused by unintended function invocations during module initialization, which could trigger side effects and fail at startup.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

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Configuration used: defaults

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Run ID: 3a1631d5-d8a0-42a2-834a-6b11e3646af7

📥 Commits

Reviewing files that changed from the base of the PR and between b86091d and faa1528.

⛔ Files ignored due to path filters (1)

• Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (5)

• CHANGELOG.md
• CLAUDE.md
• Cargo.toml
• crates/perry-runtime/src/closure/tests.rs
• crates/perry-runtime/src/object/field_get_set.rs

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📝 Walkthrough

Walkthrough

Version bumped to 0.5.1201. The fix adds a short-circuit in js_object_get_field_by_name so that when a closure receiver is a registered module-default wrapper and the requested property is __esModule or default, the read returns immediately without auto-calling the wrapper. The #5437 exclusion list is also extended with these two keys. A regression test verifies the wrapper is never invoked during those probe reads.

Changes

CJS interop probe short-circuit for module-default wrappers

Layer / File(s)	Summary
Short-circuit and exclusion-list fix crates/perry-runtime/src/object/field_get_set.rs	Adds a new early-return block for module-default wrapper closures: __esModule reads return undefined and default reads return the wrapper value itself. Extends the #5437 auto-call exclusion list to cover both default and __esModule.
Regression test: wrapper not called during probe crates/perry-runtime/src/closure/tests.rs	Adds a panic-based extern probe function and a test that registers a module-default wrapper and asserts neither __esModule nor default reads invoke the wrapper.
Version bump and changelog Cargo.toml, CLAUDE.md, CHANGELOG.md	Workspace version incremented to 0.5.1201; changelog entry documents the CJS interop probe fix and its regression test.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• PerryTS/perry#5546: Introduced the module-default wrapper auto-call logic in field_get_set.rs that this PR partially overrides with the new short-circuit for __esModule/default probe reads.

Poem

🐇 A wrapper once called without warning or care,
Made modules explode with side-effects rare.
Now __esModule and default just peek,
The wrapper stays silent — no crash, no squeak!
Short-circuit complete, the boot hops with ease. 🌿

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/w6-debug-interop-noautocall-5437

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