fix(runtime): honor promisify.custom on stream.pipeline/finished (#6692)

[proggeramlug]

Summary

Fixes #6692. Node defines stream.pipeline[util.promisify.custom] and stream.finished[util.promisify.custom], pointing at the promise-based node:stream/promises implementations. So promisify(stream.pipeline) in Node returns a (...streams) => Promise with no trailing callback.

Perry never installed those hooks, so promisify(stream.pipeline) fell back to the generic callback-appending wrapper. The bundled node-fetch that pi uses to download fd does:

const pipeline = promisify(Stream.pipeline);   // expects Node's promise impl
...
await pipeline(body, dest);

Routing that through the generic wrapper (instead of Node's dedicated promise-pipeline) is where the stream args got dropped under some dispatch paths, surfacing as TypeError: The "streams" argument must be specified (ERR_MISSING_ARGS).

Fix

Install the promisify.custom symbol on the stream.pipeline / stream.finished bound-native exports, pointing at the corresponding stream/promises callables. The existing custom_promisified_value path in util_promisify.rs then honors them, so promisify(stream.pipeline) returns the dedicated, well-tested promise-pipeline (thunk_streamP_pipeline, registered rest fixed_arity = 2) instead of the generic wrapper — matching Node exactly and sidestepping the fragile forwarding path entirely.

• object/native_module/callable_exports.rs: wire the custom hook when minting the pipeline / finished exports (GC-rooted via a handle scope; no-ops if stream/promises is unavailable, leaving the generic fallback in place).
• node_submodules/mod.rs: stream_promises_export_callable helper that installs the submodule registry entry (so the lookup succeeds even when the program never imported stream/promises) and returns its export value.

Behavior parity (Node 26.5.0)

expression	before	after / Node
typeof stream.pipeline[Symbol.for("nodejs.util.promisify.custom")]	undefined	function
typeof stream.finished[Symbol.for("nodejs.util.promisify.custom")]	undefined	function
promisify(pipeline)(src, dst)	generic wrapper	promise-pipeline; resolves undefined

Testing

• New test-files/test_gap_promisify_pipeline_custom_6692.ts — byte-matches Node 26.5.0 (custom-symbol presence, promisified pipeline with a transform stage, promisified finished). Verified under both the fast dev build and the full auto-optimize / LTO (release) path.
• Existing test_parity_stream_promises, test_issue_3070_stream_promises_input_validation, test_issue_1856_1857_exports_promisify still byte-match Node.
• cargo test -p perry-runtime --lib stream_promises / native_module_stream suites pass.

Notes

• Per maintainer instruction this PR carries no version bump / changelog entry.
• Separate pre-existing gap (not addressed here): a web ReadableStream passed as a pipeline body isn't recognized by the stream/promises body validator — after this change it rejects with ERR_INVALID_ARG_TYPE (previously the generic path silently hung). Both diverge from Node, which accepts web streams; that's a distinct web-stream-support gap.

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Added promise-based custom behavior for util.promisify when promisifying stream.pipeline and stream.finished.

• Bug Fixes

  • Ensures promisified pipeline/finished properly hook into the corresponding stream/promises implementations, with correct handling for unknown exports.

• Tests

  • Added a test validating util.promisify.custom for stream.pipeline (including transform stages) and stream.finished promise resolution behavior.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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Reviewing files that changed from the base of the PR and between 8ec4a2b and db9f364.

📒 Files selected for processing (1)

• crates/perry-runtime/src/object/native_module/callable_exports.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• crates/perry-runtime/src/object/native_module/callable_exports.rs

---

📝 Walkthrough

Walkthrough

The runtime adds util.promisify.custom hooks for stream.pipeline and stream.finished, resolving implementations from stream/promises. A regression test verifies hook exposure and promisified pipeline and finished behavior, including transformed streams.

Changes

Stream promisify integration

Layer / File(s)	Summary
Attach stream promisify hooks crates/perry-runtime/src/node_submodules/mod.rs, crates/perry-runtime/src/object/native_module/callable_exports.rs	Adds stream/promises export lookup and attaches the corresponding promise implementations to stream.pipeline and stream.finished through util.promisify.custom.
Validate promisified stream behavior test-files/test_gap_promisify_pipeline_custom_6692.ts	Tests custom hook exposure, promisified pipelines with and without a transform, and promisified finished completion.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Test
  participant util_promisify
  participant stream_pipeline
  participant stream_promises
  Test->>util_promisify: promisify stream.pipeline
  util_promisify->>stream_pipeline: read util.promisify.custom
  stream_pipeline-->>util_promisify: return promise implementation
  Test->>util_promisify: invoke with streams
  util_promisify->>stream_promises: run promise-based pipeline
  stream_promises-->>Test: resolve undefined

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🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: honoring promisify.custom for stream.pipeline/finished.
Description check	✅ Passed	The description covers the summary, fix, testing, and issue reference, and is mostly complete despite a few optional template sections being omitted.
Linked Issues check	✅ Passed	The changes add Node-compatible promisify.custom hooks for stream.pipeline and stream.finished and include parity tests matching #6692's requirements.
Out of Scope Changes check	✅ Passed	The diff stays focused on stream promisify behavior, supporting lookup, and tests, with no clear unrelated or extra-scope changes.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@crates/perry-runtime/src/object/native_module/callable_exports.rs`:
- Around line 81-88: Propagate the relocated pointer from
attach_stream_promisify_custom: at
crates/perry-runtime/src/object/native_module/callable_exports.rs:81-88, shadow
value with the function’s returned f64; at
crates/perry-runtime/src/object/native_module/callable_exports.rs:228-260,
change attach_stream_promisify_custom to return f64 and return
target.get_nanbox_f64() after allocating operations so the caller receives the
updated pointer.

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Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: e1b51b46-8d2e-48bb-a577-08212353fadd

📥 Commits

Reviewing files that changed from the base of the PR and between a323f6d and 8ec4a2b.

📒 Files selected for processing (3)

• crates/perry-runtime/src/node_submodules/mod.rs
• crates/perry-runtime/src/object/native_module/callable_exports.rs
• test-files/test_gap_promisify_pipeline_custom_6692.ts