fix(runtime): any-typed Headers/collection-handle .keys()/.entries()/.values() returned empty

[proggeramlug]

An any-typed .keys()/.entries()/.values() call folds to the array-only Expr::Array{Keys,Entries,Values} (perry-hir #597, so any-typed real arrays iterate through the index-based for-of lowering). The runtime helpers behind those (js_array_{keys,entries,values}_iter_obj) read the receiver as a heap ArrayHeader.

A Web Headers (and FormData / URLSearchParams) instance is a fetch-band registry handle, not an ArrayHeader. So an any-typed iterator method on such a handle read the handle id as an array length and yielded an empty iterator — while .has()/.get() (dynamic dispatch) and the computed headers["keys"]() form worked correctly.

Impact

A large esbuild-bundled CLI app builds request headers, wraps them as { values: Headers }, and merges them via yield* wrapper.values.entries(). Because wrapper.values is any-typed, .entries() folded to ArrayEntries -> empty -> every header (including auth) was silently dropped, and the request failed its SDK validateHeaders check ("Could not resolve authentication method"). With this fix the credential reaches the wire (verified: the compiled app opens a TLS connection to the API and sends the authenticated request).

Fix

collection_iter_obj_for_receiver (perry-runtime/src/array/iter_object.rs) already routes Map/Set receivers to their iterators. Route fetch-band handles through js_native_call_method -> js_headers_{keys,entries,values} (which return a materialized, iterable array) as well. Non-collection fetch handles (Response/Request/Blob) and genuine plain objects still fall through to the empty-array path.

Test

crates/perry/tests/issue_any_typed_collection_handle_iterator.rs — an any-typed Headers (type erased through an object property) iterates via .keys()/.entries()/.values() and yield* delegation, byte-for-byte matching Node.

Summary by CodeRabbit

• Bug Fixes

  • Fixed iterator behavior for Headers, FormData, and URLSearchParams when accessed through erased or generic object references.
  • .keys(), .values(), and .entries() now return proper iterable results instead of falling back to empty iteration in these cases.
  • Improved support for delegation patterns like yield* with these collection iterators.

• Tests

  • Added coverage for iterator behavior on Headers when used through an any boundary.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 9357c001-a3b4-4508-9cc8-30e6d2f33cdc

📥 Commits

Reviewing files that changed from the base of the PR and between 49867d5 and 77c3d71.

📒 Files selected for processing (2)

• crates/perry-runtime/src/array/iter_object.rs
• crates/perry/tests/issue_any_typed_collection_handle_iterator.rs

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📝 Walkthrough

Walkthrough

Adds a fetch-handle-aware branch in collection_iter_obj_for_receiver that dispatches .keys()/.values()/.entries() calls on non-heap fetch handles (Headers/FormData/URLSearchParams) through js_native_call_method, falling back to existing collection iterator logic otherwise. A regression test validates Headers iteration under type erasure.

Changes

Fetch Handle Iterator Fix

Layer / File(s)	Summary
Fetch-handle iterator dispatch crates/perry-runtime/src/array/iter_object.rs	Adds address-band detection for fetch handles and routes .keys()/.values()/.entries() calls through js_native_call_method, falling back to prior Map/Set logic when not applicable.
Regression test for Headers iteration crates/perry/tests/issue_any_typed_collection_handle_iterator.rs	Adds test helpers and a regression test compiling/running TypeScript that erases Headers via any and verifies .keys(), .values(), .entries(), yield* delegation, and .has() results.

Estimated code review effort: 2 (Simple) | ~15 minutes

Possibly related PRs

• PerryTS/perry#5442: Addresses incorrect routing of Response.headers fetch-handle objects for iterator methods, preventing wrong/empty results.
• PerryTS/perry#5549: Modifies js_get_iterator's handle-band guard for fetch-handle-backed iterables, closely related to the iterator resolution fixed here.
• PerryTS/perry#5964: Extends the same js_native_call_method dispatch layer used here to support URLSearchParams under type erasure.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is specific and accurately summarizes the runtime fix for empty any-typed fetch-handle iterators.
Description check	✅ Passed	The description covers the summary, root cause, fix, and test, though it doesn't follow the template headings exactly.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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