fix(forms): release removed Signal Forms array fields

[erkamyaman]

What and why

On each push, wrapSignalSubmit walks structure.materializedChildren() and wraps every new field's submitState.selfSubmitting.set, pushing an undo closure onto entry.unwrap. That closure holds a reference to the field. The list was only emptied in unwrapSignalRoot, when the whole form root goes away.

With a real form(), removing an array item drops its field from materializedChildren(), and adding an item creates a brand-new field. So any Signal Form with a dynamic array (todo lists, line items, "add another address") kept every field it ever rendered, along with that field's nested fields and signal graph, for as long as the form stayed on the page. On a long-lived page that grows without limit.

The fix:

• entry.unwrap is now a Map from flag to undo function
• each pass records the flags it reaches, then unwraps and deletes the ones it didn't, which releases removed fields and restores their original set
• removing the whole form still unwraps everything

How it was verified

New test in forms-collector.test.ts with a real Signal Forms Tasks form. It adds and removes an array item 10 times with a push after each step, forces garbage collection, and checks with WeakRefs that the removed fields can be collected. On main all of them are still alive. With the fix none of the checked ones are. All package tests pass.

• pnpm commit:check (commit messages follow the guidelines)
• pnpm format:check
• pnpm typecheck (includes the ngc template checks)
• pnpm test:devtools (all passing)
• pnpm skills:check (when .claude/ changed): not changed
• No docs change needed: the fix makes the code match existing docs (no-docs)
• pnpm extension:build and extension/ui committed (when app/ changed): not changed
• Checked in the browser with axe (when the UI changed): no UI change

Summary by CodeRabbit

• Bug Fixes
  • DevTools no longer keeps removed fields from mounted Signal Forms in memory, allowing them to be reclaimed.
  • Forms continue to submit correctly after fields are added and removed.

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: 21042090-9870-4538-9691-d1cc99d5771e

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📥 Commits

Reviewing files that changed from the base of the PR and between 58273c6 and 73d7200.

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📒 Files selected for processing (2)

• packages/devtools/src/__tests__/forms-collector.test.ts
• packages/devtools/src/forms-collector.ts

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📝 Walkthrough

Walkthrough

The Signal Forms collector now tracks submit-wrapper restoration callbacks by flag and removes wrappers for flags absent from a later traversal. A new test removes array items, checks that their field nodes can be collected, and submits the mounted form.

Changes

Signal Forms wrapper cleanup

Layer / File(s)	Summary
Track and restore submit wrappers packages/devtools/src/forms-collector.ts, packages/devtools/src/__tests__/forms-collector.test.ts	The collector stores restoration callbacks by flag, restores wrappers for flags no longer reached, and clears callbacks when unwrapping a root. The test removes array items, checks their collection, and confirms the mounted form records a submit event.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

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Merge Risk | ⚪ Minimal · up to 73d72

Merge Risk: ⚪ Minimal · up to 73d72

The removed-field retention fix is covered by a mounted-form test, and no actionable issue remains before merge.

Security Architecture Review

Security architecture risk: ⚪ Minimal · up to 73d72

The change releases instrumentation for removed form fields while preserving the original submission setters. The apparent new public entrypoint is a test fixture, not an expanded production interface. No material security risk was identified in the reviewed change.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The changed behavior is confined to submit instrumentation on forms already discovered by the collector. The comparison adds neither a production caller nor greater submission authority; the new entrypoint-like declarations are test-only.

Trust Boundaries and Controls

• inferred — Cleanup changes diagnostic ownership rather than validation or action authority. The wrapper preserves the original setter call, and Signal Forms submission continues through the existing form-root submission path.

Resilience and Maintainability Implications

• inferred — Not reached is broader than removed: traversal limits and failed reads can cause a mounted flag to lose instrumentation until rediscovery. This can reduce diagnostic event continuity, including around pending submissions, but the cleanup restores rather than disables the application setter. No security-control dependency on those events was established in the inspected path.

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Pre-merge checks | 4 | 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: releasing removed Signal Forms array fields and fixing their retained references.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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