Fix FieldArray active and touched meta

[erikras-richard-agent]

Summary

• aggregate subscribed FieldArray meta.active from the currently active child field
• aggregate subscribed FieldArray meta.touched from touched child fields
• keep the optimized default subscription intact and add regression coverage for the explicit active/touched subscription path

Closes #175

Test Plan

• yarn nps typescript
• yarn test
• yarn nps lint

Summary by CodeRabbit

• Improvements

  • FieldArray components now correctly expose meta.active and meta.touched states when subscribed, providing accurate tracking of field focus and interaction status.

• Tests

  • Added test coverage for FieldArray meta state behavior with focus and blur interactions.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: a0fd8a15-990e-451f-9e5b-4e4835f255a7

📥 Commits

Reviewing files that changed from the base of the PR and between abe54d9 and 3280c9c.

📒 Files selected for processing (2)

• src/FieldArray.test.tsx
• src/useFieldArray.ts

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📝 Walkthrough

Walkthrough

The PR fixes meta.active and meta.touched being undefined for FieldArray by conditionally computing them as aggregate properties of child fields only when requested via subscription options. A new test verifies the behavior works correctly on focus and blur events.

Changes

FieldArray Meta Aggregation

Layer / File(s)	Summary
Helper & Imports src/useFieldArray.ts	Adds useFormState import and isArrayField helper to identify fields belonging to the array; introduces explicit defaultSubscription for { length, value, error }.
Subscription Logic src/useFieldArray.ts	Uses useFormState with computed subscription for active and/or touched based on caller-provided options; extracts field state and builds metaWithoutLength by copying meta descriptors while excluding length.
Conditional Meta Getters src/useFieldArray.ts	Conditionally defines enumerable lazy getters for active and touched on metaWithoutLength, computing them from formState and checking whether the array has active/touched descendant fields via isArrayField.
Tests & Verification src/FieldArray.test.tsx	Adds test case verifying that meta.active and meta.touched aggregate correctly when subscribed to; asserts initial state, then validates state changes on focus and blur of array inputs.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• final-form/react-final-form-arrays#195: Modifies useFieldArray's subscription-driven meta behavior and default subscription handling for active/touched properties.
• final-form/react-final-form-arrays#188: Changes how FieldArray meta properties like active/touched are produced and exposed through descriptor manipulation.

Suggested reviewers

• erikras

Poem

🐰 The array's feelings, long kept still,
Now shine when asked with subscription's will,
Active and touched from children below,
Aggregate up with a lazy getter's glow,
FieldArray's heart beats true at last!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: fixing FieldArray's meta.active and meta.touched properties, which directly addresses the core issue.
Linked Issues check	✅ Passed	The PR implements both required behaviors from issue #175: aggregating meta.active when any child field is active, and aggregating meta.touched when any child field has been touched.
Out of Scope Changes check	✅ Passed	All changes are scoped to implementing the fix for meta.active and meta.touched aggregation; no unrelated modifications detected in the changeset.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ 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-fieldarray-meta-active-touched-175

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