Components: Complete native-core FocusZone lifecycle and focus-result qualification #4374

Goal

Finish the native focus-request qualification left by the native-core modernization milestone. Part of #4274. Modern APIs remain /macos and /windows previews; this issue does not grant root or Win32 admission.

Observed baseline — 2026-10-15

On user/jasonvmo/native-lib2 at b55d6c9a3, Windows RNW 0.81.35 passes native default/first/last/specific focused-identity requests, disabled/unfocusable/outside-target refusal, retained detached handles, legacy navigation, and entry inside an owned Callout popup. macOS Fabric and Paper pass the authored command/lifetime cases. Pre-aborted and wrapper-rejected requests do not qualify native in-flight races.

Remaining work and acceptance

• Exercise native generation mismatch, late/stale result fencing, target replacement, pending abort, unmount during a request, and inactive-window refusal on Windows and both macOS renderers. Confirm no window reactivation, no implicit pre-mount queue, exactly-once settlement, and actual focused/responder identity.
• Retain tests that explicit commands override entry preferences without regressing remembered focus, Tab/Shift+Tab exit, disabled refusal, or focus in owned popups.
• Qualify macOS field-editor normalization and VoiceOver interactions beyond current authored runtime cases.
• Track the separately deferred macOS FocusZone navigation port: preserve the proven ObjC algorithm unless a Swift port has a reviewed parity contract and complete legacy/modern keyboard evidence. Do not rewrite merely for language uniformity.
• Record exact host/fork/renderer versions, commands, executed/pass/fail/skip counts, and race evidence. JS tests, compilation, and skipped native cases are not runtime qualification.

Evidence and reproduction

The retired handoff is retained in Git at b55d6c9a3:packages/agentic/native-core/plans/modernization.md. Contracts: packages/agentic/native-core/src/components/focus-zone/SPEC.md; shared rules: packages/agentic/native-core/AGENTS.md and references/agents/focus/.

From apps/storybook, use STORYBOOK_SMOKE_STORY='native-*' yarn storybook smoke --windows --mode stories-and-tests, and the equivalent --macos / --macos --paper lanes. Run native-core package checks and codegen:windows --check. Preserve owned app/helper/input cleanup.