Infrastructure: Qualify native-core Win32 capabilities, peer floors, publishing, and root admission #4376

Goal

Resolve the packaging and all-host admission gates deferred by native-core modernization. Part of #4275; coordinate component semantics with #4274.

Observed baseline — 2026-10-15

Modern Callout/FocusZone/live-target APIs are platform previews in /macos and /windows, require React 19 and the current native registration, and are not root or /win APIs. The baked Office Win32 host retains /legacy; no new managed fields/commands are dispatched to its registrations. Existing build/source/Node checks do not prove old-peer native compatibility or all-host behavior.

Acceptance

• Establish a named supported React/RN/fork/renderer matrix, including oldest declared peers, and run consuming native codegen/build/runtime checks before changing peer declarations.
• Obtain Win32 capability evidence for each mandatory modern operation. Do not infer support or impossibility from missing observation infrastructure, and never send an unverified managed protocol to a baked host.
• Decide and document publishing/peer floors and platform-preview versus root admission. Preserve legacy aliases, host ownership, and compatibility; do not implicitly raise legacy peer floors.
• Verify packed archives in consuming hosts: codegen identity/provider registration, native sources/generated artifacts, JS/declarations, shims, commands/events/refs, and no machine-local/intermediate outputs.
• Admit root or /win exports only after equivalent mandatory behavior is demonstrated on every supported desktop host/version combination. Compile checks, platform previews, and skips do not satisfy admission.
• Keep the package README, export-map/ownership/type tests, component contracts, and release notes aligned with actual admission evidence.

Evidence

Retired handoff: b55d6c9a3:packages/agentic/native-core/plans/modernization.md. Durable rules/contracts remain in packages/agentic/native-core/README.md, AGENTS.md, and src/components/*/SPEC.md. Run native-core format/lint/build/test, codegen:windows --check, Callout/FocusZone shim tests, publishing/changeset checks, and the consuming native matrix; do not label JS-only checks native qualification.