T2.3: Damage-based partial rendering via per-node dirty flags

[RtlZeroMemory]

Summary

• add per-node dirty tracking (dirty + selfDirty) on runtime instances during commit reconciliation
• propagate dirty state up the runtime tree for child, prop, and layout-driven changes
• enable clean-subtree skipping in render DFS while preserving clip stack correctness
• force subtree rendering when a parent container is self-dirty to preserve visual equivalence under coarse damage rect redraws
• clear runtime dirty flags after successful frame submission
• document partial-rendering dirty/skip behavior in the layout guide

Tests

• added correctness coverage in packages/core/src/renderer/__tests__/renderer.partial.test.ts (26 deterministic tests)
• added perf coverage in packages/core/src/renderer/__tests__/renderer.partial.perf.test.ts (11 deterministic tests)
• total new tests: 37

Validation

• npm run lint
• npm run build
• npm run typecheck
• node scripts/run-tests.mjs
  • pass: 2525
  • fail: 0

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 8b72275d44

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".