Record Phase 538 eraser feasibility boundary

[ExplodingUFO]

Summary

• Record Phase 538 as the eraser behavior/API feasibility gate for GitHub Phase 538: eraser behavior/API feasibility gate #199 / bead avalonia-node-map-a3w.
• Clarify that current selection.delete / Delete Selection / selection-delete evidence is graph-selection deletion, not an eraser cursor, collision trail, or eraser-specific hit-testing route.
• Update EN/ZH parity docs and focused roadmap docs tests while preserving Phase 539-540 as future tracker-backed work.

Closes #199

Merge Order Note

• PR Add hosted lasso pointer mode actions #198 has already merged into master.
• PR Record Phase 538 eraser feasibility boundary #200 is now the lowest open PR in the whiteboard stack. Downstream PRs starting with Phase 539: record drawing primitive model gate #202 must not merge before this PR clears the required review gate.

Test Plan

• dotnet test tests\AsterGraph.Demo.Tests\AsterGraph.Demo.Tests.csproj -c Release --filter "FullyQualifiedName~ParityRoadmapDocs_RecordPhase538EraserBehaviorApiFeasibilityGateInBothLocales" --verbosity minimal
• dotnet test tests\AsterGraph.Demo.Tests\AsterGraph.Demo.Tests.csproj -c Release --verbosity minimal
• dotnet build AsterGraph.sln -c Release --verbosity minimal
• git diff --check

[ExplodingUFO]

Readiness note for external review (2026-05-13):

• Reviewed the Phase 538 docs/test diff: docs/en/phase-0-reactflow-parity-audit.md, docs/zh-CN/phase-0-reactflow-parity-audit.md, and tests/AsterGraph.Demo.Tests/ReactFlowParityRoadmapDocsTests.cs.
• Fresh local verification in .worktrees/phase-538-eraser-feasibility passed:
  • dotnet test tests\AsterGraph.Demo.Tests\AsterGraph.Demo.Tests.csproj -c Release --filter "FullyQualifiedName~ParityRoadmapDocs_RecordPhase538EraserBehaviorApiFeasibilityGateInBothLocales" --verbosity minimal
  • dotnet test tests\AsterGraph.Demo.Tests\AsterGraph.Demo.Tests.csproj -c Release --verbosity minimal (281 passed)
  • dotnet build AsterGraph.sln -c Release -v:minimal
  • git diff --check
• GitHub checks are green and the branch is mergeable; the remaining blocker is the required external review (reviewDecision=REVIEW_REQUIRED).

No admin-bypass requested; leaving this PR pending required review.

[ExplodingUFO]

Current blocker update (2026-05-13, after stale-master repair):

• PR Record Phase 538 eraser feasibility boundary #200 is still the lowest open PR in the whiteboard stack.
• Current head: 636f2622a97af73de4b59ae3165dd5cebdb77f09.
• The previous stale-master conflict was resolved by merging master into feature/phase-538-eraser-feasibility; the branch now reports mergeable=MERGEABLE.
• All GitHub checks on the current head are successful, including hygiene-proof, framework matrix (net8.0, net9.0, net10.0), linux-validation, macos-validation, contract-proof, and both release-validation jobs.
• Local verification after the merge repair also passed:
  • focused Phase 538 roadmap-doc test: 1/1
  • full AsterGraph.Demo.Tests: 281/281
  • git diff --check: clean

Remaining blocker is only repository review policy: reviewDecision=REVIEW_REQUIRED, mergeStateStatus=BLOCKED. I cannot approve my own PR. Do not merge downstream PRs (#202 and later) until this PR receives an eligible review/approval or an explicit admin-bypass decision.

[ExplodingUFO]

PR #200 stack refresh (2026-05-14):

• This remains the lowest open blocker in the whiteboard stack.
• GitHub now reports PR Record Phase 538 eraser feasibility boundary #200 as MERGEABLE with mergeStateStatus=BLOCKED only because reviewDecision=REVIEW_REQUIRED.
• Current base/head: master at 90cd610699f667fde1d9a074e7df00b60e9a2227, feature/phase-538-eraser-feasibility at 636f2622a97af73de4b59ae3165dd5cebdb77f09.
• All listed CI checks on the head are green, including hygiene-proof, framework-matrix (net8.0, net9.0, net10.0), linux-validation, macos-validation, contract-proof, and release-validation.
• The downstream stack PRs Phase 539: record drawing primitive model gate #202 through Phase 564: whiteboard annotation migration and compatibility proof #252 currently report MERGEABLE/CLEAN.

Next action needed: an eligible GitHub review/approval for #200, or explicit admin-bypass authorization. I am not merging downstream PRs or bypassing this gate without that decision.