[Fooftilly]

Summary

Next incremental B1 coverage slice under #651, following merged #666.

Expand the same informational Vitest coverage workflow to include frontend-app/src/workspace/transitions.ts using the existing src/workspace/workspace.test.ts tests. Workspace state transitions affect pane visibility, tab relocation, focus, and safe close/mode changes. This extends the coverage sample to an important correctness-sensitive area without changing runtime behavior.

Small, bounded scope

• Changes one file: .github/workflows/vitest-coverage-pilot.yml.
• Reuses the exact locked Vitest 5.0.2 and coverage-v8 5.0.2, npm ci, and the same existing job/check. No new dependencies, jobs, artifacts, or workflow permissions.
• Runs four existing Vitest test files together and instruments exactly four requested source modules: lifecycle/tab-leave.ts, lifecycle/owner-resource.ts, query/retry.ts, and workspace/transitions.ts.
• Reports separate per-module line and branch counts/percentages with a four-module-only aggregate; fails if an expected source has no measurements, an unexpected source appears, any metric is empty, or aggregate counts disagree.
• Informational only: no coverage target or threshold, no additional coverage upload, no ordinary PRKS gate changes.
• Extends PR path triggers solely for workspace transitions source and its test file.

Verification

• Run the changed Vitest coverage pilot. Verify that the additional workspace/transitions.ts module appears in the Actions summary, all four suites pass, and both line and branch denominators are nonzero. Do not extrapolate to frontend-wide coverage.

• Check that prior three-module measurements remain stable (from ci: expand Vitest coverage to owner-resource lifecycle (#651) #666: tab-leave.ts 77/94 lines and 53/84 branches; owner-resource.ts 71/71 lines and 53/61 branches; retry.ts 7/7 lines and 6/6 branches).

• Confirm actionlint, zizmor, Static Analysis/Vue tests, PRKS Test Gate, CodeQL and the E2E planner remain green; review inline findings and fix any confirmed defects before requesting a merge.

• Verified on the synchronized latest head: Vitest coverage run 38588806263 passed 56/56 tests in four suites, with these measured scoped results:

  Source	Lines	Branches
  tab-leave.ts	77/94 (81.9%)	53/84 (63.1%)
  owner-resource.ts	71/71 (100.0%)	53/61 (86.9%)
  retry.ts	7/7 (100.0%)	6/6 (100.0%)
  workspace/transitions.ts	158/173 (91.3%)	164/219 (74.9%)
  Only these four modules	313/345 (90.7%)	276/370 (74.6%)

  The initial PR-opening event unexpectedly produced no ordinary pull_request workflows and left GitHub mergeability undetermined. A formatting-only follow-up to split the four test arguments across lines emitted a synchronize event: all eight PR checks started, mergeability became true, and the focused pilot passed.

Base master@345193bc77ecbf5dc82600cabaf2705fe796be2d.

Refs #651, #666. Do not auto-merge: the maintainer explicitly approves each merge.