Regression: successful worktree finalization mutates then never exits

[chubes4]

Problem

workspace worktree finalize can complete its mutation and remove the worktree, then remain alive without output until the caller kills it. This regresses the closed completion fixes in #964, #1068, and #1222.

Observed on DMC 0.69.12 with a clean, pushed worktree whose PR was already merged.

Reproduction

studio wp datamachine-code workspace worktree finalize \
  markdown-database-integration@feat-244-native-comments \
  --pr=https://github.com/Automattic/markdown-database-integration/pull/245 \
  --owner-terminal-outcome=success \
  --format=json

Observed:

• no stdout or stderr before an external 180-second timeout
• after timeout, the worktree path was gone, proving finalization/cleanup had committed
• the caller had no terminal receipt and could not distinguish committed success from partial failure without filesystem/GitHub spelunking
• the surviving command lifetime overlapped later SQLite lock contention

Impact

The explicit lifecycle handoff becomes ambiguous and non-idempotent from the caller's seat. Agents retry, inspect raw filesystem state, or bypass DMC exactly where DMC should provide deterministic terminal evidence.

Acceptance criteria

• Finalize emits and flushes its terminal receipt before optional cleanup work.
• The CLI process exits within a deterministic wall-clock bound after committed success.
• Every post-commit phase has a deadline and phase diagnostic.
• Interruption after commit is recoverable through an idempotent targeted status/finalize call.
• Process-level coverage proves no child process, DB transaction, WordPress shutdown callback, or lock survives successful output.
• A regression fixture uses a merged PR, clean pushed branch, and owner-terminal-outcome=success.

Related

• Targeted worktree get and finalize commands hang on a clean managed worktree #964
• Terminate successful workspace CLI commands after output #1068
• Ensure workspace inspection commands exit after rendering results #1222

AI assistance

OpenAI GPT-5.6 Sol via OpenCode ran the finalizer, verified the worktree disappeared despite caller timeout, searched existing closed fixes, and drafted this regression report. Chris Huber directed the workflow and remains responsible.