Title#

Persist worktree across phases, cleanup on task completion

Problem#

The per-phase create/destroy worktree lifecycle caused permanent stuck loops when git branch -D failed on a checked-out branch (issue #246). The aggressive pre-cleanup ran destructive git operations before each phase, making recovery impossible.

Task / Link#

Closes #272

Changes#

• Replace WorktreeService.createWorktree() with idempotent getOrCreateWorktree(): reuses existing worktree, attaches existing branch, or fresh-creates
• Remove aggressive pre-cleanup (git branch -D, git worktree remove --force) from worktree setup
• getOrCreateWorktree() runs git fetch origin on reuse to stay current
• Remove per-phase cleanupWorktree() from PhaseRouterService.executePhase() finally block
• Add terminal-state cleanup: WorktreeService.cleanupWorktree() called in InternalAdapterService.advanceAndEnqueue() when task reaches complete
• Import WorktreeModule in InternalAdapterModule for DI

Notes#

• Cleanup is wrapped in try/catch — failure is logged but does not fail the pipeline
• Concurrent phase safety maintained by the queue's serial-per-task guarantee

Testing#

• Unit tests updated for all three getOrCreateWorktree() paths: worktree-exists-reuse, branch-exists-no-worktree, fresh-create
• New unit tests in InternalAdapterService: cleanup called on terminal state, NOT called on phase advancement
• Phase-router tests updated: assert cleanupWorktree is NOT called after phase execution
• All 696 unit tests pass; lint clean (no new errors)