{
  "meta": {
    "agent": "planner",
    "task_id": "270",
    "title": "Make createWorktree() idempotent — reuse existing worktree/branch",
    "created_at": "2026-04-03T12:00:00Z"
  },
  "inputs": [
    {
      "name": "GitHub issue #270",
      "type": "context",
      "ref": "https://github.com/AgentSDE/agent-core/issues/270",
      "notes": "P0 fix for stuck retry loop when branch is checked out elsewhere"
    },
    {
      "name": "worktree.service.ts",
      "type": "file",
      "ref": "src/worktree/worktree.service.ts",
      "notes": "createWorktree() lines 24-143 — current destructive nuke-and-recreate logic"
    },
    {
      "name": "worktree.service.spec.ts",
      "type": "file",
      "ref": "src/worktree/worktree.service.spec.ts",
      "notes": "Existing unit tests using jest mocks for child_process/fs"
    }
  ],
  "outputs": [
    {
      "name": "Implementation plan",
      "type": "plan",
      "format": "md",
      "content": "plan.md"
    }
  ],
  "files": [
    {
      "path": "src/worktree/worktree.service.ts",
      "action": "modify",
      "reason": "Replace destructive worktree/branch cleanup with idempotent detect-and-reuse logic"
    },
    {
      "path": "src/worktree/worktree.service.spec.ts",
      "action": "modify",
      "reason": "Add 4 new unit tests for idempotent paths; update existing tests"
    }
  ],
  "steps": [
    {
      "id": "S1",
      "summary": "Implement idempotent createWorktree() logic with isValidWorktree helper, three-path branching (reuse/existing-branch/fresh), and remove aggressive git branch -D cleanup",
      "acceptance": [
        "isValidWorktree() helper checks git worktree list for the given path",
        "Valid existing worktree is reused with fetch+reset instead of removal",
        "Invalid/corrupted worktree directory is removed and falls through to branch-check",
        "Existing local branch without worktree uses git worktree add <path> <branch> (no -b)",
        "Fresh start (no worktree, no branch) uses git worktree add -b <branch> <path> origin/master",
        "git branch -D block (old lines 100-118) is completely removed",
        "git fetch origin errors in reuse path are surfaced, not swallowed"
      ],
      "depends_on": []
    },
    {
      "id": "S2",
      "summary": "Add unit tests for all four idempotent paths and update existing tests to match new flow",
      "acceptance": [
        "Test: worktree exists and is valid → reused without removal",
        "Test: worktree exists but is invalid → removed, falls through to branch-check",
        "Test: branch exists locally, no worktree → git worktree add without -b",
        "Test: neither exists → fresh git worktree add -b (existing behavior)",
        "Existing tests updated to remove assertions on git branch -D behavior",
        "npm run test passes with zero failures",
        "npm run lint passes with zero warnings"
      ],
      "depends_on": [
        "S1"
      ]
    }
  ],
  "risks": [
    {
      "risk": "git reset --hard in reuse path discards uncommitted changes",
      "mitigation": "Agent worktrees are ephemeral and always start from origin/master; issue explicitly requests this behavior"
    },
    {
      "risk": "isValidWorktree check via git worktree list may be slow on repos with many worktrees",
      "mitigation": "Agent repos typically have <10 worktrees; performance impact negligible"
    }
  ],
  "assumptions": [
    "Agent worktrees are always intended to start from origin/master — resetting on reuse is safe",
    "The exec() helper already surfaces errors as rejected promises — no additional error handling wrapper needed"
  ],
  "open_questions": []
}