Resolve folder-mode entity dispatch via worktree fallback (fixes #184)

[iamcxa]

Fixes #184.

Problem (recap)

Folder-mode entities (<id>-<slug>/index.md) live on a worktree branch until merge; the Rule 10 os.path.isfile(entity_path) gate in cmd_build rejects them outright, forcing break-glass dispatch.

A secondary defect surfaced while patching: os.path.splitext(os.path.basename(entity_path))[0] returns the literal "index" for every folder-mode entity, so TeamCreate rejects the duplicate names whenever multiple folder-mode entities are dispatched in the same team.

Changes — all in cmd_build (skills/commission/bin/claude-team)

1. New helper _list_worktrees(git_root)

Parses git worktree list --porcelain into [(path, branch_or_None), ...]. Returns [] on any subprocess failure (git missing, not a repo) so callers can surface a clean error rather than silently fall through.

2. New helper _resolve_entity_read_path(entity_path, workflow_dir)

Two-step resolver:

1. If os.path.isfile(entity_path) — return it (flat-layout & merged-folder happy path; zero behavior change).
2. Else enumerate worktrees via _list_worktrees() and probe each for <wt_path>/<entity_rel>. First match wins.

Returns (resolved_path, tried_paths). On total failure the helper hands every probed path back to the caller so the error message can list exactly where it looked.

3. New helper _derive_entity_slug(entity_path)

Layout-aware slug derivation:

• index.md → parent directory name (folder mode)
• anything else → filename stem (flat layout, unchanged)

4. Wire into cmd_build

• Rule 10 gate replaced with the resolver. On failure, the error lists every probed path:

  entity file not readable at '<path>'. Folder-mode worktree fallback also failed: no checked-out worktree contains a copy at the same repo-relative location. Tried: ['<a>', '<b>', ...].

• Frontmatter read (parse_frontmatter) now uses the resolved path so folder-mode worktree-only entities yield real worktree: / title: fields instead of empty values.
• Slug derivation goes through _derive_entity_slug().

5. No changes to status binary or to the emitted prompt's worktree path / git branch / read-instruction logic

The emitted prompt's worktree path was already computed from the entity's worktree: frontmatter field. Once the frontmatter is read from the resolved location, every downstream branch (worktree_path, branch = worker_key/slug, "Read the entity file at …") works without further change.

Tests

tests/test_claude_team.py::TestBuildFolderModeWorktreeOnly adds three:

Test	Verifies
test_folder_mode_worktree_only_entity_dispatches	Real git init + git worktree add of a folder entity NOT on main; build returns exit 0, agent name is spacedock-ensign-<folder-slug>-ship (not …-index-…), prompt's read-target points at worktree-side index.md, working-dir line points at the worktree.
test_folder_mode_fallback_failure_lists_tried_paths	When no worktree owns the file, error includes Folder-mode worktree fallback also failed, the project-root path, AND the unrelated worktree's candidate path.
test_flat_layout_regression_unchanged_when_file_present	Flat-layout fixture (no git repo at all) short-circuits via os.path.isfile; derived name still uses filename stem. Guards against accidental subprocess overhead and confirms the original happy path is byte-equivalent.

108 passed total (was 105 + 3 new).

What this PR does NOT touch

• plugin.json version (per maintainer release cadence).
• skills/commission/bin/status (folder-mode resolution is local to claude-team).
• The Rule 12 worktree-path rejection (line 209) — entity_path must still be project-root absolute. Folder-mode resolves THROUGH the project-root path, never around it.
• The emitted-prompt worktree-instruction block.

Verification on a real folder-mode worktree-only entity

The captain's failing dispatch from the issue, rerun against this branch:

echo '{"schema_version":1,
       "entity_path":"/Users/kent/Project/<consumer>/docs/ship-flow/057-<slug>/index.md",
       "workflow_dir":"/Users/kent/Project/<consumer>/docs/ship-flow",
       "stage":"ship",
       "checklist":["1. test"],
       "team_name":"test-team",
       "feedback_context":null,
       "scope_notes":null,
       "bare_mode":false,
       "is_feedback_reflow":false}' \
  | skills/commission/bin/claude-team build --workflow-dir /Users/kent/Project/<consumer>/docs/ship-flow

Result on this branch: exit 0, valid Agent spec JSON, prompt working-dir points at /Users/kent/Project/<consumer>/.worktrees/ship-flow-<branch-suffix>, name uses the folder slug.