Spec Kitty

Data Model — Implement-Loop Commit & Move-Task Hardening

Control-flow / maintainability mission; no persisted schema. The "model" is the partition-decision it unifies and the status-surface resolution it corrects.

The partition decision (FR-005 / FR-006 / C-007)

The three decision sites (all to consolidate)

Site	File	Role	Primary ref	kind=None routes to
Read	implement_cores.py::resolve_precondition_ref	idempotency compare	"HEAD"	PRIMARY (residue predicate) ✅ #2533-safe
Write	implement.py::_partition_files_for_commit	commit split	planning_branch	PRIMARY (residue predicate) ✅
Write	commit_router::_group_files_by_partition	commit split	placement ref	caller partition (can be COORD) ❌ #2533 hole

The disagreement set (what the characterization gate pins)

kind=None ⟺ kind_for_mission_file(path) returns None ⟺ the path is not in _PRIMARY_ARTIFACT_KINDS ∪ _PLACEMENT_ARTIFACT_KINDS. Concretely: meta.json (it is in the self-bookkeeping allowlist, not the kind map) + any unrecognized mission file.

back to the caller's partition → can be COORD.

• Residue authority: kind=None → not a coord residue → PRIMARY ("HEAD" / target).
• Kind authority (commit_router): kind_for_mission_file(file) or kind → None → falls

Unified contract (C-007): the consolidated authority MUST route kind=None → PRIMARY.

Unified authority (target shape)

is_coordination_artifact_residue_path(path) -> bool   # EXISTING mission_runtime predicate; NOT None-> PRIMARY
primary_ref_for(context) -> str                       # one cli-local expression; read & write agree

— NOT a net-new partition_of wrapper. Two of the three sites already call it (implement.py:600, implement_cores.py:268); the consolidation swaps commit_router:404's kind_for_mission_file(file) or kind classifier onto it (classifier-only — commit_router keeps resolve_placement_only for its COORD ref). Homing a new partition_of in cli/commands would invert the cli → coordination layering (C-008); mission_runtime is read-only.

cli-local (Lane A) concern (primary_ref_for) that does NOT touch commit_router.

(old per-site classifier deleted or forwarding; commit_router no longer consults is_primary_artifact_kind(kind_for_mission_file(...)) for the split) — SC-004, they cannot silently re-diverge. Scope is the three named claim/planning-commit sites only (not every predicate-consumer in the codebase).

• The shared partition authority is the existing mission_runtime.is_coordination_artifact_residue_path
• The read ("HEAD") / write (planning_branch) primary-ref unification is a SEPARATE,
• A structural test asserts the three named sites resolve partition through the one predicate

Status-surface resolution (FR-001)

move-task WP## (cwd = lane worktree)
  └─ _mt_resolve_targets → feature_dir (must derive from the canonical mission root,
        NOT a cwd-tainted locate_project_root)
        └─ _read_transactional_wp_lane → reads status.json/events from the mission root
  ⇒ transition succeeds identically whether cwd is the repo root or a lane worktree

Invariants

(now unified) sites. The #2533 regression stays green.

signature + 5-tuple return (Lane B depends on it).

(#2576 rollback_uncheck_error recording + #2513 commit-failure swallow).

coord_branch truthy AND protected planning_branch — the 767 precondition), the artifact-commit AND status-commit halves BOTH fail-closed with PlacementResolutionRequired — no silent PRIMARY-on-coord divert; the 767 fallback is removed. This is the ONLY state where the status half's unconditional-on-None raise and the artifact half agree by design.

None states — flat/legacy (no coord_branch → 755) and coord + non-protected planning_branch (790 partition split) — the artifact-commit half still commits successfully (the C-004 strangler fallback). placement_ref is None` is NOT unconditionally degenerate; 3 write-side tests + the #2533 regression drive it expecting success. WP03 characterizes the real flat/legacy None-at-this-seam behavior before FR-002 relies on the narrow condition.

• INV-1 (C-007): meta.json / kind=None / unrecognized path → PRIMARY, on all
• INV-2 (C-006): _resolve_bookkeeping_transaction_identifiers keeps its public
• INV-3 (C-001): _mt_uncheck_rollback_subtasks keeps two separate exception handlers
• INV-4 (FR-001): move-task result is cwd-independent (repo root == lane worktree).
• INV-5 (NFR-004/C-008): no net-new public/exported symbol from the degod.
• INV-6 (FR-002/C-009): on the narrow triple (placement_ref is None AND meta
• INV-7 (FR-002/C-004 — the #2463 None-overload guard): on the OTHER `placement_ref is