feat(model-divergence): full enforcement — manifest, transition, claim, audit, loop gates, detect script

Completes all 3 model-divergence enforcement subtasks:

- scripts/detect_models.py: probes opencode.json + localhost endpoints,
  builds models.json with --json/--write/--force
- scripts/status.py: CONFLICT_MATRIX, --model flag, --transition --model,
  --claim --model, --audit Category 6, model-divergence brake gate in
  --check-gate, helpers for manifest loading and conflict checking
- scripts/loop-runner.py: _role_model() helper + {model} passed via extras
  dict to _invoke_harness for implement, verify, orchestrate roles
- tests/test_model_divergence.py: 33 tests covering all enforcement layers
- Single-LLM mode: record model advisory, no conflict check
- Multi-LLM mode (2+ models): conflict matrix enforced at transition, claim,
  and loop brake gate
- Project-level models.json preferred over global ~/.automaton/models.json

scripts/loop-runner.py

@@ -375,6 +375,9 @@ def _invoke_harness(
     """Build the harness command from loop.json and invoke it. Returns stdout.
 
     extras: substitution tokens specific to this role ({artifact}, {verdict}, etc).
+    If extras contains a "model" key, the ``{model}`` token in the harness
+    command is substituted. The caller is responsible for passing the model
+    via extras (extracted from loop.json role config or manifest default).
     """
     resolved_prompt = prompt_path
     if loop_path is not None:
@@ -524,6 +527,24 @@ def _role_prompt(cfg: dict, role: str) ->Optional[str]:
     return role_cfg.get("prompt")
 
 
+def _role_model(cfg: dict, role: str) -> Optional[str]:
+    """Get the model configured for a role in loop.json, or the manifest default."""
+    roles = cfg.get("roles") or {}
+    role_cfg = roles.get(role) or {}
+    model = role_cfg.get("model")
+    if model:
+        return model
+    models_file = AUTOMATON_DIR / "models.json"
+    if models_file.exists():
+        try:
+            import json as _mj
+            manifest = _mj.loads(models_file.read_text())
+            return manifest.get("default")
+        except (OSError, _mj.JSONDecodeError):
+            pass
+    return None
+
+
 # ---------------------------------------------------------------------------
 # Work sources (task add-goal-mode)
 # ---------------------------------------------------------------------------
@@ -809,27 +830,39 @@ def cmd_tick(args, runner_state: Optional[dict] = None) -> dict:
         out_dir = _outputs_dir(loop_path)
         tick_num = state.get('iteration_count', 0) + 1
         impl_output = str(out_dir / f"tick{tick_num}-implement.json")
+        impl_model = _role_model(cfg, "implement")
+        implement_extras = {
+            "output": impl_output,
+            "current_task": current_task,
+            "task_brief": task_brief,
+            "acceptance_criteria": acceptance,
+            "next_hint": next_hint,
+        }
+        if impl_model:
+            implement_extras["model"] = impl_model
         implement_stdout = _invoke_harness(
             harness_cfg, "implement", implement_prompt, cwd,
-            extras={"output": impl_output,
-                    "current_task": current_task,
-                    "task_brief": task_brief,
-                    "acceptance_criteria": acceptance,
-                    "next_hint": next_hint},
+            extras=implement_extras,
             loop_path=loop_path, tick_num=tick_num)
         (Path(impl_output)).write_text(implement_stdout)
 
         # Step 6: spawn Verify
         verify_prompt = _role_prompt(cfg, "verify") or ""
         verify_output = str(out_dir / f"tick{tick_num}-verify.json")
+        verify_model = _role_model(cfg, "verify")
+        verify_extras = {
+            "output": verify_output,
+            "artifact": impl_output,
+            "current_task": current_task,
+            "task_brief": task_brief,
+            "acceptance_criteria": acceptance,
+            "next_hint": next_hint,
+        }
+        if verify_model:
+            verify_extras["model"] = verify_model
         verify_stdout = _invoke_harness(
             harness_cfg, "verify", verify_prompt, cwd,
-            extras={"output": verify_output,
-                    "artifact": impl_output,
-                    "current_task": current_task,
-                    "task_brief": task_brief,
-                    "acceptance_criteria": acceptance,
-                    "next_hint": next_hint},
+            extras=verify_extras,
             loop_path=loop_path, tick_num=tick_num)
         (Path(verify_output)).write_text(verify_stdout)
 
@@ -854,12 +887,18 @@ def cmd_tick(args, runner_state: Optional[dict] = None) -> dict:
         # Step 9: spawn Orchestrate
         orch_prompt = _role_prompt(cfg, "orchestrate") or ""
         orch_output = str(out_dir / f"tick{tick_num}-orchestrate.json")
+        orch_model = _role_model(cfg, "orchestrate")
+        orch_extras = {
+            "output": orch_output,
+            "verdict": json.dumps(verdict),
+            "current_task": current_task,
+            "current_phase": state.get("current_phase", ""),
+        }
+        if orch_model:
+            orch_extras["model"] = orch_model
         orch_stdout = _invoke_harness(
             harness_cfg, "orchestrate", orch_prompt, cwd,
-            extras={"output": orch_output,
-                    "verdict": json.dumps(verdict),
-                    "current_task": current_task,
-                    "current_phase": state.get("current_phase", "")},
+            extras=orch_extras,
             loop_path=loop_path, tick_num=tick_num)
         (Path(orch_output)).write_text(orch_stdout)