feat(runtime): enforce governed mutation boundaries

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a06ba0-10aa-7ea0-b20a-4f3fac39efe9

rein_aharness/runner.py

@@ -2,10 +2,10 @@
 
 Flow: lock target repo → resolve tool profile / budget from instance
 manifest → snapshot HEAD → persona bundle → prompt → agentic session →
-verify a new commit exists → kaizen metrics + hub progress event
-(+ task close). The run *fails* if the session pushed anywhere or left
-the repo dirty in a way it should not — the worker never pushes;
-publishing is a separate, explicitly-granted lane.
+validate an explicit repository grant when present → metrics + hub progress
+event (+ task close). Granted runs use durable external metrics so repository
+acceptance remains clean. The worker never pushes; publishing is a separate,
+explicitly-granted lane.
 """
 
 from __future__ import annotations
@@ -24,6 +24,7 @@ from rein_aharness.profiles import UnknownToolProfileError, get_profile
 from rein_aharness.repository_transaction import (
     DirtyRepositoryError,
     GitRepositoryError,
+    RepositoryAcceptanceError,
     RepositoryBusyError,
     RepositoryTransaction,
     RepositoryTransactionError,
@@ -116,11 +117,11 @@ def run_task(
     budget_tokens_override: int | None = None,
     transaction: RepositoryTransaction | None = None,
 ) -> RunResult:
-    if spec.repository_grant is not None:
+    if spec.repository_grant is not None and not write_metrics:
         return _refused_run(
             reason=(
-                "refused: repository_grant enforcement is not enabled; "
-                "no adapter was dispatched"
+                "refused: repository_grant runs require durable external metrics; "
+                "--no-metrics is incompatible"
             ),
             model=model,
         )
@@ -255,11 +256,62 @@ def _execute_locked_task(
 
     head_after = _git(spec.target_repo, "rev-parse", "HEAD")
     committed = head_after != head_before
+    if session_ok and spec.repository_grant is not None:
+        try:
+            tx.validate_acceptance(spec.repository_grant.acceptance_policy())
+        except RepositoryAcceptanceError as exc:
+            session_ok = False
+            reason = str(exc)
     ok = session_ok and committed
-    if session_ok and not committed:
+    if session_ok and not committed and spec.repository_grant is None:
         reason = "session completed without committing"
 
     tokens_spent = budget_tracker.spent if budget_tracker is not None else None
+    transaction_evidence = tx.evidence()
+    if spec.repository_grant is not None:
+        transaction_evidence["repository_grant"] = spec.repository_grant.evidence()
+
+    metric_metadata = {
+        "task_title": spec.title,
+        "tool_profile": profile.name,
+        "labels": list(spec.labels),
+        "completion_event_type": spec.completion_event_type,
+    }
+    if spec.repository_grant is not None:
+        metric_metadata["repository_grant_id"] = spec.repository_grant.grant_id
+
+    if write_metrics:
+        try:
+            recorder = (
+                metrics.record_external_execution
+                if spec.repository_grant is not None
+                else metrics.record_execution
+            )
+            recorder(
+                spec.target_repo,
+                spec.agent,
+                success=ok,
+                execution_time_s=execution_time_s,
+                tokens=tokens_spent,
+                committed=committed,
+                head_after=head_after,
+                reason=reason or None,
+                metadata=metric_metadata,
+                session_id=tx.transaction_id,
+            )
+            if spec.repository_grant is not None:
+                transaction_evidence["metrics"] = {
+                    "storage": "external",
+                    "session_id": tx.transaction_id,
+                    "projection_ready": True,
+                }
+        except OSError as exc:
+            if spec.repository_grant is not None:
+                ok = False
+                reason = (
+                    "required external metrics persistence failed "
+                    f"({type(exc).__name__})"
+                )
 
     result = RunResult(
         ok=ok,
@@ -275,30 +327,9 @@ def _execute_locked_task(
         tokens_spent=tokens_spent,
         execution_time_s=execution_time_s,
         tool_events=collected_events,
-        transaction=tx.evidence(),
+        transaction=transaction_evidence,
     )
 
-    if write_metrics:
-        try:
-            metrics.record_execution(
-                spec.target_repo,
-                spec.agent,
-                success=ok,
-                execution_time_s=execution_time_s,
-                tokens=tokens_spent,
-                committed=committed,
-                head_after=head_after,
-                reason=reason or None,
-                metadata={
-                    "task_title": spec.title,
-                    "tool_profile": profile.name,
-                    "labels": list(spec.labels),
-                    "completion_event_type": spec.completion_event_type,
-                },
-            )
-        except OSError:
-            pass  # metrics must not block run completion reporting
-
     if report_to_hub:
         detail = {
             "repo": spec.target_repo.name,
@@ -314,6 +345,7 @@ def _execute_locked_task(
             "budget_tokens": budget_tokens,
             "tokens_spent": tokens_spent,
             "execution_time_s": round(execution_time_s, 3),
+            "repository_transaction": transaction_evidence,
         }
         hub.post_progress_event(
             summary=f"executor run: {spec.title} ({'ok' if ok else 'failed'})",