feat(runtime): enforce governed mutation boundaries

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

tests/test_metrics.py

@@ -3,7 +3,14 @@ from __future__ import annotations
 import json
 from pathlib import Path
 
-from rein_aharness.metrics import record_execution, regenerate_summary
+import pytest
+
+from rein_aharness.metrics import (
+    external_metrics_dir,
+    record_execution,
+    record_external_execution,
+    regenerate_summary,
+)
 
 
 def test_record_execution_writes_jsonl_and_summary(tmp_path: Path) -> None:
@@ -49,3 +56,89 @@ def test_summary_aggregates_multiple(tmp_path: Path) -> None:
 
 def test_regenerate_summary_empty() -> None:
     assert regenerate_summary("x", [])["execution_count"] == 0
+
+
+def test_external_metrics_are_durable_and_projection_ready(tmp_path: Path) -> None:
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    state_dir = tmp_path / "state"
+
+    path = record_external_execution(
+        repo,
+        "coach",
+        success=True,
+        committed=True,
+        head_after="abc123",
+        metadata={"repository_grant_id": "grant-1"},
+        session_id="transaction-1",
+        state_dir=state_dir,
+    )
+
+    directory = external_metrics_dir(repo, "coach", state_dir=state_dir)
+    assert path == directory / "executions.jsonl"
+    assert path.stat().st_mode & 0o777 == 0o600
+    assert directory.stat().st_mode & 0o777 == 0o700
+    record = json.loads(path.read_text(encoding="utf-8").strip())
+    assert record["metadata"]["repository_grant_id"] == "grant-1"
+    assert record["session_id"] == "transaction-1"
+    projection = json.loads(
+        (directory / "projection.json").read_text(encoding="utf-8")
+    )
+    assert projection["repository_name"] == "repo"
+    assert projection["target_relative_directory"] == ".kaizen/metrics/coach"
+    assert not (repo / ".kaizen").exists()
+
+
+def test_external_metrics_deduplicate_transaction_replay(tmp_path: Path) -> None:
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    state_dir = tmp_path / "state"
+
+    for _attempt in range(2):
+        path = record_external_execution(
+            repo,
+            "coach",
+            success=True,
+            session_id="transaction-1",
+            state_dir=state_dir,
+        )
+
+    assert len(path.read_text(encoding="utf-8").splitlines()) == 1
+    summary = json.loads((path.parent / "summary.json").read_text(encoding="utf-8"))
+    assert summary["execution_count"] == 1
+
+
+def test_external_metrics_refuse_an_incomplete_ledger(tmp_path: Path) -> None:
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    state_dir = tmp_path / "state"
+    directory = external_metrics_dir(repo, "coach", state_dir=state_dir)
+    directory.mkdir(parents=True)
+    ledger = directory / "executions.jsonl"
+    ledger.write_text('{"incomplete":true}', encoding="utf-8")
+
+    with pytest.raises(OSError, match="incomplete record"):
+        record_external_execution(
+            repo,
+            "coach",
+            success=True,
+            state_dir=state_dir,
+        )
+
+    assert ledger.read_text(encoding="utf-8") == '{"incomplete":true}'
+
+
+def test_external_metrics_refuse_unsafe_projection_agent(tmp_path: Path) -> None:
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    state_dir = tmp_path / "state"
+
+    with pytest.raises(OSError, match="safe metrics projection"):
+        record_external_execution(
+            repo,
+            "../escape",
+            success=True,
+            state_dir=state_dir,
+        )
+
+    assert not state_dir.exists()