Add literal-format test showing exact log lines

Freezes the clock and asserts the exact bytes emitted per event, so
the on-disk log format is reviewable in the test file itself.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

nisse-dev/tests/test_oplog.py

@@ -104,6 +104,52 @@ def test_boot_reconcile_emits_action_and_verdicts(
     assert commit[0]["cause"] == "reconciliation verdict: effect verified"
 
 
+def test_literal_log_lines_for_human_readability(
+    store: StateStore, stream: io.StringIO, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """Asserts the exact bytes written per line, so the on-disk format is
+    visible here rather than only in a running system."""
+
+    class _FrozenDatetime:
+        @staticmethod
+        def now(tz: object) -> object:
+            from datetime import UTC, datetime
+
+            return datetime(2026, 9, 5, 12, 0, 0, tzinfo=UTC)
+
+    monkeypatch.setattr("nisse_dev.oplog.datetime", _FrozenDatetime)
+
+    store.transition(
+        "PLANNING_ARCH", cause="operator command: use demo", project="demo"
+    )
+    store.oplog.task_id = "demo-m2"
+    intent_id = store.begin_intent(
+        "push_branch", {"branch": "milestone-2"}, cause="milestone 2 execution"
+    )
+    store.commit_intent(intent_id, cause="push verified by Gitea query")
+
+    assert stream.getvalue().splitlines() == [
+        (
+            '{"ts": "2026-09-05T12:00:00+00:00", "agent": "nisse-dev",'
+            ' "event": "state.transition", "task_id": null,'
+            ' "cause": "operator command: use demo",'
+            ' "from": null, "to": "PLANNING_ARCH", "project": "demo"}'
+        ),
+        (
+            '{"ts": "2026-09-05T12:00:00+00:00", "agent": "nisse-dev",'
+            ' "event": "intent.begin", "task_id": "demo-m2",'
+            ' "cause": "milestone 2 execution", "intent_id": 1,'
+            ' "kind": "push_branch"}'
+        ),
+        (
+            '{"ts": "2026-09-05T12:00:00+00:00", "agent": "nisse-dev",'
+            ' "event": "intent.commit", "task_id": "demo-m2",'
+            ' "cause": "push verified by Gitea query",'
+            ' "intent_id": 1, "kind": "push_branch"}'
+        ),
+    ]
+
+
 def test_failed_resolution_emits_nothing(
     store: StateStore, stream: io.StringIO
 ) -> None: