Implement A9 state-change logging in the state store

Retrofit for the conventions merged in #4 (issue #3):

- OpLog: JSON-lines emitter with the fixed envelope (ts, agent,
  event, task_id, cause); task_id set by the orchestrator at
  unit-of-work start
- StateStore owns emission: transition, intent begin/commit/abort,
  and schema migrations each emit their event right after the
  durable write commits; callers pass the cause
- reconcile_on_boot emits boot.reconcile with action and verdicts,
  and resolves intents with reconciliation-verdict causes
- Failed resolutions emit nothing (a line exists iff the write
  committed)

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

nisse-dev/tests/test_state.py

@@ -26,7 +26,9 @@ def test_fresh_store_stamps_schema_version(db: Path) -> None:
 
 def test_transition_persists_across_reopen(db: Path) -> None:
     with StateStore(db) as store:
-        store.transition("EXECUTING", project="demo", data={"milestone": 2})
+        store.transition(
+            "EXECUTING", cause="test", project="demo", data={"milestone": 2}
+        )
     with StateStore(db) as store:
         state = store.get_state()
     assert state is not None
@@ -42,18 +44,18 @@ def test_get_state_on_fresh_store_is_none(db: Path) -> None:
 
 def test_intent_lifecycle(db: Path) -> None:
     with StateStore(db) as store:
-        intent_id = store.begin_intent("push_branch", {"branch": "m2"})
+        intent_id = store.begin_intent("push_branch", {"branch": "m2"}, cause="test")
         [pending] = store.pending_intents()
         assert pending.id == intent_id
         assert pending.kind == "push_branch"
         assert pending.payload == {"branch": "m2"}
-        store.commit_intent(intent_id)
+        store.commit_intent(intent_id, cause="test")
         assert store.pending_intents() == []
 
 
 def test_pending_intent_survives_reopen(db: Path) -> None:
     with StateStore(db) as store:
-        store.begin_intent("open_pr", {"title": "hello"})
+        store.begin_intent("open_pr", {"title": "hello"}, cause="test")
     with StateStore(db) as store:
         [pending] = store.pending_intents()
     assert pending.kind == "open_pr"
@@ -61,19 +63,19 @@ def test_pending_intent_survives_reopen(db: Path) -> None:
 
 def test_aborted_intent_is_not_pending(db: Path) -> None:
     with StateStore(db) as store:
-        intent_id = store.begin_intent("push_branch", {})
-        store.abort_intent(intent_id)
+        intent_id = store.begin_intent("push_branch", {}, cause="test")
+        store.abort_intent(intent_id, cause="test")
         assert store.pending_intents() == []
 
 
 def test_resolving_nonpending_intent_raises(db: Path) -> None:
     with StateStore(db) as store:
-        intent_id = store.begin_intent("push_branch", {})
-        store.commit_intent(intent_id)
+        intent_id = store.begin_intent("push_branch", {}, cause="test")
+        store.commit_intent(intent_id, cause="test")
         with pytest.raises(KeyError):
-            store.commit_intent(intent_id)
+            store.commit_intent(intent_id, cause="test")
         with pytest.raises(KeyError):
-            store.abort_intent(9999)
+            store.abort_intent(9999, cause="test")
 
 
 def test_migration_runs_and_bumps_version(db: Path) -> None: