Add reconciliation state-change API contract

tests/test_routers_core.py

@@ -392,3 +392,75 @@ class TestFlowEndpoints:
 
         r = await client.get(f"/workstreams/{ws['id']}")
         assert r.json()["status"] == "active"
+
+
+class TestReconciliationEndpoints:
+    async def test_classify_workstream_open_transition_write_through(self, client):
+        await _create_domain(client)
+        topic = await _create_topic(client)
+        ws = await _create_workstream(client, topic["id"])
+
+        r = await client.post("/reconciliation/state-change", json={
+            "target_type": "workstream",
+            "target_id": ws["id"],
+            "target_status": "backlog",
+            "actor": "dashboard",
+            "intent": "push back to backlog",
+            "file_backed": True,
+        })
+
+        assert r.status_code == 200
+        body = r.json()
+        assert body["current_status"] == "active"
+        assert body["target_status"] == "backlog"
+        assert body["reconciliation_class"] == "write_through"
+        assert body["write_through_result"] == "not_attempted"
+        assert body["intent"] == "push back to backlog"
+
+    async def test_classify_workstream_finish_with_open_task_needs_confirmation(self, client):
+        await _create_domain(client)
+        topic = await _create_topic(client)
+        ws = await _create_workstream(client, topic["id"])
+        await _create_task(client, ws["id"])
+
+        r = await client.post("/reconciliation/state-change", json={
+            "target_type": "workstream",
+            "target_id": ws["id"],
+            "target_status": "finished",
+            "file_backed": True,
+        })
+
+        assert r.status_code == 200
+        body = r.json()
+        assert body["tasks_terminal"] is False
+        assert body["reconciliation_class"] == "human_confirmation"
+        assert "open work" in body["reason"]
+
+    async def test_classify_task_blocked_without_reason_needs_confirmation(self, client):
+        await _create_domain(client)
+        topic = await _create_topic(client)
+        ws = await _create_workstream(client, topic["id"])
+        task = await _create_task(client, ws["id"])
+
+        r = await client.post("/reconciliation/state-change", json={
+            "target_type": "task",
+            "target_id": task["id"],
+            "target_status": "blocked",
+            "file_backed": True,
+            "task_linked": True,
+        })
+
+        assert r.status_code == 200
+        body = r.json()
+        assert body["current_status"] == "todo"
+        assert body["reconciliation_class"] == "human_confirmation"
+        assert "blocking reason" in body["reason"]
+
+    async def test_classify_unknown_workstream_returns_404(self, client):
+        r = await client.post("/reconciliation/state-change", json={
+            "target_type": "workstream",
+            "target_id": "00000000-0000-0000-0000-000000000001",
+            "target_status": "active",
+        })
+
+        assert r.status_code == 404