test: migrate sequential_ids test to In Progress contract

tests/test_webhooks.py

@@ -81,17 +81,37 @@ def test_plane_webhook_creates_task(mock_docs, mock_branch, mock_fetch_fields, m
     assert "feature/" in task["branch"]
 
 
+@patch("src.plane_sync.add_comment")
+@patch("src.plane_sync.fetch_issue_sequence_id", return_value=None)
+@patch("src.plane_sync.fetch_issue_fields",
+       side_effect=[
+           ("First task", "This is a detailed description for the first task item"),
+           ("Second task", "This is a detailed description for the second task item"),
+       ])
 @patch("src.webhooks.plane._create_gitea_branch", new_callable=AsyncMock)
 @patch("src.webhooks.plane._create_initial_docs", new_callable=AsyncMock)
-def test_plane_webhook_generates_sequential_ids(mock_docs, mock_branch):
-    """Multiple work items get sequential IDs."""
+def test_plane_webhook_generates_sequential_ids(
+    mock_docs, mock_branch, mock_fetch_fields, mock_fetch_seq, mock_add_comment
+):
+    """Multiple In Progress transitions get sequential IDs (ET-001, ET-002)."""
+    in_progress_state = {
+        "id": "b873d9eb-993c-48cd-97ac-99a9b1623967",
+        "name": "In Progress",
+        "group": "started",
+    }
     client.post("/webhook/plane", json={
-        "event": "work_item.created",
-        "data": {"id": "item-1", "name": "First task", "project": "proj-1"}
+        "event": "issue", "action": "updated",
+        "data": {
+            "id": "item-1", "name": "First task", "project": "proj-1",
+            "state": in_progress_state,
+        }
     })
     client.post("/webhook/plane", json={
-        "event": "work_item.created",
-        "data": {"id": "item-2", "name": "Second task", "project": "proj-1"}
+        "event": "issue", "action": "updated",
+        "data": {
+            "id": "item-2", "name": "Second task", "project": "proj-1",
+            "state": in_progress_state,
+        }
     })
 
     conn = get_db()