fix(kanban): migrate task session index after columns

tests/hermes_cli/test_kanban_db.py

@@ -48,6 +48,51 @@ def test_init_creates_expected_tables(kanban_home):
     assert {"tasks", "task_links", "task_comments", "task_events"} <= names
 
 
+def test_connect_migrates_legacy_db_before_optional_column_indexes(tmp_path):
+    db_path = tmp_path / "legacy-kanban.db"
+    conn = sqlite3.connect(str(db_path))
+    conn.execute("""
+        CREATE TABLE tasks (
+            id TEXT PRIMARY KEY,
+            title TEXT NOT NULL,
+            body TEXT,
+            assignee TEXT,
+            status TEXT NOT NULL,
+            priority INTEGER NOT NULL DEFAULT 0,
+            created_by TEXT,
+            created_at INTEGER NOT NULL,
+            started_at INTEGER,
+            completed_at INTEGER,
+            workspace_kind TEXT NOT NULL DEFAULT 'scratch',
+            workspace_path TEXT,
+            claim_lock TEXT,
+            claim_expires INTEGER
+        )
+    """)
+    conn.execute(
+        "INSERT INTO tasks (id, title, status, created_at) "
+        "VALUES ('legacy', 'old board task', 'ready', 1)"
+    )
+    conn.commit()
+    conn.close()
+
+    with kb.connect(db_path) as migrated:
+        task_columns = {
+            row["name"] for row in migrated.execute("PRAGMA table_info(tasks)")
+        }
+        indexes = {
+            row["name"]
+            for row in migrated.execute(
+                "SELECT name FROM sqlite_master WHERE type = 'index'"
+            )
+        }
+
+    assert "session_id" in task_columns
+    assert "idx_tasks_session_id" in indexes
+    assert "idx_tasks_tenant" in indexes
+    assert "idx_tasks_idempotency" in indexes
+
+
 # ---------------------------------------------------------------------------
 # Task creation + status inference
 # ---------------------------------------------------------------------------
@@ -462,7 +507,7 @@ def test_detect_crashed_workers_isolated_failure_normal_retry(
             )
 
 
-def test_max_runtime_uses_current_run_start_after_retry(kanban_home):
+def test_max_runtime_uses_current_run_start_after_retry(kanban_home, monkeypatch):
     """A retry should get a fresh max-runtime window.
 
     ``tasks.started_at`` intentionally records the first time the task ever
@@ -470,6 +515,8 @@ def test_max_runtime_uses_current_run_start_after_retry(kanban_home):
     ``task_runs.started_at`` row; otherwise every retry of an old task is
     immediately timed out again.
     """
+    monkeypatch.setattr(kb, "_pid_alive", lambda _pid: False)
+
     with kb.connect() as conn:
         host = kb._claimer_id().split(":", 1)[0]
         t = kb.create_task(