fix(kanban): measure max runtime from current run

tests/hermes_cli/test_kanban_db.py

@@ -182,6 +182,52 @@ def test_stale_claim_reclaimed(kanban_home):
         assert kb.get_task(conn, t).status == "ready"
 
 
+def test_max_runtime_uses_current_run_start_after_retry(kanban_home):
+    """A retry should get a fresh max-runtime window.
+
+    ``tasks.started_at`` intentionally records the first time the task ever
+    started. Runtime enforcement must therefore use the active
+    ``task_runs.started_at`` row; otherwise every retry of an old task is
+    immediately timed out again.
+    """
+    with kb.connect() as conn:
+        host = kb._claimer_id().split(":", 1)[0]
+        t = kb.create_task(
+            conn, title="retry", assignee="a", max_runtime_seconds=10,
+        )
+
+        kb.claim_task(conn, t, claimer=f"{host}:first")
+        first_run_id = kb.latest_run(conn, t).id
+        old_started = int(time.time()) - 20
+        conn.execute(
+            "UPDATE tasks SET started_at = ?, worker_pid = ? WHERE id = ?",
+            (old_started, 999999, t),
+        )
+        conn.execute(
+            "UPDATE task_runs SET started_at = ?, worker_pid = ? WHERE id = ?",
+            (old_started, 999999, first_run_id),
+        )
+
+        timed_out = kb.enforce_max_runtime(conn, signal_fn=lambda _pid, _sig: None)
+        assert timed_out == [t]
+        assert kb.get_task(conn, t).status == "ready"
+
+        kb.claim_task(conn, t, claimer=f"{host}:retry")
+        retry_run = kb.latest_run(conn, t)
+        conn.execute(
+            "UPDATE tasks SET worker_pid = ? WHERE id = ?",
+            (999999, t),
+        )
+        conn.execute(
+            "UPDATE task_runs SET worker_pid = ? WHERE id = ?",
+            (999999, retry_run.id),
+        )
+
+        timed_out = kb.enforce_max_runtime(conn, signal_fn=lambda _pid, _sig: None)
+        assert timed_out == []
+        assert kb.get_task(conn, t).status == "running"
+
+
 def test_heartbeat_extends_claim(kanban_home):
     with kb.connect() as conn:
         t = kb.create_task(conn, title="x", assignee="a")