feat: improve worker diagnostics

tests/test_worker.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from pathlib import Path
 from unittest.mock import Mock, call, patch
 
 from lai_automation.models import (
@@ -158,6 +159,22 @@ def test_run_once_returns_false_without_work(settings) -> None:
     assert Worker(settings, gitea, Mock()).run_once() is False
 
 
+def test_agent_failure_details_identify_step_limit(settings) -> None:
+    worker = Worker(settings, Mock(), Mock())
+    result = AgentResult("LimitsExceeded", "", settings.agent_step_limit, 0.2)
+
+    details = worker._agent_failure_details(
+        result,
+        elapsed=180.0,
+        trajectory=Path("/workspaces/trajectories/issue-43.traj.json"),
+    )
+
+    assert f"step limit reached ({settings.agent_step_limit})" in details
+    assert "model_calls=40" in details
+    assert "cost=0.2000" in details
+    assert "issue-43.traj.json" in details
+
+
 @patch("lai_automation.worker.GitWorkspace")
 def test_preflight_runs_setup_and_tests_without_model(
     GitWorkspace,