fix(agent): stop on workspace violations from tool errors

Treat workspace and safety guard failures as fatal regardless of whether they arrive from tool preparation, returned tool output, or raised exceptions.

Made-with: Cursor

nanobot/agent/runner.py

@@ -764,6 +764,15 @@ class AgentRunner:
                 "status": "error",
                 "detail": prep_error.split(": ", 1)[-1][:120],
             }
+            if self._is_workspace_violation(prep_error):
+                logger.warning(
+                    "Tool {} blocked by workspace/safety guard during preparation; aborting turn: {}",
+                    tool_call.name,
+                    prep_error.replace("\n", " ").strip()[:200],
+                )
+                event["detail"] = ("workspace_violation: "
+                                   + prep_error.replace("\n", " ").strip())[:160]
+                return prep_error, event, RuntimeError(prep_error)
             return prep_error + hint, event, RuntimeError(prep_error) if spec.fail_on_tool_error else None
         try:
             if tool is not None:
@@ -781,6 +790,15 @@ class AgentRunner:
             if isinstance(exc, AskUserInterrupt):
                 event["status"] = "waiting"
                 return "", event, exc
+            if self._is_workspace_violation(str(exc)):
+                logger.warning(
+                    "Tool {} blocked by workspace/safety guard; aborting turn: {}",
+                    tool_call.name,
+                    str(exc).replace("\n", " ").strip()[:200],
+                )
+                event["detail"] = ("workspace_violation: "
+                                   + str(exc).replace("\n", " ").strip())[:160]
+                return f"Error: {type(exc).__name__}: {exc}", event, exc
             if spec.fail_on_tool_error:
                 return f"Error: {type(exc).__name__}: {exc}", event, exc
             return f"Error: {type(exc).__name__}: {exc}", event, None

tests/agent/test_runner.py

@@ -312,6 +312,46 @@ async def test_runner_returns_structured_tool_error():
     ]
 
 
+@pytest.mark.asyncio
+async def test_runner_stops_on_workspace_violation_without_fail_on_tool_error():
+    from nanobot.agent.runner import AgentRunSpec, AgentRunner
+
+    provider = MagicMock()
+    provider.chat_with_retry = AsyncMock(side_effect=[
+        LLMResponse(
+            content="working",
+            tool_calls=[ToolCallRequest(id="call_1", name="read_file", arguments={"path": "/tmp/outside.md"})],
+        ),
+        LLMResponse(content="should not continue", tool_calls=[]),
+    ])
+    tools = MagicMock()
+    tools.get_definitions.return_value = []
+    tools.execute = AsyncMock(
+        side_effect=PermissionError("Path /tmp/outside.md is outside allowed directory /workspace")
+    )
+
+    runner = AgentRunner(provider)
+
+    result = await runner.run(AgentRunSpec(
+        initial_messages=[],
+        tools=tools,
+        model="test-model",
+        max_iterations=2,
+        max_tool_result_chars=_MAX_TOOL_RESULT_CHARS,
+    ))
+
+    assert provider.chat_with_retry.await_count == 1
+    assert result.stop_reason == "tool_error"
+    assert "outside allowed directory" in (result.error or "")
+    assert result.tool_events == [
+        {
+            "name": "read_file",
+            "status": "error",
+            "detail": "workspace_violation: Path /tmp/outside.md is outside allowed directory /workspace",
+        }
+    ]
+
+
 @pytest.mark.asyncio
 async def test_runner_persists_large_tool_results_for_follow_up_calls(tmp_path):
     from nanobot.agent.runner import AgentRunSpec, AgentRunner