fix(runtime): unify process and task state handling

tests/unit/mcp/test_trace_store.py

@@ -14,9 +14,12 @@
 
 """Unit tests for MCP trace store."""
 
+import glob
+import logging
 import os
 import shutil
 import tempfile
+import threading
 import uuid
 import pytest
 
@@ -91,6 +94,125 @@ def test_read_nonexistent_status(temp_trace_env):
     assert trace_store.read_status(non_existent) is None
 
 
+def test_leftover_atomic_temp_file_does_not_affect_reads(temp_trace_env):
+    """A crash between temp-write and replace leaves a .tmp file that readers ignore."""
+    trace_id = str(uuid.uuid4())
+    trace_store.init_trace(trace_id, "Crash sim", "Flash")
+
+    status_path = trace_store.get_status_path(trace_id)
+    # Simulate a writer that crashed after writing its temp file.
+    with open(f"{status_path}.{uuid.uuid4().hex}.tmp", "w", encoding="utf-8") as f:
+        f.write('{"status": "half-writ')
+
+    data = trace_store.read_status(trace_id)
+    assert data is not None
+    assert data["status"] == "running"
+    assert data["task_desc"] == "Crash sim"
+
+
+def test_failed_atomic_replace_preserves_original(temp_trace_env):
+    """If the atomic replace fails, the previous status.json stays intact."""
+    from unittest.mock import patch
+
+    trace_id = str(uuid.uuid4())
+    trace_store.init_trace(trace_id, "Original", "Flash")
+
+    def broken_replace(src, dst):
+        raise OSError("simulated replace failure")
+
+    with patch.object(trace_store, "_replace_with_retry", broken_replace):
+        with pytest.raises(OSError):
+            trace_store.write_status(trace_id, {"status": "clobbered"})
+
+    data = trace_store.read_status(trace_id)
+    assert data is not None
+    assert data["task_desc"] == "Original"
+    # The failed writer's temp file must not linger.
+    assert glob.glob(os.path.join(trace_store.get_trace_dir(trace_id), "*.tmp")) == []
+
+
+def test_corrupt_status_is_quarantined_and_read_returns_none(temp_trace_env, caplog):
+    trace_id = str(uuid.uuid4())
+    trace_store.init_trace(trace_id, "Corrupt me", "Flash")
+
+    status_path = trace_store.get_status_path(trace_id)
+    with open(status_path, "w", encoding="utf-8") as f:
+        f.write('{"status": "running", "trace_id"')  # torn write
+
+    with caplog.at_level(logging.WARNING, logger="mcp_server.utils.trace_store"):
+        assert trace_store.read_status(trace_id) is None
+
+    assert any("Corrupt status.json" in rec.message for rec in caplog.records)
+    assert os.path.exists(f"{status_path}.corrupt")
+    assert not os.path.exists(status_path)
+
+
+def test_missing_status_stays_silent(temp_trace_env, caplog):
+    with caplog.at_level(logging.WARNING, logger="mcp_server.utils.trace_store"):
+        assert trace_store.read_status(str(uuid.uuid4())) is None
+    assert caplog.records == []
+
+
+def test_update_on_corrupt_status_logs_and_drops(temp_trace_env, caplog):
+    trace_id = str(uuid.uuid4())
+    trace_store.init_trace(trace_id, "Corrupt update", "Flash")
+
+    status_path = trace_store.get_status_path(trace_id)
+    with open(status_path, "w", encoding="utf-8") as f:
+        f.write("not json at all")
+
+    with caplog.at_level(logging.WARNING, logger="mcp_server.utils.trace_store"):
+        assert trace_store.update_trace_status(trace_id, "completed") is None
+
+    assert any("Dropping status update" in rec.message for rec in caplog.records)
+    # Updating a trace that never existed stays a silent no-op.
+    caplog.clear()
+    with caplog.at_level(logging.WARNING, logger="mcp_server.utils.trace_store"):
+        assert trace_store.update_trace_status(str(uuid.uuid4()), "completed") is None
+    assert not any("Dropping status update" in rec.message for rec in caplog.records)
+
+
+def test_concurrent_read_modify_write_does_not_lose_updates(temp_trace_env):
+    """Interleaved RMW updates from two writers must not lose each other's fields."""
+    trace_id = str(uuid.uuid4())
+    trace_store.init_trace(trace_id, "Concurrency", "Flash")
+    iterations = 25
+    failures: list[BaseException] = []
+
+    def set_errors():
+        try:
+            for i in range(iterations):
+                assert trace_store.update_trace_status(
+                    trace_id, "running", error=f"err-{i}"
+                ) is not None
+        except BaseException as exc:  # noqa: BLE001 - surfaced in the main thread
+            failures.append(exc)
+
+    def set_serials():
+        try:
+            for i in range(iterations):
+                assert trace_store.update_trace_device_serial(
+                    trace_id, f"serial-{i}"
+                ) is not None
+        except BaseException as exc:  # noqa: BLE001 - surfaced in the main thread
+            failures.append(exc)
+
+    threads = [threading.Thread(target=set_errors), threading.Thread(target=set_serials)]
+    for t in threads:
+        t.start()
+    for t in threads:
+        t.join(timeout=30.0)
+
+    assert failures == []
+    final = trace_store.read_status(trace_id)
+    assert final is not None
+    # Every serialized RMW preserves the other writer's latest field, so both
+    # final values must survive regardless of which thread finished last.
+    assert final["error"] == f"err-{iterations - 1}"
+    assert final["device_serial"] == f"serial-{iterations - 1}"
+    assert final["status"] == "running"
+
+
 def test_trace_paths(temp_trace_env):
     trace_id = "test-paths-id"
     trace_dir = trace_store.get_trace_dir(trace_id)