fix: Exit the MCP server immediately on stdin EOF or SIGTERM

src/semble/cache.py

@@ -117,7 +117,10 @@ def _load_matching_metadata(
     persistence_path = PersistencePath.from_path(find_index_from_cache_folder(path, content))
     if persistence_path.non_existing():
         return None
-    metadata = json.loads(persistence_path.metadata.read_text(encoding="utf-8"))
+    try:
+        metadata = json.loads(persistence_path.metadata.read_text(encoding="utf-8"))
+    except ValueError:  # Truncated by a process killed mid-save; treat as a miss so the index is rebuilt.
+        return None
     if model_path is None:
         model_path = resolve_model_name()
     if not _metadata_matches(metadata, model_path, content):

src/semble/cli.py

@@ -3,7 +3,9 @@
 import io
 import json
 import logging
+import os
 import re
+import signal
 import sys
 import warnings
 from collections.abc import Iterator
@@ -100,6 +102,7 @@ def main() -> None:
 
 
 def _mcp_main() -> None:
+    signal.signal(signal.SIGTERM, lambda *_: os._exit(0))
     parser = argparse.ArgumentParser(
         prog="semble",
         description="Instant local code search for agents.",
@@ -112,7 +115,9 @@ def _mcp_main() -> None:
     from semble.mcp import serve
 
     content = _resolve_content(args.content, args.include_text_files)
-    asyncio.run(serve(content))
+    asyncio.new_event_loop().run_until_complete(serve(content))
+    # Skip asyncio.run's shutdown, which waits for threads still loading the model or building an index.
+    os._exit(0)
 
 
 def _resolve_content(content: list[str], include_text_files: bool) -> list[ContentType]:

src/semble/version.py

@@ -1,2 +1,2 @@
-__version_triple__ = (0, 6, 1)
+__version_triple__ = (0, 6, 2)
 __version__ = ".".join(map(str, __version_triple__))

tests/index/test_create.py

@@ -135,10 +135,7 @@ def test_load_previous_for_incremental_fails_closed(corrupt: str, tmp_path: Path
             bm25["doc_order"].reverse()
             bm25_path.write_bytes(orjson.dumps(bm25))
         elif corrupt == "corrupt_json":
-            (index_path / "metadata.json").write_bytes(b"{not json")
-            with patch("semble.cache.find_index_from_cache_folder", return_value=index_path):
-                assert load_previous_for_incremental("/some/path", "my/model", [ContentType.CODE]) is None
-            return
+            (index_path / "chunks.json").write_bytes(b"{not json")
         (index_path / "metadata.json").write_bytes(orjson.dumps(metadata))
 
     with patch("semble.cache.find_index_from_cache_folder", return_value=index_path):

tests/test_cache.py

@@ -148,7 +148,7 @@ def _write_metadata(
 
 
 def test_get_validated_cache_invalid_index(tmp_path: Path) -> None:
-    """Returns None when the index directory is missing or incomplete."""
+    """Returns None when the index directory is missing, incomplete, or has truncated metadata."""
     with patch("semble.cache.find_index_from_cache_folder", return_value=tmp_path / "missing"):
         assert get_validated_cache("/path", None, [ContentType.CODE]) is None
 
@@ -157,6 +157,12 @@ def test_get_validated_cache_invalid_index(tmp_path: Path) -> None:
     with patch("semble.cache.find_index_from_cache_folder", return_value=index_path):
         assert get_validated_cache("/path", None, [ContentType.CODE]) is None
 
+    _write_metadata(index_path, "my/model", ["code"], 0.0)
+    metadata = index_path / "metadata.json"
+    metadata.write_text(metadata.read_text()[:20])
+    with patch("semble.cache.find_index_from_cache_folder", return_value=index_path):
+        assert get_validated_cache("/path", "my/model", [ContentType.CODE]) is None
+
 
 @pytest.mark.parametrize(
     ("stored_model", "stored_content", "req_model", "req_content"),

tests/test_cli.py

@@ -1,10 +1,12 @@
+import asyncio
 import hashlib
 import json
+import signal
 import sys
 import warnings
 from importlib.resources import files
 from pathlib import Path
-from unittest.mock import MagicMock, patch
+from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 
@@ -20,13 +22,24 @@
         ["semble"],
     ],
 )
-def test_main_calls_asyncio_run(argv: list[str], monkeypatch: pytest.MonkeyPatch) -> None:
-    """main() delegates to asyncio.run(serve(...)) when no CLI subcommand is given."""
+def test_mcp_main_serves_then_exits(argv: list[str], monkeypatch: pytest.MonkeyPatch) -> None:
+    """main() serves MCP, then hard-exits with 0 on stdin EOF or SIGTERM instead of joining worker threads."""
     monkeypatch.setattr(sys, "argv", argv)
-    with patch("asyncio.run") as mock_run:
-        mock_run.side_effect = lambda coro: coro.close()
+    loop = asyncio.new_event_loop()
+    with (
+        patch("semble.cli.asyncio.new_event_loop", return_value=loop),
+        patch("semble.mcp.serve", new=AsyncMock()) as mock_serve,
+        patch("semble.cli.signal.signal") as mock_signal,
+        patch("semble.cli.os._exit") as mock_exit,
+    ):
         main()
-    mock_run.assert_called_once()
+        mock_serve.assert_awaited_once()
+        mock_exit.assert_called_once_with(0)
+        signum, handler = mock_signal.call_args.args
+        assert signum == signal.SIGTERM
+        handler(signum, None)
+        mock_exit.assert_called_with(0)
+    loop.close()
 
 
 @pytest.mark.parametrize(