fix(grep): add a subprocess timeout to ripgrep

src/fastcontext/agent/tool/grep.py

@@ -159,7 +159,13 @@ def run_rg(rg_path: str, pattern: str, path: str, **kwargs) -> str:
 
     cwd = kwargs.get("cwd", str(Path.cwd()))
 
-    output = subprocess.run(command, cwd=cwd, capture_output=True, text=True, encoding="utf-8", errors="replace")
+    timeout = 10  # seconds
+    try:
+        output = subprocess.run(
+            command, cwd=cwd, capture_output=True, text=True, encoding="utf-8", errors="replace", timeout=timeout
+        )
+    except subprocess.TimeoutExpired:
+        return f"<system-reminder>Grep timed out after {timeout}s</system-reminder>"
 
     if output.returncode == 0:
         output_text = (

tests/test_grep_timeout.py

@@ -0,0 +1,43 @@
+import asyncio
+import json
+import subprocess
+import tempfile
+from pathlib import Path
+from unittest import mock
+
+from fastcontext.agent.tool.grep import GrepTool
+
+
+def test_grep_returns_reminder_on_timeout():
+    """run_rg must bound the ripgrep subprocess and surface a system-reminder
+    instead of hanging / raising when it times out. (The outer asyncio
+    wait_for cannot interrupt the blocking subprocess.run, so the timeout
+    must live on the subprocess itself.)"""
+    grep = GrepTool()
+    with tempfile.TemporaryDirectory() as cwd:
+        (Path(cwd) / "a.txt").write_text("MATCH\n", encoding="utf-8")
+
+        with mock.patch("subprocess.run", side_effect=subprocess.TimeoutExpired(cmd="rg", timeout=10)):
+            out = asyncio.run(grep.call(json.dumps({"pattern": "MATCH", "output_mode": "content"}), cwd=cwd))
+
+        assert "<system-reminder>" in out
+        assert "timed out" in out
+
+
+def test_grep_passes_timeout_to_subprocess():
+    """The subprocess.run call must receive a positive timeout kwarg."""
+    grep = GrepTool()
+    with tempfile.TemporaryDirectory() as cwd:
+        (Path(cwd) / "a.txt").write_text("MATCH\n", encoding="utf-8")
+
+        real_run = subprocess.run
+        captured = {}
+
+        def spy(*args, **kwargs):
+            captured.update(kwargs)
+            return real_run(*args, **kwargs)
+
+        with mock.patch("subprocess.run", side_effect=spy):
+            asyncio.run(grep.call(json.dumps({"pattern": "MATCH", "output_mode": "content"}), cwd=cwd))
+
+        assert captured.get("timeout", 0) and captured["timeout"] > 0