Treat grep no matches as nonfatal

app/tools/plugins/shell_exec/__init__.py

@@ -24,10 +24,12 @@ class Tool(BaseTool):
             stdin_data=str(stdin_secret) if stdin_secret is not None else None,
         )
         output = completed.stdout if completed.returncode == 0 else completed.stderr or completed.stdout
+        grep_no_matches = "grep" in command and completed.returncode == 1 and not completed.stderr
+        ok = completed.returncode == 0 or grep_no_matches
         return ToolResult(
             tool=self.name,
-            ok=completed.returncode == 0,
+            ok=ok,
             output=output,
-            error=None if completed.returncode == 0 else f"Command failed with exit code {completed.returncode}",
+            error=None if ok else f"Command failed with exit code {completed.returncode}",
-            metadata={"exit_code": completed.returncode},
+            metadata={"exit_code": completed.returncode, "no_matches": grep_no_matches},
         )

app/tools/shell_exec.py

@@ -29,6 +29,8 @@ class ShellExecTool(BaseTool):
         )
         output = completed.stdout if completed.returncode == 0 else completed.stderr or completed.stdout
         error_output = completed.stderr or completed.stdout
+        grep_no_matches = "grep" in command and completed.returncode == 1 and not completed.stderr
+        ok = completed.returncode == 0 or grep_no_matches
         
         is_sudo_error = (
             completed.returncode != 0 and 
@@ -40,8 +42,8 @@ class ShellExecTool(BaseTool):
         
         return ToolResult(
             tool=self.name,
-            ok=completed.returncode == 0,
+            ok=ok,
             output=output,
-            error=None if completed.returncode == 0 else f"Command failed with exit code {completed.returncode}",
+            error=None if ok else f"Command failed with exit code {completed.returncode}",
-            metadata={"exit_code": completed.returncode, "needs_sudo": is_sudo_error},
+            metadata={"exit_code": completed.returncode, "needs_sudo": is_sudo_error, "no_matches": grep_no_matches},
         )

config/prompts/thinker.md

@@ -14,6 +14,9 @@ INSTRUCTIONS:
 4. If the user asks about the current local machine, filesystem, processes,
    packages, logs, runtime state, or anything that must be observed rather than
    answered from general knowledge, use an appropriate tool.
+5. For exploratory tasks, prefer one robust inspection command over many brittle
+   dependent checks. Missing optional files should be treated as information, not
+   as a fatal failure.
 
 MODE: {mode_hint}
 - If mode is "execution": create a plan with TOOL STEPS (shell_exec, file_write, etc)

tests/test_tools_flow.py

@@ -112,6 +112,23 @@ def test_shell_exec_allows_safe_command(tmp_path: Path) -> None:
     assert str(tmp_path) in result["result"]["output"]
 
 
+def test_shell_exec_treats_grep_no_matches_as_information(tmp_path: Path) -> None:
+    _write_config_tree(tmp_path)
+    controller = RuntimeController(base_dir=tmp_path)
+    result = controller.handle_task(
+        UserTask(
+            input="run grep with no matches",
+            context={
+                "requested_tool": "shell_exec",
+                "tool_args": {"command": "printf 'abc\\n' | grep definitely_missing"},
+            },
+        )
+    )
+    assert result["status"] == "completed"
+    assert result["result"]["metadata"]["exit_code"] == 1
+    assert result["result"]["metadata"]["no_matches"] is True
+
+
 def test_permission_resolution_can_resume_task(tmp_path: Path) -> None:
     _write_config_tree(tmp_path)
     controller = RuntimeController(base_dir=tmp_path)