feat: Initial library extraction from PIN LLM benchmark

DockerSandbox + LangChain file/shell tools extracted into a standalone package.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker_agent_sandbox/tools/search_files.py

@@ -0,0 +1,40 @@
+"""search_files.py – tool for finding files by name pattern inside the sandbox."""
+
+from __future__ import annotations
+
+from shlex import quote
+from typing import TYPE_CHECKING
+
+from langchain_core.tools import BaseTool, tool
+from loguru import logger
+
+if TYPE_CHECKING:
+    from docker_agent_sandbox.sandbox import DockerSandbox
+
+
+def make_search_files_tool(sandbox: "DockerSandbox") -> BaseTool:
+    """Return a search_files tool bound to *sandbox*."""
+
+    @tool
+    def search_files(pattern: str, directory: str = ".") -> str:
+        """
+        Find files whose names match *pattern* (shell glob) under *directory*.
+
+        Examples::
+
+            search_files("*.so", "/tmp/re-agent")
+            search_files("main", "/usr/bin")
+
+        Returns a newline-separated list of matching paths, or an error message.
+        """
+        logger.debug(
+            "Searching files inside sandbox: pattern={!r} dir={!r}", pattern, directory
+        )
+        exit_code, output = sandbox.exec(
+            f"find {quote(directory)} -name {quote(pattern)} -print 2>/dev/null"
+        )
+        if exit_code != 0:
+            return f"[ERROR searching {directory!r}] {output.strip()}"
+        return output.strip() or "[no matches found]"
+
+    return search_files