feat: add read_many_files tool for batch file reading

Reduces LLM round-trips by allowing multiple files to be read in a
single tool call. Uses best-effort error handling so partial failures
still return successful reads.

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

tests/unit/test_filesystem_read_many.py

@@ -0,0 +1,69 @@
+"""Tests for the read_many_files tool."""
+
+from pathlib import Path
+
+import pytest
+
+from app.models.config import AppConfig, load_config
+from app.models.tool_call import ToolResultStatus
+from app.tools.filesystem import ReadManyFilesTool
+
+
+@pytest.fixture
+def config() -> AppConfig:
+    return load_config()
+
+
+@pytest.fixture
+def tmp_workspace(tmp_path: Path, config: AppConfig) -> tuple[Path, AppConfig]:
+    """Create a temporary workspace for read_many_files tests."""
+    config.agent.workspace_root = tmp_path
+    return tmp_path, config
+
+
+class TestReadManyFilesTool:
+    def test_read_multiple_files(self, tmp_workspace: tuple[Path, AppConfig]) -> None:
+        ws, cfg = tmp_workspace
+        (ws / "a.txt").write_text("alpha")
+        (ws / "b.txt").write_text("bravo")
+        tool = ReadManyFilesTool(ws, cfg)
+        result = tool.run("tc-1", {"file_paths": ["a.txt", "b.txt"]})
+        assert result.status == ToolResultStatus.SUCCESS
+        assert "=== a.txt ===" in result.output
+        assert "alpha" in result.output
+        assert "=== b.txt ===" in result.output
+        assert "bravo" in result.output
+
+    def test_partial_failure(self, tmp_workspace: tuple[Path, AppConfig]) -> None:
+        ws, cfg = tmp_workspace
+        (ws / "exists.txt").write_text("hello")
+        tool = ReadManyFilesTool(ws, cfg)
+        result = tool.run("tc-2", {"file_paths": ["exists.txt", "missing.txt"]})
+        assert result.status == ToolResultStatus.SUCCESS
+        assert "hello" in result.output
+        assert "[ERROR]" in result.output
+        assert "=== missing.txt ===" in result.output
+
+    def test_all_files_fail(self, tmp_workspace: tuple[Path, AppConfig]) -> None:
+        ws, cfg = tmp_workspace
+        tool = ReadManyFilesTool(ws, cfg)
+        result = tool.run("tc-3", {"file_paths": ["no1.txt", "no2.txt"]})
+        assert result.status == ToolResultStatus.ERROR
+        assert "All files failed" in (result.error or "")
+
+    def test_empty_file_paths(self, tmp_workspace: tuple[Path, AppConfig]) -> None:
+        ws, cfg = tmp_workspace
+        tool = ReadManyFilesTool(ws, cfg)
+        result = tool.run("tc-4", {"file_paths": []})
+        assert result.status == ToolResultStatus.ERROR
+        assert "empty" in (result.error or "").lower()
+
+    def test_path_security_inline_error(self, tmp_workspace: tuple[Path, AppConfig]) -> None:
+        ws, cfg = tmp_workspace
+        (ws / "safe.txt").write_text("ok")
+        tool = ReadManyFilesTool(ws, cfg)
+        result = tool.run("tc-5", {"file_paths": ["safe.txt", "../../etc/passwd"]})
+        assert result.status == ToolResultStatus.SUCCESS
+        assert "ok" in result.output
+        assert "[ERROR]" in result.output
+        assert "outside" in result.output.lower()

tests/unit/test_tools.py

@@ -108,7 +108,7 @@ class TestToolRegistry:
         registry = create_default_registry(workspace, config)
         names = set(registry.get_all().keys())
         assert names == {
-            "read_file", "list_dir", "grep_files", "find_files",
+            "read_file", "read_many_files", "list_dir", "grep_files", "find_files",
             "write_file", "make_dir", "delete_file",
             "str_replace", "patch_apply",
             "run_command",
@@ -118,7 +118,7 @@ class TestToolRegistry:
     def test_schema_export(self, workspace: Path, config: AppConfig) -> None:
         registry = create_default_registry(workspace, config)
         schemas = registry.get_openai_tools_schema()
-        assert len(schemas) == 11
+        assert len(schemas) == 12
         assert all(s["type"] == "function" for s in schemas)