TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 3: refactor(mcp_client): migrate L254 list_directory to Result[T] (Phase 3 site 3)

Legacy list_directory (str) now delegates to list_directory_result (Result[str]).
The try/except Exception is REMOVED.

Audit: mcp_client BC count 38 -> 37.

src/mcp_client.py

@@ -209,29 +209,16 @@ def search_files(path: str, pattern: str) -> str:
  return "; ".join(e.ui_message() for e in resolved.errors)
 
 def list_directory(path: str) -> str:
- """List entries in a directory. Returns a compact text table."""
- p, err = _resolve_and_check(path)
- if err or p is None:
-  return err
- if not p.exists(): return f"ERROR: path not found: {path}"
- if not p.is_dir(): return f"ERROR: not a directory: {path}"
- try:
-  entries = sorted(p.iterdir(), key=lambda e: (e.is_file(), e.name.lower()))
-  lines = [f"Directory: {p}", ""]
-  count = 0
-  for entry in entries:
-  # Blacklist check
-   name = entry.name.lower()
-   if name == "history.toml" or name.endswith("_history.toml"):
-    continue
-   kind = "file" if entry.is_file() else "dir "
-   size = f"{entry.stat().st_size:>10,} bytes" if entry.is_file() else ""
-   lines.append(f"  [{kind}]  {entry.name:<40}  {size}")
-   count += 1
-  lines.append(f"  ({count} entries)")
-  return "\n".join(lines)
- except Exception as e:
-  return f"ERROR listing '{path}': {e}"
+ """List entries in a directory. Returns a compact text table.
+
+ Thin wrapper over list_directory_result; the legacy str shape is
+ preserved for backward compatibility, but the try/except Exception
+ lives in the Result variant.
+ """
+ resolved = list_directory_result(path)
+ if resolved.ok:
+  return resolved.data
+ return "; ".join(e.ui_message() for e in resolved.errors)
 
 def read_file(path: str) -> str:
  """Return the UTF-8 content of a file, or an error string."""