TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 3: refactor(mcp_client): migrate L414 get_file_summary to Result[T] (Phase 3 site 6)

Added get_file_summary_result(Result[str]) inside the Result Variants region.
Legacy get_file_summary (str) now delegates to get_file_summary_result.

Audit: mcp_client BC count 35 -> 34.

src/mcp_client.py

@@ -433,19 +433,15 @@ def get_file_summary(path: str) -> str:
  Return the heuristic summary for a file (same as the initial context block).
  For .py files: imports, classes, methods, functions, constants.
  For .toml: table keys. For .md: headings. Others: line count + preview.
+
+ Thin wrapper over get_file_summary_result; the legacy str shape is
+ preserved for backward compatibility, but the try/except Exception
+ lives in the Result variant.
  """
- p, err = _resolve_and_check(path)
- if err or p is None:
-  return err
- if not p.exists():
-  return f"ERROR: file not found: {path}"
- if not p.is_file():
-  return f"ERROR: not a file: {path}"
- try:
-  content = p.read_text(encoding="utf-8")
-  return summarize.summarise_file(p, content)
- except Exception as e:
-  return f"ERROR summarising '{path}': {e}"
+ resolved = get_file_summary_result(path)
+ if resolved.ok:
+  return resolved.data
+ return "; ".join(e.ui_message() for e in resolved.errors)
 
 def get_file_slice(path: str, start_line: int, end_line: int) -> str:
  """Return a specific line range from a file."""