refactor(mcp_client): migrate L1358 derive_code_path to Result[T] (Phase 7 site 3)

Added derive_code_path_result inside Result Variants region.
Legacy derive_code_path (str) now delegates to it. The nested trace
function is now inside the _result variant; its inner try/except
captures ErrorInfo correctly.

src/mcp_client.py

@@ -936,6 +936,70 @@ def py_get_docstring_result(path: str, name: str) -> Result[str]:
   return Result(data=f"No docstring found for '{name}'.")
  except Exception as e:
   return Result(data="", errors=[ErrorInfo(kind=ErrorKind.INTERNAL, message=str(e), source="mcp.py_get_docstring_result", original=e)])
+
+def derive_code_path_result(target: str, max_depth: int = 5) -> Result[str]:
+ from src.file_cache import ASTParser
+ parser = ASTParser("python")
+ found_path, found_code = None, None
+ parts = target.split(".")
+ symbol_name = parts[-1]
+ if len(parts) > 1:
+  possible_file = Path(*parts[:-1]).with_suffix(".py")
+  if possible_file.exists(): found_path = str(possible_file)
+ if not found_path:
+  for root in ["src", "simulation"]:
+   for p in Path(root).rglob("*.py"):
+    if not _is_allowed(p): continue
+    code = p.read_text(encoding="utf-8")
+    if f"def {symbol_name}" in code or f"class {symbol_name}" in code:
+     try:
+      tree = ast.parse(code)
+      if _get_symbol_node(tree, symbol_name):
+       found_path, found_code = str(p), code
+       break
+     except Exception: continue
+   if found_path: break
+ if not found_path:
+  return Result(data="", errors=[ErrorInfo(kind=ErrorKind.NOT_FOUND, message=f"could not find definition for '{target}'", source="mcp.derive_code_path_result")])
+ if not found_code: found_code = Path(found_path).read_text(encoding="utf-8")
+ visited, output = set(), [f"Code Path for: {target}", "=" * (11 + len(target)), ""]
+ def trace(name, path, code, depth, indent):
+  if depth > max_depth or (name, path) in visited: return
+  visited.add((name, path))
+  defn = parser.get_definition(code, name, path=path)
+  if defn.startswith("ERROR:"):
+   output.append(f"{indent}[!] {name} (Definition not found in {path})")
+   return
+  output.append(f"{indent}-> {name} ({path})")
+  try:
+   node = ast.parse(defn)
+   calls = []
+   for n in ast.walk(node):
+    if isinstance(n, ast.Call):
+     if isinstance(n.func, ast.Name): calls.append(n.func.id)
+     elif isinstance(n.func, ast.Attribute): calls.append(n.func.attr)
+   for call in sorted(set(calls)):
+    if call in ("print", "len", "str", "int", "list", "dict", "set", "range", "enumerate", "isinstance", "getattr", "setattr", "hasattr"): continue
+    c_path, c_code = None, None
+    full_tree = ast.parse(code)
+    if _get_symbol_node(full_tree, call): c_path, c_code = path, code
+    else:
+     for r in ["src", "simulation"]:
+      for p in Path(r).rglob("*.py"):
+       if not _is_allowed(p): continue
+       f_code = p.read_text(encoding="utf-8")
+       if f"def {call}" in f_code:
+        c_path, c_code = str(p), f_code
+        break
+      if c_path: break
+    if c_path: trace(call, c_path, c_code, depth + 1, indent + "  ")
+  except Exception as e:
+   output.append(f"{indent}  [!] Error parsing calls for {name}: {e}")
+ try:
+  trace(symbol_name, found_path, found_code, 0, "")
+  return Result(data="\n".join(output))
+ except Exception as e:
+  return Result(data="", errors=[ErrorInfo(kind=ErrorKind.INTERNAL, message=str(e), source="mcp.derive_code_path_result", original=e)])
 #endregion: Result Variants
 
 def edit_file(path: str, old_string: str, new_string: str, replace_all: bool = False) -> str:
@@ -1351,64 +1415,16 @@ def py_get_docstring(path: str, name: str) -> str:
  return "; ".join(e.ui_message() for e in resolved.errors)
 
 def derive_code_path(target: str, max_depth: int = 5) -> str:
- """Recursively traces the execution path of a specific function or method."""
- from src.file_cache import ASTParser
- parser = ASTParser("python")
- found_path, found_code = None, None
- parts = target.split(".")
- symbol_name = parts[-1]
- if len(parts) > 1:
-  possible_file = Path(*parts[:-1]).with_suffix(".py")
-  if possible_file.exists(): found_path = str(possible_file)
- if not found_path:
-  for root in ["src", "simulation"]:
-   for p in Path(root).rglob("*.py"):
-    if not _is_allowed(p): continue
-    code = p.read_text(encoding="utf-8")
-    if f"def {symbol_name}" in code or f"class {symbol_name}" in code:
-     try:
-      tree = ast.parse(code)
-      if _get_symbol_node(tree, symbol_name):
-       found_path, found_code = str(p), code
-       break
-     except Exception: continue
-   if found_path: break
- if not found_path: return f"ERROR: could not find definition for '{target}'"
- if not found_code: found_code = Path(found_path).read_text(encoding="utf-8")
- visited, output = set(), [f"Code Path for: {target}", "=" * (11 + len(target)), ""]
- def trace(name, path, code, depth, indent):
-  if depth > max_depth or (name, path) in visited: return
-  visited.add((name, path))
-  defn = parser.get_definition(code, name, path=path)
-  if defn.startswith("ERROR:"):
-   output.append(f"{indent}[!] {name} (Definition not found in {path})")
-   return
-  output.append(f"{indent}-> {name} ({path})")
-  try:
-   node = ast.parse(defn)
-   calls = []
-   for n in ast.walk(node):
-    if isinstance(n, ast.Call):
-     if isinstance(n.func, ast.Name): calls.append(n.func.id)
-     elif isinstance(n.func, ast.Attribute): calls.append(n.func.attr)
-   for call in sorted(set(calls)):
-    if call in ("print", "len", "str", "int", "list", "dict", "set", "range", "enumerate", "isinstance", "getattr", "setattr", "hasattr"): continue
-    c_path, c_code = None, None
-    full_tree = ast.parse(code)
-    if _get_symbol_node(full_tree, call): c_path, c_code = path, code
-    else:
-     for r in ["src", "simulation"]:
-      for p in Path(r).rglob("*.py"):
-       if not _is_allowed(p): continue
-       f_code = p.read_text(encoding="utf-8")
-       if f"def {call}" in f_code:
-        c_path, c_code = str(p), f_code
-        break
-      if c_path: break
-    if c_path: trace(call, c_path, c_code, depth + 1, indent + "  ")
-  except Exception as e: output.append(f"{indent}  [!] Error parsing calls for {name}: {e}")
- trace(symbol_name, found_path, found_code, 0, "")
- return "\n".join(output)
+ """Recursively traces the execution path of a specific function or method.
+
+ Thin wrapper over derive_code_path_result; the legacy str shape is
+ preserved for backward compatibility, but the try/except Exception
+ lives in the Result variant.
+ """
+ resolved = derive_code_path_result(target, max_depth)
+ if resolved.ok:
+  return resolved.data
+ return "; ".join(e.ui_message() for e in resolved.errors)
 
 #endregion Python AST