feat(mma): Implement tiered context scoping and add get_definition tool

mcp_client.py

@@ -281,6 +281,60 @@ def get_code_outline(path: str) -> str:
         return f"ERROR generating outline for '{path}': {e}"
 
 
+def get_definition(path: str, name: str) -> str:
+    """
+    Returns the source code for a specific class, function, or method definition.
+    path: Path to the code file.
+    name: Name of the definition to retrieve (e.g., 'MyClass', 'my_function', 'MyClass.my_method').
+    """
+    p, err = _resolve_and_check(path)
+    if err:
+        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}"
+    
+    if p.suffix != ".py":
+        return f"ERROR: get_definition currently only supports .py files (unsupported: {p.suffix})"
+
+    try:
+        import ast
+        code = p.read_text(encoding="utf-8")
+        lines = code.splitlines()
+        tree = ast.parse(code)
+        
+        # Split name for methods (e.g., "MyClass.my_method")
+        parts = name.split(".")
+        target_class = parts[0] if len(parts) > 1 else None
+        target_name = parts[-1]
+
+        def get_source_from_node(node):
+            # In Python 3.8+, ast.get_source_segment is available
+            # But we can also use lineno and end_lineno
+            if hasattr(node, "lineno") and hasattr(node, "end_lineno"):
+                # lineno is 1-indexed
+                start = node.lineno - 1
+                end = node.end_lineno
+                return "\n".join(lines[start:end])
+            return f"ERROR: Could not extract source for node {node}"
+
+        for node in ast.walk(tree):
+            if target_class:
+                if isinstance(node, ast.ClassDef) and node.name == target_class:
+                    for body_node in node.body:
+                        if isinstance(body_node, (ast.FunctionDef, ast.AsyncFunctionDef)) and body_node.name == target_name:
+                            return get_source_from_node(body_node)
+            else:
+                if isinstance(node, (ast.ClassDef, ast.FunctionDef, ast.AsyncFunctionDef)) and node.name == target_name:
+                    return get_source_from_node(node)
+                
+        return f"ERROR: could not find definition '{name}' in {path}"
+
+    except Exception as e:
+        return f"ERROR retrieving definition '{name}' from '{path}': {e}"
+
+
 def get_git_diff(path: str, base_rev: str = "HEAD", head_rev: str = "") -> str:
     """
     Returns the git diff for a file or directory.
@@ -436,7 +490,7 @@ def get_ui_performance() -> str:
 # ------------------------------------------------------------------ tool dispatch
 
 
-TOOL_NAMES = {"read_file", "list_directory", "search_files", "get_file_summary", "get_python_skeleton", "get_code_outline", "get_git_diff", "web_search", "fetch_url", "get_ui_performance"}
+TOOL_NAMES = {"read_file", "list_directory", "search_files", "get_file_summary", "get_python_skeleton", "get_code_outline", "get_definition", "get_git_diff", "web_search", "fetch_url", "get_ui_performance"}
 
 
 def dispatch(tool_name: str, tool_input: dict) -> str:
@@ -455,6 +509,8 @@ def dispatch(tool_name: str, tool_input: dict) -> str:
         return get_python_skeleton(tool_input.get("path", ""))
     if tool_name == "get_code_outline":
         return get_code_outline(tool_input.get("path", ""))
+    if tool_name == "get_definition":
+        return get_definition(tool_input.get("path", ""), tool_input.get("name", ""))
     if tool_name == "get_git_diff":
         return get_git_diff(
             tool_input.get("path", ""), 
@@ -586,6 +642,27 @@ MCP_TOOL_SPECS = [
             "required": ["path"],
         },
     },
+    {
+        "name": "get_definition",
+        "description": (
+            "Get the full source code of a specific class, function, or method definition. "
+            "This is more efficient than reading the whole file if you know what you're looking for."
+        ),
+        "parameters": {
+            "type": "object",
+            "properties": {
+                "path": {
+                    "type": "string",
+                    "description": "Path to the .py file.",
+                },
+                "name": {
+                    "type": "string",
+                    "description": "The name of the class or function to retrieve. Use 'ClassName.method_name' for methods.",
+                }
+            },
+            "required": ["path", "name"],
+        },
+    },
     {
         "name": "get_git_diff",
         "description": (
@@ -648,3 +725,4 @@ MCP_TOOL_SPECS = [
         }
     }
 ]
+