fix(mcp): decode URI-encoded schema refs

nanobot/agent/tools/mcp.py

@@ -317,13 +317,17 @@ def _extract_nullable_branch(options: Any) -> tuple[dict[str, Any], bool] | None
 
 def _resolve_local_schema_ref(root: dict[str, Any], ref: str) -> Any:
     """Resolve a local JSON Pointer without accepting remote references."""
-    if ref == "#":
+    if not ref.startswith("#"):
+        raise ValueError("not a local JSON Pointer")
+
+    pointer = urllib.parse.unquote(ref[1:], errors="strict")
+    if not pointer:
         return root
-    if not ref.startswith("#/"):
+    if not pointer.startswith("/"):
         raise ValueError("not a local JSON Pointer")
 
     current: Any = root
-    for raw_part in ref[2:].split("/"):
+    for raw_part in pointer[1:].split("/"):
         part = raw_part.replace("~1", "/").replace("~0", "~")
         if isinstance(current, dict):
             current = current[part]
@@ -347,15 +351,22 @@ def _rewrite_local_schema_refs(schema: dict[str, Any]) -> dict[str, Any]:
 
         rewritten = dict(value)
         ref = rewritten.get("$ref")
-        is_rewritable_ref = isinstance(ref, str) and (
-            ref == "#" or (ref.startswith("#/") and not ref.startswith("#/$defs/"))
+        is_rewritable_ref = False
+        if isinstance(ref, str) and not ref.startswith("#/$defs/"):
+            try:
+                pointer = urllib.parse.unquote(ref[1:], errors="strict")
+            except (UnicodeDecodeError, ValueError):
+                pass
+            else:
+                is_rewritable_ref = ref.startswith("#") and (
+                    not pointer or pointer.startswith("/")
                 )
         if is_rewritable_ref:
             name = rewritten_refs.get(ref)
             if name is None:
                 try:
                     target = _resolve_local_schema_ref(schema, ref)
-                except (KeyError, IndexError, TypeError, ValueError):
+                except (KeyError, IndexError, TypeError, UnicodeDecodeError, ValueError):
                     logger.warning("MCP tool schema contains an unresolved local $ref: {}", ref)
                 else:
                     assert isinstance(ref, str)

tests/tools/test_mcp_tool.py

@@ -309,6 +309,27 @@ def test_wrapper_preserves_existing_defs_refs() -> None:
     assert wrapper.parameters["$defs"]["value"]["type"] == "string"
 
 
+def test_wrapper_resolves_uri_encoded_json_pointer() -> None:
+    tool_def = SimpleNamespace(
+        name="demo",
+        description="demo tool",
+        inputSchema={
+            "type": "object",
+            "properties": {
+                "space name/value": {"type": "string"},
+                "alias": {"$ref": "#/properties/space%20name~1value"},
+            },
+        },
+    )
+
+    wrapper = MCPToolWrapper(SimpleNamespace(call_tool=None), "test", tool_def)
+
+    generated_ref = wrapper.parameters["properties"]["alias"]["$ref"]
+    assert generated_ref.startswith("#/$defs/ref_")
+    generated_name = generated_ref.removeprefix("#/$defs/")
+    assert wrapper.parameters["$defs"][generated_name] == {"type": "string"}
+
+
 def test_normalize_windows_stdio_command_is_noop_off_windows(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None: