fix(tooling): strip MCP: prefix in Cursor hook tool_name matching

IDE postToolUse reports tool_name as MCP:pi_subagent_*; without stripping,
guard-pi-dispatch skipped shape checks. Confirmed via live pi_subagent_roles.

scripts/tests/test_cursor_hooks.py

@@ -224,6 +224,34 @@ class GuardPiDispatchTest(unittest.TestCase):
         }
         self.assertEqual(self._run(payload).get("permission"), "allow")
 
+    def test_ask_mcp_prefixed_tool_name_bad_sha(self):
+        # IDE postToolUse/beforeMCP observed tool_name="MCP:pi_subagent_*"
+        payload = {
+            "mcp_server_name": "pi-subagents",
+            "tool_name": "MCP:pi_subagent_run",
+            "tool_input": {
+                "worktree": "/tmp/wt",
+                "task_id": "t1",
+                "request": {
+                    "role_id": "research",
+                    "request_id": "research-001",
+                    "goal": "g",
+                    "authorization_ref": "a",
+                    "source_sha": "HEAD",
+                    "input_files": [],
+                    "timeout_seconds": 30,
+                },
+            },
+        }
+        self.assertEqual(self._run(payload).get("permission"), "ask")
+
+    def test_allow_mcp_prefixed_roles(self):
+        payload = {
+            "tool_name": "MCP:pi_subagent_roles",
+            "tool_input": {"worktree": "/tmp/wt", "task_id": "t1"},
+        }
+        self.assertEqual(self._run(payload).get("permission"), "allow")
+
 
 class GuardPiShellTest(unittest.TestCase):
     SCRIPT = HOOKS / "guard-pi-shell.sh"
@@ -288,6 +316,16 @@ class PiReceiptContextTest(unittest.TestCase):
         self.assertIn("additional_context", parsed)
         self.assertIn("run_status", parsed["additional_context"])
 
+    def test_injects_for_mcp_prefixed_tool_name(self):
+        code, parsed, err = _run_hook(
+            self.SCRIPT,
+            {"tool_name": "MCP:pi_subagent_roles", "mcp_server_name": "pi-subagents"},
+            env=self.env,
+            cwd=self.root,
+        )
+        self.assertEqual(code, 0, err)
+        self.assertIn("additional_context", parsed)
+
     def test_noop_for_unrelated(self):
         code, parsed, err = _run_hook(
             self.SCRIPT,