fix(pi-model-modes): reject prototype property names

Author: zigai

extensions/pi-model-modes/src/mode-picker.ts

@@ -39,6 +39,9 @@ const THINKING_UNSET_LABEL = "(don't change)";
 function isReservedModeName(name: string): boolean {
     return (
         name === CUSTOM_MODE_NAME ||
+        name === "__proto__" ||
+        name === "constructor" ||
+        name === "prototype" ||
         name === MODE_UI_CONFIGURE ||
         name === MODE_UI_ADD ||
         name === MODE_UI_BACK

extensions/pi-model-modes/test/mode-controller.test.ts

@@ -1,7 +1,18 @@
 import assert from "node:assert/strict";
-import { test } from "vitest";
+import { mkdir, mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import {
+    ExtensionRunner,
+    ModelRegistry,
+    ModelRuntime,
+    SessionManager,
+    discoverAndLoadExtensions,
+} from "@earendil-works/pi-coding-agent";
+import { test, vi } from "vitest";
 
 import { ModeController } from "../src/mode-controller.ts";
+import { ModePicker } from "../src/mode-picker.ts";
 
 function createController(): ModeController {
     return new ModeController({
@@ -27,6 +38,61 @@ test("mode controllers own independent runtime state", () => {
     assert.equal(second.thinkingLevelStatusEnabled, false);
 });
 
+test.each(["__proto__", "constructor", "prototype"])(
+    "renaming a mode to %s is rejected without losing the saved mode",
+    async (name) => {
+        const root = await mkdtemp(join(tmpdir(), "pi-model-modes-rename-"));
+        vi.stubEnv("PI_CODING_AGENT_DIR", join(root, "agent"));
+        const configPath = join(root, "agent", "extension-settings", "pi-model-modes.json");
+        const original = JSON.stringify({
+            currentMode: "review",
+            modes: { review: { provider: "local", modelId: "small" } },
+        });
+        try {
+            await mkdir(join(configPath, ".."), { recursive: true });
+            await writeFile(configPath, original);
+            const loaded = await discoverAndLoadExtensions([], root, join(root, "agent"));
+            const models = await ModelRuntime.create({
+                authPath: join(root, "auth.json"),
+                modelsPath: null,
+                refreshOnCreate: false,
+            });
+            const runner = new ExtensionRunner(
+                loaded.extensions,
+                loaded.runtime,
+                root,
+                SessionManager.inMemory(root),
+                new ModelRegistry(models),
+            );
+            const choices = ["Configure modes…", "review", "Change name"];
+            const inputs = [name];
+            const notifications: string[] = [];
+            runner.setUIContext(
+                {
+                    ...runner.getUIContext(),
+                    select: async () => choices.shift(),
+                    input: async () => inputs.shift(),
+                    notify: (message) => {
+                        notifications.push(message);
+                    },
+                },
+                "rpc",
+            );
+            const controller = createController();
+
+            await new ModePicker(controller).select(runner.createContext());
+            assert.equal(await readFile(configPath, "utf8"), original);
+            assert.deepEqual(controller.modes.modes, {
+                review: { provider: "local", modelId: "small" },
+            });
+            assert.deepEqual(notifications, [`Mode name "${name}" is reserved`]);
+        } finally {
+            vi.unstubAllEnvs();
+            await rm(root, { recursive: true, force: true });
+        }
+    },
+);
+
 test("mode controller derives settings reads from the explicit extension context", () => {
     const controller = createController();
     assert.deepEqual(