diff --git a/.forgejo/workflows/checkpr.yml b/.forgejo/workflows/checkpr.yml
new file mode 100644
index 0000000..2f6dc9f
--- /dev/null
+++ b/.forgejo/workflows/checkpr.yml
@@ -0,0 +1,34 @@
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  checkpr:
+    runs-on: fedora-41
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Bun
+        uses: oven-sh/setup-bun@v2
+        with:
+          bun-version-file: 'package.json'
+
+      - name: Cache Dependencies
+        id: dependencies-cache
+        uses: actions/cache@v4
+        with:
+          path: ~/.bun/install/cache
+          key: ${{ runner.os }}-bun-${{ hashFiles('**/bun.lockb') }}
+          restore-keys: |
+            ${{ runner.os }}-bun-
+
+      - name: Install Dependencies
+        run: bun install
+
+      - name: Validate types
+        run: bun typecheck
+
+      - name: Build Dist
+        run: VITE_CODE_VERSION=$GITHUB_SHA bun dist
diff --git a/.forgejo/workflows/depoly.yml b/.forgejo/workflows/depoly.yml
index edba093..0ad6d10 100644
--- a/.forgejo/workflows/depoly.yml
+++ b/.forgejo/workflows/depoly.yml
@@ -30,6 +30,9 @@ jobs:
       - name: Install Dependencies
         run: bun install
 
+      - name: Validate types
+        run: bun typecheck
+
       - name: Build Dist (Staging)
         run: VITE_CODE_VERSION=$GITHUB_SHA bun dist -m staging
         if: env.GITHUB_REF_NAME == 'master'
diff --git a/package.json b/package.json
index 219b2e0..4e04928 100644
--- a/package.json
+++ b/package.json
@@ -9,7 +9,8 @@
     "dev": "vite --host 0.0.0.0",
     "preview": "vite preview",
     "dist": "vite build",
-    "count-source-lines": "exec scripts/src-lc.sh"
+    "count-source-lines": "exec scripts/src-lc.sh",
+    "typecheck": "tsc --noEmit --skipLibCheck"
   },
   "keywords": [],
   "author": "Rubicon",
diff --git a/src/platform/polyfills.ts b/src/platform/polyfills.ts
index 032207a..1af3341 100644
--- a/src/platform/polyfills.ts
+++ b/src/platform/polyfills.ts
@@ -15,3 +15,24 @@ if (typeof window.crypto.randomUUID === "undefined") {
       ) as `${string}-${string}-${string}-${string}-${string}`;
     };
 }
+
+
+if (typeof Promise.withResolvers === "undefined") {
+  // Chrome/Edge 119, Firefox 121, Safari/iOS 17.4
+
+  // Promise.withResolvers is generic and works with subclasses - the typescript built-in decl
+  // could not handle the subclassing case.
+  Promise.withResolvers = function <T>(this: AnyPromiseConstructor<T>) {
+    let resolve!: PromiseWithResolvers<T>["resolve"], reject!: PromiseWithResolvers<T>["reject"];
+    // These variables are expected to be set after `new this()`
+
+    const promise = new this((resolve0, reject0) => {
+      resolve = resolve0;
+      reject = reject0;
+    })
+
+    return {
+      promise, resolve, reject
+    }
+  }
+}
diff --git a/src/serviceworker/main.ts b/src/serviceworker/main.ts
index 71a4f37..99305a9 100644
--- a/src/serviceworker/main.ts
+++ b/src/serviceworker/main.ts
@@ -4,23 +4,27 @@ import { dispatchCall, isJSONRPCCall, type Call } from "./workerrpc";
 
 function isServiceWorker(
   self: WorkerGlobalScope,
+  // @ts-ignore: workaround for workbox logger.d.ts decl
 ): self is ServiceWorkerGlobalScope {
-  return !!(self as unknown as ServiceWorkerGlobalScope).registration;
+  return (
+    (self as unknown as Record<string, unknown>)["serviceWorker"] instanceof
+    ServiceWorker
+  );
 }
 
-if (isServiceWorker(self)) {
-  cleanupOutdatedCaches();
-  precacheAndRoute(self.__WB_MANIFEST, {
-    cleanURLs: false,
-  });
-
-  // auto update
-  self.skipWaiting();
-  clientsClaim();
-} else {
+if (!isServiceWorker(self)) {
   throw new TypeError("This entry point must be run in a service worker");
 }
 
+cleanupOutdatedCaches();
+precacheAndRoute(self.__WB_MANIFEST, {
+  cleanURLs: false,
+});
+
+// auto update
+self.skipWaiting();
+clientsClaim();
+
 export const Service = {
   ping() {},
 };
@@ -29,6 +33,9 @@ self.addEventListener("message", (event: MessageEvent<unknown>) => {
   const payload = event.data;
   if (typeof payload !== "object") return;
   if (isJSONRPCCall(payload as Record<string, unknown>)) {
-    dispatchCall(Service, event as MessageEvent<Call<unknown>>);
+    dispatchCall(
+      Service,
+      event as MessageEvent<Call<unknown>> & { source: MessageEventSource },
+    );
   }
 });
diff --git a/src/serviceworker/tsconfig.json b/src/serviceworker/tsconfig.json
index bc88f57..090edc2 100644
--- a/src/serviceworker/tsconfig.json
+++ b/src/serviceworker/tsconfig.json
@@ -1,5 +1,7 @@
 {
   "compilerOptions": {
-    "lib": ["ESNext", "WebWorker"],
+    "lib": ["WebWorker", "ESNext"],
   },
-}
\ No newline at end of file
+  "extends": ["../../tsconfig.super.json"],
+  "include": ["./**/*.ts"],
+}
diff --git a/src/serviceworker/workerrpc.ts b/src/serviceworker/workerrpc.ts
index 84bb39f..7680716 100644
--- a/src/serviceworker/workerrpc.ts
+++ b/src/serviceworker/workerrpc.ts
@@ -46,7 +46,7 @@ export type Result<T, E> = JSONRPC & { id: string | number } & (
 export function isJSONRPCResult(
   object: Record<string, unknown>,
 ): object is Result<unknown, unknown> {
-  return object["jsonrpc"] === "2.0" && object["id"] && !object["method"];
+  return !!(object["jsonrpc"] === "2.0" && object["id"] && !object["method"]);
 }
 
 export function isJSONRPCCall(
@@ -114,6 +114,9 @@ export class ResultDispatcher {
     {
       const callback = this.map.get(id);
       if (!callback) return;
+      // Now the callback is not undefined
+
+      // Fast path
       if (typeof callback !== "boolean") {
         callback(message);
         this.map.delete(id);
@@ -121,28 +124,30 @@ export class ResultDispatcher {
       }
     }
 
-    return new Promise<void>((resolve) => {
-      let retried = 0;
+    const { promise, resolve } = Promise.withResolvers<undefined>();
 
-      const checkAndDispatch = () => {
-        const callback = this.map.get(id);
-        if (typeof callback !== "boolean") {
-          callback(message);
-          this.map.delete(id);
-          resolve();
-          return;
-        }
-        setTimeout(checkAndDispatch, 0);
-        if (++retried > 3) {
-          console.warn(
-            `retried ${retried} time(s) but the callback is still disappeared, id is "${id}"`,
-          );
-        }
-      };
+    let retried = 0;
 
-      // start the loop
-      checkAndDispatch();
-    });
+    const checkAndDispatch = () => {
+      const callback = this.map.get(id);
+      if (typeof callback !== "boolean") {
+        callback!(message); // the nullability is already checked before
+        this.map.delete(id);
+        resolve(undefined);
+        return;
+      }
+      setTimeout(checkAndDispatch, 0);
+      if (++retried > 3) {
+        console.warn(
+          `retried ${retried} time(s) but the callback is still disappeared, id is "${id}"`,
+        );
+      }
+    };
+
+    // start the loop
+    checkAndDispatch();
+
+    return promise;
   }
 
   createTypedCall<
@@ -159,14 +164,16 @@ export class ResultDispatcher {
   }
 }
 
-type AnyService = Record<string, ((...args: unknown[]) => unknown) | undefined>
+type AnyService = Record<string, (...args: unknown[]) => unknown>;
 
-export async function dispatchCall<
-  S extends AnyService,
->(service: S, event: MessageEvent<Call<unknown>>) {
+export async function dispatchCall<S extends Partial<AnyService>>(
+  service: S,
+  event: MessageEvent<Call<unknown>> & { source: MessageEventSource },
+) {
   try {
     const fn = service[event.data.method];
     if (!fn) {
+      console.warn("requested unknown method", event.data.method, event.data);
       if (event.data.id)
         return event.source.postMessage({
           jsonrpc: "2.0",
@@ -176,10 +183,12 @@ export async function dispatchCall<
             message: "Method not found",
           },
         } as Result<void, void>);
+
+      return;
     }
 
     try {
-      const result = await fn(...event.data.params as unknown[]);
+      const result = await fn(...(event.data.params as unknown[]));
 
       if (!event.data.id) return;
 
diff --git a/tsconfig.json b/tsconfig.json
index b92e528..feaab58 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,20 +1,11 @@
 {
   "compilerOptions": {
-    "strict": true,
-    "target": "ESNext",
-    "module": "esnext",
-    "moduleResolution": "node",
-    "allowSyntheticDefaultImports": true,
-    "esModuleInterop": true,
     "jsx": "preserve",
     "jsxImportSource": "solid-js",
     "types": ["vite/client", "vite-plugin-pwa/solid"],
-    "noEmit": true,
-    "isolatedModules": true,
-    "resolveJsonModule": true,
-    "paths": {
-      "~platform/*": ["./src/platform/*"],
-      "~material/*": ["./src/material/*"]
-    }
-  }
+    "lib": ["ESNext", "DOM", "DOM.Iterable"]
+  },
+  "include": ["./src/**/*.ts", "./src/**/*.tsx", "./*.ts", "./types/**.ts"],
+  "exclude": ["./src/serviceworker/**"],
+  "extends": ["./tsconfig.super.json"]
 }
diff --git a/tsconfig.super.json b/tsconfig.super.json
new file mode 100644
index 0000000..9cf8e60
--- /dev/null
+++ b/tsconfig.super.json
@@ -0,0 +1,17 @@
+{
+  "compilerOptions": {
+    "strict": true,
+    "target": "ESNext",
+    "module": "esnext",
+    "moduleResolution": "node",
+    "allowSyntheticDefaultImports": true,
+    "esModuleInterop": true,
+    "noEmit": true,
+    "isolatedModules": true,
+    "resolveJsonModule": true,
+    "paths": {
+      "~platform/*": ["./src/platform/*"],
+      "~material/*": ["./src/material/*"]
+    }
+  }
+}
diff --git a/types/lib.esnext.promise.d.ts b/types/lib.esnext.promise.d.ts
new file mode 100644
index 0000000..5df9b56
--- /dev/null
+++ b/types/lib.esnext.promise.d.ts
@@ -0,0 +1,26 @@
+interface AnyPromiseWithResolvers<T, Instance> {
+  promise: Instance;
+  resolve: (value: T | PromiseLike<T>) => void;
+  reject: (reason?: any) => void;
+}
+
+type AnyPromiseConstructor<T> = new (
+  executor: (
+    resolve: PromiseWithResolvers<T>["resolve"],
+    reject: PromiseWithResolvers<T>["reject"],
+  ) => void,
+) => Promise<T>;
+
+interface PromiseConstructor {
+  /**
+   * Creates a new Promise and returns it in an object, along with its resolve and reject functions.
+   * @returns An object with the properties `promise`, `resolve`, and `reject`.
+   *
+   * ```ts
+   * const { promise, resolve, reject } = Promise.withResolvers<T>();
+   * ```
+   */
+  withResolvers<T, K extends AnyPromiseConstructor<T>>(
+    this: K,
+  ): AnyPromiseWithResolvers<T, InstanceType<K>>;
+}