diff --git a/package.json b/package.json
index 02adbeb7e6a3..8c01dcca1924 100644
--- a/package.json
+++ b/package.json
@@ -59,11 +59,12 @@
     "packElectron:win": "yarn build:release:electron && electron-builder build --win --project packages/apps-electron",
     "postinstall": "polkadot-dev-yarn-only",
     "postinstall:electron": "electron-builder install-app-deps",
-    "start": "yarn clean && cd packages/apps && yarn polkadot-exec-webpack serve --config webpack.serve.cjs --port 3000",
+    "start": "yarn clean && cd packages/apps && yarn polkadot-exec-webpack serve --config webpack.serve.cjs --port 3001",
     "start:electron": "yarn clean:electronBuild && concurrently 'yarn build:devElectronMain && cd packages/apps-electron && electron ./build/electron.js' 'yarn build:devElectronRenderer'",
     "test": "polkadot-dev-run-test --env browser ^typesBundle ^chainEndpoints ^chainTypes ^page- ^react- ^apps-electron",
     "test:all": "polkadot-dev-run-test --env browser ^chainEndpoints ^chainTypes",
     "test:one": "polkadot-dev-run-test --env browser",
+    "test:quip-signing": "node scripts/quipSigning.mjs",
     "test:skipped": "echo 'tests skipped'"
   },
   "devDependencies": {
diff --git a/packages/apps/src/initQuipSigner.spec.ts b/packages/apps/src/initQuipSigner.spec.ts
new file mode 100644
index 000000000000..65950804edbe
--- /dev/null
+++ b/packages/apps/src/initQuipSigner.spec.ts
@@ -0,0 +1,54 @@
+// Copyright 2017-2026 @polkadot/apps authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+/// <reference types="@polkadot/dev-test/globals.d.ts" />
+
+import { shouldInjectQuipSigner } from './initQuipSigner.js';
+
+describe('Quip development signer gating', (): void => {
+  const originalNodeEnv = process.env.NODE_ENV;
+  const originalQuipDevSigner = process.env.QUIP_DEV_SIGNER;
+
+  beforeEach((): void => {
+    process.env.NODE_ENV = 'test';
+    delete process.env.QUIP_DEV_SIGNER;
+    window.localStorage.clear();
+    window.history.replaceState({}, '', '/');
+  });
+
+  afterAll((): void => {
+    process.env.NODE_ENV = originalNodeEnv;
+
+    if (originalQuipDevSigner === undefined) {
+      delete process.env.QUIP_DEV_SIGNER;
+    } else {
+      process.env.QUIP_DEV_SIGNER = originalQuipDevSigner;
+    }
+  });
+
+  it('is opt-in in development', (): void => {
+    expect(shouldInjectQuipSigner()).toBe(false);
+
+    process.env.QUIP_DEV_SIGNER = '1';
+
+    expect(shouldInjectQuipSigner()).toBe(true);
+  });
+
+  it('supports the explicit local query and storage toggles', (): void => {
+    window.history.replaceState({}, '', '/?quipSigner=1');
+    expect(shouldInjectQuipSigner()).toBe(true);
+
+    window.history.replaceState({}, '', '/');
+    window.localStorage.setItem('quip:devSigner', 'true');
+    expect(shouldInjectQuipSigner()).toBe(true);
+  });
+
+  it('cannot be enabled in a production bundle', (): void => {
+    process.env.NODE_ENV = 'production';
+    process.env.QUIP_DEV_SIGNER = '1';
+    window.history.replaceState({}, '', '/?quipSigner=1');
+    window.localStorage.setItem('quip:devSigner', 'true');
+
+    expect(shouldInjectQuipSigner()).toBe(false);
+  });
+});
diff --git a/packages/apps/src/initQuipSigner.ts b/packages/apps/src/initQuipSigner.ts
index 877693ef6cb8..1c6fe1b963f9 100644
--- a/packages/apps/src/initQuipSigner.ts
+++ b/packages/apps/src/initQuipSigner.ts
@@ -1,6 +1,8 @@
 // Copyright 2017-2026 @polkadot/apps authors & contributors
 // SPDX-License-Identifier: Apache-2.0
 
+import { GenericExtrinsicSignatureV4 } from '@polkadot/types';
+
 const ENABLED_VALUES = new Set(['1', 'true', 'yes', 'on']);
 const STORAGE_KEY = 'quip:devSigner';
 
@@ -20,6 +22,7 @@ const DEV_SEEDS = [
 ];
 
 interface QuipDevProvider {
+  hasAccount: (address: string) => boolean;
   importMnemonic: (
     name: string,
     mnemonic: string,
@@ -33,6 +36,7 @@ interface QuipDevProvider {
  * (which would be a circular dependency).
  */
 export interface QuipSignerUiApi {
+  canSign: (address: string) => boolean;
   importMnemonic: (name: string, mnemonic: string) => Promise<string>;
 }
 
@@ -70,7 +74,13 @@ function isEnabledByStorage (): boolean {
   }
 }
 
-function shouldInjectQuipSigner (): boolean {
+export function shouldInjectQuipSigner (): boolean {
+  // The page-memory seed provider is intentionally development-only. Query
+  // parameters and localStorage must never turn it on in a production bundle.
+  if (process.env.NODE_ENV === 'production') {
+    return false;
+  }
+
   return isEnabledValue(process.env.QUIP_DEV_SIGNER) ||
     isEnabledByQuery() ||
     isEnabledByStorage();
@@ -84,8 +94,8 @@ export async function initQuipSigner (): Promise<void> {
   isInjected = true;
 
   const [signerModule, wasmModule] = await Promise.all([
-    import('../../../quip-protocol-rs/js/quip-signer/src/index.js'),
-    import('../../../quip-protocol-rs/js/quip-transaction-crypto-wasm/quip_transaction_crypto_wasm.js')
+    import('../../../../quip-protocol-rs/js/quip-signer/src/index.js'),
+    import('../../../../quip-protocol-rs/js/quip-transaction-crypto-wasm/quip_transaction_crypto_wasm.js')
   ]);
 
   await wasmModule.default();
@@ -93,7 +103,7 @@ export async function initQuipSigner (): Promise<void> {
   // Quip's hybrid signature (3828 bytes) is larger than polkadot-js's hardcoded
   // 256-byte fake signature, which breaks `paymentInfo`/fee estimation. Patch
   // signFake to size the fake from the registry before any tx flow runs.
-  signerModule.patchExtrinsicSignFake();
+  signerModule.patchExtrinsicSignFake(GenericExtrinsicSignatureV4);
 
   const { accounts, provider } = await signerModule.DevSeedProvider.fromSeeds(wasmModule, DEV_SEEDS);
 
@@ -103,7 +113,10 @@ export async function initQuipSigner (): Promise<void> {
   });
 
   quipProvider = provider;
-  globalThis.quipSigner = { importMnemonic: importQuipMnemonic };
+  globalThis.quipSigner = {
+    canSign: (address) => provider.hasAccount(address),
+    importMnemonic: importQuipMnemonic
+  };
 
   console.info(`Quip dev signer injected ${accounts.length} account${accounts.length === 1 ? '' : 's'}`);
 }
diff --git a/packages/react-signer/src/TxSigned.tsx b/packages/react-signer/src/TxSigned.tsx
index c4e8a305fd61..83920bc73874 100644
--- a/packages/react-signer/src/TxSigned.tsx
+++ b/packages/react-signer/src/TxSigned.tsx
@@ -57,6 +57,38 @@ const EMPTY_INNER: InnerTx = { innerHash: null, innerTx: null };
 
 let qrId = 0;
 
+interface QuipSignerUiApi {
+  canSign: (address: string) => boolean;
+}
+
+function quipSigningError (address: string | null): string | null {
+  if (!address) {
+    return null;
+  }
+
+  let source: unknown;
+
+  try {
+    source = keyring.getPair(address).meta.source;
+  } catch {
+    return null;
+  }
+
+  if (source !== 'quip') {
+    return null;
+  }
+
+  const quipSigner = (globalThis as unknown as { quipSigner?: QuipSignerUiApi }).quipSigner;
+
+  if (!quipSigner) {
+    return 'Quip signing is unavailable. Enable the development signer or connect a Quip signer.';
+  }
+
+  return quipSigner.canSign(address)
+    ? null
+    : 'This is a view-only Quip account. Its signing key is not available.';
+}
+
 function unlockAccount ({ isUnlockCached, signAddress, signPassword }: AddressProxy): string | null {
   let publicKey;
 
@@ -215,9 +247,15 @@ async function extractParams (api: ApiPromise, address: string, options: Partial
       throw new Error(`Unable to find injected source for ${address}`);
     }
 
+    const unavailable = quipSigningError(address);
+
+    if (unavailable) {
+      throw new Error(unavailable);
+    }
+
     const injected = await web3FromSource(source);
 
-    assert(injected, `Unable to find a signer for ${address}`);
+    assert(injected?.signer, `Injected signer "${source}" is unavailable for ${address}`);
 
     return ['signing', address, { ...options, signer: injected.signer }, false];
   }
@@ -256,7 +294,7 @@ function TxSigned ({ className, currentItem, isQueueSubmit, queueSize, requestAd
 
   useEffect((): void => {
     setFlags(tryExtract(senderInfo.signAddress));
-    setPasswordError(null);
+    setPasswordError(quipSigningError(senderInfo.signAddress));
   }, [senderInfo]);
 
   // when we are sending the hash only, get the wrapped call for display (proxies if required)
@@ -420,6 +458,7 @@ function TxSigned ({ className, currentItem, isQueueSubmit, queueSize, requestAd
   }, [flags.isQr, flags.isLocal, isSubmit, t]);
 
   const isAutoCapable = senderInfo.signAddress && (queueSize > 1) && isSubmit && !(flags.isHardware || flags.isMultisig || flags.isProxied || flags.isQr || flags.isUnlockable) && !isRenderError;
+  const isQuipSigningUnavailable = !!quipSigningError(senderInfo.signAddress);
 
   if (!isBusy && isAutoCapable && initialIsQueueSubmit) {
     setBusy(true);
@@ -508,7 +547,7 @@ function TxSigned ({ className, currentItem, isQueueSubmit, queueSize, requestAd
               : 'sign-in-alt'
           }
           isBusy={isBusy}
-          isDisabled={!senderInfo.signAddress || isRenderError}
+          isDisabled={!senderInfo.signAddress || isRenderError || isQuipSigningUnavailable}
           label={signLabel}
           onClick={_doStart}
           tabIndex={2}
diff --git a/quip-protocol-rs b/quip-protocol-rs
index ed7f83a5fa7c..ad1321f37627 160000
--- a/quip-protocol-rs
+++ b/quip-protocol-rs
@@ -1 +1 @@
-Subproject commit ed7f83a5fa7c2330424f751fadb0f20564215935
+Subproject commit ad1321f3762707852713e8f3fecc1b3973398099
diff --git a/scripts/quipSigning.mjs b/scripts/quipSigning.mjs
new file mode 100644
index 000000000000..ef6a05919726
--- /dev/null
+++ b/scripts/quipSigning.mjs
@@ -0,0 +1,7 @@
+// Copyright 2017-2026 @polkadot/apps authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+// Runs the canonical signer integration from the protocol repository. Keeping
+// this Apps entry point avoids duplicating protocol assertions or dependency
+// resolution between the two workspaces.
+await import('../quip-protocol-rs/js/quip-signer/test/local-node.mjs');