diff --git a/web/supabase/functions/_shared/__tests__/identity-auth.test.ts b/web/supabase/functions/_shared/__tests__/identity-auth.test.ts
index ffab3d97..55dfb3f1 100644
--- a/web/supabase/functions/_shared/__tests__/identity-auth.test.ts
+++ b/web/supabase/functions/_shared/__tests__/identity-auth.test.ts
@@ -15,6 +15,7 @@ import {
 import { Keyring } from 'npm:@pezkuwi/keyring@14.0.25'
 import { cryptoWaitReady, encodeAddress } from 'npm:@pezkuwi/util-crypto@14.0.25'
 import { stringToU8a, u8aToHex, u8aWrapBytes } from 'npm:@pezkuwi/util@14.0.25'
+import * as substrateSr25519 from 'npm:@scure/sr25519@2.4.0'
 
 import {
   verifyWalletSignature,
@@ -65,6 +66,27 @@ Deno.test('verifyWalletSignature: signature over a DIFFERENT message is rejected
   assertEquals(await verifyWalletSignature('message-B', sig, alice.address), false)
 })
 
+// The Pezkuwi Wallet mobile app signs a message in the standard `substrate` sr25519
+// context, not Pezkuwi's `bizinikiwi` (measured 2026-10-01). The keyring above signs
+// like the extension, so without these the mobile path was never exercised.
+const phone = substrateSr25519.secretFromSeed(crypto.getRandomValues(new Uint8Array(32)))
+const phoneAddress = encodeAddress(substrateSr25519.getPublicKey(phone), 42)
+const signAsPhone = (msg: string) => u8aToHex(substrateSr25519.sign(phone, u8aWrapBytes(msg)))
+
+Deno.test('verifyWalletSignature: mobile-wallet signature (substrate context) passes', async () => {
+  const msg = 'Pezkuwi P2P Withdrawal\ntoken:HEZ'
+  assert(await verifyWalletSignature(msg, signAsPhone(msg), phoneAddress))
+})
+
+Deno.test('verifyWalletSignature: substrate-context signature claimed for another address is rejected', async () => {
+  const msg = 'authorize me'
+  assertEquals(await verifyWalletSignature(msg, signAsPhone(msg), alice.address), false)
+})
+
+Deno.test('verifyWalletSignature: substrate-context signature over a DIFFERENT message is rejected', async () => {
+  assertEquals(await verifyWalletSignature('message-B', signAsPhone('message-A'), phoneAddress), false)
+})
+
 Deno.test('verifyWalletSignature: empty / malformed signatures return false (no throw)', async () => {
   assertEquals(await verifyWalletSignature('m', '', alice.address), false)
   assertEquals(await verifyWalletSignature('m', '0x', alice.address), false)
diff --git a/web/supabase/functions/_shared/identity-auth.ts b/web/supabase/functions/_shared/identity-auth.ts
index a58cc1cc..6bc4424e 100644
--- a/web/supabase/functions/_shared/identity-auth.ts
+++ b/web/supabase/functions/_shared/identity-auth.ts
@@ -16,8 +16,9 @@
 // The client-supplied `userId` is NEVER trusted for authorization. Every
 // caller can only ever act on the balance of the identity their wallet owns.
 
-import { signatureVerify, cryptoWaitReady } from 'npm:@pezkuwi/util-crypto@14.0.25'
-import { stringToU8a, u8aWrapBytes } from 'npm:@pezkuwi/util@14.0.25'
+import { signatureVerify, cryptoWaitReady, decodeAddress } from 'npm:@pezkuwi/util-crypto@14.0.25'
+import { hexToU8a, stringToU8a, u8aWrapBytes } from 'npm:@pezkuwi/util@14.0.25'
+import { verify as sr25519VerifySubstrateContext } from 'npm:@scure/sr25519@2.4.0'
 import type { ApiPromise } from 'npm:@pezkuwi/api@16.5.36'
 import type { SupabaseClient } from 'npm:@supabase/supabase-js@2'
 
@@ -87,7 +88,17 @@ export async function verifyWalletSignature(
       const res = signatureVerify(candidate, signature, signerAddress)
       if (res.isValid) return true
     }
-    return false
+    // Pezkuwi's sr25519 signs in the `bizinikiwi` context, and the extension does.
+    // The Pezkuwi Wallet mobile app does not, for a message: it picks the signing
+    // chain from the address prefix, prefix 42 falls back to Polkadot, and Polkadot
+    // gets the standard `substrate` context (measured 2026-10-01 on dks.news, where
+    // every mobile sign-in was refused for this alone). The wallet is not changed
+    // for it, so the verifier accepts both: the proof is the same -- the account's
+    // own key over a canonical, single-use challenge.
+    const publicKey = decodeAddress(signerAddress)
+    const sig = hexToU8a(signature)
+    if (publicKey.length !== 32 || sig.length !== 64) return false
+    return [raw, wrapped].some((candidate) => sr25519VerifySubstrateContext(candidate, sig, publicKey))
   } catch (_e) {
     return false
   }