[#397] Emit event on signer deployment

modules/passkey/contracts/SafeWebAuthnSignerFactory.sol

@@ -42,6 +42,7 @@ contract SafeWebAuthnSignerFactory is ISafeSignerFactory {
         if (_hasNoCode(signer)) {
             SafeWebAuthnSignerProxy created = new SafeWebAuthnSignerProxy{salt: bytes32(0)}(address(SINGLETON), x, y, verifiers);
             require(address(created) == signer);
+            emit Created(signer, x, y, verifiers);
         }
     }
 

modules/passkey/contracts/interfaces/ISafeSignerFactory.sol

@@ -10,6 +10,15 @@ import {P256} from "../libraries/P256.sol";
  * @custom:security-contact bounty@safe.global
  */
 interface ISafeSignerFactory {
+    /**
+     * @notice Emitted when a new signer is created.
+     * @param signer The signer address.
+     * @param x The x-coordinate of the public key.
+     * @param y The y-coordinate of the public key.
+     * @param verifiers The P-256 verifiers to use.
+     */
+    event Created(address signer, uint256 x, uint256 y, P256.Verifiers verifiers);
+
     /**
      * @notice Gets the unique signer address for the specified data.
      * @dev The unique signer address must be unique for some given data. The signer is not

modules/passkey/test/SafeWebAuthnSignerProxyFactory.spec.ts

@@ -90,6 +90,20 @@ describe('SafeWebAuthnSignerFactory', () => {
       expect(await factory.createSigner.staticCall(x, y, verifiers)).to.eq(signer)
       await expect(factory.createSigner(x, y, verifiers)).to.not.be.reverted
     })
+
+    it('Should emit event only once', async () => {
+      const { factory, verifiers } = await setupTests()
+
+      const x = ethers.id('publicKey.x')
+      const y = ethers.id('publicKey.y')
+
+      const signer = await factory.createSigner.staticCall(x, y, verifiers)
+
+      await expect(factory.createSigner(x, y, verifiers))
+        .to.emit(factory, 'Created')
+        .withArgs(signer, x, y, verifiers)
+      await expect(factory.createSigner(x, y, verifiers)).not.to.emit(factory, 'Created')
+    })
   })
 
   describe('isValidSignatureForSigner', function () {