feat(governance): emit PublicKeyRegistered event on public-key registration

contracts/governance/src/lib.rs

@@ -156,6 +156,15 @@ pub mod governance {
         pub proposer: AccountId,
     }
 
+    /// Emitted when a signer registers (or overwrites) their ECDSA public key.
+    #[ink(event)]
+    pub struct PublicKeyRegistered {
+        #[ink(topic)]
+        pub signer: AccountId,
+        pub public_key: [u8; 33],
+        pub timestamp: u64,
+    }
+
     // =========================================================================
     // Storage
     // =========================================================================
@@ -575,11 +584,19 @@ pub mod governance {
         }
 
         /// Register an ECDSA public key for cryptographic signature verification.
+        ///
+        /// Emits a `PublicKeyRegistered` event (also on overwrite) so that signer
+        /// key rotations remain observable to auditors and off-chain indexers.
         #[ink(message)]
         pub fn register_public_key(&mut self, public_key: [u8; 33]) -> Result<(), Error> {
             let caller = self.env().caller();
             self.ensure_signer(caller)?;
             self.signer_public_keys.insert(caller, &public_key);
+            self.env().emit_event(PublicKeyRegistered {
+                signer: caller,
+                public_key,
+                timestamp: self.env().block_timestamp(),
+            });
             Ok(())
         }
 

contracts/governance/src/tests.rs

@@ -470,6 +470,38 @@ mod tests {
         );
     }
 
+    #[ink::test]
+    fn register_public_key_emits_public_key_registered_event() {
+        use scale::Decode as _;
+
+        let mut gov = create_governance();
+        let accounts = default_accounts();
+        ink::env::test::set_block_timestamp::<ink::env::DefaultEnvironment>(42);
+        set_caller(accounts.alice);
+
+        gov.register_public_key([0x03; 33]).unwrap();
+
+        let events = ink::env::test::recorded_events().collect::<Vec<_>>();
+        let decoded =
+            PublicKeyRegistered::decode(&mut &events[0].data[..]).expect("decode event");
+        assert_eq!(decoded.signer, accounts.alice);
+        assert_eq!(decoded.public_key, [0x03; 33]);
+        assert_eq!(decoded.timestamp, 42);
+
+        // Overwriting an existing key is a rotation and must also be traceable.
+        ink::env::test::set_block_timestamp::<ink::env::DefaultEnvironment>(99);
+        set_caller(accounts.bob);
+        gov.register_public_key([0x04; 33]).unwrap();
+        gov.register_public_key([0x05; 33]).unwrap();
+
+        let events = ink::env::test::recorded_events().collect::<Vec<_>>();
+        assert_eq!(events.len(), 3);
+        let decoded = PublicKeyRegistered::decode(&mut &events[2].data[..]).expect("decode event");
+        assert_eq!(decoded.signer, accounts.bob);
+        assert_eq!(decoded.public_key, [0x05; 33]);
+        assert_eq!(decoded.timestamp, 99);
+    }
+
     /// Brute-force recount helper mirroring the pre-#972 scan semantics:
     /// tallies each proposal by its *final* status and computes the
     /// participation average over Executed/Rejected proposals.