fix: avoid livelock after mining delay

libsigner/src/v0/messages.rs

@@ -1072,6 +1072,7 @@ impl From<&RejectReason> for RejectReasonPrefix {
             RejectReason::NoSignerConsensus => RejectReasonPrefix::NoSignerConsensus,
             RejectReason::ConsensusHashMismatch { .. } => RejectReasonPrefix::ConsensusHashMismatch,
             RejectReason::ProblematicTransactions => RejectReasonPrefix::ProblematicTransactions,
+            RejectReason::ProposalTooOld => RejectReasonPrefix::ProposalTooOld,
             RejectReason::Unknown(_) => RejectReasonPrefix::Unknown,
             RejectReason::NotRejected => RejectReasonPrefix::NotRejected,
         }
@@ -1160,6 +1161,9 @@ pub enum RejectReason {
     /// The block marks one or more transactions as problematic, which signers
     /// do not yet allow
     ProblematicTransactions,
+    /// The block proposal's header timestamp is older than the signer's
+    /// configured `block_proposal_max_age_secs`
+    ProposalTooOld,
     /// The block was approved, no rejection details needed
     NotRejected,
     /// Handle unknown codes gracefully
@@ -1210,6 +1214,9 @@ pub enum RejectReasonPrefix {
     /// The block marks one or more transactions as problematic, which signers
     /// do not yet allow
     ProblematicTransactions = 17,
+    /// The block proposal's header timestamp is older than the signer's
+    /// configured `block_proposal_max_age_secs`
+    ProposalTooOld = 18,
     /// Unknown reject code, for forward compatibility
     Unknown = 254,
     /// The block was approved, no rejection details needed
@@ -1238,6 +1245,7 @@ impl RejectReasonPrefix {
             Self::NoSignerConsensus => 15,
             Self::ConsensusHashMismatch => 16,
             Self::ProblematicTransactions => 17,
+            Self::ProposalTooOld => 18,
             Self::Unknown => 254,
             Self::NotRejected => 255,
         }
@@ -1265,6 +1273,7 @@ impl From<u8> for RejectReasonPrefix {
             15 => Self::NoSignerConsensus,
             16 => Self::ConsensusHashMismatch,
             17 => Self::ProblematicTransactions,
+            18 => Self::ProposalTooOld,
             255 => Self::NotRejected,
             // For forward compatibility, all other values are unknown
             _ => Self::Unknown,
@@ -1930,6 +1939,7 @@ impl StacksMessageCodec for RejectReason {
             | RejectReason::IrrecoverablePubkeyHash
             | RejectReason::NoSignerConsensus
             | RejectReason::ProblematicTransactions
+            | RejectReason::ProposalTooOld
             | RejectReason::Unknown(_)
             | RejectReason::NotRejected => {
                 // No additional data to serialize / deserialize
@@ -1975,6 +1985,7 @@ impl StacksMessageCodec for RejectReason {
                 RejectReason::ConsensusHashMismatch { expected, actual }
             }
             RejectReasonPrefix::ProblematicTransactions => RejectReason::ProblematicTransactions,
+            RejectReasonPrefix::ProposalTooOld => RejectReason::ProposalTooOld,
             RejectReasonPrefix::Unknown => RejectReason::Unknown(type_prefix_byte),
             RejectReasonPrefix::NotRejected => RejectReason::NotRejected,
         };
@@ -2081,6 +2092,12 @@ impl std::fmt::Display for RejectReason {
                     "The block has an irrecoverable associated miner public key hash."
                 )
             }
+            RejectReason::ProposalTooOld => {
+                write!(
+                    f,
+                    "The block proposal's header timestamp is older than the maximum proposal age."
+                )
+            }
             RejectReason::NoSignerConsensus => {
                 write!(f, "No signer consensus reached.")
             }

stacks-node/src/tests/signer/v0/mod.rs

@@ -126,6 +126,7 @@ pub mod failed_txs;
 pub mod late_block_proposal;
 pub mod missing_burn_block_proposal;
 pub mod problematic_txs;
+pub mod proposal_replication_void;
 pub mod reorg;
 pub mod signers_consider_consensus_blocks;
 pub mod signers_consider_late_proposals;
@@ -2529,6 +2530,7 @@ pub fn wait_for_block_rejections_from_signers(
     })?;
     Ok(result)
 }
+
 /// Waits for at least 70% of the provided signers to send an update for a block with the specificed burn block height and parent tenure stacks block height and message version
 pub fn wait_for_state_machine_update(
     timeout_secs: u64,
@@ -5979,8 +5981,10 @@ fn block_validation_pending_table() {
 
 #[test]
 #[ignore]
-/// Test the block_proposal_max_age_secs signer configuration option. It should reject blocks that are
-/// invalid but within the max age window, otherwise it should simply drop the block without further processing.
+/// Test the block_proposal_max_age_secs signer configuration option. Blocks that are
+/// invalid but within the max age window are rejected after validation; blocks past the
+/// max age window are rejected immediately (without validation) with ProposalTooOld so
+/// the miner learns to re-mine instead of re-sending the same stale block forever.
 ///
 /// Test Setup:
 /// The test spins up five stacks signers, one miner Nakamoto node, and a corresponding bitcoind.
@@ -5990,11 +5994,12 @@ fn block_validation_pending_table() {
 /// An invalid block proposal with a recent timestamp is forcibly written to the miner's slot to simulate the miner proposing a block.
 /// The signers process the invalid block and broadcast a block response rejection to the respective .signers-XXX-YYY contract.
 /// A second block proposal with an outdated timestamp is then submitted to the miner's slot to simulate the miner proposing a very old block.
-/// The test confirms no further block rejection response is submitted to the .signers-XXX-YYY contract.
+/// The test confirms the stale proposal is also rejected (with ProposalTooOld), and never accepted.
 ///
 /// Test Assertion:
 /// - Each signer successfully rejects the recent invalid block proposal.
-/// - No signer submits a block proposal response for the outdated block proposal.
+/// - Each signer rejects the outdated block proposal with the ProposalTooOld reason.
+/// - No signer accepts either block.
 /// - The stacks tip does not advance
 fn block_proposal_max_age_rejections() {
     if env::var("BITCOIND_TEST") != Ok("1".into()) {
@@ -6054,8 +6059,16 @@ fn block_proposal_max_age_rejections() {
             match message {
                 SignerMessage::BlockResponse(BlockResponse::Rejected(BlockRejection {
                     signer_signature_hash,
+                    response_data,
                     ..
                 })) => {
+                    if signer_signature_hash == block_signer_signature_hash_1 {
+                        assert_eq!(
+                            response_data.reject_reason,
+                            RejectReason::ProposalTooOld,
+                            "Stale proposal must be rejected as ProposalTooOld"
+                        );
+                    }
                     let entry = status_map.entry(signer_signature_hash).or_insert((0, 0));
                     entry.0 += 1;
                 }
@@ -6073,7 +6086,10 @@ fn block_proposal_max_age_rejections() {
             .get(&block_signer_signature_hash_1)
             .cloned()
             .unwrap_or((0, 0));
-        assert_eq!(block_1_status, (0, 0));
+        assert_eq!(
+            block_1_status.1, 0,
+            "Block 1 (stale) must never be accepted"
+        );
 
         let block_2_status = status_map
             .get(&block_signer_signature_hash_2)
@@ -6084,7 +6100,7 @@ fn block_proposal_max_age_rejections() {
         info!("Block 2 status";
             "accepted" => %block_2_status.1, "rejected" => %block_2_status.0
         );
-        Ok(block_2_status.0 > num_signers * 7 / 10)
+        Ok(block_2_status.0 > num_signers * 7 / 10 && block_1_status.0 > num_signers * 7 / 10)
     })
     .expect("Timed out waiting for block rejections");