feat: add proposal expiry mechanism and finalize_expired_proposal

contracts/contracts/group_treasury/src/lib.rs

@@ -332,7 +332,7 @@ impl GroupTreasuryContract {
         if proposal.status != ProposalStatus::Active {
             panic!("proposal is not pending");
         }
-        if env.ledger().timestamp() >= proposal.expires_at {
+        if proposal.status == ProposalStatus::Expired || env.ledger().timestamp() >= proposal.expires_at {
             panic!("proposal expired");
         }
         if env

contracts/contracts/group_treasury/src/storage.rs

@@ -18,6 +18,7 @@ pub enum ProposalStatus {
     Passed,
     Rejected,
     Executed,
+    Expired,
 }
 
 #[contracttype]

contracts/contracts/proposals/src/lib.rs

@@ -25,7 +25,7 @@ use soroban_sdk::{contract, contractimpl, symbol_short, Address, Env, String, Sy
 
 pub use storage::{
     DataKey, Proposal, ProposalCreatedEvent, ProposalExecutedEvent, ProposalFinalizedEvent,
-    ProposalStatus, VoteCastEvent,
+    ProposalStatus, VoteCastEvent, ProposalExpiredEvent,
 };
 
 // ── Contract ─────────────────────────────────────────────────────────────────
@@ -191,6 +191,28 @@ impl ProposalsContract {
         new_status
     }
 
+    pub fn finalize_expired_proposal(env: Env, proposal_id: u64) {
+        let mut proposal = Self::load_proposal(&env, proposal_id);
+
+        if !matches!(proposal.status, ProposalStatus::Active) {
+            panic!("proposal not Pending");
+        }
+        let now = env.ledger().timestamp();
+        if now <= proposal.expires_at {
+            panic!("proposal not expired");
+        }
+
+        proposal.status = ProposalStatus::Expired;
+        env.storage()
+            .instance()
+            .set(&DataKey::Proposal(proposal_id), &proposal);
+
+        env.events().publish(
+            (Symbol::new(&env, "proposal_expired"),),
+            ProposalExpiredEvent { id: proposal_id },
+        );
+    }
+
     /// Execute a Passed proposal. Refuses unless `status == Passed`.
     /// MVP execution simply flips the status to `Executed` and emits
     /// the event; downstream wiring (treasury withdrawals, etc.) can

contracts/contracts/proposals/src/storage.rs

@@ -16,6 +16,7 @@ pub enum ProposalStatus {
     Passed,
     Rejected,
     Executed,
+    Expired,
 }
 
 #[contracttype]
@@ -71,6 +72,12 @@ pub struct ProposalFinalizedEvent {
     pub no_votes: u32,
 }
 
+#[contracttype]
+#[derive(Clone)]
+pub struct ProposalExpiredEvent {
+    pub id: u64,
+}
+
 #[contracttype]
 #[derive(Clone)]
 pub struct ProposalExecutedEvent {

contracts/contracts/proposals/src/test.rs

@@ -313,6 +313,43 @@ fn create_with_past_expiry_panics() {
     );
 }
 
+#[test]
+#[should_panic(expected = "proposal not expired")]
+fn finalize_expired_before_expiry_panics() {
+    let env = Env::default();
+    let (client, _padmin, alice, _bob, _carol, _treasury, _tadmin, m, token_id) = setup(&env);
+
+    let id = create_proposal_in(&env, &client, &alice, 1_000, &m, &token_id, &alice, 1);
+    client.finalize_expired_proposal(&id);
+}
+
+#[test]
+#[should_panic(expected = "proposal not Pending")]
+fn finalize_expired_when_passed_panics() {
+    let env = Env::default();
+    let (client, _padmin, alice, _bob, _carol, _treasury, _tadmin, m, token_id) = setup(&env);
+
+    let id = create_proposal_in(&env, &client, &alice, 500, &m, &token_id, &alice, 1);
+
+    advance_time(&env, 501);
+    client.finalize_proposal(&id); // becomes Passed
+    client.finalize_expired_proposal(&id);
+}
+
+#[test]
+fn finalize_expired_success() {
+    let env = Env::default();
+    let (client, _padmin, alice, _bob, _carol, _treasury, _tadmin, m, token_id) = setup(&env);
+
+    let id = create_proposal_in(&env, &client, &alice, 500, &m, &token_id, &alice, 1);
+
+    advance_time(&env, 501);
+    client.finalize_expired_proposal(&id);
+
+    let proposal = client.get_proposal(&id);
+    assert_eq!(proposal.status, ProposalStatus::Expired);
+}
+
 // ─────────────────────────────────────────────────────────────────────────────
 // execute_withdraw acceptance criteria