fix(programs): reject rent_payment < 2 for CMint decompression (L-10)

forester/tests/test_compressible_mint.rs

@@ -12,6 +12,7 @@ use light_client::{
     local_test_validator::{spawn_validator, LightValidatorConfig},
     rpc::{LightClient, LightClientConfig, Rpc},
 };
+use light_compressible::rent::SLOTS_PER_EPOCH;
 use light_token::instruction::{
     derive_mint_compressed_address, find_mint_address, CreateMint, CreateMintParams,
 };
@@ -89,7 +90,7 @@ async fn create_decompressed_mint(
         .unwrap()
         .value;
 
-    // Build params - rent_payment = 0 makes the mint immediately compressible (no auto-decompress period)
+    // Build params - rent_payment = 2 is the minimum required by the program
     let params = CreateMintParams {
         decimals,
         address_merkle_tree_root_index: rpc_result.addresses[0].root_index,
@@ -100,7 +101,7 @@ async fn create_decompressed_mint(
         bump,
         freeze_authority: None,
         extensions: None,
-        rent_payment: 0, // Immediately compressible for testing
+        rent_payment: 2, // Minimum required epochs of rent prepayment
         write_top_up: 0,
     };
 
@@ -267,7 +268,7 @@ async fn test_compressible_mint_bootstrap() {
 
 /// Test that MintCompressor can compress decompressed mints
 ///
-/// This test creates a mint with rent_payment=0 (immediately compressible),
+/// This test creates a mint with rent_payment=2, warps past the rent period,
 /// then verifies the compressor can close the on-chain mint account.
 ///
 /// Run with: cargo test -p forester --test test_compressible_mint -- --nocapture
@@ -381,14 +382,18 @@ async fn test_compressible_mint_compression() {
             .expect("Failed to create RPC pool"),
     );
 
-    // Get ready accounts - with rent_payment=0, the mint is immediately compressible
+    // Warp past the rent prepayment period so the mint becomes compressible
+    let current_slot = rpc.get_slot().await.unwrap();
+    let future_slot = current_slot + 2 * SLOTS_PER_EPOCH;
+    rpc.warp_to_slot(future_slot).await.expect("warp_to_slot");
+
     let current_slot = rpc.get_slot().await.unwrap();
     let ready_accounts = tracker.get_ready_to_compress(current_slot);
     println!("Ready to compress: {} mints", ready_accounts.len());
 
     assert!(
         !ready_accounts.is_empty(),
-        "Mint should be ready to compress with rent_payment=0"
+        "Mint should be ready to compress after rent period expires"
     );
 
     // Create compressor and compress
@@ -447,9 +452,9 @@ async fn test_compressible_mint_compression() {
 ///
 /// This test verifies the full subscription flow:
 /// 1. Start AccountSubscriber with MintAccountTracker
-/// 2. Create two decompressed mints: one with rent, one immediately compressible
+/// 2. Create two decompressed mints with rent_payment=2
 /// 3. Assert subscriber picks up both accounts (tracker.len() == 2)
-/// 4. Run MintCompressor to compress the immediately compressible mint
+/// 4. Warp past rent period, run MintCompressor to compress one mint
 /// 5. Assert account is closed and tracker is updated via direct removal
 ///
 /// Run with: cargo test -p forester --test test_compressible_mint test_compressible_mint_subscription -- --nocapture
@@ -511,7 +516,7 @@ async fn test_compressible_mint_subscription() {
     // Give subscribers time to connect
     sleep(Duration::from_secs(2)).await;
 
-    // Create first decompressed mint (immediately compressible with rent_payment=0)
+    // Create first decompressed mint (rent_payment=2)
     let (mint_pda_1, compression_address_1, _mint_seed_1, _bump_1) =
         create_decompressed_mint(&mut rpc, &payer, payer.pubkey(), 9).await;
     println!("Created first decompressed mint at: {}", mint_pda_1);
@@ -575,6 +580,11 @@ async fn test_compressible_mint_subscription() {
             .expect("Failed to create RPC pool"),
     );
 
+    // Warp past the rent prepayment period so mints become compressible
+    let current_slot = rpc.get_slot().await.unwrap();
+    let future_slot = current_slot + 2 * SLOTS_PER_EPOCH;
+    rpc.warp_to_slot(future_slot).await.expect("warp_to_slot");
+
     // Get ready-to-compress accounts
     let current_slot = rpc.get_slot().await.unwrap();
     let ready_accounts = tracker.get_ready_to_compress(current_slot);
@@ -584,7 +594,7 @@ async fn test_compressible_mint_subscription() {
         current_slot
     );
 
-    // Both mints should be ready (rent_payment=0)
+    // Both mints should be ready after rent period expires
     assert_eq!(
         ready_accounts.len(),
         2,

forester/tests/test_indexer_interface.rs

@@ -233,7 +233,7 @@ async fn test_indexer_interface_scenarios() {
         address_sig
     );
 
-    // ============ Scenario 4: Decompressed Mint (CreateMint with rent_payment=0) ============
+    // ============ Scenario 4: Decompressed Mint (CreateMint with rent_payment=2) ============
     // This creates a compressed mint that is immediately decompressed to an on-chain CMint account.
     // The compressed account only contains the 32-byte mint_pda reference (DECOMPRESSED_PDA_DISCRIMINATOR).
     // Full mint data is on-chain in the CMint account owned by LIGHT_TOKEN_PROGRAM_ID.
@@ -277,7 +277,7 @@ async fn test_indexer_interface_scenarios() {
         bump: decompressed_mint_bump,
         freeze_authority: None,
         extensions: None,
-        rent_payment: 0, // Immediately compressible
+        rent_payment: 2, // Minimum required epochs of rent prepayment
         write_top_up: 0,
     };
 
@@ -342,7 +342,7 @@ async fn test_indexer_interface_scenarios() {
         bump: compressed_mint_bump,
         freeze_authority: Some(payer.pubkey()), // Add freeze authority for variety
         extensions: None,
-        rent_payment: 0, // Immediately compressible
+        rent_payment: 2, // Minimum required epochs of rent prepayment
         write_top_up: 0,
     };
 

programs/compressed-token/program/src/compressed_token/mint_action/actions/decompress_mint.rs

@@ -27,7 +27,7 @@ use crate::{
 ///
 /// ## Process Steps
 /// 1. **State Validation**: Ensure mint is not already decompressed
-/// 2. **Rent Payment Validation**: rent_payment must be 0 or >= 2
+/// 2. **Rent Payment Validation**: rent_payment must be >= 2
 /// 3. **Config Validation**: Validate CompressibleConfig account
 /// 4. **Write Top-Up Validation**: write_top_up must not exceed max_top_up
 /// 5. **Add Compressible Extension**: Add CompressionInfo to the compressed mint extensions
@@ -51,10 +51,13 @@ pub fn process_decompress_mint_action(
         return Err(ErrorCode::CMintAlreadyExists.into());
     }
 
-    // 2. rent_payment == 1 is rejected - epoch boundary edge case
-    if action.rent_payment == 1 {
-        msg!("Prefunding for exactly 1 epoch is not allowed. Use 0 or 2+ epochs.");
-        return Err(ErrorCode::OneEpochPrefundingNotAllowed.into());
+    // 2. CMint requires at least 2 epochs of rent prepayment (always compressible)
+    if action.rent_payment < 2 {
+        msg!(
+            "CMint requires at least 2 epochs of rent prepayment. Got {}.",
+            action.rent_payment
+        );
+        return Err(ErrorCode::InvalidRentPayment.into());
     }
 
     let executing = validated_accounts