refactor: relax ata decompress signer check, feat: add ata decompress idempotent

js/compressed-token/src/v3/layout/layout-transfer2.ts

@@ -31,6 +31,7 @@ export const EXTENSION_DISCRIMINANT_COMPRESSIBLE = 32;
 export const COMPRESSION_MODE_COMPRESS = 0;
 export const COMPRESSION_MODE_DECOMPRESS = 1;
 export const COMPRESSION_MODE_COMPRESS_AND_CLOSE = 2;
+export const COMPRESSION_MODE_DECOMPRESS_IDEMPOTENT = 3;
 
 /**
  * Compression struct for Transfer2 instruction

program-libs/token-interface/src/error.rs

@@ -206,6 +206,12 @@ pub enum TokenError {
 
     #[error("ATA derivation failed or mismatched for is_ata compressed token")]
     InvalidAtaDerivation,
+
+    #[error("DecompressIdempotent requires exactly 1 input and 1 compression")]
+    IdempotentDecompressRequiresSingleInput,
+
+    #[error("DecompressIdempotent is only supported for ATA accounts (is_ata must be true)")]
+    IdempotentDecompressRequiresAta,
 }
 
 impl From<TokenError> for u32 {
@@ -277,6 +283,8 @@ impl From<TokenError> for u32 {
             TokenError::DecompressAmountMismatch => 18064,
             TokenError::CompressionIndexOutOfBounds => 18065,
             TokenError::InvalidAtaDerivation => 18066,
+            TokenError::IdempotentDecompressRequiresSingleInput => 18067,
+            TokenError::IdempotentDecompressRequiresAta => 18068,
             TokenError::HasherError(e) => u32::from(e),
             TokenError::ZeroCopyError(e) => u32::from(e),
             TokenError::CompressedAccountError(e) => u32::from(e),

program-libs/token-interface/src/instructions/transfer2/compression.rs

@@ -16,6 +16,10 @@ pub enum CompressionMode {
     /// Signer must be rent authority, token account must be compressible
     /// Not implemented for spl token accounts.
     CompressAndClose,
+    /// Permissionless ATA decompress with single-input constraint.
+    /// Requires CompressedOnly extension with is_ata=true.
+    /// On-chain behavior is identical to Decompress.
+    DecompressIdempotent,
 }
 
 impl ZCompressionMode {
@@ -24,7 +28,10 @@ impl ZCompressionMode {
     }
 
     pub fn is_decompress(&self) -> bool {
-        matches!(self, ZCompressionMode::Decompress)
+        matches!(
+            self,
+            ZCompressionMode::Decompress | ZCompressionMode::DecompressIdempotent
+        )
     }
 
     pub fn is_compress_and_close(&self) -> bool {
@@ -35,6 +42,7 @@ impl ZCompressionMode {
 pub const COMPRESS: u8 = 0u8;
 pub const DECOMPRESS: u8 = 1u8;
 pub const COMPRESS_AND_CLOSE: u8 = 2u8;
+pub const DECOMPRESS_IDEMPOTENT: u8 = 3u8;
 
 impl<'a> ZeroCopyAtMut<'a> for CompressionMode {
     type ZeroCopyAtMut = Ref<&'a mut [u8], u8>;
@@ -204,6 +212,20 @@ impl Compression {
             decimals: 0,
         }
     }
+
+    pub fn decompress_idempotent(amount: u64, mint: u8, recipient: u8) -> Self {
+        Compression {
+            amount,
+            mode: CompressionMode::DecompressIdempotent,
+            mint,
+            source_or_recipient: recipient,
+            authority: 0,
+            pool_account_index: 0,
+            pool_index: 0,
+            bump: 0,
+            decimals: 0,
+        }
+    }
 }
 
 impl ZCompressionMut<'_> {
@@ -212,6 +234,7 @@ impl ZCompressionMut<'_> {
             COMPRESS => Ok(CompressionMode::Compress),
             DECOMPRESS => Ok(CompressionMode::Decompress),
             COMPRESS_AND_CLOSE => Ok(CompressionMode::CompressAndClose),
+            DECOMPRESS_IDEMPOTENT => Ok(CompressionMode::DecompressIdempotent),
             _ => Err(TokenError::InvalidCompressionMode),
         }
     }
@@ -226,7 +249,7 @@ impl ZCompression<'_> {
                     .checked_add((*self.amount).into())
                     .ok_or(TokenError::ArithmeticOverflow)
             }
-            ZCompressionMode::Decompress => {
+            ZCompressionMode::Decompress | ZCompressionMode::DecompressIdempotent => {
                 // Decompress: subtract from balance (tokens are being removed from spl token pool)
                 current_balance
                     .checked_sub((*self.amount).into())