fix: panic on unknown extension types in CToken equality check

program-libs/ctoken-interface/Cargo.toml

@@ -9,6 +9,7 @@ license = "MIT"
 anchor = ["light-compressed-account/anchor", "dep:anchor-lang", "light-compressible/anchor"]
 solana = ["dep:solana-program-error", "dep:solana-sysvar", "solana-msg"]
 default = []
+test-only = []
 profile-program = []
 profile-heap = ["dep:light-heap"]
 poseidon = ["light-hasher/poseidon"]
@@ -51,6 +52,7 @@ light-account-checks = { workspace = true, features = [
     "solana",
 ] }
 spl-token-metadata-interface = "0.6.0"
+light-ctoken-interface = { workspace = true, features = ["poseidon", "test-only"] }
 light-hasher = { workspace = true, features = ["keccak", "sha256", "poseidon"] }
 
 [lints.rust.unexpected_cfgs]

program-libs/ctoken-interface/src/state/ctoken/zero_copy.rs

@@ -231,6 +231,7 @@ impl<'a> Deref for ZCToken<'a> {
     }
 }
 
+#[cfg(feature = "test-only")]
 impl PartialEq<CToken> for ZCToken<'_> {
     fn eq(&self, other: &CToken) -> bool {
         // Compare basic fields
@@ -380,7 +381,23 @@ impl PartialEq<CToken> for ZCToken<'_> {
                                 }
                             }
                         }
-                        _ => return false, // Different extension types
+                        // Mismatched known extension types (e.g., Compressible vs TokenMetadata)
+                        (
+                            crate::state::extensions::ZExtensionStruct::Compressible(_),
+                            crate::state::extensions::ExtensionStruct::TokenMetadata(_),
+                        )
+                        | (
+                            crate::state::extensions::ZExtensionStruct::TokenMetadata(_),
+                            crate::state::extensions::ExtensionStruct::Compressible(_),
+                        ) => return false,
+                        // Unknown or unhandled extension types should panic to surface bugs early
+                        (zc_ext, regular_ext) => {
+                            panic!(
+                                "Unknown extension type comparison: ZCToken extension {:?} vs CToken extension {:?}",
+                                std::mem::discriminant(zc_ext),
+                                std::mem::discriminant(regular_ext)
+                            );
+                        }
                     }
                 }
             }
@@ -392,6 +409,7 @@ impl PartialEq<CToken> for ZCToken<'_> {
     }
 }
 
+#[cfg(feature = "test-only")]
 impl PartialEq<ZCToken<'_>> for CToken {
     fn eq(&self, other: &ZCToken<'_>) -> bool {
         other.eq(self)

program-tests/utils/Cargo.toml

@@ -21,7 +21,7 @@ solana-sdk = { workspace = true }
 thiserror = { workspace = true }
 account-compression = { workspace = true, features = ["cpi"] }
 light-compressed-token = { workspace = true, features = ["cpi"] }
-light-ctoken-interface = { workspace = true }
+light-ctoken-interface = { workspace = true, features = ["test-only"] }
 light-system-program-anchor = { workspace = true, features = ["cpi"] }
 light-registry = { workspace = true, features = ["cpi"] }
 spl-token = { workspace = true, features = ["no-entrypoint"] }