chore: add missing compressible extension placeholder

[ananas-block]

Changes:

• add compressed only placeholder to CompressibleExtension

Summary by CodeRabbit

• Refactor

  • Consolidated compressible extension data into a nested info container across the codebase; behavior and control flow preserved.

• Chores

  • Updated token account size and rent-exemption values to reflect the new layout.

• Tests

  • Adjusted tests and utilities to match the new nested extension shape without changing observable behavior.

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Walkthrough

Introduces a new CompressibleExtension wrapper that nests CompressionInfo under an info field and updates all code paths to access compressible fields and methods via .info (e.g., .info.compress_to_pubkey, .info.get_last_funded_epoch, .info.calculate_top_up_lamports). Constants and zero-copy layouts updated accordingly.

Changes

Cohort / File(s)	Summary
Extension type & zero-copy layout program-libs/ctoken-interface/src/state/extensions/extension_struct.rs	Added CompressibleExtension { compression_only, info }; changed ExtensionStruct::Compressible and zero-copy encode/decode to use CompressibleExtension.
Constants & sizes program-libs/ctoken-interface/src/constants.rs	Switched constant size to use CompressibleExtension::LEN; updated COMPRESSIBLE_TOKEN_ACCOUNT_SIZE doc and COMPRESSIBLE_TOKEN_RENT_EXEMPTION value (2700480 → 2707440).
Zero-copy config & equality program-libs/ctoken-interface/src/state/ctoken/zero_copy.rs	Added CompressibleExtensionConfig; CompressedTokenConfig::new_compressible now nests CompressionInfoConfig inside it; PartialEq updated to compare zc_comp.info.* fields.
Tests & spl compatibility program-libs/ctoken-interface/tests/ctoken/spl_compat.rs, programs/compressed-token/program/tests/compress_and_close.rs	Tests updated to construct and access compressible payloads via CompressibleExtension/CompressibleExtensionConfig and comp.info.* fields.
Compressed-token program: init/claim/transfer programs/compressed-token/program/src/shared/initialize_ctoken_account.rs, programs/compressed-token/program/src/claim.rs, programs/compressed-token/program/src/ctoken_transfer.rs	Zero-copy creation now uses CompressibleExtension::zero_copy_at_mut, initializes compression_only, and routes calls/fields through .info (e.g., claim_and_update, calculate_top_up_lamports).
Compressed-token program: close account & compression flows programs/compressed-token/program/src/close_token_account/processor.rs, programs/compressed-token/program/src/transfer2/compression/ctoken/compress_and_close.rs, programs/compressed-token/program/src/transfer2/compression/ctoken/compress_or_decompress_ctokens.rs	Replaced direct compressible fields/methods with .info.* equivalents across validation, distribution, and compression processing.
Forester & sdk test helpers forester/src/compressible/compressor.rs, forester/src/compressible/state.rs, sdk-libs/program-test/src/compressible.rs, sdk-libs/program-test/src/forester/compress_and_close_forester.rs	Updated accesses and calls to use compressible_ext.info.* and info.get_last_funded_epoch(...).
SDK & token client sdk-libs/ctoken-sdk/src/compressed_token/v2/compress_and_close.rs, sdk-libs/token-client/src/instructions/transfer2.rs	Changed packing and instruction metadata collection to read compression_authority, rent_sponsor, compress_to_pubkey via .info.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

• Areas to spot-check:
  • COMPRESSIBLE_TOKEN_ACCOUNT_SIZE calculation and the adjusted rent-exemption constant.
  • PartialEq in zero-copy ZCToken to ensure all relevant nested fields are compared.
  • All moved method calls: calculate_top_up_lamports, get_last_funded_epoch, claim_and_update invoked on .info.
  • Zero-copy initialization sites ensuring compression_only is set and info is passed where expected.

Possibly related PRs

• refactor: ctoken sdk builder instructions2 #2069 — related at code-level: introduces/uses the CompressibleExtension wrapper and impacts extension access sites modified here.
• fix: calculate_top_up_lamports #2060 — related: changes internal rent/top-up logic (e.g., calculate_top_up_lamports, get_last_funded_epoch) which are now called via .info.
• fix: correct epochs_funded_ahead calculation for lagging claims #2087 — related: modifies compression/top-up calculations that this PR now routes through the nested info access.

Suggested reviewers

• sergeytimoshin

Poem

🌱 A little wrapper, tidy and new,
Info tucked in, fields in view,
Calls redirected, paths made clear,
Consistent access far and near,
Small change, neat lines — hooray, review! 🎉

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title accurately describes the main change: adding a missing compression_only placeholder field to CompressibleExtension, which is the core structural modification across all modified files.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 70.00%.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch jorrit/chore-add-missing-compressible-ext-placeholder

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[coderabbitai]

Actionable comments posted: 2

[coderabbitai]

Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

program-libs/ctoken-interface/tests/ctoken/spl_compat.rs (1)

577-602: Consider adding test coverage for compression_only field.

The PartialEq tests verify mismatches for compress_to_pubkey and account_version, but the new compression_only field is always set to false. Consider adding a test case that verifies the comparison behavior when compression_only differs between instances:

// Test compression_only mismatch
let ctoken_diff_compression_only = CToken {
    extensions: Some(vec![ExtensionStruct::Compressible(CompressibleExtension {
        compression_only: true,  // Different from buffer which has false
        info: compression_info,
    })]),
    ..ctoken.clone()
};
assert_ne!(zctoken, ctoken_diff_compression_only);

♻️ Duplicate comments (2)

program-libs/ctoken-interface/src/state/extensions/extension_struct.rs (2)

165-168: Stale comment: still references CompressionInfo instead of CompressibleExtension.

The inline comment on line 166 says "CompressionInfo size" but the code correctly uses CompressibleExtension::byte_len. This was flagged in a prior review and should be updated for consistency.

             ExtensionStructConfig::Compressible(config) => {
-                // 1 byte for discriminant + CompressionInfo size
+                // 1 byte for discriminant + CompressibleExtension size
                 1 + CompressibleExtension::byte_len(config)?
             }

---

257-257: Define CompressibleExtensionConfig struct in extension_struct.rs.

The ExtensionStructConfig::Compressible variant references CompressibleExtensionConfig, but this type is not defined anywhere in the crate. The struct is imported in zero_copy.rs and used in tests with a field info: CompressionInfoConfig, following the same pattern as TokenMetadataConfig. Add the missing struct definition in extension_struct.rs and ensure it's exported from state/extensions/mod.rs.