[bhavidhingra]

Description

Fixes the Token-2022 confidential-transfer wire so SDK-built account enablement actually works on-chain. Two defects live in the encoder (modules/sdk-coin-sol), both of which make every ConfigureAccount fail:

1. ConfigureAccount wrote the deprecated 79-byte payload. Token-2022 no longer carries the ElGamal pubkey in the instruction data — the key is recovered from the accompanying VerifyPubkeyValidity proof context. New layout: [27][2] + decryptable_zero_balance(36) + maximum_pending_balance_credit_counter(u64) + proof_instruction_offset(i8) = 47 bytes. The elgamalPubkey param is removed from ConfigureConfidentialTransferAccount (the caller still needs the key to generate the proof, but it is not instruction data).

2. Reallocate reserved only ConfidentialTransferAccount. For a mint carrying TransferFeeConfig, ConfigureAccount also initializes ConfidentialTransferFeeAmount, so the account must be 68 bytes larger (64 payload + TLV header). Reallocate now appends extension type 17 when the mint is fee-bearing.

The pinned @solana/spl-token (0.4.13) enum predates the confidential-fee members, so type 17 is declared locally with the Token-2022 enum order cited.

API change (unreleased CT lane only): elgamalPubkey removed from configureAccount; new optional mintHasTransferFeeConfig on createAta / ReallocateConfidentialTransferAccount. Consumers (wallet-platform #63702) must pass the flag for fee-bearing mints and stop passing elgamalPubkey.

Issue Number

CHALO-2030

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Breaking change for the unreleased confidential-transfer SDK API (param removed/added as described above)

How Has This Been Tested?

• Unit: ConfigureAccount wire-bytes test asserts the exact 47-byte layout and offsets; new createAta reallocate tests assert the extension list [5] versus [5, 17]. Both were written failing first (79 ≠ 47, 3 ≠ 5 bytes) against the previous encoders.
• mocha in modules/sdk-coin-sol: 895 passing / 0 failing (Node 24).
• Devnet (acceptance gate): CreateATA → Reallocate → ConfigureAccount → VerifyPubkeyValidity confirmed by the real Token-2022 program on devnet:
  • plain CT mint — 469B account, extensions ImmutableOwner, ConfidentialTransferAccount(295B)
  • TransferFeeConfig CT mint — 549B account, extensions ImmutableOwner, TransferFeeAmount(8B), ConfidentialTransferAccount(295B), ConfidentialTransferFeeAmount(64B)
  • control run with the fee extension omitted — ConfigureAccount fails with invalid account data, confirming the shortfall the fix prevents

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My code compiles correctly for both Node and Browser environments
• I have commented my code, particularly in hard-to-understand areas
• My commits follow Conventional Commits and I have properly described any BREAKING CHANGES
• The ticket or github issue was included in the commit message as a reference
• I have made corresponding changes to the documentation and on any new/updated functions and/or methods
• I have added tests that prove my fix is effective and that my feature works
• New and existing unit tests pass locally with my changes

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[linear-code]

CHALO-2030

[github-actions]

⚠️ Compatibility checks are failing on Node.js 27-nightly (experimental, non-blocking). This does not block merge, but it signals an incompatibility to fix before this release becomes supported.

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