docs: correct Token-2022 extension policy and credit Moonsong Labs

[dev-jodee]

Summary

• Correct the README's Token-2022 extension claim: the program only rejects a configured `TransferHook` (hook `authority` or `program_id` set), not the seven extensions previously listed. The other six error codes (`MintHasPermanentDelegate`, `MintHasTransferFee`, etc.) are reserved and never fire — see `program/src/instructions/helpers/token.rs` `validate_mint_extensions`.
• Add an Acknowledgments section crediting Moonsong Labs for the initial design and implementation.

Test Plan

• Docs-only change. Behavior is already covered by `tests/integration-tests/src/test_initialize_subscription_authority.rs` (`initialize_subscription_authority_token_2022`), which asserts PermanentDelegate / TransferFee / unconfigured-TransferHook mints succeed and a configured TransferHook is rejected.

[greptile-apps]

Greptile Summary

This PR corrects the README's Token-2022 extension policy and adds an Acknowledgments section. The previous text incorrectly listed seven rejected extensions; the actual validate_mint_extensions function in program/src/instructions/helpers/token.rs only checks for extension type 14 (TransferHook) and only rejects it when any of its 64 bytes are non-zero (i.e., when the hook authority or program_id is set).

• README correction: Replaces the inaccurate seven-extension list with the precise rule: only a configured TransferHook is rejected; an inert one (both fields unset/zero) is allowed. This matches the existing wording already in CLAUDE.md and the actual on-chain logic.
• Acknowledgments section: Adds credit to Moonsong Labs for the initial design and implementation, inserted before the existing CI Pipeline section.

Confidence Score: 5/5

Documentation-only change with no modifications to program logic, state, or client code — safe to merge.

The updated README wording is consistent with both the actual validate_mint_extensions implementation in token.rs (which checks only extension type 14 and only rejects non-zero data) and the existing CLAUDE.md policy note. The Acknowledgments section is a straightforward prose addition. No code paths are touched.

No files require special attention.

Important Files Changed

Filename	Overview
README.md	Docs-only update: corrects Token-2022 extension rejection policy to match actual code behavior and adds Moonsong Labs acknowledgment. Both changes are accurate and consistent with CLAUDE.md and the implementation in token.rs.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Token-2022 mint account] --> B{Has extensions?}
    B -- No extensions --> C[✅ Accepted]
    B -- Has extensions --> D[Iterate TLV entries]
    D --> E{ext_type == 0?}
    E -- Yes --> C
    E -- No --> F{ext_type == TransferHook\next_type == 14?}
    F -- No --> G[Skip extension]
    G --> D
    F -- Yes --> H{Any byte != 0 in\n64-byte extension data?}
    H -- No --> I[Inert hook:\nboth authority and\nprogram_id are unset]
    I --> C
    H -- Yes --> J[❌ MintHasTransferHook error\nConfigured hook rejected]

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[github-actions]

Compute Unit Report

Instruction	Samples	Min CUs	Max CUs	Avg CUs	Est Cost (Low) [SOL]	Est Cost (Med) [SOL]	Est Cost (High) [SOL]
cancel_subscription	22	1720	2030	1919	0.000005000	0.000005076	0.000005959
close_subscription_authority	10	1803	1833	1806	0.000005000	0.000005072	0.000005903
create_fixed_delegation	41	3522	15522	5265	0.000005001	0.000005210	0.000007632
create_plan	97	3436	12436	4846	0.000005001	0.000005193	0.000007423
create_recurring_delegation	29	3553	9555	4487	0.000005001	0.000005179	0.000007243
delete_plan	9	359	359	359	0.000005000	0.000005014	0.000005179
init_subscription_authority	173	6226	20968	9187	0.000005002	0.000005367	0.000009593
resume_subscription	3	1723	1723	1723	0.000005000	0.000005068	0.000005861
revoke_delegation	19	255	519	353	0.000005000	0.000005014	0.000005176
subscribe	32	6485	16985	8273	0.000005002	0.000005330	0.000009136
transfer_fixed	9	5479	11466	7364	0.000005002	0.000005294	0.000008682
transfer_recurring	19	5591	14452	7229	0.000005002	0.000005289	0.000008614
transfer_subscription	10	5838	10341	7943	0.000005002	0.000005317	0.000008971
update_plan	22	424	503	477	0.000005000	0.000005019	0.000005238

Generated: 2026-06-03