docs: document SAC recognition and SEP-41 event decoding

[joan-bisbal]

Documents the existing SAC recognition and SEP-41 decoding path in the indexer (implemented in #262).

Covers how SacRegistry maps Soroban contract addresses to their underlying classic assets, which SEP-41 events the parser decodes (transfer, mint, burn, clawback), and how to extend the decoder for additional token standards.

No code changes -- documentation only.

[Depo-dev]

This PR's title and commit message say it implements SAC recognition and binary decoding, but the diff is only this three-line file restating the description. No recognition logic, no decoder, no tests.

That work also already exists on dev: crates/indexer/src/parser/sac.rs is ~220 lines with 11 unit tests, landed under issue #262, and SacRegistry is wired into Parser::with_sac_registry. So there is nothing here to add on top of it.

Two more things to fix if you reopen this: the base branch should be dev (that is where all feature work lands, main trails it), and the file starts with a UTF-8 BOM, which we do not use anywhere else in docs/.

If you want to contribute to this area, the useful next step would be extending the existing decoder rather than re-describing it. Happy to point you at an open issue that still needs work.

[Depo-dev]

Hey @joan-bisbal — thanks for this, the doc itself is genuinely useful and I'd like to get it merged. Two things to sort out first, both about framing rather than content.

The title says feat:, which sets the expectation that this adds the SAC recognition and decoding implementation. It doesn't — the diff is one markdown file. And the code it describes already exists: crates/indexer/src/parser/sac.rs and token_events.rs are both on dev today, and issue #262 was closed when they landed. So what you've actually written is documentation for shipped work, which is valuable, but someone reading the commit log a year from now would be misled about when the feature arrived.

Could you retitle it to docs: document SAC recognition and SEP-41 event decoding (or similar)?

The description could also do more work. Right now it says "Implements first-class recognition and binary decoding" — which repeats the same wrong implication. Something like this would be more accurate and more useful to a reviewer:

Documents the existing SAC recognition and SEP-41 decoding path in the indexer (implemented in #262).

Covers how SacRegistry maps Soroban contract addresses to their underlying classic assets, which SEP-41 events the parser decodes (transfer, mint, burn, clawback), and how to extend the decoder for additional token standards.

No code changes — documentation only.

That way the title, the description, and the diff all agree with each other. Once that's updated I'm happy to merge. Let me know if you'd rather I just push the retitle myself.

[joan-bisbal]

Thanks for the review. Both changes done:

• Retitled to docs: document SAC recognition and SEP-41 event decoding
• Updated the description to reflect that this documents shipped work from Contracts: first-class Stellar Asset Contract (SAC) recognition and decoding #262, not a new implementation
• Renamed file to kebab-case (sac-recognition-decoding.md)

Ready for re-review.