feat(sdk): add indexer discovery provider

[m-kus]

TL;DR

Add IndexerDiscoveryProvider to support discovery via the indexer API, with reorg handling and cursor-based pagination.

What changed?

• Added IndexerDiscoveryProvider implementation that communicates with the discovery service API
• Implemented reorg detection and recovery in the ActionCompiler
• Updated API endpoint paths to match the latest discovery service spec
• Added cursor conversion utilities between SDK and API formats
• Added comprehensive tests for the indexer discovery provider
• Updated verification checklist to include SDK checks

---

This change is 

[m-kus]

• feat(e2e): starknet integration demo explorer #467 : 3 dependent PRs (#480 , #502 , #512 )
• feat(discovery-service): add fallback for chain state, e2e test in the starknet integration environment #466
• feat(e2e): add indexer e2e test suite with sdk devnet helpers #486
• feat(sdk): add indexer discovery provider #485 👈 (View in Graphite)
• feat(discovery-service): add preflight check endpoint #484
• feat(discovery-service): add outgoing state sync endpoint #483
• feat(discovery-service): add incoming sync endpoint with validation and error handling #482
• feat(discovery-service): centralize configuration into config module #481
• feat(discovery-core): add transfer preflight check #474
• feat(discovery-core): add outgoing state sync orchestrator #473
• feat(discovery-core): add incoming state sync orchestrator #472
• feat(discovery-core): add paginated last-note-index search with bisection #471
• feat(discovery-core): add paginated outgoing channel discovery #470
• refactor: propagate compliance-to-auditor rename and fee params to sdk and rust #505
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[Yoni-Starkware]

@Yoni-Starkware reviewed 4 files and all commit messages, and made 1 comment.
Reviewable status: 4 of 7 files reviewed, 1 unresolved discussion (waiting on ittaysw and m-kus).

---

sdk/src/internal/indexer-discovery.ts line 136 at r1 (raw file):

      } else if (lastKnownBlock) {
        body.last_known_block = lastKnownBlock;
      }

Note that you're not enforcing this on the Rust side

Code quote:

      if (blockRef) {
        body.block_ref = blockRef;
      } else if (lastKnownBlock) {
        body.last_known_block = lastKnownBlock;
      }

[m-kus]

@m-kus resolved 1 discussion.
Reviewable status: 3 of 8 files reviewed, all discussions resolved (waiting on ittaysw and Yoni-Starkware).

[Yoni-Starkware]

@Yoni-Starkware partially reviewed 1 file and made 1 comment.
Reviewable status: 4 of 8 files reviewed, 1 unresolved discussion (waiting on ittaysw and m-kus).

---

sdk/src/internal/indexer-discovery.ts line 538 at r2 (raw file):

    const sender = BigInt(n.sender_addr);
    const channelKey =
      channelKeyMap.get(n.sender_addr) ?? existingChannels.get(sender)?.channelKey ?? 0n;

Is this reachable? should we throw an error instead?

Code quote:

 0n;

[m-kus]

@m-kus made 1 comment.
Reviewable status: 3 of 8 files reviewed, 1 unresolved discussion (waiting on ittaysw and Yoni-Starkware).

---

sdk/src/internal/indexer-discovery.ts line 538 at r2 (raw file):

Previously, Yoni-Starkware (Yoni) wrote…

Is this reachable? should we throw an error instead?

Done.

[Yoni-Starkware]

@Yoni-Starkware made 2 comments and resolved 1 discussion.
Reviewable status: 3 of 8 files reviewed, 2 unresolved discussions (waiting on ittaysw and m-kus).

---

sdk/src/internal/indexer-discovery.ts line 238 at r2 (raw file):

            subchannel_discovery_complete: false,
            subchannels,
          };

Please share this code

Code quote:

            for (const [token, nonces] of existing.tokens) {
              subchannels[toHex(token)] = {
                last_note_index: nonces.noteNonce > 0 ? nonces.noteNonce - 1 : undefined,
              };
            }
          }
          apiCursor.channels![toHex(rb)] = {
            channel_key: toHex(info.key),
            subchannel_discovery_complete: false,
            subchannels,
          };

---

sdk/src/internal/indexer-discovery.ts line 375 at r4 (raw file):

    apiCursor.channels![toHex(sender)] = {
      channel_key: toHex(icc.channelKey),
      subchannel_discovery_complete: !!tokenFilter,

What if you have a token in your filter, but no notes from this token in noteIndexes? don't you need to discover subchannels in this case?

Code quote:

      subchannel_discovery_complete: !!tokenFilter,

[m-kus]

@m-kus made 1 comment and resolved 1 discussion.
Reviewable status: 3 of 8 files reviewed, 1 unresolved discussion (waiting on ittaysw and Yoni-Starkware).

---

sdk/src/internal/indexer-discovery.ts line 375 at r4 (raw file):

Previously, Yoni-Starkware (Yoni) wrote…

What if you have a token in your filter, but no notes from this token in noteIndexes? don't you need to discover subchannels in this case?

Done.

[Yoni-Starkware]

@Yoni-Starkware reviewed 5 files and all commit messages, made 1 comment, and resolved 1 discussion.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on ittaysw).