Bug: `GraphQLIndexer.subscribe` sends `subscribe` before `connection_ack`

[Jaydbrown]

src/indexer.ts:162-173 — on socket.onopen the client sends connection_init and then immediately, in the same tick, sends the subscribe message.

The graphql-transport-ws protocol requires the client to wait for the server's connection_ack before sending any subscribe. A spec-compliant server (graphql-ws, Hasura, Apollo Router, …) closes the socket with 4401/4408 when it receives subscribe first.

Impact

Subscriptions fail against compliant GraphQL servers; onclose then fires and the subscription is torn down (silently — see the companion issue). Only lenient servers work.

Suggested fix

Track handshake state: send subscribe only after receiving { type: 'connection_ack' }; queue the subscribe payload until then.

[Alfredzee]

@Alfredzee has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I would like to work on this issue

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