[Feature] Streaming Support for SSE and NDJSON (used for LLMs)

[RawthiL]

Summary

Added streaming support for contentypes:

• "text/event-stream" (https://en.wikipedia.org/wiki/Server-sent_events)
• "application/x-ndjson" (https://docs.mulesoft.com/dataweave/latest/dataweave-formats-ndjson)

These are streams delimited by newlines (\n) that can be supported by Pocket Network without any change to the verification and accounting logic.

The first one, text/event-stream, is the one used by streaming LLM responses (OpenAI format) and is a functionality that we need asap.

Primary Changes:

• Added new file http_stream.go that implements streaming responses of the mentioned types.
• Added a custom delimiter for the Pocket Network streamed responses, necessary to avoid collision with arbitrary payloads and supplier signature.
• Modified sync.go to check for the backend response headers and implement either this streaming protocol or respond normally (read full response first and then relay)

Secondary Changes:

• Modified the order of some checks in the serveSyncRequest() function, to keep code more tidy.
• Modified processStreamRequest to provide an example on how to support streaming responses by an app.
• Modified processStreamRequest to make code more modular and re-use functions between normal and streamed response.

Checks:

I tested this in beta-testnet, against a vLLM enpoint, using this custom RM and the pocketd relayminer relay command:

pocketd relayminer relay \
    --app=pokt1wvn4a8kj4mfnq0cjakadskxwr2zkev35psjxh9 \
    --supplier=pokt19a3t4yunp0dlpfjrp7qwnzwlrzd5fzs2gjaaaj \
    --node=https://shannon-testnet-grove-rpc.beta.poktroll.com  \
    --grpc-addr=shannon-testnet-grove-grpc.beta.poktroll.com:443 \
    --grpc-insecure=false \
    --payload='{"messages": [{"role": "user", "content": "Tell me how to properly eat a Choripan."}],"max_tokens":200, "model":"pocket_network", "stream":true}' \
    --supplier-public-endpoint-override=http://localhost:8545/v1/chat/completions \
    --network=beta

response:

{"level":"warn","time":"2025-06-24T16:40:29-03:00","message":"⚠️ Using override endpoint URL: http://localhost:8546/v1/chat/completions"}
{"level":"info","time":"2025-06-24T16:40:29-03:00","message":"✅ JSON-RPC request payload serialized."}
{"level":"info","time":"2025-06-24T16:40:29-03:00","message":"✅ Relay request built."}
{"level":"info","time":"2025-06-24T16:40:29-03:00","message":"✅ Retrieved private key for app pokt1wvn4a8kj4mfnq0cjakadskxwr2zkev35psjxh9"}
{"level":"info","time":"2025-06-24T16:40:29-03:00","message":"✅ Relay request signed."}
{"level":"info","time":"2025-06-24T16:40:29-03:00","message":"✅ Relay request marshaled."}
{"level":"info","time":"2025-06-24T16:40:29-03:00","message":"✅ Endpoint URL parsed: http://localhost:8546/v1/chat/completions"}
{"level":"info","time":"2025-06-24T16:40:30-03:00","message":"🔍 Content-Type: text/event-stream; charset=utf-8"}
{"level":"info","time":"2025-06-24T16:40:30-03:00","message":"🌊 Handling streaming response with status:"}
{"level":"info","time":"2025-06-24T16:40:30-03:00","message":"📦 Read chunk of length 449"}
{"level":"info","time":"2025-06-24T16:40:30-03:00","message":"✅ Deserialized response body as JSON map: map[choices:[map[delta:map[content: role:assistant] finish_reason:<nil> index:0 logprobs:<nil>]] created:1.75079403e+09 id:chat-2b20014c1d124d1da32d6a71139ea77e model:pocket_network object:chat.completion.chunk]"}
{"level":"info","time":"2025-06-24T16:40:30-03:00","message":"📦 Read chunk of length 213"}
{"level":"info","time":"2025-06-24T16:40:30-03:00","message":"📦 Read chunk of length 432"}
{"level":"info","time":"2025-06-24T16:40:30-03:00","message":"✅ Deserialized response body as JSON map: map[choices:[map[delta:map[content:Ch] finish_reason:<nil> index:0 logprobs:<nil>]] created:1.75079403e+09 id:chat-2b20014c1d124d1da32d6a71139ea77e model:pocket_network object:chat.completion.chunk]"}
{"level":"info","time":"2025-06-24T16:40:30-03:00","message":"📦 Read chunk of length 213"}
{"level":"info","time":"2025-06-24T16:40:30-03:00","message":"📦 Read chunk of length 432"}
{"level":"info","time":"2025-06-24T16:40:31-03:00","message":"✅ Deserialized response body as JSON map: map[choices:[map[delta:map[content:or] finish_reason:<nil> index:0 logprobs:<nil>]] created:1.75079403e+09 id:chat-2b20014c1d124d1da32d6a71139ea77e model:pocket_network object:chat.completion.chunk]"}
{"level":"info","time":"2025-06-24T16:40:31-03:00","message":"📦 Read chunk of length 213"}
{"level":"info","time":"2025-06-24T16:40:31-03:00","message":"📦 Read chunk of length 432"}
{"level":"info","time":"2025-06-24T16:40:31-03:00","message":"✅ Deserialized response body as JSON map: map[choices:[map[delta:map[content:ip] finish_reason:<nil> index:0 logprobs:<nil>]] created:1.75079403e+09 id:chat-2b20014c1d124d1da32d6a71139ea77e model:pocket_network object:chat.completion.chunk]"}
{"level":"info","time":"2025-06-24T16:40:31-03:00","message":"📦 Read chunk of length 213"}
{"level":"info","time":"2025-06-24T16:40:31-03:00","message":"📦 Read chunk of length 432"}
{"level":"info","time":"2025-06-24T16:40:31-03:00","message":"✅ Deserialized response body as JSON map: map[choices:[map[delta:map[content:an] finish_reason:<nil> index:0 logprobs:<nil>]] created:1.75079403e+09 id:chat-2b20014c1d124d1da32d6a71139ea77e model:pocket_network object:chat.completion.chunk]"}
{"level":"info","time":"2025-06-24T16:40:31-03:00","message":"📦 Read chunk of length 213"}
{"level":"info","time":"2025-06-24T16:40:31-03:00","message":"📦 Read chunk of length 433"}
{"level":"info","time":"2025-06-24T16:40:32-03:00","message":"✅ Deserialized response body as JSON map: map[choices:[map[delta:map[content: is] finish_reason:<nil> index:0 logprobs:<nil>]] created:1.75079403e+09 id:chat-2b20014c1d124d1da32d6a71139ea77e model:pocket_network object:chat.completion.chunk]"}
...

Type of change

Select one or more from the following:

• New feature, functionality or library
• Bug fix
• Code health or cleanup
• Documentation
• Other (specify)

Sanity Checklist

• I have updated the GitHub Issue Metadata: assignees, reviewers, labels, project, iteration and milestone
• For docs: make docusaurus_start
• For small changes: make go_develop_and_test and make test_e2e
• For major changes: devnet-test-e2e label to run E2E tests in CI
• For migration changes: make test_e2e_oneshot
• 'TODO's, configurations and other docs

[jorgecuesta]

@RawthiL Please update it with a rebase, but after that is LGTM 🚀

Now it needs to get reviewed by Pocket Team @red-0ne @Olshansk

[Olshansk]

@jorgecuesta @RawthiL Just to set some expectations (since everyone has a lot going on):

• Might take our team a few days to get to this PR
• I don't know (without reviewing) if it'll require changes or be an auto-approval

To expedite things, lmk if you want us to build a similar binary to this dev release so you're not blocked.

[jorgecuesta]

@jorgecuesta @RawthiL Just to set some expectations (since everyone has a lot going on):

• Might take our team a few days to get to this PR
• I don't know (without reviewing) if it'll require changes or be an auto-approval

To expedite things, lmk if you want us to build a similar binary to this dev release so you're not blocked.

I think it is smooth, a dev release will be great. But Idk if that will allow me to get the image of it.

[Olshansk]

@RawthiL Could you please reopen this PR as a branch of the main repo and not your fork?

It'll enable me to publish a dev-release (and push review changes when I get around to it).

[RawthiL]

Closing in favor of internal branch PR:
#1570