AgenticCode/openspec/specs/chat-streaming/spec.md at 00e7df2802f018a8e5afac5a178701cc4a135c53

Files

local 00e7df2802 feat: wire chat UI to Responses API with streaming

Add ChatController that proxies POST /api/chat to the local Responses API
(localhost:8317/v1/responses) with SSE streaming. Client reads tokens via
SetBrowserResponseStreamingEnabled and renders them incrementally. Includes
thinking indicator, input disabled during streaming, and error handling.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

2026-04-04 01:54:28 +01:00

2.4 KiB

Raw Blame History

Purpose

Define the streaming AI response pipeline — backend proxy to the Responses API, SSE delivery to the WASM client, configuration, and error handling.

Requirements

Requirement: Chat endpoint proxies to Responses API

The API backend SHALL expose POST /api/chat that accepts a list of messages and proxies the request to the local Responses API at a configurable base URL using the POST /v1/responses endpoint.

Scenario: Successful proxy request

WHEN the client sends a POST to /api/chat with a message list
THEN the API forwards the messages to the Responses API with the configured model and returns the response

Requirement: Streaming response delivery

The API backend SHALL stream the Responses API's SSE events back to the WASM client as text/event-stream, forwarding response.output_text.delta events so the client can render tokens incrementally.

Scenario: Tokens stream to client

WHEN the Responses API emits response.output_text.delta events
THEN the backend forwards each delta as an SSE event to the client containing the text fragment

Scenario: Stream completes

WHEN the Responses API emits response.completed
THEN the backend signals stream completion to the client

Requirement: Configurable proxy target

The Responses API base URL and model name SHALL be configurable via appsettings.json in the API project, not hardcoded.

Scenario: Configuration read at startup

WHEN the API starts
THEN it reads ResponsesApi:BaseUrl and ResponsesApi:Model from configuration

Requirement: Client streams from backend

The WASM client SHALL call POST /api/chat with SetBrowserResponseStreamingEnabled(true) and HttpCompletionOption.ResponseHeadersRead, then iterate the SSE stream to update the UI token by token.

Scenario: Client reads streaming response

WHEN the client sends a chat request
THEN it reads the response stream incrementally and appends each text delta to the assistant message in real time

Requirement: Error propagation

If the Responses API returns an error or is unreachable, the API backend SHALL return an appropriate HTTP error status and the client SHALL display the error to the user.

Scenario: Proxy unreachable

WHEN the Responses API is not running
THEN the client displays an error message instead of an assistant response

2.4 KiB Raw Blame History