00e7df2802
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>
56 lines
2.4 KiB
Markdown
56 lines
2.4 KiB
Markdown
## Purpose
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Define the streaming AI response pipeline — backend proxy to the Responses API, SSE delivery to the WASM client, configuration, and error handling.
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## Requirements
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### Requirement: Chat endpoint proxies to Responses API
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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.
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#### Scenario: Successful proxy request
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- **WHEN** the client sends a POST to `/api/chat` with a message list
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- **THEN** the API forwards the messages to the Responses API with the configured model and returns the response
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### Requirement: Streaming response delivery
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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.
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#### Scenario: Tokens stream to client
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- **WHEN** the Responses API emits `response.output_text.delta` events
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- **THEN** the backend forwards each delta as an SSE event to the client containing the text fragment
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#### Scenario: Stream completes
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- **WHEN** the Responses API emits `response.completed`
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- **THEN** the backend signals stream completion to the client
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### Requirement: Configurable proxy target
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The Responses API base URL and model name SHALL be configurable via `appsettings.json` in the API project, not hardcoded.
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#### Scenario: Configuration read at startup
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- **WHEN** the API starts
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- **THEN** it reads `ResponsesApi:BaseUrl` and `ResponsesApi:Model` from configuration
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### Requirement: Client streams from backend
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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.
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#### Scenario: Client reads streaming response
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- **WHEN** the client sends a chat request
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- **THEN** it reads the response stream incrementally and appends each text delta to the assistant message in real time
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### Requirement: Error propagation
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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.
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#### Scenario: Proxy unreachable
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- **WHEN** the Responses API is not running
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- **THEN** the client displays an error message instead of an assistant response
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