Chat Handlers

Handler Overview

Chat handlers in chat/handlers.rs split into two categories:

1. Pure DB operations — conversation CRUD handled entirely in Rust against PostgreSQL
2. gRPC-proxied operations — message sending and streaming delegated to the Intelligence service

Conversation CRUD (Pure Rust + DB)

create_conversation

POST /chat/conversations
Body: { title?: string, metadata?: object }

• Generates a new Uuid::new_v4() for the conversation ID (note: the conversations table has id UUID PRIMARY KEY with no DEFAULT gen_random_uuid() — the caller must provide the UUID)
• Inserts row into conversations with user_id from auth_middleware extension
• Returns: { id, user_id, title, metadata, created_at, updated_at }

list_conversations

GET /chat/conversations?cursor=<uuid>&limit=<n>

• Cursor-based pagination ordered by updated_at DESC
• Filters by user_id from session
• Returns: { conversations[], next_cursor?, total_count }

get_conversation

GET /chat/conversations/{id}

• Fetches from conversations table (verifies user_id ownership)
• Fetches messages from chat_messages table (written by Python Intelligence)
• Ownership check: WHERE id = $1 AND user_id = $2
• Returns full conversation with messages and source chunks

update_conversation / delete_conversation

• Both verify user_id ownership before mutation
• DELETE cascades to chat_messages via foreign key

Message Operations (gRPC-proxied)

send_message (Non-streaming)

stream_chat (SSE Streaming)

SSE Bridge implementation uses async-stream + Axum’s Sse<impl Stream<Item = Event>>:

let stream = async_stream::stream! {
    while let Some(chunk) = grpc_stream.message().await? {
        let event = Event::default().data(serde_json::to_string(&chunk)?);
        yield Ok::<Event, Error>(event);
    }
}
Sse::new(stream).keep_alive(KeepAlive::default())

generate_conversation_title

POST /chat/conversations/{id}/generate-title
Body: { user_message: string, assistant_message: string }

• Calls gRPC Chat.GenerateTitle(GenerateTitleRequest)
• Intelligence service uses the LLM to generate a concise title
• Rust updates conversations.title in DB
• Returns: { title: string }

Error Handling

Chat handler errors are typed in chat/error.rs. gRPC status codes are mapped to HTTP status codes: