Django Channels consumer: websocket connection, auth, message events

[mehalyna]

Task 4 — Django Channels consumer: websocket connection, auth, message events

Title: realtime: implement WebSocket consumer(s) for messaging using Django Channels

API / behavior

• WebSocket endpoint: ws://<host>/ws/chat/

• Authentication: accept JWT in Sec-WebSocket-Protocol or use session cookie (documented).

• On connect: authenticate user, subscribe to channels for user (user.<userid>) and to conversation groups when requested.

• Events:

  • join_conversation { "conversation_id": "uuid" } → subscribe group conversation.<id>.
  • leave_conversation
  • send_message { "conversation_id","body","attachments":[upload_ids] } → validate, call service.create_message, publish message_received.
  • typing and presence signals forwarded to other participants.
  • mark_read { "conversation_id" } → call service.mark_messages_read and emit read_receipt.

• Outgoing events:

  • message_received (to conversation group) with message payload.
  • read_receipt, typing, presence events.

Acceptance

• Consumer unit tests (channels testing) that:

  • Auth works,
  • send_message persists the message and broadcasts to conversation participants,
  • join/leave subscription works,
  • read receipts emitted correctly.

Dependencies

• Redis channel layer (Channels).
• Messaging service (Task 3).
• Auth middleware for Channels.

Notes

• Keep consumer logic thin: validate + call service + publish event.
• Ensure proper exception handling to avoid leaking info.