Real-Time (Polling) Shared Progress for Concurrent Same-URL Chat Creation

[avishek0769]

Summary

If multiple users create chats for the same docs URL and same mode at the same time, all should see shared progress from a single ingestion job.

Problem

Progress tracking is currently keyed per chat/job, so parallel requests for the same source can produce duplicate ingestion and inconsistent progress visibility.

Expected Solution

Introduce source-level ingestion lock and progress channel keyed by source identity (normalizedUrl + mode). First request starts ingestion; subsequent requests subscribe to the same in-flight progress and attach when complete.

Scope

• backend/controllers/chat.controller.js
• backend/chatWorker.js
• Redis key strategy and queue deduplication logic
• src/pages/Dashboard.tsx polling/progress display behavior

Acceptance Criteria

• Concurrent same-source creations do not enqueue duplicate ingestion work.
• All involved users/chats receive consistent progress updates.
• Completion attaches each waiting chat to the produced source/index.
• Failure state is propagated consistently to all subscribers.

Notes

Current status/progress keying can be redesigned around chatSource identity instead of chat id.