Module ws 

WebSocket handler and watch subscription manager.

This module provides two major components:

1. WatchManager — a thread-safe subscription registry that manages watch lifecycles (subscribe, poll, unsubscribe, add/remove IDs).

2. ws_handler — an Axum WebSocket upgrade endpoint (GET /api/ws) that handles Haystack watch operations over JSON messages.

Structs

WatchManager

Manages watch subscriptions for change polling.

Functions

ws_handler

WebSocket upgrade handler for /api/ws.