fix(mint): handle websocket disconnect frames cleanly

[b-l-u-e]

While reviewing and testing fix(websocket): support generic quote kinds, websocket integration tests passed but produced noisy teardown errors in the mint logs. This PR fixes the underlying disconnect handling

Root cause: LedgerEventClientManager.start() treated a websocket.disconnect frame as “no text, keep looping” instead of exiting. On server shutdown (ASGI 1012), the loop called receive() again, which raised RuntimeError, triggered a double-close, and logged ERROR | Exception in ASGI application.

Motivation

While running websocket subscription tests for the generic quote kinds PR:

poetry run pytest tests/wallet/test_wallet_subscription.py -q

All tests passed (3 passed), but pytest teardown produced alarming mint logs:

Before (broken teardown)

TRACE | 127.0.0.1:45068 - ASGI [14] Receive {'type': 'websocket.disconnect', 'code': 1012}
DEBUG | cashu.mint.router:websocket_endpoint:231 | Exception: Cannot call "receive" once a disconnect message has been received.
TRACE | 127.0.0.1:45068 - ASGI [14] Send {'type': 'websocket.close', 'code': 1000, 'reason': ''}
TRACE | 127.0.0.1:45068 - ASGI [14] Raised exception
ERROR | Exception in ASGI application
INFO  | connection closed

The disconnect frame was received, but the receive loop ignored it and called receive() again.

After (clean teardown)

TRACE | 127.0.0.1:50118 - ASGI [8] Receive {'type': 'websocket.disconnect', 'code': 1012}
DEBUG | cashu.mint.router:websocket_endpoint:227 | Websocket disconnected:
TRACE | 127.0.0.1:50118 - ASGI [8] Completed
INFO  | connection closed

No exception, no double-close, no ASGI error.

Changes

• cashu/mint/events/client.py — exit the receive loop when a websocket.disconnect frame is received (raise WebSocketDisconnect with the frame's code).
• cashu/mint/router.py — unify websocket endpoint cleanup:
  • always remove the client from the event manager in finally
  • only call websocket.close() if the socket is not already disconnected
• tests/mint/test_mint_websocket_protocol.py — add regression test for disconnect frame handling

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.99%. Comparing base (a1ff72c) to head (5513703).
⚠️ Report is 52 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
cashu/mint/router.py	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1014      +/-   ##
==========================================
+ Coverage   74.90%   74.99%   +0.08%     
==========================================
  Files          99      111      +12     
  Lines       11685    12066     +381     
==========================================
+ Hits         8753     9049     +296     
- Misses       2932     3017      +85     

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[a1denvalu3]

Very nice PR thank you!