# WSS transport lifetime patch

`mvt_websocket_client.c` is the Apache-2.0 ESP-IDF v4.4.7 component:
https://github.com/espressif/esp-idf/blob/v4.4.7/components/esp_websocket_client/esp_websocket_client.c

Original file SHA-256 (LF):
`8b3beca133d9bd2c293fd4e4494aadbcb42f02c6750d06a789c4d32ffd3b2a1d`.
The accompanying Apache-2.0 license is `MVT-WEBSOCKET-LICENSE`.

It replaces the SDK archive implementation only when `HAS_MVT_WSS_GATEWAY=1`.
Public headers and transport/TLS implementations remain those of the pinned SDK.

The original task polls the transport outside `client->lock`, while a failed send
closes that transport under the lock. Concurrent failures can free the same TLS
state twice. This was observed after an OTA trial boot, with the backtrace ending
in `esp_tls_internal_event_tracker_destroy` / `multi_heap_free`.

Local changes:

- Poll/read-error abort and the graceful-close poll share the existing recursive
  mutex with sends and receives. Polls use 20 ms to bound sender lock waits.
- After releasing the mutex, the higher-priority receiver blocks for one tick.
  `taskYIELD()` alone does not let a lower-priority sender acquire the mutex.
- Task final close also holds that mutex. STOPPED is published after the final
  client access, and destroy waits for STOPPED even when `run` is already false.
- Start sets `run` and clears STOPPED before scheduling the task, preventing an
  immediate stop/destroy from freeing a task that has not started yet.
- A clean-close poll timeout continues waiting instead of exiting the task.

`tests/wss/websocket_poll_test.cpp` exercises the production poll helper with
simultaneous send failure and read failure, reconnect state and graceful close.
The gateway allows 1000 ms for a TLS write instead of 20 ms. A write failure still
closes the connection and discards the partial frame; it is never treated as sent.
Send-lock contention on a still-connected client retains the queued message for
retry. It does not tear down the TLS session. Reconnect waits until the OTA worker
has exited and uses the normal retry interval after client destruction, allowing
FreeRTOS idle cleanup to reclaim the deleted task stacks before a new handshake.

Release 2.7.15.2410: frame reception has a 30-second total deadline,
checks cancellation between reads and rejects a stalled incomplete frame.
The production helper is exercised by tests/wss/websocket_receive_test.cpp.