* fix(server): increase WS buffer/replay limits and add backpressure warning
During long-running agent sessions (e.g. ultrawork loops with many tool
calls), the browser WebSocket client can briefly fall behind the server.
When the outbound buffer exceeds the limit, the server force-disconnects
with close code 1013, and the small replay buffer (512 events) is
insufficient to recover all missed events — leaving the UI permanently
stalled.
Changes:
- Raise MESSAGE_STREAM_WS_MAX_BUFFERED_BYTES from 4 MB to 16 MB to
tolerate larger bursts without disconnecting
- Add MESSAGE_STREAM_WS_BACKPRESSURE_WARN_BYTES (12 MB) threshold that
sends a one-shot "backpressure" frame to the client before the hard
disconnect, giving it a chance to shed low-priority updates
- Raise MESSAGE_STREAM_GLOBAL_REPLAY_LIMIT from 512 to 2048 so more
events survive brief reconnection gaps
- Add tests for the backpressure warning behavior (emit, dedup, reset)
* fix(ui): batch event flushes under backpressure
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Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>
