bare websockets

[benedikt-bartscher]

saves ~11.6 KB gz / ~41 KB raw frontend size (a small js chunk replaces whole socketio)
dropped python deps: wsproto, simple-websocket, python-socketio, python-engineio, bidict
new benchmarks in test_event_transport.py show about 2x performance increase compared to socketio

also migrates AppHarness to granian for consistency. otherwise downstream tests using AppHarness still need uvicorn and wsproto/websockets

[codspeed-hq]

Merging this PR will not alter performance

✅ 32 untouched benchmarks
🆕 4 new benchmarks
⏩ 8 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
🆕	Simulation	test_transport_inbound_socketio	N/A	7.9 ms	N/A
🆕	Simulation	test_transport_inbound_websocket	N/A	4.5 ms	N/A
🆕	Simulation	test_transport_outbound_socketio	N/A	15.4 ms	N/A
🆕	Simulation	test_transport_outbound_websocket	N/A	6.7 ms	N/A

---

_{Comparing benedikt-bartscher:make-sio-optional (64396a2) with main (dd96aea)}

Footnotes

1. 8 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[greptile-apps]

Greptile Summary

The PR replaces the default Socket.IO transport with a lightweight plain-WebSocket protocol while retaining Socket.IO as an optional transport.

• Adds matching browser and backend WebSocket framing, handshake, heartbeat, reconnect, size-limit, origin, and malformed-input handling.
• Makes Socket.IO, Uvicorn, and related dependencies optional and migrates AppHarness to Granian.
• Updates event processing, tests, benchmarks, dependency metadata, and release notes for the new transport.

Confidence Score: 5/5

The PR appears safe to merge because the previously reported transport issues are fixed or explicitly accepted and no blocking failure remains.

No blocking failure remains.

Important Files Changed

Filename	Overview
reflex/event_namespace.py	Implements the plain-WebSocket backend protocol and now closes malformed or undeserializable client frames while correctly enforcing the configured UTF-8 byte limit.
packages/reflex-base/src/reflex_base/.templates/web/utils/helpers/websocket.js	Adds the browser WebSocket transport, including handshake, heartbeat watchdog, reconnect-compatible callbacks, buffering, and documented timeout durations.
packages/reflex-base/src/reflex_base/.templates/web/utils/state.js	Selects the plain or optional Socket.IO client transport and coordinates connection setup, reconnection, and unmount cleanup.
reflex/app.py	Registers the selected event transport and integrates the plain-WebSocket route into the application runtime.
reflex/utils/exec.py	Updates backend launch paths and Uvicorn WebSocket limits for the transport configuration.
reflex/testing.py	Migrates AppHarness backend serving to Granian and adjusts test-server lifecycle management.
pyproject.toml	Moves transport-specific server and Socket.IO dependencies into optional extras.
tests/units/test_event_namespace.py	Covers connection handling, malformed-frame closure, invalid events, UTF-8 size boundaries, heartbeat behavior, and transport error handling.

_{Reviews (27): Last reviewed commit: "Merge branch 'main' into make-sio-option..." | Re-trigger Greptile}

[cubic-dev-ai]

All reported issues were addressed across 19 files

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[cubic-dev-ai]

All reported issues were addressed across 17 files

<sub>Requires human review: Auto-approval blocked because this review re-detected 1 unresolved issue already reported by Cubic.

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[cubic-dev-ai]

All reported issues were addressed across 4 files (changes from recent commits).

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[cubic-dev-ai]

All reported issues were addressed across 4 files (changes from recent commits).

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[cubic-dev-ai]

All reported issues were addressed across 6 files (changes from recent commits).

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[cubic-dev-ai]

All reported issues were addressed across 6 files (changes from recent commits).

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[cubic-dev-ai]

All reported issues were addressed across 1 file (changes from recent commits).

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[cubic-dev-ai]

All reported issues were addressed across 2 files (changes from recent commits).

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[cubic-dev-ai]

All reported issues were addressed across 2 files (changes from recent commits).

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[abulvenz]

I really like this lightweight approach 👍 .
One thing that is dropped, correct me if I see this wrong: under the hood socketio supports HTTP long-polling in case a websocket connection cannot be established (e.g. due to badly configured load balancers, reverse proxies or simply disabled client support). In most cases that should be fixed anyways on server side for performance reasons.

[benedikt-bartscher]

I really like this lightweight approach 👍 . One thing that is dropped, correct me if I see this wrong: under the hood socketio supports HTTP long-polling in case a websocket connection cannot be established (e.g. due to badly configured load balancers, reverse proxies or simply disabled client support). In most cases that should be fixed anyways on server side for performance reasons.

Thanks 🙏

Yes, the new bare websockets implementation does not support http long-polling yet. However one could still choose the old socketio based transport to archive this. Also iirc longpolling was disabled by default anyway, i guess not a lot of users use it. If this is really needed i could add support to our bare websockets implementation as well.

[benedikt-bartscher]

check out #6984

edit: done in 9caa24b