withKeys: no surface area on Lynx — document as no-op and close

[KealanAU]

Investigation

Before implementing withKeys, I investigated whether Lynx exposes event.key on any platform.

Web preview — keydown fires but key is stripped

The web preview does fire keydown events, but the Worker boundary crossing (createCrossThreadEvent) strips all keyboard-specific fields. The payload received in the BG thread:

{"type":"keydown","timestamp":5272.4,"target":{"uniqueId":18},"currentTarget":{"uniqueId":18},"detail":0,"params":{}}

No key, no code, no keyCode. params is empty.

Native — hardware keyboard Enter never reaches JS as keydown

Tested via simulator with a physical Mac keyboard (BKSHIDKeyboardDevice, layout "Australian"). The iOS UIEvent type 4 (keyboard) was received and recognised, but Lynx's C++ core intercepted it before JS:

Keyboard receives keyEvent type: 4; subtype: 0
Keyboard adds a string
[touch_event_handler.cc(367)] SendCustomEvent event name:confirm tag:29

touch_event_handler.cc converts Enter directly to confirm. No keydown is ever emitted to the JS layer — regardless of whether the keyboard is virtual or physical.

Conclusion

withKeys has no surface area on any Lynx target:

Platform	keydown fires?	event.key available?
Lynx web preview	Yes	No — stripped at Worker boundary
Lynx native (virtual keyboard)	No	N/A
Lynx native (hardware keyboard)	No — converted to confirm by touch_event_handler.cc	N/A

The existing stub (return fn) is the correct runtime behaviour. The only gap is documentation.

Proposal

• Keep the stub as-is
• Add a JSDoc to withKeys explaining why it's a no-op (same pattern as .prevent from Feature(event-modifiers): add event modifier (self, once, prevent, stop) #155)
• Add a line in the vue-compatibility docs (en + zh)
• No implementation, no tests, no example app

PR: #(171)

[Huxpro]

Thanks for the thorough investigation! The analysis clearly shows withKeys has no surface area on any Lynx target. We'll track the documentation fix (JSDoc + compat docs update) via #171.