Forward HIDInputReportEvent.timeStamp to button listeners

[mouadennasri]

Problem

Consumers of this library running real-time audio routing on top of HID button input need to know when the user actually pressed the button, not when the JS handler eventually ran.

Under main-thread starvation (long React renders, focus handlers, etc.) the inputreport event sits in the browser event queue for hundreds of ms before dispatch. Today the event's timeStamp is read off event.data and discarded inside onInputReport/handleButtonPress, so the ButtonEventListener callback has no way to recover the press time.

Symptom: under load, every nav appears to happen "now" (handler-fire time), so any logic that correlates HID input with audio frames (speech onset, transcription windows, etc.) misroutes when the queue delay exceeds the audio window. DOM events (keydown, pointerdown, etc.) all expose event.timeStamp natively, so HID is the only input modality where queue-aware back-dating isn't possible today.

Change

Forward event.timeStamp from the underlying HIDInputReportEvent through handleButtonPress to each ButtonEventListener, as a third positional argument:

export type ButtonEventListener = (
  device: DictationDevice,
  bitMask: ButtonEvent,
  eventTimeStamp: number,  // ← new
) => void | Promise<void>;

Touched: dictation_device_base.ts, speechmike_hid_device.ts (override + proxy-device propagation path).

Compatibility

The added parameter is positional and additive. Existing ButtonEventListener implementations that take (device, bitMask) are still assignable to the new type — TypeScript permits assigning a fewer-arg function where more-arg is expected, and JavaScript ignores extra arguments at runtime. No call site update is required for consumers that don't need the timestamp.

Tests

Updated check_button_mapping to assert the new arg via jasmine.any(Number). Added an explicit eventTimeStamp value to the SpeechMike proxy-device propagation test so the forwarded value is verified end-to-end. Webpack build compiles cleanly.

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