Handle TUI trackpad wheel reversal

Co-authored-by: Orca <help@stably.ai>

src/renderer/src/lib/pane-manager/pane-terminal-mouse-wheel.test.ts

@@ -243,6 +243,21 @@ describe('terminal mouse wheel multiplier', () => {
     expect(reports).toEqual([0, 0, 0, 1])
   })
 
+  it('does not burst-boost rapid trackpad-like pixel deltas', () => {
+    const state = createTerminalTuiMouseWheelDistanceState()
+
+    const reports = [0, 16, 32, 48].map((timeStamp) =>
+      resolveTerminalTuiMouseWheelReportCount(
+        { deltaY: 4, deltaMode: DOM_DELTA_PIXEL, timeStamp },
+        1,
+        state,
+        { cellHeight: 16 }
+      )
+    )
+
+    expect(reports).toEqual([0, 0, 0, 1])
+  })
+
   it('resets pending fractional distance when the user changes direction', () => {
     const state = createTerminalTuiMouseWheelDistanceState()
 
@@ -269,7 +284,7 @@ describe('terminal mouse wheel multiplier', () => {
     expect(shouldMultiplyTerminalMouseWheel(wheelEvent(), terminalElement(false))).toBe(false)
   })
 
-  it('leaves trackpad-like pixel scrolling one-to-one', () => {
+  it('handles trackpad-like TUI pixel scrolling while mouse reporting is active', () => {
     expect(
       shouldMultiplyTerminalMouseWheel(
         wheelEvent({
@@ -278,7 +293,7 @@ describe('terminal mouse wheel multiplier', () => {
         }),
         terminalElement()
       )
-    ).toBe(false)
+    ).toBe(true)
   })
 
   it('multiplies notched mouse wheel ticks even when Chromium exposes a small pixel delta', () => {
@@ -358,6 +373,58 @@ describe('terminal mouse wheel multiplier', () => {
     expect(shouldMultiplyTerminalMouseWheel(dispatched[0]!, target)).toBe(false)
   })
 
+  it('replays trackpad-like TUI pixel scrolling with responsive direction reversal', async () => {
+    vi.stubGlobal('WheelEvent', TestWheelEvent)
+    const handlers: ((event: WheelEvent) => boolean)[] = []
+    const target = Object.assign(new EventTarget(), {
+      classList: {
+        contains: (className: string) => className === 'enable-mouse-events'
+      }
+    }) as unknown as EventTarget & HTMLElement
+    const dispatched: WheelEvent[] = []
+    target.addEventListener('wheel', (event) => dispatched.push(event as WheelEvent))
+    attachTerminalMouseWheelMultiplier(
+      {
+        attachCustomWheelEventHandler: (handler) => {
+          handlers.push(handler)
+        },
+        element: target,
+        rows: 24
+      },
+      { getTuiMouseWheelMultiplier: () => 1 }
+    )
+
+    const events = [
+      [4, 0],
+      [4, 16],
+      [4, 32],
+      [4, 48],
+      [-4, 64],
+      [-4, 80],
+      [-4, 96],
+      [-4, 112]
+    ].map(([deltaY, timeStamp]) => {
+      const event = new TestWheelEvent('wheel', {
+        bubbles: true,
+        cancelable: true,
+        deltaMode: DOM_DELTA_PIXEL,
+        deltaY
+      }) as WheelEvent
+      Object.defineProperty(event, 'timeStamp', {
+        configurable: true,
+        value: timeStamp
+      })
+      return event
+    })
+
+    for (const event of events) {
+      expect(handlers[0]?.(event)).toBe(false)
+      await Promise.resolve()
+    }
+
+    expect(dispatched.map((entry) => entry.deltaY)).toEqual([1, -1])
+  })
+
   it('drains resolved TUI wheel reports without a frame-rate cap', async () => {
     vi.stubGlobal('WheelEvent', TestWheelEvent)
     const handlers: ((event: WheelEvent) => boolean)[] = []

src/renderer/src/lib/pane-manager/pane-terminal-mouse-wheel.ts

@@ -1,7 +1,6 @@
 import type { Terminal } from '@xterm/xterm'
 import {
   createTerminalTuiMouseWheelDistanceState,
-  isDiscreteTerminalTuiWheelEvent,
   normalizeTerminalTuiMouseWheelMultiplier,
   resolveTerminalTuiMouseWheelReportCount,
   resolveTerminalWheelDirection
@@ -110,8 +109,7 @@ export function shouldMultiplyTerminalMouseWheel(
     isReplayedWheelEvent(event) ||
     !terminalElement?.classList.contains(XTERM_MOUSE_REPORTING_CLASS) ||
     event.deltaY === 0 ||
-    event.shiftKey ||
-    !isDiscreteTerminalTuiWheelEvent(event)
+    event.shiftKey
   ) {
     return false
   }

src/renderer/src/lib/pane-manager/pane-terminal-tui-wheel-reports.ts

@@ -67,6 +67,11 @@ function legacyVerticalWheelDelta(event: TerminalTuiWheelEventInput): number | n
   return null
 }
 
+function hasDiscreteLegacyWheelDelta(event: TerminalTuiWheelEventInput): boolean {
+  const legacyDelta = legacyVerticalWheelDelta(event)
+  return legacyDelta !== null && Math.abs(legacyDelta) >= LEGACY_MOUSE_WHEEL_DELTA_MIN
+}
+
 export function isDiscreteTerminalTuiWheelEvent(event: TerminalTuiWheelEventInput): boolean {
   if ((event.deltaMode ?? DOM_DELTA_PIXEL) !== DOM_DELTA_PIXEL) {
     return true
@@ -76,8 +81,15 @@ export function isDiscreteTerminalTuiWheelEvent(event: TerminalTuiWheelEventInpu
     return true
   }
 
-  const legacyDelta = legacyVerticalWheelDelta(event)
-  return legacyDelta !== null && Math.abs(legacyDelta) >= LEGACY_MOUSE_WHEEL_DELTA_MIN
+  return hasDiscreteLegacyWheelDelta(event)
+}
+
+function canBurstBoostWheelEvent(event: TerminalTuiWheelEventInput): boolean {
+  if ((event.deltaMode ?? DOM_DELTA_PIXEL) !== DOM_DELTA_PIXEL) {
+    return true
+  }
+
+  return hasDiscreteLegacyWheelDelta(event)
 }
 
 function wheelInputTime(event: TerminalTuiWheelEventInput): number | null {
@@ -130,6 +142,13 @@ function resolveBurstWheelDistanceRows(
   state: TerminalTuiMouseWheelDistanceState,
   distanceRows: number
 ): number {
+  if (!canBurstBoostWheelEvent(event)) {
+    state.fastStreak = 0
+    state.lastDistanceRows = null
+    state.lastInputAt = null
+    return 0
+  }
+
   const currentInputAt = wheelInputTime(event)
   if (currentInputAt === null) {
     state.fastStreak = 0