fix(mobile): serialize accessory key presses

mobile/src/terminal/terminal-accessory-repeat.test.ts

@@ -60,6 +60,28 @@ describe('terminal accessory repeat', () => {
     expect(send).toHaveBeenCalledTimes(1)
   })
 
+  it('serializes a new press behind the previous press send', async () => {
+    vi.useFakeTimers()
+    const first = deferred()
+    const sent: string[] = []
+    const send = vi.fn((input: string) => {
+      sent.push(input)
+      return input === 'down' ? first.promise.then(() => true) : Promise.resolve(true)
+    })
+    const repeat = createTerminalAccessoryRepeatController<string>()
+
+    repeat.start('down', send)
+    repeat.stop()
+    repeat.start('up', send)
+
+    expect(sent).toEqual(['down'])
+
+    first.resolve()
+    await vi.advanceTimersByTimeAsync(0)
+    expect(sent).toEqual(['down', 'up'])
+    repeat.stop()
+  })
+
   it('stops repeating when the transport rejects a send', async () => {
     vi.useFakeTimers()
     const send = vi.fn(() => Promise.reject(new Error('disconnected')))

mobile/src/terminal/terminal-accessory-repeat.ts

@@ -19,6 +19,28 @@ export function createTerminalAccessoryRepeatSender<TInput>(
 export function createTerminalAccessoryRepeatController<TInput>() {
   let generation = 0
   let timer: ReturnType<typeof setTimeout> | null = null
+  let dispatchTail: Promise<void> | null = null
+
+  const dispatch = (
+    input: TInput,
+    send: TerminalAccessoryRepeatSender<TInput>,
+    activeGeneration: number
+  ) => {
+    const sendIfCurrent = () =>
+      generation === activeGeneration ? send(input) : Promise.resolve(false)
+    const result = dispatchTail ? dispatchTail.then(sendIfCurrent) : sendIfCurrent()
+    const settled = result.then(
+      () => undefined,
+      () => undefined
+    )
+    dispatchTail = settled
+    void settled.then(() => {
+      if (dispatchTail === settled) {
+        dispatchTail = null
+      }
+    })
+    return result
+  }
 
   const stop = () => {
     generation += 1
@@ -39,7 +61,7 @@ export function createTerminalAccessoryRepeatController<TInput>() {
         if (generation !== activeGeneration) {
           return
         }
-        void send(input).then(
+        void dispatch(input, send, activeGeneration).then(
           (sent) => {
             if (sent && generation === activeGeneration) {
               schedule(TERMINAL_ACCESSORY_REPEAT_INTERVAL_MS)
@@ -50,7 +72,7 @@ export function createTerminalAccessoryRepeatController<TInput>() {
       }, delayMs)
     }
 
-    void send(input).then(
+    void dispatch(input, send, activeGeneration).then(
       (sent) => {
         if (sent && generation === activeGeneration) {
           schedule(