fix: iOS Safari Chinese punctuation and emoji input

Fix input handling for Chinese punctuation (，。！？) and emoji on iOS Safari.

The issue occurs because:
1. iOS Safari fires keydown (setting _keyDownSeen=true)
2. Then fires input event with ev.composed=true
3. But NO composition events are triggered for punctuation

The old condition `(!ev.composed || !this._keyDownSeen)` would reject these
inputs because both conditions are true.

For emoji, there's a timing issue:
1. compositionend fires → isComposing becomes false
2. input event fires → old fix would accept (duplicate!)
3. setTimeout in CompositionHelper fires → sends emoji (first copy)

The fix:
1. Change condition to check `!compositionHelper.isComposing`
2. Also check `!compositionHelper.isSendingComposition` to catch the
   window between compositionend and setTimeout callback
3. Add public getter for isSendingComposition in CompositionHelper

This correctly:
- Accepts punctuation input (not composing, not pending)
- Rejects input during active composition
- Rejects input when CompositionHelper has pending setTimeout
- Prevents emoji duplication

Fixes #3070, #4486

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: mylukin

package-lock.json

@@ -1241,10 +1241,16 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
    * @param ev The input event to be handled.
    */
   protected _inputEvent(ev: InputEvent): boolean {
-    // Only support emoji IMEs when screen reader mode is disabled as the event must bubble up to
-    // support reading out character input which can doubling up input characters
-    // Based on these event traces: https://github.com/xtermjs/xterm.js/issues/3679
-    if (ev.data && ev.inputType === 'insertText' && (!ev.composed || !this._keyDownSeen) && !this.optionsService.rawOptions.screenReaderMode) {
+    // Handle direct text input (not from composition).
+    // We skip input events when:
+    // - isComposing: Active composition in progress (e.g., emoji picker, CJK IME)
+    // - isSendingComposition: compositionend fired but setTimeout hasn't sent data yet
+    // CompositionHelper handles input in these cases to prevent duplicates.
+    // When NOT composing/sending, we accept input even if ev.composed=true, which fixes
+    // iOS Safari Chinese punctuation input (issue #3070, #4486).
+    // Screen reader mode needs the event to bubble for accessibility announcements.
+    const compositionHelper = this._compositionHelper!;
+    if (ev.data && ev.inputType === 'insertText' && !compositionHelper.isComposing && !compositionHelper.isSendingComposition && !this.optionsService.rawOptions.screenReaderMode) {
       if (this._keyPressHandled) {
         return false;
       }

src/browser/CoreBrowserTerminal.ts

@@ -344,6 +344,9 @@ export class MockCompositionHelper implements ICompositionHelper {
   public get isComposing(): boolean {
     return false;
   }
+  public get isSendingComposition(): boolean {
+    return false;
+  }
   public compositionstart(): void {
     throw new Error('Method not implemented.');
   }

src/browser/TestUtils.test.ts

@@ -40,6 +40,7 @@ export type LineData = CharData[];
 
 export interface ICompositionHelper {
   readonly isComposing: boolean;
+  readonly isSendingComposition: boolean;
   compositionstart(): void;
   compositionupdate(ev: CompositionEvent): void;
   compositionend(): void;

src/browser/Types.ts

@@ -32,9 +32,11 @@ export class CompositionHelper {
 
   /**
    * Whether a composition is in the process of being sent, setting this to false will cancel any
-   * in-progress composition.
+   * in-progress composition. This is true between compositionend and when the setTimeout callback
+   * fires to actually send the data.
    */
   private _isSendingComposition: boolean;
+  public get isSendingComposition(): boolean { return this._isSendingComposition; }
 
   /**
    * Data already sent due to keydown event.