epicenter icon indicating copy to clipboard operation
epicenter copied to clipboard
verified publisher icon epicenter-so

Windows: Intermittent failures in 'paste at cursor' functionality

Open Serenisoft opened this issue 3 months ago • 6 comments

Problem Description

The current Windows implementation of the 'paste at cursor' functionality has intermittent failures (approximately 5-10% of cases). When failures occur, the transcription completes successfully, but the simulated Ctrl+V keystroke doesn't reach the target application.

Current Behavior

  • Transcription works correctly
  • Clipboard operations (save, write, restore) succeed
  • Key simulation reports success (both Enigo and Windows SendInput API)
  • However, the paste operation fails to execute in the target application sporadically
  • Success rate varies between applications and timing conditions
  • Issue persists across different implementations (Enigo, Windows SendInput API, various timing delays)

Expected Behavior

  • 100% reliable paste operations across all Windows applications
  • Consistent behavior regardless of focus switching or application type

Technical Investigation

The issue has been investigated across multiple approaches:

Key Simulation Analysis

  • Enigo library: Individual key events with delays - sporadic failures
  • Windows SendInput API: Batched events with keyboard state checking - sporadic failures persist
  • Timing variations: Tested delays from 50ms to 400ms - failures continue

Debugging Results

Windows SendInput API consistently reports success:

📊 SendInput result: 4 of 4 events processed
🎯 SendInput: All 4 events successfully processed
✅ Windows SendInput API succeeded

Despite successful key simulation, paste operations still fail intermittently in applications like VS Code and Notepad++.

Environment

  • Platform: Windows (all versions tested)
  • App Version: Whispering v7.5.1
  • Component: write_text function in src-tauri/src/lib.rs
  • Feature: Paste at cursor functionality
  • Applications tested: VS Code, Notepad++, various text editors

Analysis: Root Cause Unknown

The intermittent nature of failures, combined with successful key simulation reporting, suggests the issue may be related to:

  • Target application input handling
  • Windows clipboard system behavior
  • Focus/window state management
  • Timing between clipboard operations and key simulation

Further investigation needed to identify the actual root cause of these sporadic paste failures.

This issue affects user experience significantly as the paste at cursor functionality is core to the transcription workflow.

Serenisoft avatar Sep 26 '25 20:09 Serenisoft

Could maintainers please add the bug and windows labels to this issue? This is a Windows-specific reliability bug affecting the paste at cursor functionality.

Serenisoft avatar Sep 26 '25 21:09 Serenisoft

thanks for the detailed report, very helpful! We’ll add the bug and windows labels. could you also let us know which app version you're using?

thisisharsh7 avatar Sep 26 '25 21:09 thisisharsh7

This.

ss1v avatar Sep 26 '25 21:09 ss1v

thanks for the detailed report, very helpful! We’ll add the bug and windows labels. could you also let us know which app version you're using?

Done! Added Whispering v7.5.1 to the Environment section. Same issue in 7.4. Fiddling with some different approaches to see what can work. Seems like keyboard input with automation is a known windows issue...

Serenisoft avatar Sep 26 '25 21:09 Serenisoft

🎯 Root Cause Identified

After extensive debugging, I've identified the root cause of the intermittent paste failures:

The Real Problem: Alt-Key Focus Stealing

The issue occurs when using Alt-key shortcuts (like Alt+Z) to trigger recording operations. In Windows, the Alt key can activate menu bars and cause focus changes, which makes the text cursor disappear from the target application.

What happens:

  1. User presses Alt+Z to start or stop recording
  2. Alt key triggers Windows focus management behavior if by accident clicking alt one more time.
  3. Cursor disappears from text field (focus stolen)
  4. Paste operation fails because target field no longer has focus
  5. Manual Ctrl+V works after clicking back into text field (restoring focus)

Evidence & Testing

  • ✅ 68 consecutive successful paste operations when using non-Alt shortcuts
  • ✅ Cursor visibly disappears when Alt key is pressed in text fields
  • ✅ 100% reliability with Ctrl+Shift+Z instead of Alt+Z

Solution

Change shortcut from Alt-based to Ctrl-based combinations:

  • ❌ Problematic: Alt+Z, Alt+Shift+R
  • ✅ Recommended: Ctrl+Shift+Z, Ctrl+Shift+R

The default shortcuts (Ctrl+Shift+;) don't have this issue.

Note

This turned out to be a classic PEBKAC (Problem Exists Between Keyboard And Chair) situation! 😅 However, since Alt-key shortcuts can cause focus stealing issues in Windows, this could affect other users as well.

⚠️ Consider adding a warning in documentation about avoiding Alt-key shortcuts on Windows for clipboard-related operations.

This is not a bug in Whispering's paste functionality - it's a Windows quirk with Alt-key focus management that affects any application using Alt-based shortcuts for clipboard operations.

Serenisoft avatar Sep 26 '25 22:09 Serenisoft

Thanks so much for digging into this @Serenisoft 🙌 since it's not a whispering bug. we’ll discuss and add a doc note

thisisharsh7 avatar Sep 26 '25 23:09 thisisharsh7