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Toasty - Session Context for Future Claude Sessions

What is Toasty?

A Windows CLI tool that shows toast notifications when AI coding agents (Claude Code, Gemini CLI, GitHub Copilot) finish tasks. Key feature: click the toast to bring your terminal back to foreground.

Why It Exists

When using AI CLI agents, you alt-tab away while waiting. The agent finishes but you don't notice. Toasty solves this with:

  1. Native Windows toast notification when agent stops
  2. Click-to-focus: clicking the toast brings your terminal window back

Architecture

Core Components

  • main.cpp - Single-file C++ using WinRT for toast notifications
  • Embedded PNG icons for each AI agent (Claude, Gemini, Copilot, Codex, Cursor)
  • toasty://focus protocol handler for click-to-focus

How Click-to-Focus Works

  1. When showing a toast, we walk the process tree to find the parent terminal window (Windows Terminal, VS Code, etc.)
  2. Save that HWND to registry (HKCU\Software\Toasty\LastConsoleWindow)
  3. Toast XML includes activationType="protocol" launch="toasty://focus"
  4. When user clicks toast, Windows launches toasty.exe --focus
  5. --focus reads HWND from registry and brings window to foreground

Focus Challenges (Windows Security)

Protocol handlers run in a restricted context - Windows blocks random apps from stealing focus. We use multiple techniques:

  • AttachThreadInput() to borrow focus permission
  • SendInput() with empty mouse event to simulate user activity
  • SwitchToThisWindow() works better than SetForegroundWindow() for protocol handlers
  • keybd_event() with ALT key to help with focus

Hook Formats (Important!)

Claude Code (~/.claude/settings.json)

{
  "hooks": {
    "Stop": [{
      "hooks": [{
        "type": "command",
        "command": "D:\\path\\to\\toasty.exe \"Task complete\" -t \"Claude Code\"",
        "timeout": 5000
      }]
    }]
  }
}

Note: Nested hooks array is required!

Gemini CLI (~/.gemini/settings.json)

{
  "hooks": {
    "AfterAgent": [{
      "hooks": [{
        "type": "command",
        "command": "D:\\path\\to\\toasty.exe \"Gemini finished\" -t \"Gemini\"",
        "timeout": 5000
      }]
    }]
  }
}

Note: Same nested structure as Claude. Uses AfterAgent not Stop.

GitHub Copilot (.github/hooks/toasty.json in repo)

{
  "version": 1,
  "hooks": {
    "sessionEnd": [{
      "type": "command",
      "bash": "toasty 'Copilot finished' -t 'GitHub Copilot'",
      "powershell": "D:\\path\\to\\toasty.exe 'Copilot finished' -t 'GitHub Copilot'",
      "timeoutSec": 5
    }]
  }
}

Auto-Detection

Toasty walks the process tree looking for known parent processes:

  • If launched by claude.exe -> uses Claude icon/title
  • If launched by node with @google/gemini in cmdline -> uses Gemini icon/title
  • etc.

This means you can just run toasty "Done" and it picks the right branding.

Key Issues We Hit & Fixed

1. Hook Settings Not Reloading

Problem: Changed hook settings but nothing happened. Solution: Must restart Claude Code to reload settings.json. Settings are only read at startup.

2. Gemini Hook Format

Problem: Gemini CLI wasn't triggering toasty. Solution: Gemini needs the nested hooks array structure (same as Claude), not flat format.

3. Click-to-Focus Not Working from Hooks

Problem: Clicking toast worked when testing manually, but not when triggered from Claude Code hook. Cause: We thought it was Windows security restrictions on protocol handlers, but it was actually just that hook settings weren't reloaded. Solution: Restart Claude Code. The aggressive focus techniques we added (SendInput, SwitchToThisWindow) may help in edge cases anyway.

4. Finding the Right Window

Problem: GetConsoleWindow() returns NULL for GUI subsystem apps, and process tree walking sometimes fails. Solution: Multiple fallbacks:

  1. Walk process tree with CreateToolhelp32Snapshot to find parent with visible window
  2. If that fails, enumerate all windows looking for CASCADIA_HOSTING_WINDOW_CLASS (Windows Terminal) or ConsoleWindowClass

Version History

  • v0.1 - Basic toast notifications
  • v0.2 - Auto-detection of parent AI agent, embedded icons
  • v0.3 - Click-to-focus feature (protocol handler)
  • v0.4 - Code cleanup (HandleGuard, to_lower), fixed Gemini hook format
  • v0.5 - Improved click-to-focus reliability, removed debug logging

Build

cmake -B build -G "Visual Studio 17 2022"
cmake --build build --config Release
# Output: build/Release/toasty.exe

Commands

toasty "message"                    # Show toast (auto-detects agent)
toasty "message" -t "Title"         # Custom title
toasty "message" --app claude       # Force specific agent branding
toasty --install                    # Install hooks for detected agents
toasty --install claude             # Install hook for specific agent
toasty --uninstall                  # Remove all hooks
toasty --status                     # Show detection/installation status
toasty --register                   # Re-register app (troubleshooting)
toasty --focus                      # Internal: called by protocol handler

Files

  • main.cpp - All the code
  • resource.h / resources.rc - Icon resources
  • icons/*.png - Source icons (embedded at compile time)
  • CMakeLists.txt - Build config

Testing Tips

  1. After changing hook settings, restart Claude Code
  2. Test toasty directly first: .\build\Release\toasty.exe "Test" -t "Test"
  3. Click the toast to verify focus works
  4. Then test via hook by completing a task

Owner

Scott Hanselman (@shanselman)