Gemini Completion Sound

Plays a pleasant double-chime when Gemini finishes generating, only if the tab is not in focus.
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// ==UserScript==
// @name         Gemini Completion Sound
// @namespace    http://tampermonkey.net/
// @version      2025-02-19
// @description  Plays a pleasant double-chime when Gemini finishes generating, only if the tab is not in focus.
// @author       Vincent Nahn
// @homepage     https://vincentnahn.com
// @match        https://gemini.google.com/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=gemini.google.com
// @grant        none
// @license      MIT
// ==/UserScript==

(function() {
    'use strict';

    let isGenerating = false;

    // Function to generate a pleasant, bell-like double chime
    function playNotificationSound() {
        const audioCtx = new (window.AudioContext || window.webkitAudioContext)();

        // Helper function to play a single note with a smooth fade-out (envelope)
        function playNote(frequency, startTime, duration) {
            const oscillator = audioCtx.createOscillator();
            const gainNode = audioCtx.createGain();

            // 'sine' waves are the smoothest sounding
            oscillator.type = 'sine';
            oscillator.frequency.value = frequency;

            oscillator.connect(gainNode);
            gainNode.connect(audioCtx.destination);

            // Create a pleasant volume envelope (no harsh clicks)
            gainNode.gain.setValueAtTime(0, startTime);
            // Quick fade-in to 15% volume
            gainNode.gain.linearRampToValueAtTime(0.15, startTime + 0.05);
            // Smooth, lingering fade-out
            gainNode.gain.exponentialRampToValueAtTime(0.001, startTime + duration);

            oscillator.start(startTime);
            oscillator.stop(startTime + duration);
        }

        const now = audioCtx.currentTime;

        // Play an ascending major third (C5 to E5) for a happy, "task complete" feel
        playNote(523.25, now, 0.8);        // First note (C5)
        playNote(659.25, now + 0.15, 1.0); // Second note (E5) comes in slightly after
    }

    const observer = new MutationObserver(() => {
        const stopButton = document.querySelector('[aria-label*="Stop"]');

        if (stopButton && !isGenerating) {
            isGenerating = true;
        }

        if (isGenerating && !stopButton) {
            isGenerating = false;

            if (!document.hasFocus()) {
                playNotificationSound();
            }
        }
    });

    observer.observe(document.body, {
        childList: true,
        subtree: true
    });

})();