feat(plugin):Background Music plugin

Added a plugin so users can upload and play a .wav audio file as background music. added volume setting, made sure the file is stored across version updates/downdates, made the music stop when the tab is unfocussed, and registered the plugin as official.

src/plugins/built-in/backgroundMusic/BackgroundMusicSetting.svelte

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+<script lang="ts">
+  import localforage from 'localforage'
+  import { onMount } from 'svelte'
+
+  let fileInput = $state<HTMLInputElement | undefined>(undefined)
+  let dragging = $state(false)
+  let filename = $state<string | undefined>(undefined)
+  let durationText = $state<string | undefined>(undefined)
+
+  const store = localforage.createInstance({
+    name: 'background-music-store',
+    storeName: 'music',
+  })
+
+  async function loadExisting() {
+    const name = await store.getItem<string>('audio-name')
+    filename = name ?? undefined
+  }
+
+  onMount(() => { loadExisting() })
+
+  function triggerSelect() { fileInput?.click() }
+
+  async function handleFiles(files: FileList | null) {
+    const file = files?.[0]
+    if (!file) return
+    // Restrict to WAV only for best responsiveness
+    const isWav = file.type === 'audio/wav' || file.name.toLowerCase().endsWith('.wav')
+    if (!isWav) {
+      alert('Please select a .wav audio file')
+      return
+    }
+
+    await store.setItem('audio-blob', file)
+    await store.setItem('audio-name', file.name)
+    filename = file.name
+
+    // Probe duration
+    try {
+      const url = URL.createObjectURL(file)
+      const audio = new Audio(url)
+      await new Promise<void>((resolve, reject) => {
+        audio.onloadedmetadata = () => resolve()
+        audio.onerror = () => reject()
+      })
+      if (!isNaN(audio.duration) && audio.duration !== Infinity) {
+        const minutes = Math.floor(audio.duration / 60)
+        const seconds = Math.round(audio.duration % 60)
+        durationText = `${minutes}:${seconds.toString().padStart(2, '0')}`
+      } else {
+        durationText = undefined
+      }
+      URL.revokeObjectURL(url)
+    } catch {
+      durationText = undefined
+    }
+
+    window.dispatchEvent(new Event('betterseqta-background-music-updated'))
+  }
+
+  function onFileChange() { handleFiles(fileInput?.files || null) }
+
+  function onDrop(event: DragEvent) {
+    event.preventDefault()
+    dragging = false
+    handleFiles(event.dataTransfer?.files || null)
+  }
+
+  async function removeAudio() {
+    await store.removeItem('audio-blob')
+    await store.removeItem('audio-name')
+    filename = undefined
+    durationText = undefined
+    window.dispatchEvent(new Event('betterseqta-background-music-stop'))
+  }
+</script>
+
+<div
+  class="flex relative justify-between items-center rounded-lg px-3 py-2 cursor-pointer select-none border border-zinc-300 dark:border-zinc-600 bg-white/20 dark:bg-zinc-800/30"
+  onclick={() => triggerSelect()}
+  ondragover={(e) => { e.stopPropagation(); dragging = true }}
+  ondragleave={() => dragging = false}
+  ondrop={onDrop}
+  onkeydown={(e) => {
+    if (e.key === 'Enter' || e.key === ' ') {
+      e.preventDefault()
+      triggerSelect()
+    }
+  }}
+  role="button"
+  tabindex="0"
+>
+  <div class="flex items-center gap-3">
+    <div class="flex gap-2 items-center px-3 py-1 text-xs rounded-lg border border-dashed transition border-zinc-300 dark:border-zinc-600 text-zinc-500 dark:text-zinc-400 hover:text-zinc-700 dark:hover:text-zinc-300">
+      <span class="text-lg font-IconFamily">{'\ued47'}</span>
+      <span>{filename ? 'Change audio' : 'Upload audio'}</span>
+    </div>
+    {#if filename}
+      <div class="text-xs text-zinc-600 dark:text-zinc-300">
+        {filename}{#if durationText} • {durationText}{/if}
+      </div>
+    {/if}
+  </div>
+  {#if filename}
+    <button
+      class="flex justify-center items-center m-1 text-lg dark:text-white size-7"
+      onclick={(e) => { e.stopPropagation(); removeAudio() }}
+      aria-label="Remove audio"
+    >&#215;</button>
+  {/if}
+  <input type="file" accept="audio/wav" class="hidden" bind:this={fileInput} onchange={onFileChange} />
+  {#if dragging}
+    <div class="absolute inset-0 rounded-lg bg-zinc-200/40 dark:bg-zinc-700/40"></div>
+  {/if}
+</div>
+
+

src/plugins/built-in/backgroundMusic/index.ts

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+import type { Plugin } from "@/plugins/core/types";
+import { defineSettings, componentSetting, numberSetting } from "@/plugins/core/settingsHelpers";
+import styles from "./styles.css?inline";
+import BackgroundMusicSetting from "./BackgroundMusicSetting.svelte";
+import localforage from "localforage";
+
+const settings = defineSettings({
+  uploader: componentSetting({
+    title: "Background Music",
+    description: "Upload a .wav audio file to play in the background.",
+    component: BackgroundMusicSetting,
+  }),
+  volume: numberSetting({
+    title: "Volume",
+    description: "Set background music volume",
+    default: 0.5,
+    min: 0,
+    max: 1,
+    step: 0.05,
+  }),
+});
+
+const store = localforage.createInstance({
+  name: "background-music-store",
+  storeName: "music",
+});
+
+let currentAudio: HTMLAudioElement | null = null;
+let currentObjectUrl: string | null = null;
+let cleanupRegistered = false;
+let pendingGestureCancel: (() => void) | null = null;
+let visibilityResumeTimeout: number | null = null;
+
+async function loadAudioBlob(): Promise<Blob | null> {
+  const blob = await store.getItem<Blob>("audio-blob");
+  return blob && blob instanceof Blob ? blob : null;
+}
+
+function stopAndCleanupAudio(): void {
+  if (currentAudio) {
+    currentAudio.pause();
+    currentAudio.src = "";
+    currentAudio.remove();
+    currentAudio = null;
+  }
+  if (currentObjectUrl) {
+    URL.revokeObjectURL(currentObjectUrl);
+    currentObjectUrl = null;
+  }
+}
+
+function ensureGestureStart(handler: () => void): () => void {
+  const eventTypes = ["pointerdown", "keydown", "touchstart"]; // broad user gesture coverage
+  const listener = () => {
+    handler();
+    for (const type of eventTypes) {
+      window.removeEventListener(type, listener);
+    }
+  };
+  for (const type of eventTypes) {
+    window.addEventListener(type, listener, { once: true, passive: true });
+  }
+  return () => {
+    for (const type of eventTypes) {
+      window.removeEventListener(type, listener);
+    }
+  };
+}
+
+async function startPlayback(volume: number): Promise<void> {
+  const blob = await loadAudioBlob();
+  if (!blob) return;
+
+  stopAndCleanupAudio();
+
+  currentObjectUrl = URL.createObjectURL(blob);
+  const audio = new Audio(currentObjectUrl);
+  audio.loop = true;
+  audio.volume = Math.max(0, Math.min(1, volume));
+  audio.preload = "auto";
+  audio.crossOrigin = "anonymous";
+  audio.style.display = "none";
+  document.body.appendChild(audio);
+  currentAudio = audio;
+
+  try {
+    // Attempt immediate play; may be blocked until gesture
+    await audio.play();
+  } catch {
+    // Ignore; will be started after gesture if enabled
+  }
+}
+
+const backgroundMusicPlugin: Plugin<typeof settings> = {
+  id: "background-music",
+  name: "Background Music",
+  description: "Play your own music in the background while SEQTA is open.",
+  version: "1.0.0",
+  settings,
+  styles,
+  disableToggle: true,
+  defaultEnabled: false,
+
+  run: async (api) => {
+    await api.storage.loaded;
+
+    // react to specific setting changes
+    api.settings.onChange("volume" as any, (value: any) => {
+      const vol = (typeof value === "number" ? value : 0.5) as number;
+      if (currentAudio) currentAudio.volume = Math.max(0, Math.min(1, vol));
+    });
+
+    // Note: Stop button/event removed by user; no stop handling needed
+
+    // Start if we have audio and autoplay is enabled
+    const tryStart = async () => {
+      const vol = (api.settings as any).volume ?? 0.5;
+      await startPlayback(vol);
+    };
+
+    // Always arm gesture start and attempt immediate start
+    const cancel = ensureGestureStart(() => { tryStart(); });
+    cleanupRegistered = true;
+    (window as any).__betterseqta_bg_music_cancel__ = cancel;
+    tryStart();
+
+    // Pause on tab hide, resume on show with a small delay
+    const visHandler = () => {
+      if (!currentAudio) return;
+      if (document.visibilityState === "hidden") {
+        if (visibilityResumeTimeout !== null) {
+          clearTimeout(visibilityResumeTimeout);
+          visibilityResumeTimeout = null;
+        }
+        currentAudio.pause();
+      } else if (document.visibilityState === "visible") {
+        if (visibilityResumeTimeout !== null) {
+          clearTimeout(visibilityResumeTimeout);
+        }
+        visibilityResumeTimeout = window.setTimeout(() => {
+          visibilityResumeTimeout = null;
+          currentAudio?.play().catch(() => {});
+        }, 200);
+      }
+    };
+    document.addEventListener("visibilitychange", visHandler);
+
+    // Allow uploads to trigger refresh
+    const uploadedHandler = () => {
+      const vol = (api.settings as any).volume ?? 0.5;
+      startPlayback(vol);
+    };
+    window.addEventListener("betterseqta-background-music-updated", uploadedHandler);
+
+    return () => {
+      document.removeEventListener("visibilitychange", visHandler);
+      window.removeEventListener("betterseqta-background-music-updated", uploadedHandler);
+      if (cleanupRegistered && (window as any).__betterseqta_bg_music_cancel__) {
+        (window as any).__betterseqta_bg_music_cancel__();
+        (window as any).__betterseqta_bg_music_cancel__ = undefined;
+      }
+      if (pendingGestureCancel) { pendingGestureCancel(); pendingGestureCancel = null; }
+      if (visibilityResumeTimeout !== null) { clearTimeout(visibilityResumeTimeout); visibilityResumeTimeout = null; }
+      stopAndCleanupAudio();
+    };
+  },
+};
+
+export default backgroundMusicPlugin;
+
+

src/plugins/built-in/backgroundMusic/styles.css

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+.background-music-hidden{display:none}
+