feat: add sound effects for hud actions

Closes #174

js/src/App.tsx

@@ -18,6 +18,7 @@ import {
   RouteErrorBoundary,
   TopLevelErrorBoundary,
 } from "@/components/app-error-boundary";
+import { SoundEffectsProvider } from "@/lib/sound-effects/sound-effects-provider";
 
 const queryClient = createQueryClient();
 
@@ -87,8 +88,10 @@ const AppWithProviders = () => (
   <TopLevelErrorBoundary>
     <TooltipProvider>
       <QueryClientProvider client={queryClient}>
-        <App />
-        <Toaster />
+        <SoundEffectsProvider>
+          <App />
+          <Toaster />
+        </SoundEffectsProvider>
       </QueryClientProvider>
     </TooltipProvider>
   </TopLevelErrorBoundary>

js/src/assets.d.ts

@@ -2,3 +2,8 @@ declare module "*.wav" {
   const src: string;
   export default src;
 }
+
+declare module "*.mp3" {
+  const src: string;
+  export default src;
+}

js/src/features/settings-page.tsx

@@ -1,6 +1,6 @@
 import { useEffect, useState } from "react";
 import { useNavigate } from "react-router-dom";
-import { ChevronRight, LogOut, User, Info, Shield, Mail, Mic, LifeBuoy, FileText } from "lucide-react";
+import { ChevronRight, LogOut, User, Info, Shield, Mail, Mic, LifeBuoy, FileText, Volume2 } from "lucide-react";
 import { Avatar, AvatarFallback } from "@/components/ui/avatar";
 import { Separator } from "@/components/ui/separator";
 import { Switch } from "@/components/ui/switch";
@@ -10,6 +10,7 @@ import { Muted } from "@/components/ui/typography";
 import { ScrollArea } from "@/components/ui/scroll-area";
 import { CopyableEmail } from "@/components/copyable-email";
 import { useAuthStore } from "@/stores/auth-store";
+import { useSoundEffectsStore } from "@/stores/sound-effects-store";
 import { apiClient } from "@/api/client";
 import { logError, toUserMessage } from "@/lib/errors";
 import { toast } from "sonner";
@@ -73,6 +74,8 @@ export default function SettingsPage() {
   const [emailNotifications, setEmailNotifications] = useState(
     user?.email_notifications_enabled ?? true,
   );
+  const soundEffectsEnabled = useSoundEffectsStore((s) => s.enabled);
+  const setSoundEffectsEnabled = useSoundEffectsStore((s) => s.setEnabled);
   const [version, setVersion] = useState<string>();
 
   useEffect(() => {
@@ -146,6 +149,19 @@ export default function SettingsPage() {
               onCheckedChange={handleToggleEmailNotifications}
             />
           </div>
+          <div className="flex w-full items-center gap-3 px-4 py-3">
+            <span className="text-muted-foreground flex size-5 items-center justify-center">
+              <Volume2 className="size-4" />
+            </span>
+            <span className="min-w-0 flex-1 text-sm font-medium">
+              Sound effects
+            </span>
+            <Switch
+              size="sm"
+              checked={soundEffectsEnabled}
+              onCheckedChange={setSoundEffectsEnabled}
+            />
+          </div>
         </SettingsGroup>
 
         <Separator className="mt-4" />

js/src/lib/sound-effects/engine.ts

@@ -0,0 +1,152 @@
+/**
+ * Web Audio engine for HUD sound effects.
+ *
+ * Uses AudioBufferSourceNode for low-latency, overlapping playback (HTMLAudio
+ * can't overlap the same source and stalls when triggered rapidly). Adds a
+ * small pitch jitter on each play so repeated sounds don't feel robotic — the
+ * trick games use to keep keypress chirps from grating.
+ */
+
+import { logError } from "@/lib/errors";
+
+type EngineOptions = {
+  /** Master volume 0..1 applied on top of per-call volume. */
+  masterVolume: number;
+  /** When false, all play() calls are no-ops. */
+  enabled: boolean;
+};
+
+type PlayOptions = {
+  /** 0..1, multiplied with master volume. */
+  volume?: number;
+  /** ±fraction of playbackRate jitter; 0.05 = ±5%. */
+  pitchVariance?: number;
+  /** Skip if the same sound was played within this many ms. Prevents audible doubling on rapid triggers. */
+  throttleMs?: number;
+};
+
+class SoundEffectsEngine {
+  private ctx: AudioContext | null = null;
+  private masterGain: GainNode | null = null;
+  private limiter: DynamicsCompressorNode | null = null;
+  private buffers = new Map<string, AudioBuffer>();
+  private loading = new Map<string, Promise<AudioBuffer | null>>();
+  private lastPlayedAt = new Map<string, number>();
+  private options: EngineOptions = { masterVolume: 0.02, enabled: true };
+
+  setOptions(next: Partial<EngineOptions>) {
+    this.options = { ...this.options, ...next };
+    if (this.masterGain) {
+      this.masterGain.gain.value = this.options.masterVolume;
+    }
+  }
+
+  /** Lazy AudioContext init. Browsers (and Electron in some configs) start it suspended until a user gesture. */
+  private getContext(): AudioContext | null {
+    if (this.ctx) return this.ctx;
+    try {
+      const Ctor =
+        window.AudioContext ??
+        (window as unknown as { webkitAudioContext?: typeof AudioContext })
+          .webkitAudioContext;
+      if (!Ctor) return null;
+      this.ctx = new Ctor();
+      this.masterGain = this.ctx.createGain();
+      this.masterGain.gain.value = this.options.masterVolume;
+
+      // Brickwall limiter: caps peaks regardless of system volume so the
+      // click stays controlled when the OS volume is cranked. Threshold sets
+      // the ceiling; high ratio + fast attack make it a hard limiter.
+      this.limiter = this.ctx.createDynamicsCompressor();
+      this.limiter.threshold.value = -24; // dB ceiling for peaks
+      this.limiter.knee.value = 0;
+      this.limiter.ratio.value = 20;
+      this.limiter.attack.value = 0.001;
+      this.limiter.release.value = 0.08;
+
+      this.masterGain.connect(this.limiter);
+      this.limiter.connect(this.ctx.destination);
+      return this.ctx;
+    } catch (err) {
+      logError(err, { scope: "soundEffects.createContext" });
+      return null;
+    }
+  }
+
+  /**
+   * Preload a sound by name from a URL. Safe to call multiple times — caches.
+   * Missing/failed loads resolve to null and the sound silently no-ops on play.
+   */
+  preload(name: string, url: string): Promise<AudioBuffer | null> {
+    if (this.buffers.has(name)) {
+      return Promise.resolve(this.buffers.get(name)!);
+    }
+    const existing = this.loading.get(name);
+    if (existing) return existing;
+
+    const ctx = this.getContext();
+    if (!ctx) return Promise.resolve(null);
+
+    const promise = fetch(url)
+      .then((res) => {
+        if (!res.ok) throw new Error(`HTTP ${res.status} loading ${url}`);
+        return res.arrayBuffer();
+      })
+      .then((data) => ctx.decodeAudioData(data))
+      .then((buffer) => {
+        this.buffers.set(name, buffer);
+        return buffer;
+      })
+      .catch((err) => {
+        logError(err, { scope: "soundEffects.preload", name });
+        return null;
+      });
+
+    this.loading.set(name, promise);
+    return promise;
+  }
+
+  play(name: string, opts: PlayOptions = {}) {
+    if (!this.options.enabled) return;
+
+    const buffer = this.buffers.get(name);
+    if (!buffer) return; // silently skip if not loaded
+
+    const ctx = this.ctx;
+    const master = this.masterGain;
+    if (!ctx || !master) return;
+
+    // Resume suspended context (autoplay policies). Resume is async but
+    // start(0) is queued correctly once the context resumes.
+    if (ctx.state === "suspended") {
+      void ctx.resume().catch((err) =>
+        logError(err, { scope: "soundEffects.resume" }),
+      );
+    }
+
+    const throttleMs = opts.throttleMs ?? 15;
+    const now = ctx.currentTime * 1000;
+    const last = this.lastPlayedAt.get(name) ?? -Infinity;
+    if (now - last < throttleMs) return;
+    this.lastPlayedAt.set(name, now);
+
+    const source = ctx.createBufferSource();
+    source.buffer = buffer;
+
+    const variance = opts.pitchVariance ?? 0.04;
+    if (variance > 0) {
+      // Centered around 1.0; e.g. variance 0.04 → 0.96..1.04
+      const jitter = 1 + (Math.random() * 2 - 1) * variance;
+      source.playbackRate.value = jitter;
+    }
+
+    const gain = ctx.createGain();
+    gain.gain.value = opts.volume ?? 1;
+
+    source.connect(gain).connect(master);
+    source.start(0);
+  }
+}
+
+export const soundEffects = new SoundEffectsEngine();
+export type { PlayOptions };

js/src/lib/sound-effects/sound-effects-provider.tsx

@@ -0,0 +1,102 @@
+import { useEffect } from "react";
+import { preloadAllSounds, playSound } from "./sounds";
+
+/**
+ * Mounts global HUD sound behavior:
+ * - Preloads every registered sound file once.
+ * - Plays "click" on any click whose target (or ancestor) is recognizably
+ *   clickable: <button>, <a>, role="button"/etc., or `cursor: pointer`.
+ *   Centralizing here means div/span clickables get sound automatically
+ *   without touching every call site.
+ * - Plays "key-tap" on keydown OUTSIDE text inputs, so navigating menus and
+ *   overlays feels tactile but typing into compose stays silent.
+ */
+export function SoundEffectsProvider({ children }: { children: React.ReactNode }) {
+  useEffect(() => {
+    preloadAllSounds();
+  }, []);
+
+  useEffect(() => {
+    const handler = (e: MouseEvent) => {
+      if (e.button !== 0) return; // left click only
+      if (!(e.target instanceof Element)) return;
+      if (isClickable(e.target)) playSound("click");
+    };
+    document.addEventListener("click", handler);
+    return () => document.removeEventListener("click", handler);
+  }, []);
+
+  useEffect(() => {
+    const handler = (e: KeyboardEvent) => {
+      if (e.repeat) return;
+      if (isPureModifier(e.key)) return;
+      if (isTextInputTarget(e.target)) return;
+
+      if (e.key === "Escape" || e.key === "Enter" || e.key === "Tab") {
+        playSound("key-action");
+      } else {
+        playSound("key-tap");
+      }
+    };
+    window.addEventListener("keydown", handler);
+    return () => window.removeEventListener("keydown", handler);
+  }, []);
+
+  return children;
+}
+
+const CLICKABLE_ROLES = new Set([
+  "button",
+  "link",
+  "menuitem",
+  "menuitemcheckbox",
+  "menuitemradio",
+  "tab",
+  "switch",
+  "checkbox",
+  "radio",
+  "option",
+]);
+
+/**
+ * Walks up to MAX_DEPTH ancestors looking for a recognizably-clickable element.
+ * Tag/role checks are cheap — getComputedStyle is the fallback for div-style
+ * clickables that only signal intent through `cursor: pointer`.
+ */
+function isClickable(target: Element): boolean {
+  const MAX_DEPTH = 6;
+  let el: Element | null = target;
+  for (let depth = 0; el && depth < MAX_DEPTH; depth++, el = el.parentElement) {
+    const tag = el.tagName;
+    if (tag === "BUTTON" || tag === "A" || tag === "SUMMARY") return true;
+    const role = el.getAttribute("role");
+    if (role && CLICKABLE_ROLES.has(role)) return true;
+    if (window.getComputedStyle(el).cursor === "pointer") return true;
+  }
+  return false;
+}
+
+function isPureModifier(key: string): boolean {
+  return key === "Shift" || key === "Control" || key === "Meta" || key === "Alt";
+}
+
+function isTextInputTarget(target: EventTarget | null): boolean {
+  if (!(target instanceof HTMLElement)) return false;
+  const tag = target.tagName;
+  if (tag === "TEXTAREA") return true;
+  if (tag === "INPUT") {
+    const type = (target as HTMLInputElement).type;
+    return (
+      type === "" ||
+      type === "text" ||
+      type === "search" ||
+      type === "email" ||
+      type === "url" ||
+      type === "password" ||
+      type === "tel" ||
+      type === "number"
+    );
+  }
+  if (target.isContentEditable) return true;
+  return false;
+}

js/src/lib/sound-effects/sounds.ts

@@ -0,0 +1,57 @@
+/**
+ * Sound registry. To add a new effect, drop the file under
+ * `js/assets/sounds/` and add a line to REGISTERED below.
+ *
+ * Names referenced from code that aren't in REGISTERED fall back to "click",
+ * so the system feels alive end-to-end with one asset and stays consistent
+ * as more are added.
+ */
+
+import clickUrl from "../../../assets/sounds/click.mp3";
+import { soundEffects, type PlayOptions } from "./engine";
+
+/** Effect names referenced from code. Unmapped names fall back to "click". */
+export type SoundName =
+  | "click"
+  | "key-tap"
+  | "key-action"
+  | "submit"
+  | "error"
+  | "open"
+  | "close";
+
+/** Files that exist on disk. Add a line when you drop a new file. */
+const REGISTERED: Partial<Record<SoundName, string>> = {
+  click: clickUrl,
+};
+
+/** Per-sound default play options. Tuned for HUD feel — subtle and slightly varied. */
+const SOUND_DEFAULTS: Record<SoundName, PlayOptions> = {
+  click: { volume: 0.7, pitchVariance: 0.04 },
+  "key-tap": { volume: 0.4, pitchVariance: 0.08, throttleMs: 25 },
+  "key-action": { volume: 0.6, pitchVariance: 0.04 },
+  submit: { volume: 0.85, pitchVariance: 0.02 },
+  error: { volume: 0.7, pitchVariance: 0 },
+  open: { volume: 0.6, pitchVariance: 0.03 },
+  close: { volume: 0.5, pitchVariance: 0.03 },
+};
+
+const FALLBACK: SoundName = "click";
+
+let preloaded = false;
+
+/** Preload every registered sound file. Idempotent. Called once at app start. */
+export function preloadAllSounds(): void {
+  if (preloaded) return;
+  preloaded = true;
+  for (const [name, url] of Object.entries(REGISTERED)) {
+    if (url) void soundEffects.preload(name, url);
+  }
+}
+
+/** Play a sound by name. Falls back to "click" if no dedicated file is registered. */
+export function playSound(name: SoundName, override?: PlayOptions) {
+  const defaults = SOUND_DEFAULTS[name];
+  const resolvedName = REGISTERED[name] ? name : FALLBACK;
+  soundEffects.play(resolvedName, { ...defaults, ...override });
+}

js/src/lib/sound-effects/use-sound-effect.ts

@@ -0,0 +1,15 @@
+import { useCallback } from "react";
+import { playSound, type SoundName } from "./sounds";
+import type { PlayOptions } from "./engine";
+
+/**
+ * Returns a stable `play(name, opts?)` function. The engine respects the
+ * global enabled/volume state from the sound effects store, so callers don't
+ * need to subscribe themselves.
+ */
+export function useSoundEffect() {
+  const play = useCallback((name: SoundName, opts?: PlayOptions) => {
+    playSound(name, opts);
+  }, []);
+  return { play };
+}

js/src/stores/sound-effects-store.ts

@@ -0,0 +1,40 @@
+import { create } from "zustand";
+import { soundEffects } from "@/lib/sound-effects/engine";
+
+const ENABLED_KEY = "llink:soundEffects-enabled";
+const DEFAULT_ENABLED = true;
+
+function loadEnabled(): boolean {
+  try {
+    const v = localStorage.getItem(ENABLED_KEY);
+    return v === null ? DEFAULT_ENABLED : v === "true";
+  } catch {
+    return DEFAULT_ENABLED;
+  }
+}
+
+interface SoundEffectsState {
+  enabled: boolean;
+  setEnabled: (enabled: boolean) => void;
+}
+
+export const useSoundEffectsStore = create<SoundEffectsState>((set) => {
+  const initialEnabled = loadEnabled();
+
+  // Sync engine with persisted state on first load. Master volume is a fixed
+  // tuning constant in the engine — no UI control.
+  soundEffects.setOptions({ enabled: initialEnabled });
+
+  return {
+    enabled: initialEnabled,
+    setEnabled: (enabled) => {
+      set({ enabled });
+      soundEffects.setOptions({ enabled });
+      try {
+        localStorage.setItem(ENABLED_KEY, String(enabled));
+      } catch {
+        // storage unavailable
+      }
+    },
+  };
+});