Notification sounds: hand-picked mp3 palette + error/milestone cues

Replace the synthesized WAV blips with curated mp3 effects:
- error ("haiya") plays on LLM-down/timeout and save failures, debounced
  and on-transition-only, with a reassuring bilingual bubble
- milestone (Chinese fanfare) now fires every 100 words
- all other notifications draw from a rotating pop pool that never repeats
  the last sound, so batches of suggestions/tips stay lively

playPop() replaces the per-suggestion-type sound map; thread llmDown through
PetalCompanion -> useCompanion for the error cue. Old synth WAVs removed.

Claude-Session: https://claude.ai/code/session_016Yr6jELuRc7hyzYLccQKZd

web/src/components/Companion/useCompanion.ts

@@ -3,6 +3,7 @@ import type { SaveStatus } from '../../hooks/useAutoSave'
 import {
   BREAKS,
   ENCOURAGEMENTS,
+  ERRORS,
   GREETING,
   MILESTONES,
   TIPS,
@@ -12,13 +13,13 @@ import {
   type Line,
 } from './tips'
 import { analyzeProse } from './prose'
-import { playSound } from '../../audio/sounds'
+import { playPop, playSound, type SoundName } from '../../audio/sounds'
 
 // The kitten's expression. Maps to a Lottie animation when assets are present,
 // otherwise to an emoji placeholder (see PetalCompanion).
 export type Mood = 'idle' | 'happy' | 'talking' | 'sleeping' | 'celebrate'
 
-export type BubbleTone = 'cheer' | 'tip' | 'break'
+export type BubbleTone = 'cheer' | 'tip' | 'break' | 'error'
 export interface Bubble extends Line {
   tone: BubbleTone
 }
@@ -26,6 +27,9 @@ export interface Bubble extends Line {
 interface Signals {
   wordCount: number
   saveStatus: SaveStatus
+  // True while the writing-assist LLM is unreachable (timeout / down). A
+  // false→true flip earns a gentle "haiya".
+  llmDown: boolean
   // Monotonic counters bumped by the app on each editor change / accepted
   // suggestion — lets the companion react without a full event bus.
   editTick: number
@@ -62,7 +66,7 @@ function readBubbleMs(b: Bubble): number {
 // useCompanion is the behavior engine: it watches writing signals and decides
 // when the kitten speaks, what mood it shows, and how to pace itself so the
 // companion feels alive without interrupting. UI-agnostic — returns state only.
-export function useCompanion({ wordCount, saveStatus, editTick, acceptTick, text }: Signals) {
+export function useCompanion({ wordCount, saveStatus, llmDown, editTick, acceptTick, text }: Signals) {
   const [mood, setMood] = useState<Mood>('idle')
   const [bubble, setBubble] = useState<Bubble | null>(null)
 
@@ -88,7 +92,8 @@ export function useCompanion({ wordCount, saveStatus, editTick, acceptTick, text
 
   // Show a bubble + talking mood, then settle back. `proactive` messages respect
   // the spacing floor; user-triggered ones (cheers) always go through.
-  const say = useCallback((b: Bubble, opts?: { proactive?: boolean; celebrate?: boolean }) => {
+  const say = useCallback(
+    (b: Bubble, opts?: { proactive?: boolean; celebrate?: boolean; sound?: SoundName }) => {
     const t = now()
     if (opts?.proactive) {
       if (bubble) return
@@ -96,11 +101,11 @@ export function useCompanion({ wordCount, saveStatus, editTick, acceptTick, text
       lastProactive.current = t
     }
     sleeping.current = false
-    // A soft sound to match the bubble's mood — celebrations cheer, gentle
-    // cheers sparkle, break nudges chime, and tips give a little bubble pop.
-    playSound(
-      opts?.celebrate ? 'cheer' : b.tone === 'cheer' ? 'shimmer' : b.tone === 'break' ? 'chime' : 'pop',
-    )
+    // A sound to match the bubble: callers can name a specific one (the milestone
+    // fanfare, the "haiya" on errors); everything else gets a rotating pop so the
+    // same blip never repeats back to back.
+    if (opts?.sound) playSound(opts.sound)
+    else playPop()
     setBubble(b)
     setMood(opts?.celebrate ? 'celebrate' : 'talking')
     clearTimeout(bubbleTimer.current)
@@ -196,11 +201,39 @@ export function useCompanion({ wordCount, saveStatus, editTick, acceptTick, text
       const n = MILESTONES[nextMilestone.current]
       nextMilestone.current += 1
       // Skip silently if we're just loading a long doc (no edits yet).
-      if (!firstEdit.current) say({ ...milestoneLine(n), tone: 'cheer' }, { celebrate: true })
+      if (!firstEdit.current)
+        say({ ...milestoneLine(n), tone: 'cheer' }, { celebrate: true, sound: 'milestone' })
     }
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [wordCount])
 
+  // Trouble — a save failed or the writing-assist LLM went unreachable. Play the
+  // playful "haiya" and reassure her, but never spam: at most one per gap, and
+  // only on the *transition* into trouble (not while it lingers).
+  const lastError = useRef(0)
+  const ERROR_GAP = 20_000
+  const wasLlmDown = useRef(false)
+  const haiya = useCallback(() => {
+    const t = now()
+    if (t - lastError.current < ERROR_GAP) {
+      playSound('error') // still acknowledge it, just without a fresh bubble
+      return
+    }
+    lastError.current = t
+    say({ ...pick(ERRORS), tone: 'error' }, { sound: 'error' })
+  }, [say])
+
+  useEffect(() => {
+    if (saveStatus === 'error') haiya()
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [saveStatus])
+
+  useEffect(() => {
+    if (llmDown && !wasLlmDown.current) haiya()
+    wasLlmDown.current = llmDown
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [llmDown])
+
   // Occasional gentle cheer on a successful save (kept rare so it isn't noise).
   useEffect(() => {
     if (saveStatus === 'saved' && Math.random() < 0.18) {