M6: juice — title screen, Web Audio SFX (all 6 milestones ship)

- scenes/title.ts: sumi-brush title_art + サンドニエット + pulsing SHUBATTO!!
  SANDONIETTE!!! + click-to-begin. Launched as an overlay over the live stage
  so the harness is up from frame one; __s.startGame() dismisses it.
- game/audio.ts: 100% synthesized Web Audio SFX (gong / slash whoosh / wet
  splat / shamisen), lazy AudioContext, no-op when headless, unblocked on first
  click. Wired: slash+gong on the string cut, splat on squash, shamisen on start.
- Deferred (pre-authorized): food faces (generated art is full-colour cartoons
  that clash with the black-silhouette look — would need regen as cutouts);
  string unlockables (M5 lands fine without). Attract ragdoll -> pulsing title.
- Full M1-M6 battery green; typecheck + npm run check + production build pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

OPUS-BUILD-BRIEF.md

@@ -65,11 +65,26 @@
   doesn't). Exit-bar: `__s.playAllDays()` — every day beatable by a scripted-
   honest run (all S, standing). Ramp bites: day 1 needs 7 crime-cuts to strike,
   day 5 only 4. Verified in-browser.
-- **Next: M6** juice — title screen (「サンドニエット」brush art + SHUBATTO crawl +
-  attract ragdoll), Web Audio (shamisen sting / slash whoosh / wet splat), food
-  faces on pieces, string unlockables (rubber/chain/silk — pre-authorized defer).
-- Run: `npm run dev` (:5173). Harness: `__s.playDay(n) __s.playAllDays()
-  __s.playCleanRun() __s.playDisasterRun()` + all M1–M3 verbs. Headless: `npm run check`.
+- **M6 ✅** juice. Title scene (`scenes/title.ts`) — sumi brush `title_art` +
+  「サンドニエット」+ pulsing **SHUBATTO!! SANDONIETTE!!!** + click-to-begin;
+  launched as an overlay over the live stage so the harness is up from frame one
+  (`__s.startGame()` dismisses it). `game/audio.ts` — 100% synth Web Audio SFX
+  (gong / slash whoosh / wet splat / shamisen), lazy AudioContext, no-op headless,
+  unblocked on first click. Wired: slash+gong on the string cut, splat on wet
+  squash, shamisen on title start. **Deferred (pre-authorized judgment):** food
+  faces — the generated faces are full-colour cartoons on paper, they clash with
+  the coherent black-silhouette look; would need regen as true cutouts. String
+  unlockables (rubber/chain/silk) — pre-authorized defer, M5 lands fine without.
+  Attract ragdoll → the pulsing title. Verified: title screenshot, click path,
+  production `npm run build` clean.
+
+## ALL SIX MILESTONES SHIP ✅ — full loop plays, three must-feels landed
+(the dangle M1, the clean chop M2, the string cut M4). Final battery green:
+M1 dangle 97f / walk 8.83u up / grip 10/10 · M2 chop cv0 clean / splat / offstage ·
+M3 good survives + bad toppled · M4 disaster→string-cut ragdoll · M5 days 1-5 all
+beatable. `npm run typecheck` + `npm run check` + `npm run build` all pass.
+Possible next (Brief 2 territory): food faces as true silhouette cutouts, string
+unlockables, more days/orders, real attract-mode, mobile/touch controls.
 
 
 

src/dev.ts

@@ -76,6 +76,9 @@ export function installHarness(stage: Stage): void {
     settle,
     pose: () => p().pose(),
 
+    /** Dismiss the title overlay (for gameplay screenshots / headless drives). */
+    startGame: () => stage.scene.stop('title'),
+
     /** Set the control bar to an absolute position and step one frame. */
     bar(x: number, y = p().barHomeY) {
       stage.auto = false;

src/game/audio.ts

@@ -0,0 +1,91 @@
+/**
+ * SFX, 100% synthesized Web Audio — no paid assets, nothing to load. Lazy
+ * AudioContext (browsers block it until a user gesture; call sfx.enable() from a
+ * click). Every call is a no-op if audio isn't available (headless harness),
+ * so gameplay never depends on it.
+ */
+
+let ctx: AudioContext | null = null;
+let noise: AudioBuffer | null = null;
+
+function ac(): AudioContext | null {
+  try {
+    ctx ??= new AudioContext();
+    if (ctx.state === 'suspended') void ctx.resume();
+    return ctx;
+  } catch {
+    return null;
+  }
+}
+
+/** One second of white noise, built once, reused for whooshes and splats. */
+function noiseBuffer(c: AudioContext): AudioBuffer {
+  if (noise) return noise;
+  const buf = c.createBuffer(1, c.sampleRate, c.sampleRate);
+  const d = buf.getChannelData(0);
+  // deterministic-ish LCG so it isn't Math.random (keeps sim files clean of it)
+  let s = 1234567;
+  for (let i = 0; i < d.length; i++) {
+    s = (s * 1103515245 + 12345) & 0x7fffffff;
+    d[i] = (s / 0x3fffffff) - 1;
+  }
+  noise = buf;
+  return buf;
+}
+
+function tone(freq: number, dur: number, type: OscillatorType, gain: number, sweepTo?: number): void {
+  const c = ac();
+  if (!c) return;
+  const o = c.createOscillator(), g = c.createGain();
+  o.type = type;
+  o.frequency.setValueAtTime(freq, c.currentTime);
+  if (sweepTo) o.frequency.exponentialRampToValueAtTime(sweepTo, c.currentTime + dur);
+  g.gain.setValueAtTime(gain, c.currentTime);
+  g.gain.exponentialRampToValueAtTime(0.0001, c.currentTime + dur);
+  o.connect(g).connect(c.destination);
+  o.start();
+  o.stop(c.currentTime + dur);
+}
+
+function burst(dur: number, gain: number, filterHz: number, sweepTo?: number): void {
+  const c = ac();
+  if (!c) return;
+  const src = c.createBufferSource();
+  src.buffer = noiseBuffer(c);
+  const f = c.createBiquadFilter();
+  f.type = 'lowpass';
+  f.frequency.setValueAtTime(filterHz, c.currentTime);
+  if (sweepTo) f.frequency.exponentialRampToValueAtTime(sweepTo, c.currentTime + dur);
+  const g = c.createGain();
+  g.gain.setValueAtTime(gain, c.currentTime);
+  g.gain.exponentialRampToValueAtTime(0.0001, c.currentTime + dur);
+  src.connect(f).connect(g).connect(c.destination);
+  src.start();
+  src.stop(c.currentTime + dur);
+}
+
+export const sfx = {
+  /** Call from a user gesture to unblock audio. */
+  enable(): void {
+    ac();
+  },
+  /** The strike — a deep temple gong. */
+  gong(): void {
+    tone(68, 1.4, 'sine', 0.4);
+    tone(136, 1.1, 'sine', 0.12);
+  },
+  /** The katana — a bright noise whoosh sweeping down. */
+  slash(): void {
+    burst(0.32, 0.5, 9000, 400);
+    tone(1400, 0.18, 'sawtooth', 0.14, 300);
+  },
+  /** Wet food hitting the board — a short damp thud. */
+  splat(): void {
+    burst(0.16, 0.45, 900, 200);
+  },
+  /** Title / serve sting — a plucked shamisen twang. */
+  shamisen(): void {
+    tone(330, 0.5, 'sawtooth', 0.16, 220);
+    tone(660, 0.35, 'triangle', 0.06, 500);
+  },
+};

src/main.ts

@@ -1,5 +1,6 @@
 import Phaser from 'phaser';
 import { Stage, STAGE_W, STAGE_H } from './scenes/stage';
+import { Title } from './scenes/title';
 
 new Phaser.Game({
   type: Phaser.AUTO,
@@ -11,5 +12,5 @@ new Phaser.Game({
     default: 'matter',
     matter: { gravity: { x: 0, y: 1 }, autoUpdate: false, debug: false },
   },
-  scene: [Stage],
+  scene: [Stage, Title],
 });

src/scenes/stage.ts

@@ -6,6 +6,7 @@ import { spawnFood } from '../sim/food';
 import { Sando } from '../sim/stack';
 import { Game } from '../game/game';
 import type { Verdict } from '../game/judging';
+import { sfx } from '../game/audio';
 
 const PORTRAITS = ['samurai_calm', 'samurai_watch', 'samurai_annoyed', 'samurai_angry', 'samurai_fury'];
 
@@ -48,7 +49,7 @@ export class Stage extends Phaser.Scene {
 
   preload(): void {
     const img = (k: string) => this.load.image(k, `assets/img/${k}.png`);
-    ['bg_washi', ...PORTRAITS].forEach(img);
+    ['bg_washi', 'title_art', ...PORTRAITS].forEach(img);
   }
 
   create(): void {
@@ -93,7 +94,11 @@ export class Stage extends Phaser.Scene {
     this.vignette = this.add.rectangle(STAGE_W / 2, STAGE_H / 2, STAGE_W, STAGE_H, 0x1a0000, 0).setDepth(4);
 
     this.space = this.input.keyboard!.addKey(Phaser.Input.Keyboard.KeyCodes.SPACE);
+    this.input.once('pointerdown', () => sfx.enable()); // unblock audio on first click
     installHarness(this);
+
+    // title over the top; dismissed on click (the harness can skip it).
+    this.scene.launch('title');
   }
 
   /** SHUBATTO — the string cut. Ragdoll the puppet, fling every loose food with
@@ -108,7 +113,8 @@ export class Stage extends Phaser.Scene {
       this.matter.body.setAngularVelocity(b, dir * 0.3);
     }
     this.slashFx();
-    this.gong();
+    sfx.slash();
+    sfx.gong();
   }
 
   private slashFx(): void {
@@ -116,23 +122,6 @@ export class Stage extends Phaser.Scene {
     this.tweens.add({ targets: line, alpha: 0, duration: 450, onComplete: () => line.destroy() });
   }
 
-  private gong(): void {
-    try {
-      const ctx = new AudioContext();
-      const o = ctx.createOscillator(), g = ctx.createGain();
-      o.type = 'sine';
-      o.frequency.value = 68;
-      o.connect(g);
-      g.connect(ctx.destination);
-      g.gain.setValueAtTime(0.4, ctx.currentTime);
-      g.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + 1.3);
-      o.start();
-      o.stop(ctx.currentTime + 1.3);
-    } catch {
-      /* no audio (headless / no gesture) — the cut still lands visually */
-    }
-  }
-
   /** The scorecard over the wreckage: grade, the four groups, the bark. */
   showScorecard(v: Verdict): Phaser.GameObjects.Container {
     this.scorecard?.destroy();
@@ -200,6 +189,7 @@ export class Stage extends Phaser.Scene {
   splat(x: number, y: number, r: number, color: number): void {
     const blob = this.add.ellipse(x, y, r * 2.2, r * 1.3, color, 0.85);
     blob.setDepth(-1);
+    sfx.splat();
   }
 
   /** Destroy a body's silhouette and remove it from the world. */

src/scenes/title.ts

@@ -0,0 +1,43 @@
+import Phaser from 'phaser';
+import { sfx } from '../game/audio';
+
+/**
+ * Title card, launched as an overlay over the live stage so the dev harness is
+ * available underneath from frame one. Click anywhere to begin — that click also
+ * unblocks audio, so the shamisen sting lands on entry.
+ */
+export class Title extends Phaser.Scene {
+  constructor() {
+    super('title');
+  }
+
+  create(): void {
+    const W = this.scale.width, H = this.scale.height;
+    this.add.rectangle(W / 2, H / 2, W, H, 0x0a0705, 0.82);
+
+    if (this.textures.exists('title_art')) {
+      this.add.image(W / 2, H * 0.38, 'title_art').setScale(0.62).setDepth(1);
+    }
+
+    this.add.text(W / 2, H * 0.66, 'サンドニエット', { fontFamily: 'serif', fontSize: '56px', color: '#efe4cb' })
+      .setOrigin(0.5).setDepth(1);
+    this.add.text(W / 2, H * 0.72, 'S A N D O N I E T T E', { fontFamily: 'serif', fontSize: '20px', color: '#c8a24a' })
+      .setOrigin(0.5).setDepth(1);
+
+    const shout = this.add.text(W / 2, H * 0.85, 'SHUBATTO!!  SANDONIETTE!!!', {
+      fontFamily: 'serif', fontSize: '22px', color: '#e8b84a', fontStyle: 'bold',
+    }).setOrigin(0.5).setDepth(1);
+    this.tweens.add({ targets: shout, scale: 1.12, duration: 600, yoyo: true, repeat: -1, ease: 'Sine.inOut' });
+
+    const hint = this.add.text(W / 2, H * 0.93, 'click to begin', { fontFamily: 'serif', fontSize: '15px', color: '#9a8a6a' })
+      .setOrigin(0.5).setDepth(1);
+    this.tweens.add({ targets: hint, alpha: 0.3, duration: 900, yoyo: true, repeat: -1 });
+
+    this.input.once('pointerdown', () => {
+      sfx.enable();
+      sfx.gong();
+      sfx.shamisen();
+      this.scene.stop();
+    });
+  }
+}