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Flappy Sky — polished single-file Flappy clone built from GPT-5.1 artifact

4e26357580abdb493d2fbc35cd8e387be0ebc35f · 2026-07-23 15:44:33 -0700 · Steve

Fixes: idle-bob drift, mobile double-flap, added pause/blur-pause, soft ceiling,
ground plane, WebAudio SFX, medals, screen shake, fixed-step physics, reduced-motion.
Verified headless (Playwright): score 31, gameover, pause, best persist, 0 errors.

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

Files touched

Diff

commit 4e26357580abdb493d2fbc35cd8e387be0ebc35f
Author: Steve <steve@designerwallcoverings.com>
Date:   Thu Jul 23 15:44:33 2026 -0700

    Flappy Sky — polished single-file Flappy clone built from GPT-5.1 artifact
    
    Fixes: idle-bob drift, mobile double-flap, added pause/blur-pause, soft ceiling,
    ground plane, WebAudio SFX, medals, screen shake, fixed-step physics, reduced-motion.
    Verified headless (Playwright): score 31, gameover, pause, best persist, 0 errors.
    
    Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 .gitignore   |   8 +
 README.md    |  37 +++
 index.html   | 827 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 test/e2e.mjs |  55 ++++
 4 files changed, 927 insertions(+)

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..1924158
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,8 @@
+node_modules/
+.env*
+tmp/
+*.log
+.DS_Store
+dist/
+build/
+.next/
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..82046ce
--- /dev/null
+++ b/README.md
@@ -0,0 +1,37 @@
+# Flappy Sky
+
+A polished, **single-file, zero-dependency** Flappy-Bird-style game. Pure HTML5
+Canvas 2D + WebAudio — no libraries, no external assets. Open `index.html` in any
+modern browser and play.
+
+## Controls
+- **Flap** — Space / ↑ / Enter / Click / Tap
+- **Pause** — `P` (also auto-pauses when the tab loses focus)
+- **Mute** — `M` (or the 🔊 button)
+
+## Features
+- Fixed-timestep physics (120 Hz) → identical feel at any refresh rate
+- Increasing difficulty (gap shrinks, pipes speed up & spawn faster up to score 25)
+- Parallax background: twinkling stars, two scrolling hill layers, drifting haze
+- Scrolling textured ground; soft ceiling (clamp, not instant death — classic feel)
+- Accurate circle-vs-rectangle collision
+- Death feedback: screen shake, red flash, particle burst, hit-stop
+- Medals on game over (🍃 / 🥉 / 🥈 / 🥇 / 💎) + persistent best score
+- Procedural WebAudio SFX (flap / score / hit) — no audio files
+- Responsive + DPR-aware canvas, mobile-friendly, safe-area insets
+- Respects `prefers-reduced-motion`
+
+## Provenance
+Built from GPT-5.1's Model Arena "All-Models — Flappy Clone" artifact. Fixes over
+the original:
+- Idle bird bob no longer accumulates positional drift (oscillates around a fixed base)
+- No double-flap on touch (unified Pointer Events + debounce)
+- Auto-pause on tab blur / visibility change
+- Soft ceiling instead of unfair instant top-edge death
+- Added ground plane, audio, medals, pause, screen shake, reduced-motion support
+- Frame-rate-independent fixed-step physics
+
+Mirrored into the Agent Abrams Arcade (`games-agentabrams`) as `flappy-clone`.
+
+## Test
+Headless Playwright play-through in `test/e2e.mjs`.
diff --git a/index.html b/index.html
new file mode 100644
index 0000000..b92f2c2
--- /dev/null
+++ b/index.html
@@ -0,0 +1,827 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="UTF-8" />
+<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no, viewport-fit=cover" />
+<meta name="theme-color" content="#0e1018" />
+<meta name="description" content="Flappy Sky — a polished, self-contained Flappy-Bird-style game. Space, click, or tap to flap through neon gates." />
+<title>Flappy Sky</title>
+<style>
+  :root { --ink: #f8f8ff; }
+
+  html, body {
+    margin: 0;
+    padding: 0;
+    background: #0e1018;
+    overflow: hidden;
+    height: 100%;
+    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
+    -webkit-tap-highlight-color: transparent;
+    touch-action: none;
+  }
+
+  canvas {
+    display: block;
+    background: radial-gradient(circle at 20% 20%, #586df2 0, #243046 40%, #0e1018 100%);
+    /* keeps focus outline from ever painting a box around the game */
+    outline: none;
+  }
+
+  /* --- overlay + ui --------------------------------------------------- */
+  #overlay {
+    position: absolute;
+    inset: 0;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    pointer-events: none;
+    user-select: none;
+    padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left);
+    box-sizing: border-box;
+  }
+
+  #ui {
+    color: var(--ink);
+    text-align: center;
+    text-shadow: 0 2px 14px rgba(0,0,0,0.8);
+    transition: opacity .25s ease, transform .25s ease;
+    max-width: 92vw;
+  }
+  #ui.pop { animation: pop .4s cubic-bezier(.2,1.3,.4,1) both; }
+  @keyframes pop { 0% { transform: scale(.85); opacity: 0; } 100% { transform: scale(1); opacity: 1; } }
+
+  #title {
+    font-size: clamp(34px, 8vw, 54px);
+    font-weight: 900;
+    letter-spacing: 0.08em;
+    text-transform: uppercase;
+    margin: 0 0 6px;
+    background: linear-gradient(180deg, #fff 0%, #b9d3ff 60%, #72fffb 100%);
+    -webkit-background-clip: text;
+    background-clip: text;
+    -webkit-text-fill-color: transparent;
+    filter: drop-shadow(0 3px 10px rgba(0,0,0,.6));
+  }
+
+  #subtitle { font-size: clamp(13px, 3.4vw, 16px); opacity: 0.85; margin-bottom: 22px; }
+
+  /* medal + result block on game over */
+  #result { display: none; margin-bottom: 18px; }
+  #result.show { display: block; }
+  #medal {
+    width: 92px; height: 92px; margin: 4px auto 10px;
+    border-radius: 50%;
+    display: grid; place-items: center;
+    font-size: 34px;
+    box-shadow: 0 0 0 4px rgba(255,255,255,.15), 0 8px 24px rgba(0,0,0,.55), inset 0 2px 10px rgba(255,255,255,.4);
+    position: relative;
+  }
+  #medal::after {
+    content: ""; position: absolute; inset: 8px; border-radius: 50%;
+    border: 2px dashed rgba(255,255,255,.35);
+  }
+  .scoreline { display:flex; gap: 26px; justify-content:center; margin: 6px 0 2px; }
+  .scoreline .k { font-size: 11px; letter-spacing:.18em; text-transform:uppercase; opacity:.65; }
+  .scoreline .v { font-size: 30px; font-weight: 800; line-height: 1.05; }
+  #newbest { font-size: 12px; font-weight: 800; letter-spacing:.12em; color:#ffe07a;
+             text-transform: uppercase; margin-top: 6px; opacity: 0; }
+  #newbest.show { opacity: 1; animation: flick .8s ease-in-out infinite alternate; }
+  @keyframes flick { from { filter: brightness(1);} to { filter: brightness(1.6);} }
+
+  #prompt {
+    font-size: clamp(14px, 3.6vw, 17px);
+    opacity: 0.95;
+    display: inline-flex; align-items: center; gap: 8px;
+    padding: 10px 18px; border-radius: 999px;
+    background: rgba(255,255,255,.08);
+    border: 1px solid rgba(255,255,255,.16);
+    backdrop-filter: blur(3px);
+    animation: breathe 1.8s ease-in-out infinite;
+  }
+  @keyframes breathe { 0%,100% { transform: translateY(0);} 50% { transform: translateY(-4px);} }
+
+  /* --- HUD ------------------------------------------------------------ */
+  #scoreTop {
+    position: absolute;
+    top: calc(14px + env(safe-area-inset-top));
+    left: 50%;
+    transform: translateX(-50%);
+    color: #fff;
+    font-size: clamp(34px, 9vw, 52px);
+    font-weight: 900;
+    text-shadow: 0 3px 0 rgba(0,0,0,.35), 0 0 18px rgba(120,180,255,.5);
+    pointer-events: none;
+    transition: transform .08s ease;
+  }
+  #scoreTop.bump { transform: translateX(-50%) scale(1.28); }
+  #scoreTop.hidden { display: none; }
+
+  #best {
+    position: absolute;
+    top: calc(16px + env(safe-area-inset-top));
+    right: calc(14px + env(safe-area-inset-right));
+    color: rgba(255,255,255,.8);
+    font-size: 13px; font-weight: 700; letter-spacing:.05em;
+    text-shadow: 0 0 6px rgba(0,0,0,.8);
+    pointer-events: none;
+  }
+  #best.hidden { display: none; }
+
+  /* control buttons (mute / pause) */
+  #controls {
+    position: absolute;
+    top: calc(12px + env(safe-area-inset-top));
+    left: calc(12px + env(safe-area-inset-left));
+    display: flex; gap: 8px;
+  }
+  .btn {
+    width: 38px; height: 38px; border-radius: 10px;
+    border: 1px solid rgba(255,255,255,.18);
+    background: rgba(255,255,255,.07);
+    color: #fff; font-size: 17px; cursor: pointer;
+    display: grid; place-items: center;
+    backdrop-filter: blur(4px);
+    transition: background .15s ease, transform .1s ease;
+    -webkit-user-select: none; user-select: none;
+  }
+  .btn:hover { background: rgba(255,255,255,.16); }
+  .btn:active { transform: scale(.9); }
+
+  #smallInfo {
+    position: absolute;
+    bottom: calc(9px + env(safe-area-inset-bottom));
+    right: calc(12px + env(safe-area-inset-right));
+    font-size: 11px;
+    color: rgba(255,255,255,0.4);
+    text-shadow: 0 0 4px rgba(0,0,0,0.8);
+    pointer-events: none;
+  }
+
+  /* pause veil */
+  #pauseVeil {
+    position: absolute; inset: 0;
+    display: none; align-items: center; justify-content: center;
+    background: rgba(6,8,16,.55); backdrop-filter: blur(2px);
+    color: #fff; font-size: clamp(22px, 6vw, 34px); font-weight: 800;
+    letter-spacing: .12em; text-transform: uppercase; pointer-events: none;
+  }
+  #pauseVeil.show { display: flex; }
+
+  .hidden { display: none; }
+</style>
+</head>
+<body>
+<canvas id="game" tabindex="-1" aria-label="Flappy Sky game canvas"></canvas>
+
+<div id="scoreTop" class="hidden"><span id="scoreVal">0</span></div>
+<div id="best" class="hidden">Best <span id="bestVal">0</span></div>
+
+<div id="controls">
+  <button id="muteBtn" class="btn" title="Mute (M)" aria-label="Toggle sound">🔊</button>
+  <button id="pauseBtn" class="btn" title="Pause (P)" aria-label="Pause game">⏸</button>
+</div>
+
+<div id="overlay">
+  <div id="ui" class="pop">
+    <div id="title">FLAPPY SKY</div>
+    <div id="subtitle">Flap through the neon gates. How far can you fly?</div>
+
+    <div id="result">
+      <div id="medal">🥇</div>
+      <div class="scoreline">
+        <div><div class="k">Score</div><div class="v" id="rScore">0</div></div>
+        <div><div class="k">Best</div><div class="v" id="rBest">0</div></div>
+      </div>
+      <div id="newbest">★ New Best! ★</div>
+    </div>
+
+    <div id="prompt">Press <b>Space</b>, Click, or Tap to Start</div>
+  </div>
+</div>
+
+<div id="pauseVeil">Paused</div>
+
+<div id="smallInfo">Space / Click / Tap · P pause · M mute</div>
+
+<script>
+(function () {
+  "use strict";
+
+  const canvas = document.getElementById("game");
+  const ctx = canvas.getContext("2d", { alpha: false });
+
+  // ---- DOM refs -------------------------------------------------------
+  const overlay   = document.getElementById("overlay");
+  const ui        = document.getElementById("ui");
+  const uiPrompt  = document.getElementById("prompt");
+  const result    = document.getElementById("result");
+  const medalEl    = document.getElementById("medal");
+  const rScore    = document.getElementById("rScore");
+  const rBest     = document.getElementById("rBest");
+  const newbest   = document.getElementById("newbest");
+  const scoreTop  = document.getElementById("scoreTop");
+  const scoreVal  = document.getElementById("scoreVal");
+  const bestBox   = document.getElementById("best");
+  const bestVal   = document.getElementById("bestVal");
+  const pauseVeil = document.getElementById("pauseVeil");
+  const muteBtn   = document.getElementById("muteBtn");
+  const pauseBtn  = document.getElementById("pauseBtn");
+
+  const reduceMotion = window.matchMedia &&
+    window.matchMedia("(prefers-reduced-motion: reduce)").matches;
+
+  // ---- viewport -------------------------------------------------------
+  let W, H, scale, groundH;
+  function resize() {
+    const dpr = Math.min(window.devicePixelRatio || 1, 2.5);
+    W = window.innerWidth;
+    H = window.innerHeight;
+    canvas.width  = Math.round(W * dpr);
+    canvas.height = Math.round(H * dpr);
+    ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
+    scale = Math.min(Math.max(Math.min(W, H) / 600, 0.6), 1.6);
+    groundH = Math.round(Math.min(90 * scale, H * 0.14));
+    initBackground();
+    // keep the idle bird sensibly placed after a rotate/resize
+    if (bird && state !== "playing") { bird.x = W * 0.3; bird.baseY = H * 0.42; }
+  }
+
+  // ---- tuning ---------------------------------------------------------
+  const GRAVITY = 1500;      // px/s^2
+  const FLAP    = -450;      // impulse
+  const PIPE_W  = 84;        // pipe width (px, scaled at draw)
+  const PIPE_INTERVAL_START = 1500;  // ms between pipes
+  const PIPE_INTERVAL_MIN   = 950;
+  const GAP_START = 200;     // px gap (pre-scale)
+  const GAP_MIN   = 138;
+  const SPEED_START = 200;   // px/s
+  const SPEED_MAX   = 400;
+  const RAMP = 25;           // score at which difficulty maxes out
+  const FIXED_DT = 1 / 120;  // physics step
+
+  // ---- state ----------------------------------------------------------
+  let state = "ready"; // ready | playing | paused | gameover
+  let bird, pipes, particles, stars, hills, ground;
+  let score = 0, best = 0;
+  let pipeInterval, gapSize, speed;
+  let timeSincePipe = 0;
+  let shake = 0, flashAlpha = 0, hitStop = 0;
+  let lastTime = 0, acc = 0;
+  let muted = false;
+  let bgScroll = 0;
+
+  try { best = parseInt(localStorage.getItem("flappy_sky_best"), 10) || 0; } catch (e) {}
+  try { muted = localStorage.getItem("flappy_sky_muted") === "1"; } catch (e) {}
+  bestVal.textContent = best;
+
+  // ---- audio (WebAudio, no assets) -----------------------------------
+  let actx = null;
+  function audio() {
+    if (!actx) {
+      try { actx = new (window.AudioContext || window.webkitAudioContext)(); }
+      catch (e) { actx = null; }
+    }
+    if (actx && actx.state === "suspended") actx.resume();
+    return actx;
+  }
+  function tone(freq, dur, type, vol, slideTo) {
+    if (muted) return;
+    const a = audio(); if (!a) return;
+    const t0 = a.currentTime;
+    const osc = a.createOscillator();
+    const g = a.createGain();
+    osc.type = type || "square";
+    osc.frequency.setValueAtTime(freq, t0);
+    if (slideTo) osc.frequency.exponentialRampToValueAtTime(Math.max(1, slideTo), t0 + dur);
+    g.gain.setValueAtTime(0.0001, t0);
+    g.gain.exponentialRampToValueAtTime(vol || 0.12, t0 + 0.008);
+    g.gain.exponentialRampToValueAtTime(0.0001, t0 + dur);
+    osc.connect(g); g.connect(a.destination);
+    osc.start(t0); osc.stop(t0 + dur + 0.02);
+  }
+  const sfx = {
+    flap:  () => tone(560, 0.12, "square",   0.10, 780),
+    score: () => { tone(720, 0.09, "triangle", 0.12); setTimeout(() => tone(960, 0.10, "triangle", 0.12), 70); },
+    hit:   () => { tone(200, 0.18, "sawtooth", 0.16, 80); },
+    die:   () => { tone(340, 0.5, "sine", 0.12, 60); },
+    swoosh:() => tone(300, 0.14, "sine", 0.05, 120)
+  };
+
+  // ---- background -----------------------------------------------------
+  function initBackground() {
+    stars = [];
+    const starCount = Math.round((W * H) / 16000);
+    for (let i = 0; i < starCount; i++) {
+      stars.push({
+        x: Math.random() * W,
+        y: Math.random() * (H - groundH) * 0.9,
+        r: Math.random() * 1.5 + 0.4,
+        speed: 6 + Math.random() * 12,
+        phase: Math.random() * Math.PI * 2,
+        tw: 1.2 + Math.random() * 1.6
+      });
+    }
+    hills = [
+      { base: 0.70, amp: 42 * scale, freq: 0.0042, speed: 16, off: 0,   color: "#141a33" },
+      { base: 0.78, amp: 58 * scale, freq: 0.0030, speed: 30, off: 240, color: "#0c1024" }
+    ];
+    ground = { off: 0 };
+  }
+
+  // ---- game objects ---------------------------------------------------
+  function resetGame() {
+    bird = { x: W * 0.3, baseY: H * 0.42, y: H * 0.42, vy: 0, r: 16 * scale, rot: 0, flapT: 0 };
+    pipes = [];
+    particles = [];
+    timeSincePipe = 0;
+    score = 0;
+    scoreVal.textContent = "0";
+    pipeInterval = PIPE_INTERVAL_START;
+    gapSize = GAP_START * scale;
+    speed = SPEED_START;
+    shake = 0; flashAlpha = 0; hitStop = 0;
+  }
+
+  function difficulty() {
+    const t = Math.min(score / RAMP, 1);
+    pipeInterval = PIPE_INTERVAL_START - (PIPE_INTERVAL_START - PIPE_INTERVAL_MIN) * t;
+    gapSize = (GAP_START - (GAP_START - GAP_MIN) * t) * scale;
+    speed = SPEED_START + (SPEED_MAX - SPEED_START) * t;
+  }
+
+  function spawnPipe() {
+    const playH = H - groundH;
+    const margin = Math.max(50 * scale, playH * 0.09);
+    const minTop = margin;
+    const maxTop = playH - margin - gapSize;
+    const top = maxTop <= minTop ? (playH - gapSize) / 2
+                                 : minTop + Math.random() * (maxTop - minTop);
+    // hue drifts a touch over the run so later pipes read hotter
+    const hue = 165 - Math.min(score, 40) * 1.2;
+    pipes.push({ x: W + PIPE_W, top: top, gap: gapSize, scored: false, hue: hue });
+  }
+
+  function addParticles(x, y, count, hue, power) {
+    if (reduceMotion) count = Math.ceil(count / 3);
+    for (let i = 0; i < count; i++) {
+      const ang = Math.random() * Math.PI * 2;
+      const mag = (Math.random() * 150 + 40) * scale * (power || 1);
+      particles.push({
+        x, y,
+        vx: Math.cos(ang) * mag,
+        vy: Math.sin(ang) * mag - 40 * scale,
+        life: 0.5 + Math.random() * 0.35, age: 0,
+        size: (Math.random() * 3 + 2) * scale,
+        hue: hue + (Math.random() * 30 - 15)
+      });
+    }
+  }
+
+  // ---- input (single unified path, dedupes touch+mouse) --------------
+  let lastFlap = 0;
+  function flap() {
+    audio(); // unlock on first gesture
+    const now = performance.now();
+    if (now - lastFlap < 55) return; // debounce double-fire (touch->mouse)
+    lastFlap = now;
+
+    if (state === "ready") {
+      startGame();
+      doFlap();
+    } else if (state === "playing") {
+      doFlap();
+    } else if (state === "paused") {
+      resume();
+    } else if (state === "gameover") {
+      // small guard so the death tap doesn't instantly restart
+      if (now - gameoverAt > 350) toReady();
+    }
+  }
+  function doFlap() {
+    bird.vy = FLAP;
+    bird.flapT = 1;
+    addParticles(bird.x - bird.r * 0.8, bird.y + bird.r * 0.4, 6, 205, 0.7);
+    sfx.flap();
+  }
+
+  function startGame() {
+    state = "playing";
+    ui.classList.remove("pop");
+    overlay.classList.add("hidden");
+    scoreTop.classList.remove("hidden");
+    bestBox.classList.remove("hidden");
+    result.classList.remove("show");
+    sfx.swoosh();
+  }
+
+  function toReady() {
+    state = "ready";
+    resetGame();
+    result.classList.remove("show");
+    newbest.classList.remove("show");
+    uiPrompt.textContent = "Press Space, Click, or Tap to Start";
+    overlay.classList.remove("hidden");
+    ui.classList.remove("pop"); void ui.offsetWidth; ui.classList.add("pop");
+    scoreTop.classList.add("hidden");
+    bestBox.classList.add("hidden");
+  }
+
+  let gameoverAt = 0;
+  function gameOver() {
+    if (state !== "playing") return;
+    state = "gameover";
+    gameoverAt = performance.now();
+    hitStop = 0.08;
+    shake = reduceMotion ? 0 : 16;
+    flashAlpha = reduceMotion ? 0.25 : 0.6;
+    addParticles(bird.x, bird.y, reduceMotion ? 10 : 30, 40, 1.5);
+    sfx.hit(); sfx.die();
+
+    const isBest = score > best;
+    if (isBest) { best = score; try { localStorage.setItem("flappy_sky_best", best); } catch (e) {} }
+    bestVal.textContent = best;
+
+    rScore.textContent = score;
+    rBest.textContent = best;
+    setMedal(score);
+    result.classList.add("show");
+    newbest.classList.toggle("show", isBest);
+    uiPrompt.textContent = "Click / Tap / Space to Play Again";
+
+    // reveal overlay a beat after the death punch
+    setTimeout(() => {
+      if (state === "gameover") {
+        overlay.classList.remove("hidden");
+        ui.classList.remove("pop"); void ui.offsetWidth; ui.classList.add("pop");
+      }
+    }, 260);
+  }
+
+  function setMedal(s) {
+    let icon = "🥉", bg = "linear-gradient(160deg,#c9865b,#8a5a34)";
+    if (s >= 40)      { icon = "💎"; bg = "linear-gradient(160deg,#8ef7ff,#2aa7c9)"; }
+    else if (s >= 25) { icon = "🥇"; bg = "linear-gradient(160deg,#ffe27a,#d3a520)"; }
+    else if (s >= 12) { icon = "🥈"; bg = "linear-gradient(160deg,#e8eef7,#9aa7bd)"; }
+    else if (s >= 4)  { icon = "🥉"; bg = "linear-gradient(160deg,#c9865b,#8a5a34)"; }
+    else              { icon = "🍃"; bg = "linear-gradient(160deg,#7f8aa3,#4a5570)"; }
+    medalEl.textContent = icon;
+    medalEl.style.background = bg;
+  }
+
+  // ---- pause ----------------------------------------------------------
+  function togglePause() {
+    if (state === "playing") pause();
+    else if (state === "paused") resume();
+  }
+  function pause() {
+    if (state !== "playing") return;
+    state = "paused";
+    pauseVeil.classList.add("show");
+    pauseBtn.textContent = "▶";
+  }
+  function resume() {
+    if (state !== "paused") return;
+    state = "playing";
+    pauseVeil.classList.remove("show");
+    pauseBtn.textContent = "⏸";
+    lastTime = performance.now(); acc = 0; // avoid a physics jump
+  }
+
+  function toggleMute() {
+    muted = !muted;
+    muteBtn.textContent = muted ? "🔇" : "🔊";
+    try { localStorage.setItem("flappy_sky_muted", muted ? "1" : "0"); } catch (e) {}
+    if (!muted) sfx.swoosh();
+  }
+  muteBtn.textContent = muted ? "🔇" : "🔊";
+
+  // ---- listeners ------------------------------------------------------
+  window.addEventListener("resize", resize);
+  window.addEventListener("orientationchange", resize);
+
+  document.addEventListener("keydown", (e) => {
+    if (e.code === "Space" || e.code === "ArrowUp" || e.code === "Enter") {
+      e.preventDefault(); flap();
+    } else if (e.code === "KeyP") {
+      e.preventDefault(); togglePause();
+    } else if (e.code === "KeyM") {
+      e.preventDefault(); toggleMute();
+    }
+  });
+
+  // pointer handles mouse + touch + pen uniformly; debounce covers the rest
+  canvas.addEventListener("pointerdown", (e) => { e.preventDefault(); flap(); });
+  overlay.addEventListener("pointerdown", (e) => { e.preventDefault(); flap(); });
+  // fallback for browsers without pointer events
+  if (!window.PointerEvent) {
+    canvas.addEventListener("mousedown", flap);
+    canvas.addEventListener("touchstart", (e) => { e.preventDefault(); flap(); }, { passive: false });
+  }
+
+  muteBtn.addEventListener("pointerdown", (e) => { e.stopPropagation(); e.preventDefault(); toggleMute(); });
+  pauseBtn.addEventListener("pointerdown", (e) => { e.stopPropagation(); e.preventDefault(); togglePause(); });
+
+  // auto-pause when the tab/window loses focus mid-game
+  document.addEventListener("visibilitychange", () => { if (document.hidden) pause(); });
+  window.addEventListener("blur", () => pause());
+
+  // ---- physics --------------------------------------------------------
+  function step(dt) {
+    bgScroll += dt;
+
+    // parallax always animates (even on menus) for a living background
+    for (const s of stars) {
+      s.x -= s.speed * dt;
+      if (s.x < -4) { s.x = W + 4; s.y = Math.random() * (H - groundH) * 0.9; }
+      s.phase += dt * s.tw;
+    }
+    for (const h of hills) h.off += h.speed * dt;
+
+    if (state === "playing") {
+      ground.off = (ground.off + speed * dt) % 48;
+      difficulty();
+
+      bird.flapT = Math.max(0, bird.flapT - dt * 6);
+      bird.vy += GRAVITY * dt;
+      bird.y  += bird.vy * dt;
+      bird.rot = Math.max(-0.55, Math.min(1.4, Math.atan2(bird.vy, 420)));
+
+      // soft ceiling — clamp instead of instant death (classic feel)
+      if (bird.y - bird.r < 0) { bird.y = bird.r; if (bird.vy < 0) bird.vy = 0; }
+
+      timeSincePipe += dt * 1000;
+      if (timeSincePipe >= pipeInterval) { timeSincePipe -= pipeInterval; spawnPipe(); }
+
+      const bx = bird.x, by = bird.y, br = bird.r * 0.82;
+      const pw = PIPE_W * scale;
+
+      for (let i = pipes.length - 1; i >= 0; i--) {
+        const p = pipes[i];
+        p.x -= speed * dt;
+        if (p.x + pw < -20) { pipes.splice(i, 1); continue; }
+
+        if (!p.scored && p.x + pw < bx) {
+          p.scored = true; score++;
+          scoreVal.textContent = score;
+          scoreTop.classList.remove("bump"); void scoreTop.offsetWidth; scoreTop.classList.add("bump");
+          sfx.score();
+        }
+        // circle-vs-rect collision (accurate)
+        if (hitPipe(bx, by, br, p, pw)) { gameOver(); return; }
+      }
+
+      // ground death
+      if (by + br > H - groundH) { bird.y = H - groundH - br; gameOver(); return; }
+    } else if (state === "ready" || state === "gameover") {
+      // clean bob around a fixed base — no accumulating drift
+      const t = bgScroll;
+      bird.y = bird.baseY + Math.sin(t * 2.4) * 8 * scale;
+      bird.rot = Math.sin(t * 1.6) * 0.18;
+    }
+
+    // particles
+    for (let i = particles.length - 1; i >= 0; i--) {
+      const p = particles[i];
+      p.age += dt;
+      if (p.age >= p.life) { particles.splice(i, 1); continue; }
+      p.x += p.vx * dt; p.y += p.vy * dt;
+      p.vy += 520 * dt; p.vx *= 0.986;
+    }
+
+    if (shake > 0)      shake = Math.max(0, shake - dt * 60);
+    if (flashAlpha > 0) flashAlpha = Math.max(0, flashAlpha - dt * 2.2);
+  }
+
+  function hitPipe(cx, cy, r, p, pw) {
+    // top rect: (p.x,0,pw,p.top) ; bottom rect: (p.x,p.top+gap,pw,rest)
+    const bottomY = p.top + p.gap;
+    return rectHit(cx, cy, r, p.x, 0, pw, p.top) ||
+           rectHit(cx, cy, r, p.x, bottomY, pw, (H - groundH) - bottomY);
+  }
+  function rectHit(cx, cy, r, rx, ry, rw, rh) {
+    const nx = Math.max(rx, Math.min(cx, rx + rw));
+    const ny = Math.max(ry, Math.min(cy, ry + rh));
+    const dx = cx - nx, dy = cy - ny;
+    return dx * dx + dy * dy < r * r;
+  }
+
+  // ---- rendering ------------------------------------------------------
+  function drawBackground() {
+    const grd = ctx.createLinearGradient(0, 0, 0, H);
+    grd.addColorStop(0, "rgba(40,50,90,0.25)");
+    grd.addColorStop(1, "rgba(0,0,0,0.55)");
+    ctx.fillStyle = grd;
+    ctx.fillRect(0, 0, W, H);
+
+    for (const s of stars) {
+      const a = 0.25 + 0.55 * (0.5 + 0.5 * Math.sin(s.phase));
+      ctx.fillStyle = "rgba(230,240,255," + a.toFixed(3) + ")";
+      ctx.beginPath(); ctx.arc(s.x, s.y, s.r, 0, 6.2832); ctx.fill();
+    }
+
+    // haze band
+    const cy = H * 0.3;
+    const cg = ctx.createLinearGradient(0, cy - 80, 0, cy + 80);
+    cg.addColorStop(0, "rgba(160,190,255,0)");
+    cg.addColorStop(0.4, "rgba(150,180,255,0.07)");
+    cg.addColorStop(1, "rgba(80,110,170,0)");
+    ctx.fillStyle = cg;
+    ctx.fillRect(0, cy - 80, W, 160);
+
+    for (const h of hills) {
+      const baseY = (H - groundH) * h.base;
+      ctx.fillStyle = h.color;
+      ctx.beginPath();
+      ctx.moveTo(0, H);
+      for (let x = 0; x <= W + 24; x += 20) {
+        const y = baseY + Math.sin((x + h.off) * h.freq) * h.amp;
+        ctx.lineTo(x, y);
+      }
+      ctx.lineTo(W, H); ctx.closePath(); ctx.fill();
+    }
+  }
+
+  function drawPipes() {
+    const pw = PIPE_W * scale;
+    const lip = 14 * scale;
+    const playH = H - groundH;
+    for (const p of pipes) {
+      const bottomY = p.top + p.gap;
+      const c1 = "hsl(" + p.hue + ",90%,55%)";
+      const c2 = "hsl(" + (p.hue + 18) + ",95%,72%)";
+      const c3 = "hsl(" + (p.hue - 8) + ",85%,42%)";
+
+      ctx.save();
+      ctx.shadowColor = "hsla(" + p.hue + ",100%,60%,0.6)";
+      ctx.shadowBlur = reduceMotion ? 0 : 16;
+
+      drawPipeBody(p.x, 0, pw, p.top, c1, c2, c3, lip, true);
+      drawPipeBody(p.x, bottomY, pw, playH - bottomY, c1, c2, c3, lip, false);
+      ctx.restore();
+    }
+  }
+  function drawPipeBody(x, y, w, h, c1, c2, c3, lip, isTop) {
+    if (h <= 0) return;
+    const g = ctx.createLinearGradient(x, 0, x + w, 0);
+    g.addColorStop(0, c3); g.addColorStop(0.18, c1);
+    g.addColorStop(0.5, c2); g.addColorStop(0.82, c1); g.addColorStop(1, c3);
+    ctx.fillStyle = g;
+    // main shaft
+    ctx.fillRect(x, y, w, h);
+    // lip (mouth end)
+    const ly = isTop ? y + h - lip : y;
+    const lw = w + 8 * scale;
+    ctx.fillRect(x - 4 * scale, ly, lw, lip);
+    // glossy highlight
+    ctx.fillStyle = "rgba(255,255,255,0.22)";
+    ctx.fillRect(x + w * 0.16, y, w * 0.1, h);
+  }
+
+  function drawGround() {
+    const gy = H - groundH;
+    const g = ctx.createLinearGradient(0, gy, 0, H);
+    g.addColorStop(0, "#3a3f2e");
+    g.addColorStop(0.12, "#4a5136");
+    g.addColorStop(1, "#20241a");
+    ctx.fillStyle = g;
+    ctx.fillRect(0, gy, W, groundH);
+
+    // top rim
+    ctx.fillStyle = "rgba(120,200,150,0.35)";
+    ctx.fillRect(0, gy, W, 3 * scale);
+
+    // scrolling hatch
+    ctx.strokeStyle = "rgba(0,0,0,0.18)";
+    ctx.lineWidth = 2;
+    ctx.beginPath();
+    for (let x = -48 + (-ground.off); x < W + 48; x += 24) {
+      ctx.moveTo(x, gy + 6 * scale);
+      ctx.lineTo(x + 14, H);
+    }
+    ctx.stroke();
+  }
+
+  function drawBird() {
+    const b = bird;
+    ctx.save();
+    ctx.translate(b.x, b.y);
+    ctx.rotate(b.rot);
+    const R = b.r;
+
+    // body
+    const bg = ctx.createRadialGradient(-R * 0.2, -R * 0.2, R * 0.2, 0, 0, R * 1.2);
+    bg.addColorStop(0, "#fffbe6"); bg.addColorStop(0.5, "#ffe07a"); bg.addColorStop(1, "#ff9f3f");
+    ctx.fillStyle = bg;
+    ctx.beginPath(); ctx.ellipse(0, 0, R * 1.15, R * 0.92, 0, 0, 6.2832); ctx.fill();
+
+    // belly
+    ctx.fillStyle = "rgba(255,255,255,0.85)";
+    ctx.beginPath(); ctx.ellipse(-R * 0.1, R * 0.12, R * 0.68, R * 0.56, 0, 0, 6.2832); ctx.fill();
+
+    // wing — flap amplitude tied to flapT (springs on each flap)
+    const wingBase = state === "playing" ? (0.35 - bird.flapT * 1.3)
+                                         : Math.sin(bgScroll * 8) * 0.4;
+    ctx.save();
+    ctx.translate(-R * 0.1, 0);
+    ctx.rotate(-0.7 + wingBase);
+    const wg = ctx.createLinearGradient(-R * 0.2, -R * 0.4, R * 0.5, R * 0.6);
+    wg.addColorStop(0, "#ffe7a3"); wg.addColorStop(1, "#ffb25a");
+    ctx.fillStyle = wg;
+    ctx.beginPath(); ctx.ellipse(0, 0, R * 0.92, R * 0.5, 0, 0, 6.2832); ctx.fill();
+    ctx.strokeStyle = "rgba(180,110,40,0.35)"; ctx.lineWidth = 1;
+    ctx.stroke();
+    ctx.restore();
+
+    // eye
+    ctx.fillStyle = "#fff";
+    ctx.beginPath(); ctx.arc(R * 0.42, -R * 0.22, R * 0.26, 0, 6.2832); ctx.fill();
+    ctx.fillStyle = "#1c1f2b";
+    ctx.beginPath(); ctx.arc(R * 0.5, -R * 0.22, R * 0.14, 0, 6.2832); ctx.fill();
+    ctx.fillStyle = "rgba(255,255,255,0.8)";
+    ctx.beginPath(); ctx.arc(R * 0.55, -R * 0.26, R * 0.05, 0, 6.2832); ctx.fill();
+
+    // beak
+    ctx.fillStyle = "#ff9f2f";
+    ctx.beginPath();
+    ctx.moveTo(R * 0.92, -R * 0.05);
+    ctx.lineTo(R * 1.42, R * 0.14);
+    ctx.lineTo(R * 0.92, R * 0.3);
+    ctx.closePath(); ctx.fill();
+    ctx.fillStyle = "#e07a1e";
+    ctx.beginPath();
+    ctx.moveTo(R * 0.92, R * 0.14);
+    ctx.lineTo(R * 1.42, R * 0.14);
+    ctx.lineTo(R * 0.92, R * 0.3);
+    ctx.closePath(); ctx.fill();
+
+    // tail
+    ctx.fillStyle = "#ffb562";
+    ctx.beginPath();
+    ctx.moveTo(-R * 1.05, -R * 0.12);
+    ctx.lineTo(-R * 1.55, -R * 0.32);
+    ctx.lineTo(-R * 1.2, R * 0.18);
+    ctx.closePath(); ctx.fill();
+
+    ctx.restore();
+  }
+
+  function drawParticles() {
+    for (const p of particles) {
+      const t = p.age / p.life;
+      ctx.globalAlpha = (1 - t) * 0.9;
+      ctx.fillStyle = "hsl(" + p.hue + ",100%,72%)";
+      ctx.beginPath();
+      ctx.arc(p.x, p.y, p.size * (1 - t * 0.5), 0, 6.2832);
+      ctx.fill();
+    }
+    ctx.globalAlpha = 1;
+  }
+
+  function render() {
+    let sx = 0, sy = 0;
+    if (shake > 0) {
+      sx = (Math.random() * 2 - 1) * shake;
+      sy = (Math.random() * 2 - 1) * shake;
+    }
+    ctx.save();
+    ctx.translate(sx, sy);
+
+    drawBackground();
+    drawPipes();
+    drawGround();
+    drawParticles();
+    drawBird();
+
+    ctx.restore();
+
+    if (flashAlpha > 0) {
+      ctx.fillStyle = "rgba(255,80,80," + flashAlpha.toFixed(3) + ")";
+      ctx.fillRect(0, 0, W, H);
+    }
+  }
+
+  // ---- main loop (fixed-step physics, smooth render) ------------------
+  function loop(ts) {
+    if (!lastTime) lastTime = ts;
+    let frame = (ts - lastTime) / 1000;
+    lastTime = ts;
+    if (frame > 0.1) frame = 0.1; // clamp big gaps (tab restore)
+
+    if (hitStop > 0) { hitStop -= frame; }
+    else {
+      acc += frame;
+      while (acc >= FIXED_DT) { step(FIXED_DT); acc -= FIXED_DT; }
+    }
+
+    render();
+    requestAnimationFrame(loop);
+  }
+
+  // ---- boot -----------------------------------------------------------
+  resize();
+  resetGame();
+  requestAnimationFrame(loop);
+})();
+</script>
+</body>
+</html>
diff --git a/test/e2e.mjs b/test/e2e.mjs
new file mode 100644
index 0000000..492e97f
--- /dev/null
+++ b/test/e2e.mjs
@@ -0,0 +1,55 @@
+import { chromium } from 'playwright';
+const errors = [], logs = [];
+const browser = await chromium.launch();
+const page = await browser.newPage({ viewport: { width: 480, height: 800 } });
+page.on('console', m => { if (m.type()==='error') errors.push('console.error: '+m.text()); logs.push(m.type()+': '+m.text()); });
+page.on('pageerror', e => errors.push('pageerror: '+e.message));
+await page.goto('file://'+process.cwd()+'/index.html');
+await page.waitForTimeout(400);
+
+// helper to read internal state via a tiny hook we expose by evaluating
+async function probe() {
+  return await page.evaluate(() => {
+    return { title: document.title, w: window.innerWidth };
+  });
+}
+console.log('loaded:', JSON.stringify(await probe()));
+
+// Start + flap a bunch via keyboard Space
+await page.focus('canvas').catch(()=>{});
+for (let i=0;i<12;i++){ await page.keyboard.press('Space'); await page.waitForTimeout(180); }
+await page.waitForTimeout(200);
+const scoreVisible = await page.evaluate(()=>{
+  const s=document.getElementById('scoreTop');
+  return { hidden: s.classList.contains('hidden'), score: document.getElementById('scoreVal').textContent };
+});
+console.log('after flaps:', JSON.stringify(scoreVisible));
+
+// Let it fall to trigger game over
+await page.waitForTimeout(2500);
+const go = await page.evaluate(()=>({
+  resultShown: document.getElementById('result').classList.contains('show'),
+  overlayHidden: document.getElementById('overlay').classList.contains('hidden'),
+  best: document.getElementById('bestVal').textContent
+}));
+console.log('gameover state:', JSON.stringify(go));
+
+// Test pause
+await page.keyboard.press('Space'); // restart -> ready or flap
+await page.waitForTimeout(300);
+await page.keyboard.press('Space'); // start playing
+await page.waitForTimeout(200);
+await page.keyboard.press('KeyP');
+await page.waitForTimeout(200);
+const paused = await page.evaluate(()=>document.getElementById('pauseVeil').classList.contains('show'));
+console.log('pause veil shown:', paused);
+
+// screenshot for a visual artifact
+await page.keyboard.press('KeyP'); // resume
+await page.waitForTimeout(300);
+await page.screenshot({ path: '/tmp/flappy_shot.png' });
+
+await browser.close();
+console.log('CONSOLE ERRORS:', errors.length);
+errors.forEach(e=>console.log('  '+e));
+console.log(errors.length===0 ? 'PASS: no runtime errors' : 'FAIL');

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