// The splatter phase: shamblers, gore decals, particles. The ball is the weapon;
// tennis scoring keeps running via gameplay.splatPoint. Zombies advance toward
// your baseline — one crossing it is a point for THEM.
// (zombies <-> gameplay is a runtime-only import cycle, same pattern as input.)

import { TUNE, UI, COURT, VOLLEY, CONTACT, BOSS_ART } from './config.js';
import { G, P, ball, sendBoy, setupPoint } from './state.js';
import { splat, moan, pock, voice, boom, swish, shriek, aww, sfx } from './audio.js';
import { splatPoint, cheer, spentBall, resolveInterlude, showModal, endBossFight, aside } from './gameplay.js';

export const zombies = []; // {x, z, v, walkT, variant: 'a'|'b'|'c'}
export const gore = [];    // lawn decals {x, z, r, a}  — the flat ground layer
export const piles = [];   // 3D-ish gore mounds {x, z, size 1..4, seed} — grow where kills cluster
export const parts = [];   // splatter particles {x, y, z, vx, vy, vz, t, dark}
export const pellets = []; // machine-gun rounds during a horde {x, y, z, vx, vz, t}
export const extras = [];  // triple-serve side balls {x, y, z, vx, vy, vz, pow, t} — ballistic clones
// INCOMING hostile balls: the ball machine's shots and the chapter boss's volleys. Deliberately a
// separate array from `ball` and `extras` rather than an extension of either — the main ball is the
// one you serve and there can only be one of it, and extras are yours and kill zombies. These are
// theirs and they hurt YOU. Swat one with a swing and it becomes an `extras` entry flying back
// up-court, which is how a parry turns into a real weapon for free.
export const shots = [];   // {x, y, z, vx, vy, vz, g, t}

let spawnT = 1.5, moanT = 3;

export function spawnZombie(x, z, variant) {
  // Keyed on GAMES FINISHED, not on splatT: the old `1 + min(1.5, splatT / 70)` maxed out after
  // 105 seconds of splatter, so every shambler from roughly game 3 onward walked at the same top
  // speed for the rest of a 50-game run. Games are what the player experiences as progress.
  const ramp = 1 + Math.min(TUNE.zSpeedMax, G.runGames * TUNE.zSpeedPerGame);
  const zb = { x, z, v: TUNE.zSpeed * ramp * (0.8 + Math.random() * 0.4), walkT: Math.random() * 9,
               homeOff: (Math.random() * 2 - 1) * 0.8, variant }; // personal lane offset so they don't stack into a column
  if (variant === 'f') { zb.v = Math.min(TUNE.runnerVMax, zb.v * TUNE.runnerSpeed); shriek(); } // shriek = the fairness contract; capped so late runners stay reactable
  if (variant === 'a' || variant === 'b') zb.hp = TUNE.shamblerHp; // classic shamblers take a wound before they drop — only the runner is one-shot glass
  if (variant === 'g') { zb.v *= 0.55; zb.hp = TUNE.bruteHp; } // slow, but soaks hits
  if (variant === 'd') { zb.v *= 0.8; zb.hp = TUNE.stewardHp; } // the steward: a head taller and several hits tougher than the crowd, nothing more exotic than that
  // Every body with hp remembers its FULL hp. The wound skins used to compare against the variant's
  // TUNE constant, which meant every new body needed its own branch to look hurt; one field here and
  // the rule is "hp below full = show the wound", for anything that has a wound skin.
  if (zb.hp) zb.hpMax = zb.hp;
  if (variant === 's') zb.shieldT = 0;                         // chair up; > 0 = seconds of stagger left
  if ('fgsd'.includes(variant) && !G.seen['v' + variant]) { G.seen['v' + variant] = true; aside('ump_dress_code', 0.8); }
  if (variant === 'm') { // the rogue ball machine: furniture, not a body. It never SHAMBLES...
    zb.v = 0; zb.hp = zb.hpMax = TUNE.machHp; zb.fireT = TUNE.machCycle; zb.windT = 0;
    zb.repoT = TUNE.machRepo * (0.4 + Math.random()); // ...but it wheels itself somewhere else now and then
  }
  zombies.push(zb);
}

// the rogue ball machine, wheeled out onto the far court. It never moves and never scores; it just
// shoots at you until you deal with it.
export function spawnMachine() {
  spawnZombie((Math.random() * 2 - 1) * 3.6, 2.2 + Math.random() * 3, 'm');
  voice('ump_machine', 0.4, 0.95);
  if (!G.seen.mach) {
    G.seen.mach = true;
    showModal({ title: 'A BALL MACHINE', color: UI.warm,
      body: ['IT FIRES AT YOU ON A TIMER', 'SWING TO RETURN THE SHOT', 'OR SWISH TO BAT IT AWAY'] });
  }
}

// ---- the chapter boss. One every TUNE.bossEvery games, bigger and tougher each time. It advances
// slowly and volleys at you, so it threatens BOTH channels: its shots chip your hp, and letting it
// reach you is the ordinary instant death. Reuses the whole existing damage model — it is just a
// body with a lot of hp (see the wound() invariant in HANDOFF), so no weapon needs special-casing.
export function spawnChapterBoss(chapter) {
  const hp = TUNE.bossHp + (chapter - 1) * TUNE.bossHpPerChapter;
  zombies.push({ x: 0, z: -1.2, v: TUNE.bossSpeed, walkT: 0, homeOff: 0, variant: 'B',
    chapter, hp, hpMax: hp, scale: TUNE.bossScale + (chapter - 1) * TUNE.bossScalePer,
    fireT: TUNE.bossCycle, windT: 0, salvo: 0, salvoT: 0,
    art: BOSS_ART[(chapter - 1) % BOSS_ART.length] });  // which of the boss designs this chapter is
}

// ---- the player's second health channel. Only these two functions touch it.
export function hurtPlayer(n) {
  if (G.mode !== 'splatter' || G.hurtT > 0 || G.mode === 'eaten') return; // grace window: a volley
  G.hp -= n;                                                             // must not delete you at once
  G.hurtT = TUNE.hurtGrace; G.hurtFlash = 0.3;
  G.shake = { t: 0.22, mag: 4 };
  splat(0.7); aww(0.5);
  for (let k = 0; k < 14; k++) parts.push({ // he takes it in the chest
    x: P.x + (Math.random() * 2 - 1) * 0.2, y: 1.2, z: P.z,
    vx: (Math.random() * 2 - 1) * 2.2, vy: 0.8 + Math.random() * 2, vz: (Math.random() * 2 - 1) * 2.2,
    t: 0.35 + Math.random() * 0.35, dark: Math.random() < 0.5 });
  if (G.hp <= 0) killPlayer();
  else voice('ump_quiet_bleeding', 0.3, 0.95); // the umpire objects on your behalf. He is still watching.
}

// Death, from EITHER channel: a shambler reaching you, or your hp running out. Extracted so the two
// causes cannot drift apart — the run summary, the best-run write and the death animation are all
// here exactly once.
export function killPlayer() {
  if (G.mode === 'eaten') return;
  gore.push({ x: P.x, z: P.z, r: 0.9, a: 0.9 }); if (gore.length > 40) gore.shift();
  for (let k = 0; k < 30; k++) parts.push({
    x: P.x, y: 1.1, z: P.z,
    vx: (Math.random() * 2 - 1) * 4.5, vy: 1 + Math.random() * 4, vz: (Math.random() * 2 - 1) * 4.5,
    t: 0.5 + Math.random() * 0.5 });
  splat(1);
  voice('game_set_massacre', 0.8); aww(1); // the run is over — the crowd groans
  // the death animation runs off G.eatenT: thrash here, burst at EATEN_BURST (playerGore), summary after
  G.eatenT = 0; G.eatenAt = { x: P.x, z: P.z };
  G.mode = 'eaten'; ball.active = false; G.flash = null; G.modal = null; // zombies keep shambling for ambience
  G.horde = null; pellets.length = 0; extras.length = 0; shots.length = 0; G.mgT = 0; // everything stops
  try { // the run is over — settle it against the best (games survived, sets as tiebreak)
    const b = JSON.parse(localStorage.splatterBest || 'null') || { games: 0, sets: 0 };
    G.newBest = G.runGames > b.games; // beat it → the summary crows about it
    if (G.newBest) { b.games = G.runGames; b.sets = G.sets[0]; localStorage.splatterBest = JSON.stringify(b); }
    G.best = b;
  } catch (e) { G.best = null; } // private mode etc. — the summary just skips the best line
}

// One hostile ball, lobbed at where the player is standing. `spread` fans a volley sideways.
// It is a real ARC (solved like a serve, not fired flat) so it is readable coming in and so the
// swing window has something to meet — a flat bolt at head height is not a tennis shot.
function fireAtPlayer(x, z, spread = 0, speed = TUNE.machSpeed) {
  const y0 = 1.1;
  const tx = P.x + spread, tz = P.z;
  const d = Math.hypot(tx - x, tz - z), Tf = Math.max(0.35, d / speed);
  const g = TUNE.gravity;
  shots.push({ x, y: y0, z,
    vx: (tx - x) / Tf, vz: (tz - z) / Tf,
    vy: (0.9 - y0 + 0.5 * g * Tf * Tf) / Tf, // land at racket height, not on the grass
    g, t: Tf + 1.6 });
  pock(0.55, 190); // the thunk of the throw
}

// Which shambler steps out next. Unlocks are keyed on GAMES, not on sets won: a set is six games,
// so the old top gate (`tier >= 2`) opened around game 12 and after that the mix was frozen forever
// at 15% shield / 15% brute / 12% runner — a third of why a 50-game run stopped changing.
// Now the advanced SHARE keeps climbing after everything is unlocked, which is what makes game 40
// feel different from game 20 rather than merely faster.
function pickVariant() {
  const g = G.runGames;
  const pool = [];
  if (g >= 2 && !zombies.some(z => z.variant === 'f')) pool.push('f'); // at most one runner alive
  if (g >= 6) pool.push('g');
  if (g >= 12) pool.push('s');
  // The steward is the mildest of the pool on purpose — bigger and one hit tougher, no special rule
  // to learn — so he can arrive EARLY and thicken the ordinary crowd, which the shambler mix alone
  // never did. He is also the only advanced body that shows up in a horde (see spawnHordeZombie).
  if (g >= 4) pool.push('d');
  const nasty = Math.min(TUNE.nastyMax, g * TUNE.nastyPerGame);
  if (pool.length && Math.random() < nasty) return pool[Math.floor(Math.random() * pool.length)];
  return Math.random() < 0.5 ? 'a' : 'b';
}

// How big a target a body is. Bosses are deliberately a little more generous than a shambler —
// part of "the racket zombie doesn't seem harmable" was simply missing him.
// A BOSS BODY: takes wound damage from everything instead of being deleted by it. The brute ('g') is
// deliberately NOT one — melee/bomb/fire one-shotting a brute is a settled "power exception".
const isBoss = zb => zb.variant === 'r' || zb.variant === 'B';
const hitR = zb => zb.variant === 'g' ? 0.75 : zb.variant === 'd' ? 0.64 : zb.variant === 'r' ? 0.7
  : zb.variant === 'B' ? 0.55 * (zb.scale || 1) * 1.4 // a chapter boss is a barn door, as it should be
  : zb.variant === 'm' ? 0.8                          // the machine is a wide low box
  : 0.55;

// core kill: remove the zombie, spawn its gore/pile/particles, score. No ball coupling —
// shared by ball hits, machine-gun pellets, melee swipes, and extra (multi-serve) balls.
// how absurdly a variant dies: classics splash, the advanced roster DETONATES
const GORE_MUL = { a: 1, b: 1, f: 1.8, s: 2.5, g: 4, r: 3, m: 1.5, B: 6 }; // a chapter boss comes apart like nothing else on the court

// dark smoke: one puff, drifting up and spreading. Not gravity-bound like gore (see the parts loop).
function smokePuff(x, y, z, spread = 0.5) {
  parts.push({ x: x + (Math.random() * 2 - 1) * spread, y, z: z + (Math.random() * 2 - 1) * spread * 0.5,
    vx: (Math.random() * 2 - 1) * 0.35, vy: 0.5 + Math.random() * 0.5, vz: (Math.random() * 2 - 1) * 0.35,
    t: 0.9 + Math.random() * 0.9, smoke: true });
}

// The machine is the one thing on court that is not made of meat, and it used to burst like a body:
// blood decal, gore mound, the wet splat, a ball boy sent out to mop it. It comes apart as MACHINERY
// now — a flash, sparks, torn metal, and a column of dark smoke over a scorch mark.
function wreckMachine(zb) {
  boom(); G.shake = { t: 0.3, mag: 5 }; G.boomFlash = 0.09;
  gore.push({ x: zb.x, z: zb.z, r: 1.1, a: 0.95, scorch: true }); // burnt clay, not blood
  if (gore.length > 40) gore.shift();
  for (let k = 0; k < 26; k++) parts.push({ // sparks and burning debris
    x: zb.x, y: 0.8, z: zb.z,
    vx: (Math.random() * 2 - 1) * 4, vy: 1.5 + Math.random() * 4, vz: (Math.random() * 2 - 1) * 4,
    t: 0.3 + Math.random() * 0.5, fire: true });
  for (let k = 0; k < 26; k++) smokePuff(zb.x, 0.5 + Math.random() * 1.6, zb.z, 0.7); // a column, not a puff
}

function killZombie(i, quiet) {
  const zb = zombies[i];
  const mul = GORE_MUL[zb.variant] || 1;
  zombies.splice(i, 1);
  if (zb.variant === 'm') { // furniture, not a body: no blood, no mound, no mop boy
    wreckMachine(zb);
    if (!G.horde && !G.clearing) splatPoint('P', quiet);
    return;
  }
  if (G.interlude && zb.variant === 'r') resolveInterlude('P'); // regicide ends the duel your way — any weapon counts
  if (zb.variant === 'B') endBossFight();                       // the chapter is over
  const stains = Math.round(Math.sqrt(mul)); // advanced kills splash a scatter of stains, not one puddle
  for (let k = 0; k < stains; k++) {
    gore.push({ x: zb.x + (k ? (Math.random() * 2 - 1) * 0.9 : 0), z: zb.z + (k ? (Math.random() * 2 - 1) * 0.9 : 0),
                r: (0.45 + Math.random() * 0.35) * Math.sqrt(mul), a: 0.85 });
    if (gore.length > 40) gore.shift();
  }
  const pl = piles.find(p => Math.hypot(p.x - zb.x, p.z - zb.z) < 0.6); // stack up where kills cluster
  if (pl) pl.size = Math.min(4, pl.size + Math.round(mul / 2 + 0.5));
  else { piles.push({ x: zb.x, z: zb.z, size: Math.min(4, Math.round(mul / 2 + 0.5)), seed: Math.random() * 1e4, blobs: null, builtSize: 0 });
         if (piles.length > 30) piles.shift(); }
  const n = Math.round(30 * mul); // base bumped 24 -> 30, then the multiplier goes to work
  for (let k = 0; k < n; k++) { const dark = k >= n * 2 / 3; parts.push({ // ~1/3 dark & long-lived: settling gore
    x: zb.x, y: 0.9, z: zb.z,
    vx: (Math.random() * 2 - 1) * 3.5, vy: 1 + Math.random() * 3.5, vz: (Math.random() * 2 - 1) * 3.5,
    t: dark ? 0.6 + Math.random() * 0.6 : 0.4 + Math.random() * 0.4, dark,
  }); }
  splat();
  sfx('headshot-' + (Math.random() < 0.5 ? 1 : 2), 0.6); // random headshot crack layered on the gore burst
  sendBoy(zb.x, zb.z, true);      // a boy comes out with the mop
  // The chapter boss deliberately scores NOTHING: its reward is the chapter card and the parked game
  // beat resuming. Letting it bank a point meant splatPoint's game-over branch and endBossFight both
  // decided "what happens next" in the same frame and clobbered each other.
  if (!G.horde && !G.clearing && zb.variant !== 'B') splatPoint('P', quiet); // horde = survival, clearing = mopping up an already-won game — neither scores
}

// ---- fire. The flame ball doesn't just kill what it touches, it starts an epidemic: the kill
// ignites its neighbours, and every burning body keeps igniting whatever it shambles past.
// Read-only over zombies[] (it only sets burnT), so it is safe to call from inside a kill loop.
export function ignite(x, z, r) {
  for (const zb of zombies) {
    if (!zb || zb.burnT > 0) continue; // the boss DOES catch now — just at TUNE.bossBurnMul the rate,
                                       // so fire is a real answer to a big body instead of a no-op
    if (Math.hypot(zb.x - x, zb.z - z) < r) { zb.burnT = TUNE.burnTime; if (zb.hp === undefined) zb.hp = 1; }
  }
}

// Bank `amount` of damage on a multi-hit body and return true once it should DIE. Fractional amounts
// are legal (a machine-gun pellet chips a third of a point): they accumulate on zb.chip and only
// WHOLE points come off hp, because the wound skins and bleed() anchors switch on hp thresholds and
// a fractional hp would never match one. The caller decides HOW it dies — splatter() for the
// multi-kill fanfare, killZombie() for a quiet one — and must stop touching zb afterwards, because
// killZombie splices the array. This is the one place damage is applied, so a future boss with 20 hp
// needs no new code: every weapon is already proportional to it.
function wound(zb, amount, fx = true) {
  zb.chip = (zb.chip || 0) + amount;
  let took = 0;
  while (zb.chip >= 1 && zb.hp > 0) { zb.chip -= 1; zb.hp--; took++; }
  if (took && fx) { splat(0.5); woundBurst(zb); }
  return zb.hp <= 0;
}

// one burning body's frame: damage, spread, embers. Returns true if the fire killed it (the
// caller must then stop touching zb — killZombie splices, and splatPoint can cascade further).
function burnTick(zb, i, dt) {
  zb.burnT -= dt;
  ignite(zb.x, zb.z, TUNE.burnSpread);
  // fx off: the embers below already ARE the feedback, a wet pop per cooked hp point would be noise
  const dead = wound(zb, TUNE.burnDps * (isBoss(zb) ? TUNE.bossBurnMul : 1) * dt, false);
  if (parts.length < 110) for (let k = 0; k < 2; k++) parts.push({ // embers off the body
    x: zb.x + (Math.random() * 2 - 1) * 0.3, y: 0.5 + Math.random() * 1.4, z: zb.z,
    vx: (Math.random() * 2 - 1) * 0.5, vy: 1.2 + Math.random(), vz: (Math.random() * 2 - 1) * 0.5,
    t: 0.25 + Math.random() * 0.2, fire: true });
  if (!dead) return false;
  killZombie(i, !!G.horde);
  return true;
}

// phase B of the death animation (EATEN_BURST, config.js): the player IS the gore now. Reuses killZombie's machinery —
// the biggest mound on the court, and it stays visible under the summary scrim. That's the point.
export function playerGore() {
  const at = G.eatenAt || { x: P.x, z: P.z };
  gore.push({ x: at.x, z: at.z, r: 1.7, a: 1 }); if (gore.length > 40) gore.shift();
  piles.push({ x: at.x, z: at.z, size: 4, seed: Math.random() * 1e4, blobs: null, builtSize: 0 });
  if (piles.length > 30) piles.shift();
  for (let k = 0; k < 90; k++) parts.push({
    x: at.x, y: 1.0, z: at.z,
    vx: (Math.random() * 2 - 1) * 5.5, vy: 1 + Math.random() * 6, vz: (Math.random() * 2 - 1) * 5.5,
    t: 0.6 + Math.random() * 0.9, dark: k % 3 === 0 });
  splat(1); boom();
  G.shake = { t: 0.35, mag: 7 };
  G.boomFlash = 0.08;
}

// a small dark spatter the instant a multi-hit shambler is wounded — subtle impact pop, NOT the
// kill spray (the ongoing thin trickle is bleed()'s job). Kept low per the settled blood feel.
// The player's own wound trickle. Same rule as the zombies': blood is NEVER painted into the player
// sprite (settled feel decision) — it is live particles, sparse, thin, and the flow scales with how
// far gone he is. Together with drawChar's procedural spatter this IS the health bar.
function bleedPlayer() {
  if (parts.length > 95) return;
  const lost = G.hpMax - G.hp;
  for (let k = 0; k < lost; k++) {
    if (Math.random() > 0.22) continue; // sparse: most frames each wound emits nothing
    parts.push({
      x: P.x + (k % 2 ? 0.22 : -0.2) + (Math.random() * 2 - 1) * 0.03,
      y: 1.45 - k * 0.13, z: P.z + (Math.random() * 2 - 1) * 0.03,
      vx: (Math.random() * 2 - 1) * 0.28, vy: 0.5 + Math.random() * 0.7, vz: (Math.random() * 2 - 1) * 0.26,
      t: 0.3 + Math.random() * 0.3, dark: Math.random() < 0.55 });
  }
}

function woundBurst(zb) {
  for (let k = 0; k < 5; k++) parts.push({
    x: zb.x + (Math.random() * 2 - 1) * 0.15, y: 1.4, z: zb.z,
    vx: (Math.random() * 2 - 1) * 1.6, vy: 0.6 + Math.random() * 1.4, vz: (Math.random() * 2 - 1) * 1.6,
    t: 0.35 + Math.random() * 0.3, dark: Math.random() < 0.6 });
}

// swishing the racket cleaves every shambler in reach — it's the panic button for when they're
// already on top of you, so it stays a full sweep. TUNE.meleeCool is the brake that stops it
// from being the default attack.
// The boss skip is NOT a gap in the damage model: it is unreachable by construction. The player is
// bounded at P_BOUNDS.zMin (netZ + 1.2 = 13.1) and the boss holds z <= COURT.svcFar (5.5), so they
// are always on opposite sides of the net and meleeRange 1.7 can never span it. Left as a skip
// rather than "fixed", because a melee path to the boss would need him to cross the net first.
export function meleeSwipe(x, z, range) {
  let hit = 0;
  for (let i = zombies.length - 1; i >= 0; i--) {
    const zb = zombies[i];
    if (!zb || zb.variant === 'r') continue; // !zb: killZombie can sweep the court mid-loop
    if (zb.variant === 'm' || isBoss(zb)) { // furniture and bosses don't cleave — they take a wound
      if (Math.hypot(zb.x - x, zb.z - z) < range && wound(zb, TUNE.dmgBall)) { splatter(i); hit++; }
      continue;
    }
    if (Math.hypot(zb.x - x, zb.z - z) < range) { killZombie(i, !!G.horde); hit++; }
  }
  // The swish deliberately does NOT touch incoming shots. It used to, as a pretoss fallback — but
  // meleeSwipe runs FIRST in keyPressed, so it swallowed the very shot the new tap-to-parry was about
  // to return. One answer to a thrown ball: swing at it.
  if (hit) swish(0.35);
  return hit;
}

function splatter(i, fanfare = true) { // the MAIN ball hit a zombie
  killZombie(i, !!G.horde);
  ball.vx *= TUNE.zPierce; ball.vz *= TUNE.zPierce; // keep enough pace to plow through the next
  if (!fanfare) return;           // machine-gun pellets splatter but skip the streak fanfare / bomb meter
  ball.kills++;                   // this shot's running streak
  // escalating multi-kill fanfare — one shot, ≥2 zombies
  if (ball.kills === 2) { G.flash = { text: 'DOUBLE KILL', t: 0.9 }; cheer(1.6, 0.45); voice('double_kill', 0.4); }
  else if (ball.kills === 3) { G.flash = { text: 'TRIPLE KILL', t: 0.9 }; cheer(2.2, 0.6); voice('triple_kill', 0.4); }
  else if (ball.kills >= 4) { G.flash = { text: `MASSACRE ×${ball.kills}`, t: 0.9 }; cheer(2.8, 0.7); voice('unbelievable', 0.4); }
}

// ---- horde wave: dense spawns + an auto-firing machine-gun racket (pellets, not the match ball)
function spawnHordeZombie() { // all from the far baseline, across the court — never off-screen at the sides
  // a few stewards in the mix: the wave needs bodies that survive one pellet, or a grown horde is a
  // uniform wall of the same thing dying at the same range
  const v = Math.random() < TUNE.hordeSteward && G.runGames >= 4 ? 'd' : Math.random() < 0.5 ? 'a' : 'b';
  spawnZombie((Math.random() * 2 - 1) * 5, -1.5 - Math.random(), v);
}
let mgTick = 0;
function firePellet() {
  const a = (Math.random() * 2 - 1) * TUNE.mgSpread * Math.PI / 180, s = 26; // spread cone, straight up-court (-z)
  pellets.push({ x: P.x, y: 0.9, z: P.z, vx: Math.sin(a) * s, vz: -Math.cos(a) * s, t: 1.2 });
  if (++mgTick % 2 === 0) pock(0.25, 1400); // rapid fire tick, every 2nd round — at 12+/s every round buzzes
}
export function spawnRacketZombie() { // one takes up residence on the far court — an opponent, of sorts
  // He stiffens as the run goes on. hpMax is stored because the wound skins and bleed() anchors read
  // a FRACTION of full health now — hardcoded `hp === 2` thresholds would leave a late-run boss
  // looking pristine right up to the killing blow.
  const hp = TUNE.racketHp + Math.floor(G.runGames * TUNE.racketHpPerGame);
  zombies.push({ x: (Math.random() * 2 - 1) * 2.5, z: 3.5, v: 0, walkT: Math.random() * 9,
    variant: 'r', side: 'O', facing: 1, pose: 'idle', poseT: 0, swingT: -1, swingCool: 0, runT: 0,
    hp, hpMax: hp });
  if (!G.seen.racket) { // it is not a shambler and it does not behave like one — say so, once
    G.seen.racket = true;
    showModal({ title: 'IT HAS A RACKET', color: UI.hot,
      body: ['IT RETURNS YOUR WEAK SHOTS', 'ONLY A FULL PULL WOUNDS IT'] });
  }
}
function endHorde() {
  G.horde = null; pellets.length = 0;
  if (!zombies.some(z => z.variant === 'r')) spawnRacketZombie(); // survive the wave → a racket zombie stays
  setupPoint();                    // serve loop resumes; any zombies still standing are yours to mop up
  voice('quiet_dark', 0.5, 0.85);
}
function tickHorde(dt) {
  const h = G.horde;
  h.t -= dt;
  // h.rate is stamped by startHorde and grows per set banked — every horde used to be the same
  // twelve seconds at the same 2.5/s, so the fifth one was indistinguishable from the first.
  if ((h.spawnT -= dt) <= 0) {
    if (zombies.length < TUNE.zHordeCap) spawnHordeZombie(); // ...but bounded, see TUNE.zHordeCap
    h.spawnT = 1 / (h.rate || TUNE.hordeRate);
  }
  if ((h.mgT -= dt) <= 0) { firePellet(); h.mgT = 1 / (h.mgRate || TUNE.mgRate); }
  if (h.t <= 0) endHorde();
}

// bomb ball: everything inside bombRadius splatters at once (each kill still ++ball.kills so
// the Phase-2 fanfare escalates), plus a crater — big stain, size-3 pile, extra particles, boom.
export function explode(x, z) {
  for (let i = zombies.length - 1; i >= 0; i--) { // backwards: splatter() splices (and can sweep) the array
    const zb = zombies[i];
    if (!zb || Math.hypot(zb.x - x, zb.z - z) >= TUNE.bombRadius) continue;
    // A blast used to delete the boss outright, ignoring his hp entirely — which made BOMB the only
    // real answer to him and would have made any bigger boss meaningless. It's heavy damage now.
    if (isBoss(zb)) { if (wound(zb, TUNE.dmgBomb)) splatter(i); }
    else splatter(i);
  }
  gore.push({ x, z, r: 2.2, a: 1, scorch: true }); if (gore.length > 40) gore.shift(); // the crater — near-permanent
  gore.push({ x, z, r: 2.0, a: 0.9 }); if (gore.length > 40) gore.shift();
  // a ring of splatter thrown outward, so the blast paints the lawn instead of leaving one puddle
  for (let k = 0; k < 6; k++) {
    const a = Math.random() * 6.2832, r = TUNE.bombRadius * (0.35 + Math.random() * 0.6);
    gore.push({ x: x + Math.cos(a) * r, z: z + Math.sin(a) * r, r: 0.7 + Math.random() * 0.7, a: 0.85 });
    if (gore.length > 40) gore.shift();
  }
  const pl = piles.find(p => Math.hypot(p.x - x, p.z - z) < 0.6);
  if (pl) pl.size = Math.min(4, pl.size + 3);
  else { piles.push({ x, z, size: 4, seed: Math.random() * 1e4, blobs: null, builtSize: 0 }); if (piles.length > 30) piles.shift(); }
  // the eruption itself: a fat, slow, high-arcing column of gore rather than a camera flash
  for (let k = 0; k < 120; k++) parts.push({
    x: x + (Math.random() * 2 - 1) * 0.4, y: 0.5, z: z + (Math.random() * 2 - 1) * 0.4,
    vx: (Math.random() * 2 - 1) * 11, vy: 2 + Math.random() * 9, vz: (Math.random() * 2 - 1) * 11,
    t: 0.7 + Math.random() * 1.1, dark: k % 3 === 0,
  });
  G.hitstop = 0.18; boom();
  G.shake = { t: 0.45, mag: 9 };  // camera kick
  // a warm, brief bloom instead of a white-out — the blinding frame was doing the work the gore
  // should be doing, and on a phone it just hurt (see render.js for the colour)
  G.boomFlash = 0.06;
  if (G.idleT - G.lastOrderT > 3) { voice('order', 0.35); G.lastOrderT = G.idleT; } // the umpire loses composure
}

// wounded zombies bleed from every open wound — a fine, sparse trickle (a small spurt from the
// neck stump on the headless boss). Anchors are approximate body offsets [x, y, rise]; most
// frames a wound drips nothing, and the tight spread keeps each thread thin. Bounded low.
function bleed(zb) {
  if (parts.length > 90) return;
  let wounds;
  if (zb.variant === 'g' && zb.hp < TUNE.bruteHp) {
    // the brute opens up stage by stage: one arm, then both, then the head. Still sparse —
    // more ANCHORS, not a heavier flow (the settled feel note: blood stays thin).
    wounds = [[-0.3, 1.95, 1.1]];
    if (zb.hp <= TUNE.bruteHp - 2) wounds.push([0.42, 1.9, 1.0]);
    if (zb.hp <= TUNE.bruteHp - 3) wounds.push([0.05, 2.35, 2.0]);
    if (zb.hp <= 1) wounds.push([0.0, 1.2, 0.7]);
  }
  // the boss reads as a FRACTION of full health, not against hardcoded hp numbers: his hp scales
  // with the run now (racketHpPerGame), so `hp === 2` would leave a late-run boss bleeding from
  // nothing until the very last hit. Must stay in step with drawZombie's skin thresholds.
  else if (zb.variant === 'r' && zb.hp / (zb.hpMax || TUNE.racketHp) <= 0.34)
    wounds = [[0.05, 1.5, 2.4], [0.4, 1.15, 0.9]]; // headless: neck spurt + torn arm
  else if (zb.variant === 'r' && zb.hp / (zb.hpMax || TUNE.racketHp) <= 0.67)
    wounds = [[0.4, 1.2, 1.0]];                    // racket: torn-off arm
  else if ((zb.variant === 'a' || zb.variant === 'b') && zb.hp < TUNE.shamblerHp) wounds = [[0.28, 1.35, 0.85]]; // shambler: gashed shoulder
  else return;
  for (const w of wounds) {
    if (Math.random() > 0.4) continue; // sparse: most frames this wound emits nothing
    parts.push({
      x: zb.x + w[0] + (Math.random() * 2 - 1) * 0.03, y: w[1] + (Math.random() * 2 - 1) * 0.03, z: zb.z + (Math.random() * 2 - 1) * 0.03,
      vx: (Math.random() * 2 - 1) * 0.3, vy: w[2] * (0.6 + Math.random() * 0.5), vz: (Math.random() * 2 - 1) * 0.28,
      t: 0.3 + Math.random() * 0.3, dark: Math.random() < 0.55 });
  }
}

export function updateZombies(dt) {
  moanT -= dt;
  if (moanT <= 0) { moan(); moanT = 2.5 + Math.random() * 4; }

  if (G.mode === 'splatter') { // transition spawns are scripted, not timed
    G.splatT += dt;
    if (G.horde) tickHorde(dt); // horde: dense spawns + machine gun, ignores the cap
    else if (G.mgT > 0) { // machine-gun tin: horde firepower, regular rules
      // The burst clock ticks in EVERY phase. It used to tick only during 'rally', so anything that
      // moved the phase mid-burst (a duel calling setupPoint) froze mgT above zero forever — and
      // `G.mgT > 0` blocks serving, so the game locked up with the gun racket stuck on screen.
      G.mgT -= dt;
      if (G.phase === 'rally' && (G.mgCool -= dt) <= 0) { firePellet(); G.mgCool = 1 / TUNE.mgRate; }
      if (G.mgT <= 0) setupPoint(); // ammo dry — the serve loop resumes
    }
    if (!G.horde && !G.changeover && !G.interlude && !G.clearing && !G.bossFight) { // breathers, duels, the mop-up after a won game AND a boss fight all get a quiet court (no new spawns)
      spawnT -= dt;
      // The spawn director: games finished sets both crowd size and tempo. Both curves used to hit a
      // wall — the cap pinned at 14 by game 11 and the gap floored at 1.0 s by game 10, after which
      // the game literally stopped changing. The gap is hyperbolic now so it keeps tightening on its
      // own instead of running into a floor; zSpawnMin is only a safety stop.
      const cap = Math.min(TUNE.zMaxCap, TUNE.zMax + Math.floor(G.runGames * TUNE.zMaxPerGame));
      if (zombies.length >= cap - 1) aside('ump_hindrance', 0.6); // the court is genuinely full
      if (spawnT <= 0 && zombies.length < cap) {
        spawnZombie((Math.random() * 2 - 1) * 4.8, -1.5 - Math.random(), pickVariant());
        spawnT = Math.max(TUNE.zSpawnMin, TUNE.zSpawnEvery / (1 + G.runGames * TUNE.zSpawnAccel));
      }
    }
  }

  // ponytail: crude swept collision — grow the contact window by half the distance the ball
  // covers this frame. A full-draw smash moves ~0.7 m per frame (1.6 m on a 25 fps device, where
  // main.js clamps dt), which is wider than a shambler, so a discrete point test tunnels straight
  // through bodies. Upgrade to a real segment-vs-circle test if the fudge ever reads as a phantom
  // hit; at these speeds and radii it doesn't.
  const ballSweep = ball.active ? Math.hypot(ball.vx, ball.vz) * dt * 0.5 : 0;

  // The flame ball lights everything it FLIES PAST, not just what it kills. Without this the
  // fire never actually spread: full pierce meant the ball killed its whole lane outright, and
  // the only bodies left to catch were the ones it had already removed.
  if (ball.active && ball.flame && ball.y < 2.6) ignite(ball.x, ball.z, TUNE.burnBallR);

  // The umpire called time. The changeover is a MANDATORY breather for the player — no serving, no
  // walking — so it is one for the dead too, which is the joke: they wait, because it's still a
  // tennis match. They stand where they are, still bleeding, still burning, still lit by anything
  // in the air, but nothing advances and nothing can eat you. (The alternative — letting the player
  // walk freely during the beat — was tried and vetoed: he never walks freely during play either.)
  const held = !!G.changeover;
  if (G.hurtT > 0) G.hurtT -= dt;
  if (G.hurtFlash > 0) G.hurtFlash -= dt;
  if (G.hp < G.hpMax && G.mode === 'splatter') bleedPlayer();

  for (let i = zombies.length - 1; i >= 0; i--) {
    const zb = zombies[i];
    if (!zb) continue; // a bomb detonation splices several out mid-loop and can gut the array under us
    zb.walkT += dt;
    if (zb.burnT > 0 && burnTick(zb, i, dt)) continue; // the fire finished it — the array moved under us
    if (!held) zb.z += zb.v * (zb.burnT > 0 ? TUNE.burnPanic : 1) * dt;
    bleed(zb); // open wounds bleed every frame they're standing

    if (zb.shieldT > 0) zb.shieldT -= dt; // staggered chair comes back up when this runs out
    if (zb.hitT > 0) zb.hitT -= dt;       // boss contact cooldown (see TUNE.bossHitCool)
    // ---- the two RANGED attackers. Both wind up visibly before firing (TUNE.machWind / drawZombie's
    // charge glow) because a shot you cannot see coming is not a fairness contract, it is a gotcha.
    if (!held && !G.interlude && (zb.variant === 'm' || zb.variant === 'B') && G.mode === 'splatter'
        && zb.rollTo === undefined) { // a cart on the roll cannot aim — that is the window to close on it
      const boss = zb.variant === 'B';
      if (zb.salvo > 0) {                       // mid-volley: the rest of the balls are still coming
        if ((zb.salvoT -= dt) <= 0) {
          zb.salvo--; zb.salvoT = TUNE.bossSalvoGap;
          fireAtPlayer(zb.x, zb.z, (Math.random() * 2 - 1) * 0.35, TUNE.bossShotSpeed); // aimed at where
        }                                        // you are NOW, with only a hand's width of scatter
      } else if (zb.windT > 0) {
        zb.windT -= dt;
        if (zb.windT <= 0) {
          if (boss) { zb.salvo = TUNE.bossVolley; zb.salvoT = 0; } // the volley starts next frame
          else fireAtPlayer(zb.x, zb.z, 0, TUNE.machSpeed);
        }
      } else if ((zb.fireT -= dt) <= 0) {
        zb.fireT = boss ? TUNE.bossCycle : TUNE.machCycle;
        zb.windT = boss ? TUNE.bossWind : TUNE.machWind;
        pock(0.3, 1500); // the tell: a mechanical click as it loads
      }
    }
    if (zb.variant === 'm') { // the machine wheels itself around instead of being bolted down
      if (!held && G.mode === 'splatter' && !G.interlude) {
        if (zb.rollTo !== undefined) {
          const d = zb.rollTo - zb.x;
          if (Math.abs(d) < 0.06) { zb.rollTo = undefined; zb.repoT = TUNE.machRepo * (0.7 + Math.random() * 0.6); }
          else {
            zb.x += Math.sign(d) * Math.min(Math.abs(d), TUNE.machRoll * dt);
            if ((zb.rollT -= dt) <= 0) { pock(0.16, 150); zb.rollT = 0.4; } // castors grinding on the clay
          }
        } else if ((zb.repoT -= dt) <= 0) { zb.rollTo = (Math.random() * 2 - 1) * 3.6; zb.rollT = 0; }
      }
      if (zb.hp < zb.hpMax * 0.5 && Math.random() < dt * 6) smokePuff(zb.x, 1.1, zb.z, 0.25); // wrecked: it smokes where it stands
    }
    else if (held || zb.variant === 'r') { /* boss AI owns its x; a duelling opponent owns his */ }
    else if (G.mode === 'splatter' && zb.z > COURT.netZ) { // on YOUR half they close in — each on its own lane, not a column
      const tx = P.x + zb.homeOff;
      zb.x += Math.sign(tx - zb.x) * Math.min(Math.abs(tx - zb.x), zb.v * 0.7 * dt)
            + Math.sin(zb.walkT * 2.3) * 0.25 * dt; // shamble wobble — the approach reads organic, not tracked
    } else
      zb.x += Math.sin(zb.walkT * 1.7) * 0.15 * dt; // far half: aimless shamble
    // CONTACT IS STILL INSTANT DEATH — settled decision, and the ball machine's chip damage does not
    // soften it. Two threats that demand two different responses is the point. The machine ('m') is
    // furniture and cannot eat you.
    if (!held && G.mode === 'splatter' && zb.variant !== 'm'
        && Math.hypot(zb.x - P.x, (zb.z - P.z) * 0.75) < TUNE.eatenR + (zb.variant === 'g' ? 0.2 : 0)) // z weighted down: depth is foreshortened, so a head-on shambler eats you when it LOOKS on top of you
      killPlayer();
    if (ball.active && ball.lastHit === 'P' && ball.y < 1.9) {
      const d = Math.hypot(ball.x - zb.x, ball.z - zb.z);
      if (d < hitR(zb) + ballSweep && !(zb.hitT > 0)) { // brute and boss are bigger targets
        if (ball.bomb) { // detonate on first contact, whatever the pace
          explode(ball.x, ball.z); ball.bomb = false;
          spentBall(); break; // zombies mutated — stop this frame's loop
        }
        if (ball.flame) { // burns through anything it touches — no quality gate, no chair, no pace tax
          if (isBoss(zb)) { // a boss takes a heavy wound AND catches light
            zb.hitT = TUNE.bossHitCool;                 // ...and the ball is SPENT on it: a boss is not
            ball.lastHit = 'X'; ball.vx *= 0.3; ball.vz *= 0.3; // removed, so an unconsumed pierce ball
            if (wound(zb, TUNE.dmgFlame)) splatter(i);  // re-wounded it every single frame
            else zb.burnT = TUNE.burnTime;
            continue;
          }
          const vx0 = ball.vx, vz0 = ball.vz, bx = zb.x, bz = zb.z;
          splatter(i); ball.vx = vx0; ball.vz = vz0; // undo splatter's pierce tax: full pace through the lane
          ignite(bx, bz, TUNE.burnIgniteR);          // ...and everyone standing near the body goes up
          continue;
        }
        if (isBoss(zb)) { // boss: splat-quality wounds it; soft balls the racket one rallies (racketAI)
          if ((ball.pow || 0) >= TUNE.zSplatQ) {
            zb.hitT = TUNE.bossHitCool; // belt-and-braces: this ball is spent below, but the cooldown
            const dead = wound(zb, TUNE.dmgBall); // is what stops ANY lingering contact multi-wounding
            pock(0.6, 300);
            ball.vx *= 0.3; ball.vz *= 0.3; ball.lastHit = 'X'; // spent on the hit
            if (dead) { splatter(i); continue; }               // killing blow: full gore + point
          }
          continue; // soft balls pass through ON PURPOSE, for racketAI to return — that rally IS the
                    // feedback that it wasn't hard enough, so no clank here; see HANDOFF
        }
        if (zb.variant === 'g' || zb.variant === 'm') { // brute AND the bolted-down machine: soak
          if ((ball.pow || 0) >= TUNE.zSplatQ) {          // splat-quality hits, never stagger back
            zb.hp--; splat(0.5); pock(0.6, zb.variant === 'm' ? 700 : 220); // machine rings, meat thuds
            ball.vx *= 0.3; ball.vz *= 0.3; ball.lastHit = 'X';
            if (zb.hp <= 0) { splatter(i); continue; } // timber
          } else { pock(0.6, 300); ball.vx *= 0.6; ball.vz *= 0.6; ball.lastHit = 'X'; } // soft ball bounces off
          continue;
        }
        if (zb.variant === 's' && ball.vz < 0 && !(zb.shieldT > 0)) { // chair up, ball at its face: BLOCKED
          zb.shieldT = TUNE.shieldDown; // ...but the block staggers it — the chair drops, kill window opens
          zb.z -= TUNE.zPushback * 0.5;
          pock(0.9, 1800); // wooden clank
          ball.vx *= 0.4; ball.vz *= -0.2; ball.lastHit = 'X'; // ball caroms off the chair, spent
          continue;
        }
        if (zb.variant === 'f') { splatter(i); continue; } // the sprinter is GLASS — any touch, any quality, it bursts
        if (zb.variant === 'a' || zb.variant === 'b') { // classic shamblers soak a splat-quality wound before they drop
          if ((ball.pow || 0) >= TUNE.zSplatQ) {
            if (--zb.hp <= 0) { splatter(i); continue; }              // the second splat is the killing blow
            woundBurst(zb); splat(0.5); pock(0.6, 280);              // first splat: a bloody wound, not a death
            zb.z -= TUNE.zPushback * 0.5; ball.vx *= 0.3; ball.vz *= 0.3; ball.lastHit = 'X'; continue; // ball spent on the wound
          }
          zb.z -= TUNE.zPushback; pock(0.6, 300); ball.vx *= 0.6; ball.vz *= 0.6; ball.lastHit = 'X'; continue; // soft ball just staggers
        }
        // chair-down shield zombies (and anything hit from behind) obey the normal rules:
        if ((ball.pow || 0) >= TUNE.zSplatQ) { splatter(i); continue; }
        zb.z -= TUNE.zPushback; // weak sitters only stagger them
        pock(0.6, 300);
        ball.vx *= 0.6; ball.vz *= 0.6; ball.lastHit = 'X'; // spent — one stagger per ball
      }
    }
    if (zb.z >= COURT.L + 0.7) { aside('ump_unsportsmanlike', 0.5); zombies.splice(i, 1); if (G.mode !== 'eaten' && !G.horde && !G.clearing) splatPoint('O'); } // it reached your baseline (during a mop-up, a straggler that reaches the line just despawns — no point for them)
  }

  for (let i = pellets.length - 1; i >= 0; i--) { // machine-gun rounds: flat, fast, one-shot kills
    const pe = pellets[i];
    pe.t -= dt; pe.x += pe.vx * dt; pe.z += pe.vz * dt;
    let hit = false;
    for (let j = zombies.length - 1; j >= 0; j--) {
      const zb = zombies[j];
      if (!zb) continue;
      if (Math.hypot(zb.x - pe.x, zb.z - pe.z) < hitR(zb) + TUNE.mgPelletR) {
        // Pellets used to skip the boss entirely, so a GUN burst (and every horde) did literally
        // nothing to him with no feedback at all. They CHIP him now: dmgPellet is fractional, so
        // three rounds take a point off and the gun is a slow, committed answer rather than a no-op.
        if (isBoss(zb)) { if (wound(zb, TUNE.dmgPellet, false)) killZombie(j, true); else pock(0.45, 240); }
        else if ((zb.hp -= TUNE.dmgPelletHp) > 0) pock(0.5, 260); // only brutes soak now; a shambler drops to one round
        else killZombie(j, true);
        hit = true; break;
      }
    }
    if (hit || pe.t <= 0) pellets.splice(i, 1);
  }

  // ---- INCOMING hostile balls (ball machine, chapter boss volleys). Three outcomes, in this order:
  // a timed swing inside the volley window RETURNS it as your own ball flying up-court, the panic
  // swish (meleeSwipe, above) merely bats it away, and reaching you unanswered costs a point of hp.
  for (let i = shots.length - 1; i >= 0; i--) {
    const s = shots[i];
    s.t -= dt; s.vy -= s.g * dt;
    s.x += s.vx * dt; s.y += s.vy * dt; s.z += s.vz * dt;
    let done = s.t <= 0 || s.y < -0.25 || Math.abs(s.x) > 8 || s.z > COURT.L + 2;
    // The PARRY keeps the 0.8 depth weighting — a racket sweep really is wider than it is deep.
    // The HIT does not: weighting depth shrinks it, so contact registered while the ball was still
    // most of a metre up-court. That mismatch between what you saw and what hit you was the bug.
    const dP = Math.hypot(s.x - P.x, (s.z - P.z) * 0.8);
    const dHit = Math.hypot(s.x - P.x, s.z - P.z);
    if (!done && P.swingT >= 0 && P.swingT <= TUNE.parryWindow
        && dP < TUNE.parryReach && s.y < CONTACT.maxY) {
      // the parry: it becomes an `extras` clone — that array is already ballistic and already kills
      // zombies, so "returned shot is a live weapon" costs nothing to build.
      // It is a GLANCING blow, not a mirror. Reversing the incoming line sent every return straight
      // back up the line it arrived on — which is where the thrower is standing — so a boss was a
      // free wound per throw. Where you meet the ball across the racket face now sets the angle:
      // hitting it back INTO him is a shot you have to place your feet for.
      const off = Math.max(-1, Math.min(1, (s.x - P.x) / TUNE.parryReach)); // -1..1 across the face
      const ang = (off * TUNE.parryDeflect + (Math.random() * 2 - 1) * TUNE.parryJitter) * Math.PI / 180;
      const sp = Math.hypot(s.vx, s.vz) * 1.15;
      extras.push({ x: s.x, y: s.y, z: s.z, g: TUNE.gravity, pow: TUNE.parryPow, t: 2.5,
        vx: Math.sin(ang) * sp, vy: 4.2, vz: -Math.cos(ang) * sp });
      pock(0.85, 1300); G.flash = { text: 'RETURNED', t: 0.6 }; cheer(0.8, 0.3);
      done = true;
    }
    if (!done && dHit < TUNE.shotHitR && s.y < TUNE.shotHitY) { hurtPlayer(TUNE.machDmg); done = true; }
    if (done) shots.splice(i, 1);
  }

  for (let i = extras.length - 1; i >= 0; i--) { // triple-serve side balls: full ballistic clones
    const e = extras[i];
    e.t -= dt; e.vy -= (e.g || TUNE.gravity) * dt; // e.g: a clone flies under the SAME topspin as the ball it came from
    e.x += e.vx * dt; e.y += e.vy * dt; e.z += e.vz * dt;
    if (e.y <= 0 && e.vy < 0) { e.y = 0; e.vy = -e.vy * TUNE.bounceY; e.vx *= TUNE.bounceXZ; e.vz *= TUNE.bounceXZ; }
    let dead = e.t <= 0 || Math.abs(e.x) > 7.5 || e.z < -2 || e.z > 25.5;
    if (!dead && e.y < 1.9) for (let j = zombies.length - 1; j >= 0; j--) {
      const zb = zombies[j];
      if (!zb) continue; // killZombie can sweep the court mid-loop
      if (Math.hypot(zb.x - e.x, zb.z - e.z) < hitR(zb)
                                               + Math.hypot(e.vx, e.vz) * dt * 0.5) { // same sweep: clones inherit the smash pace
        // Side balls used to pass THROUGH the boss doing nothing at all, which is most of why a
        // TRIPLE serve read as "he can't be hurt". They wound him like the main ball now.
        if (isBoss(zb)) {
          if (e.pow >= TUNE.zSplatQ) { if (wound(zb, TUNE.dmgSide)) killZombie(j, !!G.horde); }
          else pock(0.5, 300);
        }
        else if (zb.variant === 's' && e.vz < 0 && !(zb.shieldT > 0)) { zb.shieldT = TUNE.shieldDown; pock(0.9, 1800); } // chair blocks these too
        else if (e.pow >= TUNE.zSplatQ || zb.variant === 'f') {
          if (zb.hp > 1) { zb.hp--; splat(0.4); } // wounds brutes AND shamblers
          else killZombie(j, !!G.horde);
        } else { zb.z -= TUNE.zPushback; pock(0.5, 300); }
        dead = true; break; // a side ball is spent on its first touch
      }
    }
    if (dead) extras.splice(i, 1);
  }

  for (let i = parts.length - 1; i >= 0; i--) {
    const p = parts[i];
    p.t -= dt;
    if (p.smoke) { p.vy = 0.55; p.vx *= 0.97; p.vz *= 0.97; } // smoke rises and spreads; it does not fall
    else p.vy -= 14 * dt;
    p.x += p.vx * dt; p.y += p.vy * dt; p.z += p.vz * dt;
    if (p.y < 0) { p.y = 0; p.vy = 0; p.vx *= 0.5; p.vz *= 0.5; }
    if (p.t <= 0) parts.splice(i, 1);
  }

  const boy = G.boy; // the boy mops any gore he passes over
  for (let i = gore.length - 1; i >= 0; i--) {
    const d = gore[i];
    // He scrubs HARD only while stopped and working the mop; walking past barely touches it, so
    // the stain visibly dies under him rather than fading as he drifts by.
    if (boy && Math.abs(boy.x - d.x) < 0.8 && Math.abs(boy.z - d.z) < 1.3)
      d.a -= dt * (d.scorch ? 0.16 : boy.mopT > 0 ? 0.7 : 0.2); // craters scar the lawn far longer
    if (d.a <= 0) gore.splice(i, 1);
  }
  for (let i = piles.length - 1; i >= 0; i--) { // piles shave far slower than stains — net growth wins
    const pl = piles[i];
    if (boy && Math.abs(boy.x - pl.x) < 0.7 && Math.abs(boy.z - pl.z) < 1.2) pl.size -= dt * 0.25;
    if (pl.size <= 0.3) piles.splice(i, 1);
  }
}