PLAN.md: phased zombie-mode expansion plan for follow-up implementation

Five phases, each independently shippable with verify recipes: tighter
shooting loop, multi-kill umpire fanfare, procedural gore piles, bomb
balls delivered by ball boys, horde waves with machine-gun racket.
Racket zombies deferred to a design checkpoint (Phase 6, not first cut).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

PLAN.md

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+# PLAN — Zombie mode expansion (for implementation by a follow-up session)
+
+Read HANDOFF.md FIRST (module map, verify recipes, gotchas — especially the stale-module
+cache one and "always Read current file state before editing"). This plan is ordered so
+every phase is independently shippable: implement → verify → commit → push (push = deploy,
+Oliver tests on his phone). Do NOT start a phase before the previous one is pushed.
+
+Ground rules for the implementer:
+- Zero dependencies, no build step, vanilla ES modules. Match the existing code style
+  (compact, commented for intent, TUNE knobs for anything Oliver might want to tune).
+- The tennis benchmarks in HANDOFF ("Tennis feel — CONFIRMED GOOD") MUST keep holding
+  after every phase. Run them via window.T (Browser pane, RAF paused, T.step manual).
+- New TUNE knobs go in config.js TUNE so they appear in the live T panel.
+- Mobile portrait one-handed is the primary target. Every new interaction must work with
+  one thumb: tap, flick, drag. No new buttons.
+- Sounds: synth sfx live in audio.js; umpire lines are recorded m4a in assets/audio/
+  (macOS `say -v Daniel`). Generation commands are given in Phase 2.
+
+---
+
+## Phase 1 — Tighten the shooting loop (serve-again latency, "missing balls")
+
+Problem (diagnosed): two independent causes.
+1. Input swallowed: taps/flicks during `G.phase === 'over'` (even the short 0.25s splatter
+   one) hit `keyPressed` and match NO branch — the tap is lost and a stored flick expires.
+   The player feels "I flicked and nothing came".
+2. Spent balls die slowly: a staggered ball (`lastHit === 'X'`) or a shot that missed
+   everything stays alive until it physically rolls out (|vy| < 0.8 after bounces), which
+   can take seconds when it flies long. Only then does the 0.25s over-timer even start.
+
+Changes (gameplay.js unless noted):
+- keyPressed: in splatter mode, treat `phase === 'over'` like pretoss — first force the
+  reset inline (`ball.active = false; setupPoint();`) then fall through to the existing
+  pretoss serve logic (flick → quick serve, tap → toss). The finger is now the only
+  cadence limit.
+- Ball physics block: in splatter mode kill spent/hopeless balls early:
+  `lastHit === 'X' && ball.bounces >= 1` OR out of bounds (`z < -2 || z > 25.5 ||
+  |x| > 7.5`) → `ball.active = false; G.phase = 'over'; G.overT = TUNE.splatterOverT`.
+- New TUNE knob: `splatterOverT: 0.1` (replace the hardcoded 0.25 in the dead-ball branch).
+
+Verify (Browser pane, force splatter via 3 synthetic umpire taps — see HANDOFF):
+- Flick during 'over' fires a serve the same frame (phase goes rally, ball active).
+- Spent ball dies within ~10 frames of its first post-stagger bounce.
+- Serve→serve cycle with immediate flicks ≤ 20 frames.
+- Tennis regression: 'over' handling in tennis mode UNCHANGED (points still pause 2.2s).
+
+## Phase 2 — Multi-kill applause + umpire appreciation
+
+Mechanic: one ball (or bomb, Phase 4) that splatters ≥ 2 zombies gets escalating fanfare.
+- state.js ball: add `kills: 0`. Reset to 0 in doHit and hitServe (any new shot).
+- zombies.js splatter(): `ball.kills++`. After the existing splatPoint call:
+  kills === 2 → `G.flash = {text:'DOUBLE KILL', t:0.9}; cheer(1.6, 0.45); voice('double_kill', 0.4)`
+  kills === 3 → 'TRIPLE KILL', cheer(2.2, 0.6), voice('triple_kill', 0.4)
+  kills >= 4 → `MASSACRE ×${kills}`, cheer(2.8, 0.7), voice('unbelievable', 0.4)
+  (cheer/voice are imported from gameplay/audio already; check zombies.js imports.)
+- Make natural pierce-doubles possible: splatter() currently halves pace
+  (`ball.vx *= 0.5; ball.vz *= 0.5`). Change 0.5 → `TUNE.zPierce` (new knob, 0.75), so a
+  hot ball can plow through a lined-up pair.
+- New umpire lines (record on this Mac, same voice as existing files — inspect audio.js
+  first for the exact name→file mapping):
+    say -v Daniel "Double kill. Quiet, please." -o /tmp/dk.aiff && afconvert -f m4af -d aac /tmp/dk.aiff assets/audio/double_kill.m4a
+    say -v Daniel "Triple kill. Remarkable." -o /tmp/tk.aiff && afconvert -f m4af -d aac /tmp/tk.aiff assets/audio/triple_kill.m4a
+    say -v Daniel "Unbelievable." -o /tmp/ub.aiff && afconvert -f m4af -d aac /tmp/ub.aiff assets/audio/unbelievable.m4a
+  Listen-check the files (afplay) before committing.
+
+Verify: T-script — line up 3 zombies on one lane (`T.spawnZombie(0, 8/10/12, 'a')`),
+serve a perfect-quality ball down that lane (TUNE.zSplatQ low temporarily), step, expect
+kills to accumulate, flash text escalating, no crash when the ball dies mid-streak.
+
+## Phase 3 — Gore piles (procedural graphics, no sprite pipeline)
+
+Goal: the court gets progressively more disgusting. Stains (existing) + NEW 3D-ish piles
+that grow when kills happen near each other. Ball boys shave them slowly but net growth
+wins over a long match.
+
+- zombies.js: new export `piles = []` — {x, z, size (1..4 float), seed}.
+  In splatter(): if an existing pile within 0.6m → `size = min(4, size + 1)` else push
+  new {size: 1, seed: Math.random()*1e4}. Cap 30 piles (shift oldest).
+  Boy mopping loop: overlapping pile → `size -= dt * 0.25` (slower than stain mopping);
+  remove pile at size <= 0.3. Keep stains as-is (they're the ground layer).
+- render.js: `drawGorePile(p)` — procedural pixel-art, deterministic from p.seed so piles
+  don't shimmer frame to frame. Algorithm: seeded PRNG (inline mulberry32 is fine);
+  N = 6 + size*5 blobs; each blob an ellipse at radius ≤ size*0.28m around (x,z), with a
+  vertical lift up to size*0.14m (projected: `y` offset via proj scale) so the pile has
+  HEIGHT, not just a stain; blob radii 1–3px * proj scale; colors weighted:
+  '#6e1414' '#8c1212' '#4e0e0e' '#7a2a18' + '#cfc9b0' (bone flecks, ~10%).
+  Draw order: with the gore stains (after court, before characters), split far/near of
+  the net like zombies are (a pile at z > netZ must occlude correctly). Sort by z.
+- More particles per kill: 14 → 24 in splatter(), and give ~1/3 of them longer life
+  (t up to 1.2) with darker color — check render's parts loop for where color is set.
+
+Verify: force splatter, TUNE.zSplatQ = 0, kill ~10 zombies in one area, screenshot:
+piles visible, taller/denser where kills clustered, boys visibly shrink them but slower
+than they grow. Frame time sane (no per-frame allocation in drawGorePile — precompute
+blob offsets ONCE per pile on creation, store on the pile object, don't re-run the PRNG
+every frame).
+
+## Phase 4 — Bomb balls
+
+Design (decided, but flag to Oliver if it plays badly): ball boys deliver a black bomb
+ball as a REWARD every `TUNE.bombEvery = 8` splatter kills. It's a stock (max
+`TUNE.bombMax = 3`), shown on the HUD, and the NEXT serve automatically consumes one
+(no extra input — one-handed rule). Alternative delivery ideas Oliver floated: umpire
+throws it, or court pickup — do NOT build those, just note them in the commit message.
+
+- state.js: G.bombs = 0, G.killMeter = 0.
+- zombies.js splatter(): `G.killMeter++`; at bombEvery → reset meter, and if
+  bombs < bombMax: `G.bombs++`, sendBoy() (the delivery run), voice('new_balls', 0.2)
+  + flash 'BOMB BALL'.
+- gameplay.js hitServe: in splatter mode, if `G.bombs > 0` → `G.bombs--`,
+  `ball.bomb = true` (cleared on every other serve/hit).
+- zombies.js: `explode(x, z)` — all zombies with `hypot(zx-x, zz-z) < TUNE.bombRadius`
+  (2.5) splatter (iterate a COPY or walk the array backwards — splatter() splices; each
+  kill still increments ball.kills so Phase 2 fanfare fires naturally); one big stain
+  (r ~1.4), a pile of size 3, 40 particles, `G.hitstop = 0.1`, boom sound.
+  Trigger: in the zombie-contact check, `ball.bomb` → explode at ball pos (regardless of
+  pow), ball.active = false. Also in gameplay's bounce handling: splatter && ball.bomb &&
+  first bounce → explode there.
+- audio.js: `boom()` — synth: ~80Hz sine with fast pitch drop + white-noise burst,
+  0.4s, follow the style of splat()/pock().
+- render.js: bomb ball drawn black with a 1px flickering orange fuse pixel on top
+  (drawBall gets a variant flag or check ball.bomb where the match ball is drawn).
+  HUD: when G.bombs > 0, draw that many small black circles right of the YOU score line.
+
+Verify: T-script — set killMeter to 7, kill one → bomb appears on HUD; serve → ball
+renders black; land it amid 4 clustered zombies → all die, 'MASSACRE ×4' fires, boom
+plays, big pile + stain remain. Confirm bombs don't leak into tennis mode (mode guard).
+
+## Phase 5 — Horde waves + machine-gun racket
+
+Trigger (decided): first horde when the player wins his 2nd splatter GAME, then every
+game won after. Plus the test/fun cheat: triple-tap the umpire while already in splatter
+mode → force a horde (main.js umpire listener currently calls forceZombies() which
+no-ops outside tennis — extend it: in splatter, call startHorde()).
+
+Flow: splatPoint's gameOver branch (splatter) → startHorde():
+- G.horde = {t: TUNE.hordeLen (12s), spawnT: 0}. voice('remain_seated', 0.3) + flash
+  'THEY KEEP COMING'. (Optionally record a dedicated line "They keep coming." →
+  they_keep_coming.m4a, same pipeline as Phase 2.)
+- During horde (updateZombies): ignore zMax; spawn every 1/TUNE.hordeRate (2.5/s),
+  from the far baseline AND the sides (x = ±6, z random 0..8). Zombie speed ramp applies.
+- Machine gun: while horde active the racket AUTO-FIRES — no taps needed. The thumb
+  DRAG steers the player left/right (existing touchAxis movement; disable auto-assist
+  during horde). Pellets fire straight up-court (-z) with ±4° random spread, every
+  1/TUNE.mgRate s (6/s).
+- Pellets are NOT the match ball — new lightweight array in zombies.js
+  `pellets = []` {x, y, z, vx, vz, t}: flat trajectory (no gravity, y fixed ~0.9),
+  speed ~26 m/s, t = 1.2s despawn, kill on zombie contact d < 0.55 (always splatter-
+  quality: gore + pile + splatPoint). Update them in updateZombies, render as 2×2 yellow
+  rects with a tiny ground shadow, drawn with the ball layer.
+- Umpire spam control: splatPoint gains an optional `quiet` param — during horde,
+  point voices are rate-limited (only speak if > 2s since last score line; game-win
+  lines always speak). Keep the score ticking on the HUD regardless.
+- Horde end (t ≤ 0): stop auto-fire, existing serve loop resumes (setupPoint),
+  voice('quiet_dark', 0.5, 0.85). Any zombies still alive stay alive — the player
+  mops up by serving. Eaten rule stays ON during hordes (swarms are lethal).
+- Match ball during horde: kill it (ball.active = false) at horde start; serve prompt
+  suppressed while G.horde (render gate, same spot as the eaten gate).
+- Firing sound: rapid low-vol pock(0.25, 1400) per pellet is fine — verify it doesn't
+  clip; if it does, only sound every 2nd pellet.
+
+Verify: force horde via umpire triple-tap; step 12s: spawn count ≈ 30, pellets stream
+and kill, piles accumulate, score advances with rate-limited voices, horde ends cleanly
+back into serve loop, no console errors, eaten still triggers if a zombie reaches you.
+Then the full ladder: tennis benchmarks + Phase 1–4 verifies still green.
+
+## Phase 6 — Racket zombies (NOT in the first cut — design checkpoint first)
+
+STOP: before implementing, show Oliver a one-paragraph design + the generated sprite
+sheet for approval. Rough shape agreed so far:
+- A special zombie (`variant 'r'`, has a racket) takes up residence on the FAR side and
+  RETURNS your shots — the tennis rally skill stays alive inside zombie mode.
+- Reuse the existing CPU machinery, don't rebuild it: give the racket zombie the same
+  shape trySwing/doHit need (side:'O', x, z, facing, pose, poseT, swingT) and run a
+  slimmed copy of the tennis-mode AI block for it (slower aiSpeed ~2.8, quality capped
+  ~0.55, flub ~0.2, shambling run). Your non-splat-quality shots it can return; a
+  splat-quality ball that reaches it kills it (existing contact path).
+- Its returns are live balls: if one gets past you → splatPoint('O') via the existing
+  baseline rule; you can also RALLY it back (doHit already works in splatter for the
+  player — zombieTarget will need a "prefer the racket zombie when rallying" tweak).
+- Sprite: the ONLY sprite-pipeline task in this plan (generate-image skill + scratchpad
+  slice.py — the full pipeline gotchas are in HANDOFF). Idle/run/swing poses, magenta bg.
+- Spawn: one per horde survived, or one per N games — decide with Oliver.
+
+## New TUNE knobs (summary)
+splatterOverT 0.1 · zPierce 0.75 · bombEvery 8 · bombMax 3 · bombRadius 2.5 ·
+mgRate 6 · hordeLen 12 · hordeRate 2.5
+
+## Benchmarks that must stay green after EVERY phase (scripts in HANDOFF)
+- Tennis: CPU returns ~11/12 serves; human-like tap sim = all hits, no whiffs;
+  feet-bounce tap sweep ≈ 19/30.
+- Splatter: serve→serve ≤ 20 frames with immediate flicks (Phase 1 onward);
+  eaten flow (zombie at <0.7m → EATEN overlay → tap restarts).
+- No console errors after each phase's full verify run.