// PROCITY Lane D — the rig stack. Ported faithfully from 90sDJsim web/world/index.html ~405–500
// (loadRig / spawnRig / _canon / canonRig / _rotOnly / head-bone height-normalize / the shared
// walk+idle clip driving all 19 peds). This stack is proven; the changes for PROCITY are:
//   • loaders come from core/loaders.js (promise-cached, fail-soft) instead of an inline one
//   • randomness is injected (a seeded stream) — no Math.random() in identity/placement
//   • the figure is wrapped in an outer Group whose origin sits at the feet (ground = local y=0),
//     so the sim can move/rotate a walker without re-planting it every frame.
//
// House law: one canonical clip bank drives every character (shared skeleton namespace), never a
// per-character rig. SkeletonUtils.clone gives each spawn its own skeleton off a shared base mesh.

import * as THREE from 'three';
import { clone as skeletonClone } from 'three/addons/utils/SkeletonUtils.js';
import { loadGLB } from '../core/loaders.js';

// The 19 rigged peds (17 normal + 2 comical) copied byte-identical from 90sDJsim into web/models/peds/.
// [R36 wave 2.5 — Fable ruling on F's §36.4 hold] `normal` is the CLASSIC-COVENANTED base 17 (the exact
// pre-July-20 list, order preserved — pickRig maps r01 through pool.length, so the length IS the identity).
// The 5 trellis'd DJ bodies (b339402, fbx_to_ped, 4k tris) live in `djs` and join the roster only when
// loadPedFleet's `djs` opt is on — they are APPENDED, so the default-boot pool is byte-identical to the
// pre-ruling 22-list and `?classic=1` is byte-identical to pre-July-20 (fetch surface AND crowd identity).
export const PED_NAMES = {
  normal: ['man_worker_hivis_01', 'man_suit_01', 'man_casual_01', 'man_casual_02', 'man_casual_03',
    'man_grunge_01', 'man_elder_01', 'man_athletic_01', 'man_bouncer_01', 'man_soldier_ww2_01',
    'man_dj_streetwear_01', 'woman_casual_01', 'woman_casual_02', 'woman_business_01',
    'woman_athleisure_01', 'woman_smart_01', 'woman_chef_01'],
  djs: ['woman_dj_01', 'woman_dj_02', 'woman_dj_03', 'dj_techno_01', 'dj_phrtt_01'],   // gated: dance-scene bodies, NOT in classic's pool
  comical: ['comical_luchador_01', 'comical_boy_01'],
};

// ---- Mixamo skeleton canonicalisation (the crown-jewel trick) ----
// mixamorig1Hips vs mixamorig4Hips → mixamorig Hips, so ANY clip binds to ANY character.
const _canon = s => s.replace(/mixamorig\d+/g, 'mixamorig');
// [R41 §41.3] exported so clipbank.js runs Lane E's 46 library clips through the IDENTICAL two-step
// (`_canon` then `_rotOnly`) that walk/idle/sit/look/dance have ridden since R2 — one code path, so a
// library clip cannot diverge from a base clip in how it binds. E measured 65 raw tracks → 64 after
// the filter on all 46; clipbank.js re-asserts non-empty per clip at load.
export const canonName = _canon;
function canonRig(r) {
  if (!r) return r;
  if (r.scene) r.scene.traverse(o => { o.name = _canon(o.name); });
  if (r.anims) r.anims.forEach(a => a.tracks.forEach(t => { t.name = _canon(t.name); }));
  return r;
}
// shared-clip filter: keep limb/spine rotations only — drop ALL position tracks (a different-scale
// source inflates/crumples the target) AND Hips.quaternion (a different-orientation source lays it
// flat). The character keeps its own upright bind root; the game translates walkers itself.
const _rotOnly = c => new THREE.AnimationClip(c.name, c.duration,
  c.tracks.filter(t => t.name.endsWith('.quaternion') && !/Hips\.quaternion$/i.test(t.name)));
export const rotOnlyClip = _rotOnly;   // [R41 §41.3] same filter for the library clips — see canonName
// R16 sit clip note: the sit pose ALSO rides `_rotOnly`. R16 first tried keeping `Hips.quaternion` (a
// `_rotWithHips` variant, per the R14 recon) to preserve the pelvic tilt — but the fleet rigs' bind-pose
// Hips orientation differs from the Mixamo source, so keeping the sit Hips.quaternion LAYS THE BODY FLAT
// (head folded to hip height — verified in-shell), exactly the failure the comment above documents for
// walk/idle. So the sit clip drops Hips.quaternion like every other clip; the seated read comes from the
// leg-bone bends + spawnRig's seated foot-replant. Reads seated from the crowd POV (the kit hides the legs).

// core loadGLB returns the whole gltf (scene + animations); adapt to the {scene, anims} rig shape.
function loadRig(ref) {
  return loadGLB(ref).then(g => (g ? { scene: g.scene, anims: g.animations || [] } : null));
}

// loadPedFleet(base) → a live Fleet object, returned immediately (ready:false). Arrays fill in as
// GLBs land; fleet.whenReady resolves when every load settled. The town runs on placeholders until
// then, then upgradeStreetPeople swaps them (see sim.js). Missing files just leave the fleet smaller.
// `opts.sit` (R16): also load sit.glb → fleet.sitClip (the seated-drummer pose). GATED because a raw
// sit.glb fetch would break the ?classic=1 zero-fetch-delta covenant — F passes sit:true on the gig/default
// boot, sit:false (default) under ?classic. Absent/off → fleet.sitClip stays null and the drummer falls
// back to the standing-sunk hack, so this never breaks a boot. Does NOT touch fleet.ready / determinism.
// `opts.djs` (R36 w2.5): admit the 5 trellis'd DJ bodies into the normal roster. DEFAULTS TO `dance` —
// the shell already passes `dance: !CLASSIC`, so the classic-ness signal arrives without a shell edit and
// the bodies ride the same `!CLASSIC` gate as the sit/look/dance clips: `?classic=1` fetches none of the
// five and keeps the covenanted 17-pool; every other boot gets all 22. Separable for callers that want
// dance clips without the bodies (or vice versa).
// `opts.clips` (R41 §41.3): Lane E's 46-clip MOTION LIBRARY (web/models/clips/*.glb +
// web/assets/motion_manifest.json). DEFAULTS TO `dance` for exactly the reason `djs` does — the shell
// already passes `dance: !CLASSIC` (index.html:232), so the classic-ness signal arrives with ZERO
// shell edits and the library rides the same gate as the sit/look/dance clips. `?classic=1` ⇒ no
// manifest fetch, no clip-GLB fetch, and (because the module is reached by dynamic `import()`) not
// even a clipbank.js fetch: the zero-fetch-delta covenant is untouched. `?noassets=1` never calls
// loadPedFleet at all. On, the bank fetches THREE things at boot — the 16 KB manifest and the two
// eager groups (postures.js BOOT_GROUPS: idles.glb 1 029 496 B + locomotion.glb 212 776 B) — and
// everything else lazily on first demand. `fleet.ready` deliberately does NOT depend on the bank: a
// dead manifest or a 404 group leaves the R2 8-clip fleet running exactly as it does today.
// `?clips=0` is the CONTROL ARM, and it exists because `?classic=1` is a bad control for this: it
// changes the ped pool, the sit/look/dance clips, the fog, the game and half the shell at once, so a
// draw or heap delta measured against it says nothing about the motion library specifically. This
// flag turns off the library and NOTHING else. Read the same way furniture.js reads ?noassets.
const CLIPS_OFF = (() => { try { return new URLSearchParams(location.search).get('clips') === '0'; } catch { return false; } })();

export function loadPedFleet(base = 'models/peds/', { sit = false, look = false, dance = false, djs = dance,
    clips = dance, clipBase = null, manifestUrl = null, clipGroups = null } = {}) {
  if (CLIPS_OFF) clips = false;
  const fleet = {
    normal: [], comical: [], all: [],   // all = normal ++ comical, stable index for the impostor atlas
    walkClip: null, idleClip: null, sitClip: null, lookClip: null, danceClips: [],
    bank: null,                         // R41 ClipBank | null (null ⇒ every consumer takes its base clip)
    ready: false, whenReady: null,
  };
  // DETERMINISM: fill fixed slots by PED_NAMES index, NOT push-on-resolve — otherwise the array
  // order (and thus every pickRig index + identity signature) depends on GLB load-completion timing,
  // which varies per run/machine and silently breaks "same seed → same crowd". Compact after all
  // settle (filter(Boolean) preserves the fixed relative order, so a missing file is deterministic too).
  // R36 w2.5: the DJ bodies extend the roster AFTER the base 17, so gating them off shortens the pool
  // without renumbering a single base slot — classic's pickRig mapping is the pre-July-20 one exactly.
  const normalNames = djs ? [...PED_NAMES.normal, ...PED_NAMES.djs] : PED_NAMES.normal;
  const nSlots = new Array(normalNames.length).fill(null);
  const cSlots = new Array(PED_NAMES.comical.length).fill(null);
  const jobs = [];
  normalNames.forEach((n, i) => jobs.push(loadRig(`${base}${n}.glb`).then(r => {
    if (r) { r.pedName = n; nSlots[i] = canonRig(r); } })));
  PED_NAMES.comical.forEach((n, i) => jobs.push(loadRig(`${base}${n}.glb`).then(r => {
    if (r) { r.pedName = n; cSlots[i] = canonRig(r); } })));
  // shared clips: canonicalise track names, keep rotation only
  jobs.push(loadRig(`${base}walk.glb`).then(r => {
    const c = r && r.anims && r.anims[0];
    if (c) { c.tracks.forEach(t => t.name = _canon(t.name)); fleet.walkClip = _rotOnly(c); } }));
  jobs.push(loadRig(`${base}idle.glb`).then(r => {
    const c = r && r.anims && r.anims[0];
    if (c) { c.tracks.forEach(t => t.name = _canon(t.name)); fleet.idleClip = _rotOnly(c); } }));
  if (sit) jobs.push(loadRig(`${base}sit.glb`).then(r => {                    // R16, gig/default boot only
    const c = r && r.anims && r.anims[0];
    if (c) { c.tracks.forEach(t => t.name = _canon(t.name)); fleet.sitClip = _rotOnly(c); } }));
  // [R29 Spike 1] E's look.glb (mesh-free, 65 joints, 6.5 s 'Look'). Same gate as sit — the shell passes
  // `look: !CLASSIC`, so ?classic fetches nothing and the zero-fetch-delta covenant holds. `_rotOnly` is
  // correct here for the same reason as walk/idle: it's a STANDING clip, so there's no hip descent to
  // recover and no foot re-plant needed (that trap was sit's alone — R16).
  if (look) jobs.push(loadRig(`${base}look.glb`).then(r => {
    const c = r && r.anims && r.anims[0];
    if (c) { c.tracks.forEach(t => t.name = _canon(t.name)); fleet.lookClip = _rotOnly(c); } }));
  // dance clips (mesh-free mixamorig): the club dancers play a REAL move instead of procedural sway.
  // GATED like sit/look — ?classic fetches nothing so the zero-fetch-delta covenant holds. The per-dancer
  // pick is deterministic (a separate seeded stream in _make), so 'same seed -> same crowd' is preserved.
  const DANCE_CLIPS = ['dance_party', 'dance_medium', 'dance_drink', 'dance_sway'];
  const danceSlots = new Array(DANCE_CLIPS.length).fill(null);
  if (dance) DANCE_CLIPS.forEach((n, i) => jobs.push(loadRig(`${base}${n}.glb`).then(r => {
    const c = r && r.anims && r.anims[0];
    if (c) { c.tracks.forEach(t => t.name = _canon(t.name)); danceSlots[i] = _rotOnly(c); } })));
  // [R41 §41.3] the motion library. Dynamic import ⇒ clipbank.js is not even fetched when the gate is
  // off. Fail-soft twice over: the import and the boot both swallow, so `fleet.bank` stays null and
  // every downstream `bank && bank.get(...)` falls straight through to the base clip.
  // Published SYNCHRONOUSLY, before the import even starts: consumers that must make a STREAM-
  // AFFECTING decision (the sim's bench/lean/pause rolls) need a boot-stable answer to "is the
  // library on for this boot", not "has it landed yet" — otherwise the first second of a boot would
  // draw a different number of randoms than the rest of it, and 'same seed → same crowd' would
  // depend on network timing. `fleet.bank` stays the RESIDENCY question; this is the GATE question.
  fleet.clipsRequested = !!clips;
  if (clips) jobs.push(
    Promise.all([import('./clipbank.js'), import('./postures.js')]).then(([cb, po]) => {
      const bank = new cb.ClipBank({
        clipBase: clipBase || base.replace(/peds\/?$/, 'clips/'),
        manifestUrl: manifestUrl || base.replace(/models\/peds\/?$/, 'assets/motion_manifest.json'),
      });
      fleet.bank = bank;                                 // published immediately: lazy groups can be
      return bank.boot(clipGroups || po.BOOT_GROUPS);    // kicked before the boot groups land
    }).catch((e) => { console.warn('[rigs] motion library unavailable, base clips stay:', e && e.message); }));
  fleet.whenReady = Promise.all(jobs).then(() => {
    fleet.normal = nSlots.filter(Boolean);
    fleet.comical = cSlots.filter(Boolean);
    fleet.all = [...fleet.normal, ...fleet.comical];
    fleet.danceClips = danceSlots.filter(Boolean);
    fleet.ready = fleet.all.length > 0 && !!fleet.walkClip;
    return fleet;
  });
  return fleet;
}

// deterministic ped choice: ~8% comical curveball, else a normal, indexed by a seeded stream.
// Returns { rig, index } — index is into fleet.all (stable per ped type → impostor atlas cell).
export function pickRig(fleet, r01) {
  const comical = r01 < 0.08 && fleet.comical.length ? fleet.comical : null;
  const pool = comical || fleet.normal;
  if (!pool.length) return null;
  const rig = pool[(r01 * 997 % pool.length) | 0];
  const index = fleet.all.indexOf(rig);
  return { rig, index: index < 0 ? 0 : index };
}

// ---- buildFigure: clone a rig, height-normalise off the head bone, plant feet ----
// Returns { fig, inner, head }. `fig` is an outer Group whose origin is at the feet (ground = y=0)
// — set fig.position to the ground point and fig.rotation.y to the heading. NOTE materials are
// shared across SkeletonUtils clones (cheap); don't mutate them per-instance.
const _wp = new THREE.Vector3();
const _bb = new THREE.Box3();
const _bs = new THREE.Vector3();
export function buildFigure(rig, height = 1.75) {
  const inner = skeletonClone(rig.scene);
  inner.traverse(o => { if (o.isMesh) { o.frustumCulled = false; o.castShadow = false; } });
  // FACING NORMALISE (R13 debt #4 — the RY audit). The imported GLB fleet's visual front is local +Z,
  // but EVERYTHING downstream assumes -Z: the sim's heading math (sim.js atan2(-dx,-dz)), C's pose ry
  // (counter.stand / bandPoses / watchPoints / browse points), the placeholder (toes point -Z on
  // purpose, placeholder.js:61), and the impostor bake/pick (impostor.js -Z convention). So the GLB was
  // the lone outlier: keepers faced the back wall, browsers faced away, streamed walkers moon-walked
  // (anti-travel), and band.js carried a local RY_FLIP=π to patch just the gig. Rotate the rig's own
  // mesh 180° here so its front becomes -Z like the rest of the system — one place, everyone correct,
  // near↔mid stays seamless (the impostor bakes this same figure), and the flip is purely visual (a
  // Y-rotation leaves every bone's world-Y untouched → head-height/feet-plant + the no-giants gate and
  // all seeded identity/determinism are byte-unchanged). See LANE_D_NOTES R13 + LANE_C_PUB.md pose contract.
  inner.rotation.y = Math.PI;
  const fig = new THREE.Group();
  fig.add(inner);
  fig.updateWorldMatrix(true, true);

  // height-normalise so the crown sits at `height` above the feet, then plant feet.
  // NB the Mixamo skeleton's ORIGIN is the hips (~mid-body), so the head bone's world Y in bind pose
  // is head-above-hips (~half the standing height), NOT the standing height. Normalising by that alone
  // makes every figure ~2× too tall (the R9 interior-giant blocker). Normalise by the feet→crown SPAN
  // (top head bone minus lowest bone) so a requested 1.75 m rig is 1.75 m from sole to crown.
  let headY = 0, minY = Infinity;
  inner.traverse(o => {
    if (o.isBone) {
      o.getWorldPosition(_wp);
      if (/head/i.test(o.name)) headY = Math.max(headY, _wp.y);   // crown (HeadTop_End is highest)
      minY = Math.min(minY, _wp.y);                                // sole (lowest foot/toe bone)
    }
  });
  const span = headY - minY;   // feet→crown standing height in the rig's native units
  if (headY > 1e-4 && span > 1e-4) {
    inner.scale.setScalar(height / span);
  } else {
    // no head bone found — fall back to bounding-box height so we never ship a giant/ant
    _bb.setFromObject(inner); _bb.getSize(_bs);
    if (_bs.y > 1e-4) inner.scale.setScalar(height / _bs.y);
  }
  fig.updateWorldMatrix(true, true);
  minY = Infinity;
  inner.traverse(o => { if (o.isBone) { o.getWorldPosition(_wp); minY = Math.min(minY, _wp.y); } });
  if (minY === Infinity) { _bb.setFromObject(inner); minY = _bb.min.y; }
  inner.position.y = -minY;               // feet at outer y=0

  let head = null;
  inner.traverse(o => { if (!head && o.isBone && /head/i.test(o.name)) head = o; });
  return { fig, inner, head, nominalHeight: height };
}

// bind a clip to an inner figure, keeping only tracks whose target bones exist (else three spams
// "No target node found" per missing bone). Returns the AnimationAction (not yet played).
function _action(mixer, inner, clip) {
  if (!clip) return null;
  const nodes = new Set();
  inner.traverse(o => { if (o.name) nodes.add(o.name); });
  const bindable = clip.tracks.filter(t => nodes.has(t.name.split('.')[0]));
  const useClip = bindable.length === clip.tracks.length
    ? clip : new THREE.AnimationClip(clip.name, clip.duration, bindable);
  return mixer.clipAction(useClip);
}

// Dispose only what a SkeletonUtils clone actually OWNS: its Skeleton's per-instance bone texture.
// Geometry + materials are SHARED by reference across every clone and the fleet base rig — disposing
// them here would tear down GPU resources still in use by all sibling citizens of the same ped type.
function _disposeInner(inner) {
  const skels = new Set();
  inner.traverse(o => { if (o.isSkinnedMesh && o.skeleton) skels.add(o.skeleton); });
  skels.forEach(s => s.dispose?.());
}

// ---- spawnRig: single-clip figure (keepers, impostor baking). Height baked in. ----
export function spawnRig(rig, { ry = 0, clip = null, height = 1.75, phase = 0, seated = false } = {}) {
  if (!rig || !rig.scene) return null;
  const { fig, inner, head } = buildFigure(rig, height);
  fig.rotation.y = ry;
  const mixer = new THREE.AnimationMixer(inner);
  const chosen = clip || rig.anims.find(c => /idle/i.test(c.name)) || rig.anims[1] || rig.anims[0];
  const act = _action(mixer, inner, chosen);
  const bindPlantY = inner.position.y;   // R41: the STANDING feet-plant, to restore before any re-plant
  let curAct = act;
  let seatBone = null;
  if (act) {
    act.time = phase * (act.getClip().duration || 0); act.play();
    // R16 SEATED re-plant (OPT-IN — standing spawns skip this, so keepers/browsers/band are byte-identical).
    // buildFigure planted the BIND pose; a sit clip lowers the hips + swings the legs, so re-plant the POSED
    // feet to y=0: tick the mixer once to bake the pose, find the lowest bone, drop the figure so the soles
    // return to the deck. One-time (a drummer's feet don't travel); this recovers the hip descent that
    // _rotWithHips leaves out by dropping the (scale-unsafe) Hips.position track.
    if (seated) {
      mixer.update(0);
      inner.updateWorldMatrix(true, true);
      let m = Infinity;
      inner.traverse(o => { if (o.isBone) { o.getWorldPosition(_wp); m = Math.min(m, _wp.y); } });
      if (isFinite(m)) inner.position.y -= m;
      // R17 pelvic-lean: cache the mid-spine bone so seatedLean() can tilt the torso forward each frame (the
      // sit clip can't — Hips.quaternion is unusable on these rigs). Seated-only; standing rigs get no seatBone.
      inner.traverse(o => { if (!seatBone && o.isBone && /Spine1$/i.test(o.name)) seatBone = o; });
    }
  }
  // [R41 §41.3] setClip — swap this single-clip figure onto a motion-library clip AFTER it was built.
  // This is the self-healing seam: a keeper / browser / gig member is posed with whatever clip exists
  // at spawn (the R2 idle in the worst case) and upgrades in place the frame its lazily-fetched group
  // lands, so WHICH clip it was assigned never depends on load timing — only how soon it shows.
  //
  // The re-plant is the R29 lesson generalised. `_rotOnly` drops the Hips POSITION track (it must —
  // a foreign-scale source would inflate the rig), so a clip's authored vertical motion comes out as
  // the FEET moving instead of the hips: measured up to +0.205 m on look.glb. spawnRig's original
  // seated re-plant samples ONCE at t=0, which is right for a fixed pose and wrong for a clip whose
  // lowest bone travels. So this samples the posed skeleton at PLANT_SAMPLES points across the clip
  // and plants the MINIMUM — the soles can then never sink through the floor, and the residual float
  // is the clip's own authored range, not an arbitrary phase's error. Absolute (reset → measure →
  // correct), never incremental, and scale-aware via fig.scale.y.
  const PLANT_SAMPLES = 6;
  function _plant() {
    inner.position.y = bindPlantY;
    const clipDur = (curAct && curAct.getClip().duration) || 0;
    const t0 = curAct ? curAct.time : 0;
    let lo = Infinity;
    for (let i = 0; i < PLANT_SAMPLES; i++) {
      if (curAct) curAct.time = clipDur * (i / PLANT_SAMPLES);
      mixer.update(0);
      inner.updateWorldMatrix(true, true);
      inner.traverse(o => { if (o.isBone) { o.getWorldPosition(_wp); if (_wp.y < lo) lo = _wp.y; } });
      if (clipDur <= 0) break;
    }
    if (curAct) { curAct.time = t0; mixer.update(0); }
    if (!isFinite(lo)) return;
    const S = fig.scale.y || 1;
    inner.position.y -= (lo - fig.position.y) / S;
  }
  function setClip(next, { seated: st = seated, phase: ph = phase } = {}) {
    if (!next) return false;
    const na = _action(mixer, inner, next);
    if (!na) return false;
    if (curAct && curAct !== na) { curAct.stop(); curAct.setEffectiveWeight(0); }
    if (next._pcLoop === 'pingpong') na.setLoop(THREE.LoopPingPong, Infinity);
    curAct = na;
    na.reset().play().setEffectiveWeight(1);
    na.time = ph * (next.duration || 0);
    _plant();
    if (st) {
      fig.userData.procitySeated = true;
      seatBone = null;
      inner.traverse(o => { if (!seatBone && o.isBone && /Spine1$/i.test(o.name)) seatBone = o; });
    }
    return true;
  }
  function dispose() { mixer.stopAllAction(); mixer.uncacheRoot(inner); _disposeInner(inner); }
  return { fig, inner, mixer, height, head, get seatBone() { return seatBone; }, setClip, dispose };
}

// R17 pelvic-lean: tilt a seated fig's torso forward, applied AFTER the mixer each frame. The mixer resets
// the bone's quaternion from the clip every frame, so this is a CONSTANT offset (not an accumulation). Only
// seated figs (drummer, bench-sit loiterers) call it; standing rigs have no seatBone → never leaned.
const _LEAN_AXIS = new THREE.Vector3(1, 0, 0);
const _LEAN_Q = new THREE.Quaternion();
export function seatedLean(spine, angle = 0.34) {
  if (spine) spine.quaternion.multiply(_LEAN_Q.setFromAxisAngle(_LEAN_AXIS, angle));
}

// ---- makeActor: near-tier pedestrian with walk↔idle crossfade (built at nominal height; the sim
// scales the outer Group per-citizen so pooled actors are height-agnostic and reusable). ----
export function makeActor(rig, { walkClip, idleClip, sitClip = null, lookClip = null, nominalHeight = 1.75 } = {}) {
  if (!rig || !rig.scene) return null;
  const { fig, inner, head, nominalHeight: nom } = buildFigure(rig, nominalHeight);
  const bindPlantY = inner.position.y;   // R17 bench-sit: the standing feet-plant, to restore after a sit
  const mixer = new THREE.AnimationMixer(inner);
  // [R41 §41.3] one AnimationAction per SOURCE clip, memoised. Pooled actors are recycled across
  // citizens of the same ped type, so the per-citizen idle/walk cannot be baked in at construction —
  // it is swapped on acquire (≤3/frame, NEW_RIG_PER_FRAME). Memoising by source clip means a pool
  // slot that has seen five different idles pays five bindings, not five per acquire; three.js shares
  // the PropertyMixer bindings per (root, track) across all of them, so the marginal cost of an extra
  // action is its interpolants, not another copy of the skeleton.
  const _acts = new Map();
  function _act(clip) {
    if (!clip) return null;
    let a = _acts.get(clip);
    if (a === undefined) {
      a = _action(mixer, inner, clip);
      // library clips whose measured loop seam does not close play ping-pong instead of popping
      // (clipbank.js LOOP_SEAM_DEG) — `browse_pick_up` becomes crate-digging rather than a teleport.
      if (a && clip._pcLoop === 'pingpong') a.setLoop(THREE.LoopPingPong, Infinity);
      _acts.set(clip, a);
    }
    return a;
  }
  const baseWalkA = _act(walkClip || rig.anims.find(c => /walk/i.test(c.name)));
  const baseIdleA = _act(idleClip || rig.anims.find(c => /idle/i.test(c.name)));
  // R17 bench-sit: a third action, PLAYED ONLY when setSitting(true) — so walkers (and ?classic, where
  // sitClip is null) are byte-identical: sitA never plays, the plant never moves, setSitting is a no-op.
  const baseSitA = sitClip ? _act(sitClip) : null;
  // [R29 Spike 1] the glance — same opt-in shape as sitA: PLAYED ONLY when setLooking(true), so walkers,
  // placeholders and ?classic (lookClip null) are byte-identical — lookA never advances the mixer.
  const baseLookA = lookClip ? _act(lookClip) : null;
  // R41: the four live slots. They START at the base actions, so an actor nobody swaps is the R40
  // actor exactly; setIdleClip/setWalkClip/setSitting(_,clip)/setLooking(_,_,clip) re-point them.
  let walkA = baseWalkA, idleA = baseIdleA, sitA = baseSitA, lookA = baseLookA;
  let seatBone = null;
  if (baseSitA) inner.traverse(o => { if (!seatBone && o.isBone && /Spine1$/i.test(o.name)) seatBone = o; });
  // [R29] foot bones, cached once for the per-frame plant (see plantFeet). Only built when a posed clip
  // exists, so walkers/?classic pay nothing. R41: built lazily too, since a lean clip can arrive later.
  let footBones = null;
  function _footBones() {
    if (footBones !== null) return footBones;
    const fb = []; inner.traverse(o => { if (o.isBone && /(Toe|Foot)/i.test(o.name)) fb.push(o); });
    footBones = fb.length ? fb : false;
    return footBones;
  }
  if (baseLookA) _footBones();
  let sitting = false, looking = false;
  let moving = null;   // tri-state so the first setMoving always applies
  // both actions play; exactly one holds weight 1 at rest, setMoving transfers between them
  if (walkA) { walkA.play(); walkA.setEffectiveWeight(1); }
  if (idleA) { idleA.play(); idleA.setEffectiveWeight(0); }

  // walk↔idle: instant on the first apply / fade<=0 (fresh spawn must be posted immediately),
  // otherwise a real crossFade transfers weight from the resting action to the target.
  function setMoving(m, fade = 0.28) {
    if (m === moving) return;
    const first = moving === null;
    moving = m;
    if (!(walkA && idleA)) return;
    const to = m ? walkA : idleA, from = m ? idleA : walkA;
    to.enabled = from.enabled = true;
    if (first || fade <= 0) { to.setEffectiveWeight(1); from.setEffectiveWeight(0); }
    else from.crossFadeTo(to, fade, false);   // from holds weight 1 at rest → smooth transfer
  }
  // [R41 §41.3] the per-citizen resting/moving clips. Called on ACQUIRE only (the pool hands a recycled
  // actor to a new citizen), before setPhase + setMoving(_, 0) — so `moving = null` here is enough to
  // make the next setMoving apply instantly and no crossfade can be left mid-flight. Passing null
  // restores the base clip, which is exactly what a citizen whose assigned clip has not landed yet
  // (or whose boot has no bank at all) gets ⇒ the R40 actor, byte for byte.
  function setIdleClip(clip) {
    const a = clip ? (_act(clip) || baseIdleA) : baseIdleA;
    if (!a || a === idleA) return;
    if (idleA) { idleA.setEffectiveWeight(0); idleA.stop(); }
    idleA = a; idleA.enabled = true; idleA.reset().play(); idleA.setEffectiveWeight(0);
    moving = null;
  }
  function setWalkClip(clip) {
    const a = clip ? (_act(clip) || baseWalkA) : baseWalkA;
    if (!a || a === walkA) return;
    if (walkA) { walkA.setEffectiveWeight(0); walkA.stop(); }
    walkA = a; walkA.enabled = true; walkA.reset().play(); walkA.setEffectiveWeight(0);
    moving = null;
  }
  // R17 bench-sit: snap the loitering ped into / out of the sit pose (no crossfade — a background ped
  // sitting instantly is fine, and it avoids the crossfade fighting the discrete foot-replant). The sim's
  // per-citizen scale is already on `fig`, so the re-plant is SCALE-AWARE: drop `inner` by the posed
  // lowest-bone height / scale so the seated feet land on the footpath. Restore the standing plant on stand.
  // R41: `clip` (optional) is a motion-library sit variant (sitlean.glb) for THIS citizen; omitted /
  // null ⇒ the R16 sit.glb pose, unchanged. With neither, setSitting stays the no-op it has always
  // been under ?classic.
  function setSitting(s, clip = null) {
    const target = s ? ((clip && _act(clip)) || baseSitA) : null;
    if (s && !target) return;                        // nothing to sit with → inert (classic / no clip)
    if (!s && !sitting) return;                      // already standing
    if (s && sitting && target === sitA) return;     // already in this exact pose
    if (s && sitA && sitA !== target) sitA.stop();   // swapping pose mid-sit
    if (s) sitA = target;
    sitting = s;
    moving = null;   // force the next setMoving to re-apply after standing up
    if (s) {
      if (walkA) walkA.setEffectiveWeight(0);
      if (idleA) idleA.setEffectiveWeight(0);
      sitA.reset().play().setEffectiveWeight(1);
      mixer.update(0);                                  // bake the sit pose before measuring
      inner.updateWorldMatrix(true, true);
      let w = Infinity;
      inner.traverse(o => { if (o.isBone) { o.getWorldPosition(_wp); w = Math.min(w, _wp.y); } });
      const S = fig.scale.y || 1;
      if (isFinite(w)) inner.position.y -= (w - fig.position.y) / S;   // posed soles → the footpath
      fig.userData.procitySeated = true;
    } else {
      if (sitA) sitA.stop();
      sitA = baseSitA;                                  // back to the base pose for the next citizen
      inner.position.y = bindPlantY;                    // restore the standing feet-plant
      if (idleA) idleA.setEffectiveWeight(1);
      fig.userData.procitySeated = false;
    }
  }
  // [R29 Spike 1] the standing glance during a window-shop loiter. Deliberately SIMPLER than setSitting:
  // it's a standing clip, so there is no posed foot-replant and no scale trap — the feet never leave the
  // bind plant. Unlike sit (a snap, which had to avoid a crossfade fighting the discrete replant), this
  // crossfades: idle → idle-variant reads naturally, and the sim only calls it while the ped is stopped.
  // No-op when lookClip is absent (?classic / ?noassets) ⇒ byte-identical by construction.
  // R41: `clip` (optional) is any STANDING posed library clip for this citizen — a lean against a
  // shopfront (sitlean.glb's four lean_wall_*) rides the identical seam as R29's glance, because it is
  // the identical problem: a standing clip, no hip descent to recover, but a per-frame foot float that
  // plantFeet() absorbs. Omitted / null ⇒ look.glb, unchanged.
  function setLooking(l, fade = 0.3, clip = null) {
    const target = l ? ((clip && _act(clip)) || baseLookA) : null;
    if (l && !target) return;                          // no standing pose available → inert (classic)
    if (!l && !looking) return;
    if (l && looking && target === lookA) return;      // already in this exact pose
    if (l && lookA && lookA !== target) lookA.stop();  // swapping pose mid-look
    if (l) { lookA = target; _footBones(); }
    looking = l;
    moving = null;                       // force the next setMoving to re-apply on the way out
    if (l) {
      lookA.reset().play();
      if (idleA) idleA.crossFadeTo(lookA, fade, false);
      else lookA.setEffectiveWeight(1);
      if (walkA) walkA.setEffectiveWeight(0);
    } else {
      if (idleA) { idleA.reset().play(); if (lookA) lookA.crossFadeTo(idleA, fade, false); }
      else if (lookA) lookA.setEffectiveWeight(0);
      lookA = baseLookA;                 // back to the base pose for the next citizen
      inner.position.y = bindPlantY;     // drop the plant correction — back to the standing bind plant
    }
  }
  // [R29] MEASURED, and it corrected my own assumption: I expected a standing clip to need no re-plant
  // ("no hip descent to recover"). It does. `_rotOnly` drops the Hips POSITION track to stay rig-height
  // independent, so look.glb's authored weight-shift dip cannot move the hips — it comes out as the FEET
  // rising instead: lowest bone ranges −0.009…+0.205 m over the loop vs idle's −0.04…0.00. A 20 cm hover.
  // Sit's one-time re-plant can't fix it because the float VARIES per frame, so this is the per-frame twin:
  // reset to the bind plant, measure the posed feet, drop `inner` by the float / scale. Absolute (reset →
  // measure → correct), never incremental, so it cannot drift. The result reproduces the authored motion
  // exactly — the hips dip relative to the ground instead of the feet leaving it. Scale-aware like sit's.
  // Cost is paid ONLY by glancing peds (a handful), and only on frames their mixer actually ran.
  function plantFeet() {
    if (!footBones || !looking) return;
    inner.position.y = bindPlantY;                       // reference pose
    inner.updateWorldMatrix(true, true);
    let w = Infinity;
    for (const b of footBones) { b.getWorldPosition(_wp); if (_wp.y < w) w = _wp.y; }
    if (!isFinite(w)) return;
    const S = fig.scale.y || 1;
    inner.position.y -= (w - fig.position.y) / S;        // posed soles → the footpath
  }
  // seed the clip phase so the crowd isn't in lockstep
  function setPhase(p) {
    if (walkA) walkA.time = p * (walkA.getClip().duration || 1);
    if (idleA) idleA.time = p * (idleA.getClip().duration || 1);
    if (lookA) lookA.time = p * (lookA.getClip().duration || 1);   // R29: glances desync too
    if (sitA) sitA.time = p * (sitA.getClip().duration || 1);      // R41: so does a row of bench-sitters
  }
  function dispose() { mixer.stopAllAction(); mixer.uncacheRoot(inner); _acts.clear(); _disposeInner(inner); }

  return { fig, inner, mixer, head, get seatBone() { return seatBone; }, nominalHeight: nom,
           setMoving, setSitting, setLooking, setIdleClip, setWalkClip, plantFeet, setPhase, dispose,
           hasClips: !!(walkA && idleA) };
}