// PROCITY Lane B — buildings.js
// The facade kit. Builds ONE chunk's buildings into a small, disposable set of draw calls:
//   • InstancedMesh shells + parapets + verandah posts + awning boxes  (per-instance matrix/colour)
//   • merged facade planes, grouped per skin → one mesh per skin, sharing a city-wide material
//   • one 2048² sign atlas per chunk (every sign drawn once, planes UV-mapped into it)
//   • merged door / window meshes (windows go emissive at night via applyNight)
// Everything is built in world space and collected, so a whole chunk is ~10–18 draw calls.
//
// Canonical building: front face at local +Z, footprint centred at origin, then translate to the
// lot centre (x,z) and rotate by lot.ry (see fixture_plan.js orientation note).

import * as THREE from 'three';
import { mergeGeometries } from 'three/addons/utils/BufferGeometryUtils.js';
import { rng, pick, frange, irange } from '../core/prng.js';
import { SHOP_REGISTRY } from './fixture_plan.js';
import { lotCollider } from './planutil.js';

const STOREY_H = 3.2;
const FACADE_H = 3.0;        // ground-floor shopfront height the skin covers
const PARAPET_H = 0.5;
const AWNING_DEPTH = 2.2;    // reach over the footpath
const AWNING_Y = 2.95;
const WALL_TINTS = ['#c9b8a0', '#b0b8ab', '#c4b0b0', '#a8b4c0', '#c4bc9c', '#cab89e', '#b8a890'];
const ROOF_TINT = '#5b5148';
const AWNING_SKINS = ['red', 'green', 'blue'];

// ── R26 #5 — the stocked shopfront (B's polish pick) ──────────────────────────────────────────────
// A crate-diggers' shop should read as one FROM THE FOOTPATH. The beta makes every keyed crate
// distinct *inside*; this closes the loop outside, so the player can spot a shop worth digging while
// walking past instead of door-roulette.
//
// THE MANIFEST IS THE AUTHORITY (ledger #6 — the same file F's wire consults). Deliberately NOT the
// `godverseShopId` key: keyed only means "has a stock identity", while the manifest means "a crate is
// actually here". Advertising a crate the shop hasn't got would make the street lie — the one thing
// this epoch keeps refusing to do. Fail-soft: no manifest (or ?noassets, or a shape we don't
// recognise) ⇒ no treatment ⇒ the street simply makes no promise. Never an error.
//
// The mark says "you can dig here", which is equally true of `real` and `mint` crates, so it does NOT
// leak tier — provenance belongs on C's price card and in the gates, not shouted from the footpath.
//
// Cost: ZERO extra draws / tris. The mark is drawn into the chunk's EXISTING sign-atlas cell and the
// window cue rides the EXISTING per-shop aTint attribute. Nothing new is allocated or submitted.
// The manifest is fetched LAZILY — only once a plan actually carries a keyed shop. A module-load fetch
// would have hit every boot: a pointless request (and, before G emits the file, a console 404) on the
// synthetic default, and a fetch delta on ?classic=1, whose covenant is zero-fetch. Godverse towns pay
// for it; nobody else knows it exists.
const STOCK_INDEX = 'assets/stock_godverse/index.json';
let STOCKED = null;      // Set<godverseShopId> | null = "unknown" (⇒ no treatment)
let stockReq = null;     // in-flight/settled marker — the fetch happens at most once per session
function ensureStockIndex() {
  if (stockReq) return;
  stockReq = (async () => {
  try {
    const p = new URLSearchParams(location.search);
    if (p.get('noassets') != null && p.get('noassets') !== '0') return;   // asset law: zero fetch
    const r = await fetch(STOCK_INDEX, { cache: 'force-cache' });
    if (!r.ok) return;                                                     // 404 before G emits it — fine
    const j = await r.json();
    // Tolerant of the exact shape (C pins §7 this round, G emits next wave): accept an array at
    // .shops/.entries/.atlases or the root, of ids or of objects carrying godverseShopId|id.
    const list = Array.isArray(j) ? j : (Array.isArray(j?.shops) ? j.shops
      : Array.isArray(j?.entries) ? j.entries : Array.isArray(j?.atlases) ? j.atlases : null);
    if (!list) return;
    const set = new Set();
    for (const e of list) {
      const id = typeof e === 'number' ? e : (e && (e.godverseShopId ?? e.id));
      if (Number.isSafeInteger(id) && id > 0) set.add(id);
    }
    if (set.size) STOCKED = set;
  } catch { /* fail-soft by design */ }
  })();
}
const isStocked = (shop) => !!(STOCKED && shop && Number.isSafeInteger(shop.godverseShopId) && STOCKED.has(shop.godverseShopId));

// Called once by the chunk manager at construction: start the manifest fetch as early as possible, but
// still ONLY for a plan that has keyed shops. Without this the fetch would start on the first keyed
// CHUNK — i.e. the first stocked shop you walk up to would be built before the manifest landed and
// would miss its mark. Synthetic / real / classic plans have no keyed shops ⇒ no request, ever.
export function prefetchStockIndex(plan) {
  if ((plan?.shops || []).some((s) => Number.isSafeInteger(s && s.godverseShopId))) ensureStockIndex();
}

// ── Shop-hours facade state (§3.5): closed shops show dark windows + a CLOSED plate ─────────────
// ONE shared window material + ONE shared CLOSED-plate material across every chunk, driven by two
// shared uniforms that update ONCE on a day-segment change (via the 'procity:segment' event
// lighting.js dispatches — no per-frame poll). Per-shop open/closed rides on a per-vertex `aHours`
// (vec2 = the shop's [open,close] in 24h); the shader gates window emissive (open AND night) and
// plate alpha (closed). New chunks stream in already reflecting the current hour (shared uniforms).
const _hoursUniforms = { uHour: { value: 12 }, uNight: { value: 0 } };
let _windowMat = null, _plateMat = null, _plateTex = null;

function windowMaterial() {
  if (_windowMat) return _windowMat;
  const m = new THREE.MeshStandardMaterial({
    color: 0x28323c, roughness: 0.14, metalness: 0.35, transparent: true, opacity: 0.46,
    emissive: new THREE.Color(0xffcf94), emissiveIntensity: 1.2,
  });
  m.onBeforeCompile = (shader) => {
    shader.uniforms.uHour = _hoursUniforms.uHour;
    shader.uniforms.uNight = _hoursUniforms.uNight;
    shader.vertexShader = 'attribute vec2 aHours;\nvarying vec2 vHours;\n' +
      shader.vertexShader.replace('#include <begin_vertex>', '#include <begin_vertex>\n\tvHours = aHours;');
    shader.fragmentShader = 'uniform float uHour;\nuniform float uNight;\nvarying vec2 vHours;\n' +
      shader.fragmentShader.replace('#include <emissivemap_fragment>',
        '#include <emissivemap_fragment>\n\tfloat _open = step(vHours.x, uHour) * step(uHour + 0.0001, vHours.y);\n\ttotalEmissiveRadiance *= _open * uNight;');
  };
  _windowMat = m;
  return m;
}

// ── v2: parallax interior-mapping window glass (?winmap=1, default-off) ──────────────────────────
// Single-cube interior mapping: each glass fragment casts the view ray into a virtual room box and
// shades the surface it hits (back wall + shelf silhouettes, side walls, floor/ceiling) — a plausible
// room seen through the window with real parallax, zero extra geometry. One SHARED ShaderMaterial for
// all windows (per-shop variation via aTint/aSeed attributes), same 1 draw/chunk as v1. Respects §3.5
// via the same uHour/uNight + aHours: closed-at-night rooms go dark, open rooms glow warm. Fully
// procedural (no fetch). Flag-off path is untouched (v1 windowMaterial()).
// [Lane F R16 — THE FLIP] winmap DEFAULT-ON; ?winmap=0 opts out, ?classic=1 forces off (the v2 covenant).
const WINMAP = (() => { try { const p = new URLSearchParams(location.search); const classic = p.has('classic') && p.get('classic') !== '0'; return !classic && p.get('winmap') !== '0'; } catch (e) { return false; } })();
const ROOM_TINTS = [ // muted 90s interior wall colours (RGB 0..1), seeded per shop
  [0.56, 0.44, 0.33], [0.42, 0.47, 0.52], [0.52, 0.47, 0.37], [0.47, 0.42, 0.46],
  [0.54, 0.50, 0.41], [0.40, 0.45, 0.40], [0.58, 0.49, 0.40], [0.45, 0.48, 0.55],
];
// R26 #5: a stocked shop's window room reads warm-lamp-over-crates rather than a generic 90s wall —
// the second half of the footpath tell, and free (it rides the existing per-shop aTint attribute, so
// the winmap glass is still ONE shared material / one draw per chunk).
const STOCKED_ROOM_TINT = [0.50, 0.33, 0.22];
function roomTint(shop) {
  if (isStocked(shop)) return STOCKED_ROOM_TINT;
  return ROOM_TINTS[((shop ? shop.seed : 12345) >>> 0) % ROOM_TINTS.length];
}

let _winmapMat = null;
function interiorWindowMaterial() {
  if (_winmapMat) return _winmapMat;
  _winmapMat = new THREE.ShaderMaterial({
    transparent: true,
    uniforms: { uHour: _hoursUniforms.uHour, uNight: _hoursUniforms.uNight, uRoomDepth: { value: 0.85 } },
    vertexShader: `
      attribute vec2 aHours; attribute vec3 aTangent; attribute vec3 aTint; attribute float aSeed;
      varying vec2 vUv; varying vec3 vWorldPos; varying vec3 vNormalW; varying vec3 vTangentW;
      varying vec2 vHours; varying vec3 vTint; varying float vSeed;
      void main(){
        vUv = uv; vWorldPos = position; vNormalW = normal; vTangentW = aTangent;
        vHours = aHours; vTint = aTint; vSeed = aSeed;
        gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
      }`,
    fragmentShader: `
      precision highp float;
      uniform float uHour; uniform float uNight; uniform float uRoomDepth;
      varying vec2 vUv; varying vec3 vWorldPos; varying vec3 vNormalW; varying vec3 vTangentW;
      varying vec2 vHours; varying vec3 vTint; varying float vSeed;
      float h1(float n){ return fract(sin(n * 127.1) * 43758.5453); }
      void main(){
        vec3 N = normalize(vNormalW);
        vec3 T = normalize(vTangentW);
        vec3 Bb = normalize(cross(N, T));
        vec3 rayDir = normalize(vWorldPos - cameraPosition);
        vec3 rd = vec3(dot(rayDir, T), dot(rayDir, Bb), -dot(rayDir, N));
        rd.z = max(rd.z, 1e-3);
        vec2 uv = vUv;
        float tz = uRoomDepth / rd.z;                                   // back wall
        float tx = (abs(rd.x) > 1e-4) ? (((rd.x > 0.0 ? 1.0 : 0.0) - uv.x) / rd.x) : 1e9;
        float ty = (abs(rd.y) > 1e-4) ? (((rd.y > 0.0 ? 1.0 : 0.0) - uv.y) / rd.y) : 1e9;
        if (tx <= 0.0) tx = 1e9; if (ty <= 0.0) ty = 1e9;
        float t = min(tz, min(tx, ty));
        vec3 hit = vec3(uv, 0.0) + rd * t;
        float depth = clamp(hit.z / uRoomDepth, 0.0, 1.0);
        vec3 wall = vTint;
        vec3 col;
        if (t >= tz - 1e-5) {                                            // back wall + shelves
          col = wall * 0.82;
          for (int i = 0; i < 3; i++){
            float fy = 0.22 + float(i) * 0.26 + (h1(vSeed + float(i) * 3.7) - 0.5) * 0.06;
            float band = smoothstep(0.05, 0.03, abs(hit.y - fy));
            col = mix(col, wall * 0.42, band * 0.7);
            float bx = fract(hit.x * 6.0 + h1(vSeed + float(i)));
            float prod = step(0.15, bx) * step(bx, 0.85) * step(fy, hit.y) * step(hit.y, fy + 0.11);
            col = mix(col, wall * 1.3 + vec3(0.05, 0.03, 0.02), prod * 0.45);
          }
        } else if (t >= tx - 1e-5) {
          col = wall * 0.6;                                              // side wall
        } else {
          col = (rd.y < 0.0) ? wall * 0.5 : (wall * 1.05 + 0.04);        // floor / ceiling
        }
        col *= mix(1.0, 0.55, depth);                                    // depth falloff
        float open = step(vHours.x, uHour) * step(uHour + 0.0001, vHours.y);
        float lit = (uNight > 0.5) ? (open > 0.5 ? 1.0 : 0.10) : 0.72;   // §3.5: closed@night dark
        col *= lit;
        if (uNight > 0.5 && open > 0.5) col = mix(col, col * vec3(1.0, 0.85, 0.6) * 1.7, 0.65); // warm glow
        gl_FragColor = vec4(col, 0.94);
      }`,
  });
  return _winmapMat;
}

function plateTexture() {
  if (_plateTex) return _plateTex;
  const c = document.createElement('canvas'); c.width = 256; c.height = 96;
  const x = c.getContext('2d');
  x.fillStyle = '#7a0f12'; x.fillRect(0, 0, 256, 96);
  x.strokeStyle = '#e8c8a0'; x.lineWidth = 6; x.strokeRect(7, 7, 242, 82);
  x.fillStyle = '#f0e2c0'; x.font = 'bold 52px Arial, sans-serif';
  x.textAlign = 'center'; x.textBaseline = 'middle'; x.fillText('CLOSED', 128, 52);
  _plateTex = new THREE.CanvasTexture(c); _plateTex.colorSpace = THREE.SRGBColorSpace;
  _plateTex.generateMipmaps = false; _plateTex.minFilter = THREE.LinearFilter;
  return _plateTex;
}

function closedPlateMaterial() {
  if (_plateMat) return _plateMat;
  _plateMat = new THREE.ShaderMaterial({
    uniforms: { map: { value: plateTexture() }, uHour: _hoursUniforms.uHour },
    transparent: true, depthWrite: false,
    vertexShader: 'attribute vec2 aHours; varying vec2 vHours; varying vec2 vUv;\n'
      + 'void main(){ vHours = aHours; vUv = uv; gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0); }',
    fragmentShader: 'uniform sampler2D map; uniform float uHour; varying vec2 vHours; varying vec2 vUv;\n'
      + 'void main(){ float openF = step(vHours.x, uHour) * step(uHour + 0.0001, vHours.y);\n'
      + '  vec4 t = texture2D(map, vUv); float a = t.a * (1.0 - openF);\n'
      + '  if (a < 0.02) discard; gl_FragColor = vec4(t.rgb, a); }',
  });
  return _plateMat;
}

// Update the shared facade-hours uniforms (day-segment change → open/closed re-evaluates instantly).
export function setFacadeHours(hour, night) {
  _hoursUniforms.uHour.value = hour;
  _hoursUniforms.uNight.value = night ? 1 : 0;
}
if (typeof window !== 'undefined') {
  window.addEventListener('procity:segment', (e) => { if (e.detail) setFacadeHours(e.detail.hour, !!e.detail.night); });
}

const _m4 = new THREE.Matrix4();
const _q = new THREE.Quaternion();
const _up = new THREE.Vector3(0, 1, 0);
const _s = new THREE.Vector3();
const _p = new THREE.Vector3();

// Build a flat quad (two tris) from four world-space corners + a UV rect. Corners CCW seen from +Y-ish.
function quad(c0, c1, c2, c3, uv = [0, 0, 1, 1]) {
  const g = new THREE.BufferGeometry();
  const pos = new Float32Array([
    c0[0], c0[1], c0[2], c1[0], c1[1], c1[2], c2[0], c2[1], c2[2],
    c0[0], c0[1], c0[2], c2[0], c2[1], c2[2], c3[0], c3[1], c3[2],
  ]);
  const [u0, v0, u1, v1] = uv;
  const uvs = new Float32Array([u0, v0, u1, v0, u1, v1, u0, v0, u1, v1, u0, v1]);
  g.setAttribute('position', new THREE.BufferAttribute(pos, 3));
  g.setAttribute('uv', new THREE.BufferAttribute(uvs, 2));
  g.computeVertexNormals();
  return g;
}

// quad + a per-vertex `aHours` (the shop's [open,close]) so the shared window/plate shaders can
// gate emissive / alpha per shop without per-shop materials.
function hoursQuad(c0, c1, c2, c3, hours, uv) {
  const g = quad(c0, c1, c2, c3, uv);
  const h = new Float32Array(12);
  for (let i = 0; i < 6; i++) { h[i * 2] = hours[0]; h[i * 2 + 1] = hours[1]; }
  g.setAttribute('aHours', new THREE.BufferAttribute(h, 2));
  return g;
}

// A window quad. Under ?winmap it carries the extra interior-mapping attributes (aTangent = the
// window's world-space right vector, aTint = the seeded room colour, aSeed = shelf variation). With
// the flag off it is exactly the v1 hoursQuad, so flag-off is byte-identical.
function windowQuad(c0, c1, c2, c3, hours, shop) {
  const g = hoursQuad(c0, c1, c2, c3, hours);
  if (!WINMAP) return g;
  const tx = c1[0] - c0[0], ty = c1[1] - c0[1], tz = c1[2] - c0[2];
  const tl = Math.hypot(tx, ty, tz) || 1;
  const tan = [tx / tl, ty / tl, tz / tl];
  const tint = roomTint(shop);
  const seed = shop ? ((shop.seed >>> 0) % 997) / 997 : 0.5;
  const tanA = new Float32Array(18), tintA = new Float32Array(18), seedA = new Float32Array(6);
  for (let i = 0; i < 6; i++) {
    tanA[i * 3] = tan[0]; tanA[i * 3 + 1] = tan[1]; tanA[i * 3 + 2] = tan[2];
    tintA[i * 3] = tint[0]; tintA[i * 3 + 1] = tint[1]; tintA[i * 3 + 2] = tint[2];
    seedA[i] = seed;
  }
  g.setAttribute('aTangent', new THREE.BufferAttribute(tanA, 3));
  g.setAttribute('aTint', new THREE.BufferAttribute(tintA, 3));
  g.setAttribute('aSeed', new THREE.BufferAttribute(seedA, 1));
  return g;
}

// Transform a local (lx,ly,lz) point to world via a lot's (x,z,ry).
function toWorld(lot, lx, ly, lz, out) {
  const cos = Math.cos(lot.ry || 0), sin = Math.sin(lot.ry || 0);
  out[0] = lot.x + (lx * cos + lz * sin);
  out[1] = ly;
  out[2] = lot.z + (-lx * sin + lz * cos);
  return out;
}

/**
 * buildChunkBuildings(chunkData, ctx) → chunk building bundle.
 *   chunkData: { lots:[], shops:[] }
 *   ctx: { skins, citySeed, night }
 * returns { group, colliders, doorMesh|null, doorRects, applyNight, dispose }
 */
export function buildChunkBuildings(chunkData, ctx) {
  const { skins } = ctx;
  const group = new THREE.Group();
  group.name = 'chunk-buildings';
  // R26 #5: ask for the stock manifest only if this town has keyed shops at all (once per session).
  // Synthetic / real / classic boots never carry a godverseShopId, so they never make the request.
  if ((chunkData.shops || []).some((s) => Number.isSafeInteger(s && s.godverseShopId))) ensureStockIndex();

  const boxMats = [];         // {matrix, color} — shells + parapets + posts, ONE instanced draw/chunk
  const awnings = [];         // {matrix, color} — all awning/canopy skins, ONE instanced draw/chunk
  const facadeGeos = [];      // every shopfront facade, UV-mapped into the shared atlas → 1 merged mesh
  const doorGeos = [];        // interactive shop/stall doors (raycast targets)
  const decorDoorGeos = [];   // decorative house doors (NOT raycastable → no mis-resolve to a shop)
  const windowGeos = [];      // all windows merge into 1 mesh (shared material, per-vertex aHours)
  const plateGeos = [];       // CLOSED plates, shown per-shop by the shared plate shader (closed → visible)
  const signQuads = [];       // { geo }
  const colliders = [];
  const doorRects = [];       // { shopId, name, x, z, hours }

  const shopByLot = new Map(chunkData.shops.map((s) => [s.lot, s]));

  // ── sign atlas: lay every sign in this chunk into one 2048² canvas ──
  // Atlas sized to the chunk's ACTUAL sign count (not a fixed 2048²): one row per 4 signs, so a
  // typical chunk holds a ~2048×168 strip, not a 16MB square. Mipmaps off (saves ⅓ GPU + NPOT-safe).
  const COLS = 4, CELL_W = 512, CELL_H = 168, ATLAS_W = COLS * CELL_W; // 2048 wide
  const N_SIGNS = chunkData.shops.length;                              // shops+stalls each get one
  const ATLAS_ROWS = Math.max(1, Math.ceil(N_SIGNS / COLS));
  const ATLAS_H = ATLAS_ROWS * CELL_H;
  let atlasCanvas = null, actx = null; // still lazy — shopless chunks allocate nothing
  let signCell = 0;
  const signUV = new Map(); // shopId → [u0,v0,u1,v1]
  function drawSign(shop) {
    if (signCell >= COLS * ATLAS_ROWS) return null;
    if (!atlasCanvas) {
      atlasCanvas = document.createElement('canvas');
      atlasCanvas.width = ATLAS_W; atlasCanvas.height = ATLAS_H;
      actx = atlasCanvas.getContext('2d');
      actx.clearRect(0, 0, ATLAS_W, ATLAS_H);
    }
    const col = signCell % COLS, row = (signCell / COLS) | 0;
    const px = col * CELL_W, py = row * CELL_H;
    const reg = SHOP_REGISTRY[shop.type] || SHOP_REGISTRY.opshop;
    actx.fillStyle = reg.signBg; actx.fillRect(px + 4, py + 4, CELL_W - 8, CELL_H - 8);
    actx.fillStyle = reg.signFg;
    actx.strokeStyle = reg.signFg; actx.lineWidth = 3;
    actx.strokeRect(px + 10, py + 10, CELL_W - 20, CELL_H - 20);
    // fit text
    let fs = 74; const label = String(shop.name).slice(0, 22).toUpperCase();
    actx.textAlign = 'center'; actx.textBaseline = 'middle';
    do { actx.font = `bold ${fs}px Arial, sans-serif`; fs -= 4; }
    while (actx.measureText(label).width > CELL_W - 40 && fs > 22);
    actx.fillText(label, px + CELL_W / 2, py + CELL_H / 2);
    if (isStocked(shop)) drawCrateMark(px, py, shop);   // R26 #5 — same cell, no extra draw
    const uv = [px / ATLAS_W, 1 - (py + CELL_H) / ATLAS_H, (px + CELL_W) / ATLAS_W, 1 - py / ATLAS_H];
    signUV.set(shop.id, uv);
    signCell++;
    return uv;
  }

  // A crate of records seen end-on, along the sign's foot: the shop is worth digging. Seeded off
  // shop.seed so two stocked shops don't wear the same spines (the beta's whole theme, on the
  // street). Pure canvas into the cell already being drawn ⇒ zero draws, zero tris.
  const SPINES = ['#2f2a26', '#7a2f28', '#2c4553', '#6b5a2e', '#3f2f45', '#8a6a3a', '#26463a'];
  function drawCrateMark(px, py, shop) {
    const y = py + CELL_H - 40, h = 24;
    const x0 = px + 30, x1 = px + CELL_W - 30;
    actx.fillStyle = 'rgba(0,0,0,0.30)';                       // the crate itself, in shadow
    actx.fillRect(x0 - 7, y - 5, (x1 - x0) + 14, h + 10);
    let r = ((shop.seed >>> 0) || 1) ^ 0x5bf03635;
    const rnd = () => ((r = (r * 1664525 + 1013904223) >>> 0) / 4294967296);
    for (let x = x0; x < x1 - 3; x += 6) {                     // the spines: leaning, uneven, dug-through
      const hh = h - ((rnd() * 7) | 0);
      actx.fillStyle = SPINES[(rnd() * SPINES.length) | 0];
      actx.fillRect(x, y + (h - hh), 4, hh);
    }
  }

  // ── per-lot build ──
  for (const lot of chunkData.lots) {
    const shop = shopByLot.get(lot.id);
    if (lot.use === 'house') { buildHouse(lot); continue; }
    if (lot.use === 'stall') { buildStall(lot, shop); continue; }
    buildShopfront(lot, shop);
  }

  function buildShopfront(lot, shop) {
    const seed = shop ? shop.seed : ctx.citySeed ^ 0x9e37;
    const r = rng(seed, 'bld', 0);
    const storeys = (shop && shop.storeys) || 1;
    const h = storeys * STOREY_H;
    const w = lot.w, d = lot.d;
    const wallC = new THREE.Color(WALL_TINTS[seed % WALL_TINTS.length]);

    // shell (unit box scaled) centred at (x, h/2, z)
    _p.set(lot.x, h / 2, lot.z); _q.setFromAxisAngle(_up, lot.ry || 0); _s.set(w, h, d);
    boxMats.push({ matrix: new THREE.Matrix4().compose(_p, _q, _s), color: wallC.clone() });

    // parapet cap along the front
    _p.set(lot.x, h + PARAPET_H / 2, lot.z); _s.set(w, PARAPET_H, d * 0.6);
    boxMats.push({ matrix: new THREE.Matrix4().compose(_p, _q, _s), color: new THREE.Color(ROOF_TINT) });

    // facade plane on the ground-floor front (local +Z face) — UV-mapped into the shared facade atlas
    const skin = (shop && shop.facadeSkin) || 'weatherboard';
    const fh = Math.min(h, FACADE_H);
    const zf = d / 2 + 0.02;
    const hw = w * 0.48;
    const c0 = toWorld(lot, -hw, 0.02, zf, []);
    const c1 = toWorld(lot, hw, 0.02, zf, []);
    const c2 = toWorld(lot, hw, fh, zf, []);
    const c3 = toWorld(lot, -hw, fh, zf, []);
    facadeGeos.push(quad(c0, c1, c2, c3, skins.facadeAtlasUV(skin)));

    // door (dark) — centred, on the front, proud of the facade
    const dw = 1.2, dh = 2.2, zd = zf + 0.03;
    doorGeos.push(quad(
      toWorld(lot, -dw / 2, 0.02, zd, []), toWorld(lot, dw / 2, 0.02, zd, []),
      toWorld(lot, dw / 2, dh, zd, []), toWorld(lot, -dw / 2, dh, zd, []),
    ));
    const hrs = (shop && shop.hours) || [0, 24];   // infill w/o a shop → always "open" (lit at night)
    if (shop) doorRects.push({ shopId: shop.id, name: shop.name, hours: shop.hours, x: (toWorld(lot, 0, 0, zd, [])[0]), z: toWorld(lot, 0, 0, zd, [])[2] });

    // windows flanking the door (tinted glass, emissive when OPEN at night — per-shop via aHours)
    const winW = Math.max(0.7, (w - dw) / 2 - 0.6), winH = 1.5, wy = 1.55, zw = zf + 0.025;
    const offs = [-(dw / 2 + 0.4 + winW / 2), (dw / 2 + 0.4 + winW / 2)];
    for (const ox of offs) {
      windowGeos.push(windowQuad(
        toWorld(lot, ox - winW / 2, wy - winH / 2, zw, []), toWorld(lot, ox + winW / 2, wy - winH / 2, zw, []),
        toWorld(lot, ox + winW / 2, wy + winH / 2, zw, []), toWorld(lot, ox - winW / 2, wy + winH / 2, zw, []),
        hrs, shop,
      ));
    }
    // CLOSED plate over the shopfront — visible only when the shop is shut (shader gates on aHours)
    if (shop) {
      const pw = Math.min(1.5, w * 0.4), ph = 0.5, py = 1.35, zp = zf + 0.06;
      plateGeos.push(hoursQuad(
        toWorld(lot, -pw / 2, py - ph / 2, zp, []), toWorld(lot, pw / 2, py - ph / 2, zp, []),
        toWorld(lot, pw / 2, py + ph / 2, zp, []), toWorld(lot, -pw / 2, py + ph / 2, zp, []),
        shop.hours || [0, 24],
      ));
    }

    // sign band overlaying the blank signboard region of the skin
    if (shop) {
      drawSign(shop);
      const uv = signUV.get(shop.id);
      if (uv) {
        const sh = 0.5, sy = fh - 0.35, sw = w * 0.92, zs = zf + 0.05;
        signQuads.push(quad(
          toWorld(lot, -sw / 2, sy - sh / 2, zs, []), toWorld(lot, sw / 2, sy - sh / 2, zs, []),
          toWorld(lot, sw / 2, sy + sh / 2, zs, []), toWorld(lot, -sw / 2, sy + sh / 2, zs, []),
          uv,
        ));
      }
    }

    // posted verandah + awning over the footpath (main-street shopfronts only)
    if (lot.use === 'shop' || lot.use === 'anchor') {
      const askin = AWNING_SKINS[(seed >>> 3) % AWNING_SKINS.length]; // unsigned: seed is uint32
      // awning box: thin slab reaching over the footpath at the front
      _p.copy(new THREE.Vector3().fromArray(toWorld(lot, 0, AWNING_Y, d / 2 + AWNING_DEPTH / 2, [])));
      _s.set(w, 0.16, AWNING_DEPTH);
      awnings.push({ matrix: new THREE.Matrix4().compose(_p, _q, _s), color: new THREE.Color(skins.awningColor(askin)) });
      // two posts at the awning's outer edge
      const postY = AWNING_Y / 2;
      for (const ox of [-w / 2 + 0.25, w / 2 - 0.25]) {
        _p.fromArray(toWorld(lot, ox, postY, d / 2 + AWNING_DEPTH - 0.2, []));
        _s.set(0.12, AWNING_Y, 0.12);
        boxMats.push({ matrix: new THREE.Matrix4().compose(_p, _q, _s), color: new THREE.Color('#2b2b2b') });
      }
    }

    colliders.push(lotCollider(lot));
  }

  function buildHouse(lot) {
    const seed = (ctx.citySeed ^ (lot.x * 73856093) ^ (lot.z * 19349663)) >>> 0;
    const r = rng(seed, 'house', 0);
    const h = 2.7, w = lot.w, d = lot.d;
    const wallC = new THREE.Color(WALL_TINTS[seed % WALL_TINTS.length]);
    _p.set(lot.x, h / 2, lot.z); _q.setFromAxisAngle(_up, lot.ry || 0); _s.set(w, h, d);
    boxMats.push({ matrix: new THREE.Matrix4().compose(_p, _q, _s), color: wallC });
    // simple hip roof: a squashed, slightly oversized box on top
    _p.set(lot.x, h + 0.5, lot.z); _s.set(w + 0.6, 1.0, d + 0.6);
    boxMats.push({ matrix: new THREE.Matrix4().compose(_p, _q, _s), color: new THREE.Color(ROOF_TINT) });
    // front door + two windows (decorative — houses are not enterable, so keep the door out of
    // the interactive doorMesh or the HUD raycast would mis-resolve it to the nearest shop)
    const zf = d / 2 + 0.02;
    decorDoorGeos.push(quad(
      toWorld(lot, -0.5, 0.02, zf, []), toWorld(lot, 0.5, 0.02, zf, []),
      toWorld(lot, 0.5, 2.0, zf, []), toWorld(lot, -0.5, 2.0, zf, []),
    ));
    for (const ox of [-w / 2 + 1.2, w / 2 - 1.2]) {
      windowGeos.push(windowQuad(
        toWorld(lot, ox - 0.6, 1.1, zf, []), toWorld(lot, ox + 0.6, 1.1, zf, []),
        toWorld(lot, ox + 0.6, 2.0, zf, []), toWorld(lot, ox - 0.6, 2.0, zf, []),
        [0, 24], null,   // homes glow at night (always "open")
      ));
    }
    colliders.push(lotCollider(lot));
  }

  function buildStall(lot, shop) {
    const seed = shop ? shop.seed : 4242;
    const w = lot.w, d = lot.d;
    // trestle table
    _p.set(lot.x, 0.4, lot.z); _q.setFromAxisAngle(_up, lot.ry || 0); _s.set(w, 0.8, d);
    boxMats.push({ matrix: new THREE.Matrix4().compose(_p, _q, _s), color: new THREE.Color('#6b4a30') });
    // striped canopy (awning skin) above
    const askin = AWNING_SKINS[seed % AWNING_SKINS.length];
    _p.set(lot.x, 2.2, lot.z); _s.set(w + 0.6, 0.14, d + 0.8);
    awnings.push({ matrix: new THREE.Matrix4().compose(_p, _q, _s), color: new THREE.Color(skins.awningColor(askin)) });
    // corner posts
    for (const [ox, oz] of [[-w / 2, -d / 2], [w / 2, -d / 2], [-w / 2, d / 2], [w / 2, d / 2]]) {
      _p.fromArray(toWorld(lot, ox, 1.1, oz, [])); _s.set(0.08, 2.2, 0.08);
      boxMats.push({ matrix: new THREE.Matrix4().compose(_p, _q, _s), color: new THREE.Color('#3a3a3a') });
    }
    // interaction plane on the front so you can "enter" the stall
    if (shop) {
      const zf = d / 2 + 0.02;
      doorGeos.push(quad(
        toWorld(lot, -w / 2, 0.02, zf, []), toWorld(lot, w / 2, 0.02, zf, []),
        toWorld(lot, w / 2, 1.9, zf, []), toWorld(lot, -w / 2, 1.9, zf, []),
      ));
      doorRects.push({ shopId: shop.id, name: shop.name, hours: shop.hours, x: lot.x, z: lot.z });
      drawSign(shop);
      const uv = signUV.get(shop.id);
      if (uv) {
        signQuads.push(quad(
          toWorld(lot, -w / 2, 2.0, zf + 0.05, []), toWorld(lot, w / 2, 2.0, zf + 0.05, []),
          toWorld(lot, w / 2, 2.4, zf + 0.05, []), toWorld(lot, -w / 2, 2.4, zf + 0.05, []),
          uv,
        ));
      }
      // CLOSED plate on the stall front
      const pw = Math.min(1.4, w * 0.6);
      plateGeos.push(hoursQuad(
        toWorld(lot, -pw / 2, 1.0, zf + 0.06, []), toWorld(lot, pw / 2, 1.0, zf + 0.06, []),
        toWorld(lot, pw / 2, 1.45, zf + 0.06, []), toWorld(lot, -pw / 2, 1.45, zf + 0.06, []),
        shop.hours || [0, 24],
      ));
    }
    colliders.push(lotCollider(lot));
  }

  // ── finalise instanced meshes ──
  const disposables = [];
  function makeInstanced(list, material, castShadow) {
    if (!list.length) return null;
    const geo = new THREE.BoxGeometry(1, 1, 1);
    const im = new THREE.InstancedMesh(geo, material, list.length);
    for (let i = 0; i < list.length; i++) {
      im.setMatrixAt(i, list[i].matrix);
      if (list[i].color && im.instanceColor !== undefined) im.setColorAt(i, list[i].color);
    }
    im.instanceMatrix.needsUpdate = true;
    if (im.instanceColor) im.instanceColor.needsUpdate = true;
    im.castShadow = !!castShadow; im.receiveShadow = true;
    im.frustumCulled = true;
    disposables.push(geo);
    group.add(im);
    return im;
  }
  makeInstanced(boxMats, skins.shellMaterial(), true);      // shells + parapets + posts (per-instance colour)
  makeInstanced(awnings, skins.awningMaterial(), true);     // every awning/canopy skin (per-instance colour)

  // ── finalise the facade: ALL skins merge into ONE mesh via the shared atlas (1 draw/chunk) ──
  if (facadeGeos.length) {
    const merged = mergeGeometries(facadeGeos, false);
    facadeGeos.forEach((g) => g.dispose());
    const mesh = new THREE.Mesh(merged, skins.facadeAtlasMaterial());
    mesh.receiveShadow = true; mesh.castShadow = false;
    disposables.push(merged);
    group.add(mesh);
  }

  // ── doors ──
  const doorMat = new THREE.MeshStandardMaterial({ color: 0x2a2018, roughness: 0.7 });
  disposables.push(doorMat);
  // interactive shop/stall doors — the HUD raycasts this mesh and maps hits to doorRects
  let doorMesh = null;
  if (doorGeos.length) {
    const merged = mergeGeometries(doorGeos, false);
    doorGeos.forEach((g) => g.dispose());
    doorMesh = new THREE.Mesh(merged, doorMat);
    doorMesh.userData.isDoorMesh = true;
    doorMesh.userData.doorRects = doorRects;
    disposables.push(merged);
    group.add(doorMesh);
  }
  // decorative house doors — same look, but no userData so the HUD never picks them
  if (decorDoorGeos.length) {
    const merged = mergeGeometries(decorDoorGeos, false);
    decorDoorGeos.forEach((g) => g.dispose());
    const mesh = new THREE.Mesh(merged, doorMat);
    disposables.push(merged);
    group.add(mesh);
  }

  // ── windows (merged, ONE shared material; emissive gated per-shop by the aHours shader) ──
  // ?winmap swaps in the parallax interior-mapping glass (v2); default is the v1 window material.
  if (windowGeos.length) {
    const merged = mergeGeometries(windowGeos, false);
    windowGeos.forEach((g) => g.dispose());
    const mesh = new THREE.Mesh(merged, WINMAP ? interiorWindowMaterial() : windowMaterial()); // shared → NOT disposed
    group.add(mesh);
    disposables.push(merged);
  }

  // ── CLOSED plates (merged; the shared shader shows each only while its shop is shut) ──
  if (plateGeos.length) {
    const merged = mergeGeometries(plateGeos, false);
    plateGeos.forEach((g) => g.dispose());
    const mesh = new THREE.Mesh(merged, closedPlateMaterial()); // shared → NOT disposed per chunk
    mesh.renderOrder = 2;
    group.add(mesh);
    disposables.push(merged);
  }

  // ── signs (merged, one atlas texture) ──
  if (signQuads.length) {
    const merged = mergeGeometries(signQuads.map((s) => s.geo || s), false);
    signQuads.forEach((s) => (s.geo || s).dispose());
    const tex = new THREE.CanvasTexture(atlasCanvas);
    tex.colorSpace = THREE.SRGBColorSpace; tex.anisotropy = 4;
    tex.generateMipmaps = false; tex.minFilter = THREE.LinearFilter; // ⅓ less GPU mem, NPOT-safe
    const mat = new THREE.MeshBasicMaterial({ map: tex, transparent: true });
    const mesh = new THREE.Mesh(merged, mat);
    disposables.push(merged, tex, mat);
    group.add(mesh);
  }

  // Windows + plates are now driven by the shared shop-hours uniforms (setFacadeHours on a segment
  // change), so night no longer needs a per-chunk window toggle. Kept for the ChunkManager's call.
  function applyNight() { /* no-op: window/plate state is the shared uHour/uNight uniform */ }

  function dispose() {
    group.traverse((o) => {
      if (o.isInstancedMesh) o.dispose && o.dispose();     // frees instanceMatrix/instanceColor
      if (o.isMesh || o.isInstancedMesh) o.geometry && o.geometry.dispose && o.geometry.dispose();
    });
    for (const d of disposables) d.dispose && d.dispose();
    group.clear();
  }

  return { group, colliders, doorMesh, doorRects, applyNight, dispose };
}