diff --git a/config.json b/config.json
index d1c461a4..e945d1c4 100644
--- a/config.json
+++ b/config.json
@@ -17,9 +17,5 @@
   "hashRouter": {
     "enabled": false,
     "basename": "/"
-  },
-
-  "backgroundScene": {
-    "tier": "off"
   }
 }
diff --git a/harness/scene/README.md b/harness/scene/README.md
deleted file mode 100644
index 382819ec..00000000
--- a/harness/scene/README.md
+++ /dev/null
@@ -1,19 +0,0 @@
-# Scene harness
-
-Compiles, renders and times the background scene (`src/app/features/scene/`) in headless
-Chromium. Not shipped, not run by CI.
-
-    node bundle.cjs <outdir>                  # esbuild bundle of entry.ts plus an index.html
-    node drive.cjs <outdir> compile           # compile and link each stage, JSON report
-    node drive.cjs <outdir> shots <pngdir>    # rest, mid pull-back and pulled-back screenshots
-    node drive.cjs <outdir> measure           # GPU time per pass by timer query, two viewports, two levels
-    node drive.cjs <outdir> variants          # the same with source patches (no erosion, no tree, value-only fbm)
-    node drive.cjs <outdir> phacelle          # the Phacelle gradient probe behind world.ts `phacelleGradBound`
-
-Needs `esbuild` and `playwright@1.48.2` on `NODE_PATH` and a Chromium. The first run was done on a
-host with no GPU, so `drive.cjs` launches with `--use-angle=swiftshader` (software Vulkan). On a
-machine with a GPU, remove those flags to measure the real device. `bundle.cjs` must run from a
-directory whose ancestors hold no empty `package.json` (esbuild reads them).
-
-Timings from SwiftShader are CPU time: use them for the split between passes and for before and
-after of one change, never as a phone frame time.
diff --git a/harness/scene/bundle.cjs b/harness/scene/bundle.cjs
deleted file mode 100644
index 62a47078..00000000
--- a/harness/scene/bundle.cjs
+++ /dev/null
@@ -1,35 +0,0 @@
-// Bundles entry.ts with the scene's ?raw GLSL imports into $OUT/bundle.js plus an index.html.
-// usage: node bundle.cjs <outdir>     (esbuild from NODE_PATH)
-const esbuild = require('esbuild');
-const fs = require('fs');
-const path = require('path');
-const out = process.argv[2];
-fs.mkdirSync(out, { recursive: true });
-const rawPlugin = {
-  name: 'raw',
-  setup(b) {
-    b.onResolve({ filter: /\?raw$/ }, (a) => ({
-      path: path.resolve(a.resolveDir, a.path.slice(0, -4)),
-      namespace: 'raw',
-    }));
-    b.onLoad({ filter: /.*/, namespace: 'raw' }, (a) => ({
-      contents: fs.readFileSync(a.path, 'utf8'),
-      loader: 'text',
-    }));
-  },
-};
-esbuild
-  .build({
-    entryPoints: [path.join(__dirname, 'entry.ts')],
-    bundle: true,
-    outfile: path.join(out, 'bundle.js'),
-    plugins: [rawPlugin],
-    format: 'iife',
-    target: 'es2020',
-  })
-  .then(() => {
-    fs.writeFileSync(
-      path.join(out, 'index.html'),
-      '<!doctype html><meta charset=utf-8><body style="margin:0"><canvas id=c style="width:100vw;height:100vh;display:block"></canvas><script src=bundle.js></script>'
-    );
-  });
diff --git a/harness/scene/drive.cjs b/harness/scene/drive.cjs
deleted file mode 100644
index 74c4a8b0..00000000
--- a/harness/scene/drive.cjs
+++ /dev/null
@@ -1,164 +0,0 @@
-// Drives the scene in headless Chromium (software GL unless the host has a GPU).
-// usage: node drive.cjs <bundledir> <mode> [outdir]     modes: compile | shots | measure
-// Needs playwright from NODE_PATH and PLAYWRIGHT_BROWSERS_PATH. Prints one JSON report.
-const { chromium } = require('playwright');
-const path = require('path');
-const [, , dir, mode, outdir = '.'] = process.argv;
-
-(async () => {
-  const b = await chromium.launch({
-    args: [
-      '--use-gl=angle',
-      '--use-angle=swiftshader',
-      '--enable-unsafe-swiftshader',
-      '--ignore-gpu-blocklist',
-    ],
-  });
-  const page = await b.newPage({ viewport: { width: 960, height: 540 } });
-  page.on('console', (m) => process.stderr.write(`[page] ${m.text()}\n`));
-  await page.goto('file://' + path.resolve(dir, 'index.html'));
-  const report = { mode };
-  report.renderer = await page.evaluate(() => {
-    const g = document.createElement('canvas').getContext('webgl2');
-    const e = g.getExtension('WEBGL_debug_renderer_info');
-    return g.getParameter(e ? e.UNMASKED_RENDERER_WEBGL : g.RENDERER);
-  });
-
-  if (mode === 'compile') {
-    report.stages = await page.evaluate(() => {
-      const gl = document.createElement('canvas').getContext('webgl2');
-      const S = window.__scene;
-      return ['terrain', 'atmosphere', 'resolve', 'composite'].map((stage) => {
-        const t0 = performance.now();
-        try {
-          const p = S.linkStage(gl, stage);
-          return {
-            stage,
-            ok: true,
-            ms: +(performance.now() - t0).toFixed(1),
-            sourceBytes: S.fragmentSource(stage).length,
-            log: gl.getProgramInfoLog(p),
-          };
-        } catch (e) {
-          return {
-            stage,
-            ok: false,
-            ms: +(performance.now() - t0).toFixed(1),
-            log: String(e.log || e),
-          };
-        }
-      });
-    });
-  }
-
-  if (mode === 'phacelle') {
-    report.probe = await page.evaluate(() =>
-      window.__probePhacelle(
-        window.__scene.WORLD.erodeSide.slice(),
-        window.__scene.WORLD.erodeNorm,
-        4
-      )
-    );
-  }
-
-  if (mode === 'shots') {
-    await page.evaluate(() => {
-      const c = document.getElementById('c');
-      window.__s = window.__scene.createScene({
-        canvas: c,
-        unthrottled: true,
-        fixedLevel: window.__scene.LEVELS[0],
-      });
-    });
-    const wait = (ms) => page.waitForTimeout(ms);
-    await wait(4000);
-    await page.screenshot({ path: path.join(outdir, 'rest.png') });
-    await page.evaluate(() => window.__s.login());
-    await wait(3500);
-    await page.screenshot({ path: path.join(outdir, 'mid-pullback.png') });
-    await wait(9000);
-    await page.screenshot({ path: path.join(outdir, 'pulled-back.png') });
-    report.shots = ['rest.png', 'mid-pullback.png', 'pulled-back.png'];
-  }
-
-  if (mode === 'measure' || mode === 'variants') {
-    const VARIANTS = {
-      baseline: null,
-      // What a public value-only fbm would cost: the same octaves without the gradient work.
-      valueOnlyFbm: [
-        'float terrainFbm(vec2 xz) { return cultmath_fbm_grad(vec3(xz * W_FREQ, 0.0), W_OCTAVES, W_LACUNARITY, W_GAIN).w; }',
-        'float terrainFbm(vec2 xz) { float a = 1.0, fr = 1.0, v = 0.0; for (int i = 0; i < W_OCTAVES; i++) { v += a * cultmath_snoise(vec3(xz * W_FREQ * fr, 0.0)); fr *= W_LACUNARITY; a *= W_GAIN; } return v; }',
-      ],
-      noErosion: ['#define W_ERODE_ENABLED 1', '#define W_ERODE_ENABLED 0'],
-      // Upper bound on what skipping sky rays would save: every upward ray misses at once.
-      noSkyMarch: ['    bool hit = false;\n    bool onTree = false;', '    if (rd.y > 0.0) { o_color = vec4(0.0); o_depth = W_FAR; return; }\n    bool hit = false;\n    bool onTree = false;'],
-      noTree: ['float dr = treeDistance(p, leafness);', 'float dr = 1e9; leafness = 0.0;'],
-    };
-    const wanted = mode === "variants" ? (process.env.ONLY ? process.env.ONLY.split(",") : Object.keys(VARIANTS)) : ['baseline'];
-    const sizes = [
-      [960, 540],
-      [540, 1200],
-    ];
-    report.runs = [];
-    for (const [w, h] of sizes) {
-      for (const [li, variant] of wanted.flatMap((v) =>
-        mode === 'variants'
-          ? [[0, v]]
-          : [
-              [0, v],
-              [3, v],
-            ]
-      )) {
-        await page.setViewportSize({ width: w, height: h });
-        const r = await page.evaluate(
-          ({ li, rep }) =>
-            new Promise((res) => {
-              const rows = [];
-              const c = document.getElementById('c');
-              const s = window.__scene.createScene({
-                canvas: c,
-                unthrottled: true,
-                fixedLevel: window.__scene.LEVELS[li],
-                patchSource: rep
-                  ? (st, src) =>
-                      st === 'terrain'
-                        ? rep[0].startsWith('#define')
-                          ? src.replace(/#define W_ERODE_ENABLED \d/, rep[1])
-                          : src.split(rep[0]).join(rep[1])
-                        : src
-                  : undefined,
-                onStats: (st) => {
-                  rows.push(st);
-                  if (rows.length === 40) {
-                    s.dispose();
-                    const keep = rows.slice(10);
-                    const med = (k) =>
-                      keep.map((x) => x.passMs[k]).sort((a, b) => a - b)[keep.length >> 1];
-                    res({
-                      solid: keep[0].solidSize,
-                      atm: keep[0].atmosphereSize,
-                      medianMs: {
-                        terrain: med('terrain'),
-                        atmosphere: med('atmosphere'),
-                        resolve: med('resolve'),
-                        composite: med('composite'),
-                      },
-                    });
-                  }
-                },
-              });
-              if (!s) res({ error: 'createScene returned null' });
-            }),
-          { li, rep: VARIANTS[variant] }
-        );
-        report.runs.push({ viewport: [w, h], level: li, variant, ...r });
-      }
-    }
-  }
-
-  console.log(JSON.stringify(report, null, 1));
-  await b.close();
-})().catch((e) => {
-  console.log('ERR', String(e).slice(0, 2000));
-  process.exit(1);
-});
diff --git a/harness/scene/entry.ts b/harness/scene/entry.ts
deleted file mode 100644
index d43a5453..00000000
--- a/harness/scene/entry.ts
+++ /dev/null
@@ -1,87 +0,0 @@
-// Browser entry for the harness: exposes the scene's seams to the driver. Not shipped.
-import { createScene, linkStage, ShaderCompileError } from '../../src/app/features/scene/Scene';
-import { LEVELS } from '../../src/app/features/scene/budget';
-import { fragmentSource } from '../../src/app/features/scene/shaderSource';
-import { WORLD } from '../../src/app/features/scene/world';
-
-(window as unknown as Record<string, unknown>).__scene = {
-  createScene,
-  linkStage,
-  ShaderCompileError,
-  LEVELS,
-  fragmentSource,
-  WORLD,
-};
-
-// ---- Phacelle gradient probe -----------------------------------------------------------------
-import cultmath from '../../src/app/features/scene/shaders/CultMath.glsl?raw';
-import phacelle from '../../src/app/features/scene/shaders/CultMath.Phacelle.glsl?raw';
-import { vertexSource } from '../../src/app/features/scene/shaderSource';
-
-const PROBE_FRAG = `#version 300 es
-precision highp float; precision highp int;
-${cultmath}
-${phacelle}
-uniform float u_seed; uniform vec3 u_side; uniform float u_norm; uniform float u_span;
-in vec2 v_uv; layout(location=0) out vec4 o;
-void main() {
-  // The scene samples the z = 0 slice: random points in a u_span square of it.
-  vec3 h = vec3(cultmath_pcg3d(vec3(gl_FragCoord.xy, u_seed))) ;
-  vec2 xy = vec2(float(uint(int(h.x)) >> 8), float(uint(int(h.y)) >> 8)) * (1.0 / 16777216.0) * u_span;
-  CultPhasor ph = cultmath_phacelle(vec3(xy, 0.0), u_side, 0.0, u_norm);
-  o = vec4(length(ph.cos.xyz), length(ph.sin.xyz), ph.cos.w, ph.sin.w);
-}`;
-
-/** Max |grad| of the phasor over `draws * 1024^2` random points; min/max of the cos component. */
-(window as unknown as Record<string, unknown>).__probePhacelle = (
-  side: number[],
-  norm: number,
-  draws: number
-) => {
-  const c = document.createElement('canvas');
-  const gl = c.getContext('webgl2')!;
-  gl.getExtension('EXT_color_buffer_float');
-  const mk = (t: number, s: string) => {
-    const x = gl.createShader(t)!;
-    gl.shaderSource(x, s);
-    gl.compileShader(x);
-    if (!gl.getShaderParameter(x, gl.COMPILE_STATUS)) throw new Error(gl.getShaderInfoLog(x)!);
-    return x;
-  };
-  const p = gl.createProgram()!;
-  gl.attachShader(p, mk(gl.VERTEX_SHADER, vertexSource));
-  gl.attachShader(p, mk(gl.FRAGMENT_SHADER, PROBE_FRAG));
-  gl.linkProgram(p);
-  gl.useProgram(p);
-  const N = 1024;
-  const tex = gl.createTexture();
-  gl.bindTexture(gl.TEXTURE_2D, tex);
-  gl.texStorage2D(gl.TEXTURE_2D, 1, gl.RGBA32F, N, N);
-  const fbo = gl.createFramebuffer();
-  gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
-  gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, tex, 0);
-  gl.viewport(0, 0, N, N);
-  gl.bindVertexArray(gl.createVertexArray());
-  gl.uniform3fv(gl.getUniformLocation(p, 'u_side'), side);
-  gl.uniform1f(gl.getUniformLocation(p, 'u_norm'), norm);
-  gl.uniform1f(gl.getUniformLocation(p, 'u_span'), 400);
-  const buf = new Float32Array(N * N * 4);
-  let gradCos = 0,
-    gradSin = 0,
-    vMin = 1e9,
-    vMax = -1e9,
-    n = 0;
-  for (let d = 0; d < draws; d++) {
-    gl.uniform1f(gl.getUniformLocation(p, 'u_seed'), d + 1);
-    gl.drawArrays(gl.TRIANGLES, 0, 3);
-    gl.readPixels(0, 0, N, N, gl.RGBA, gl.FLOAT, buf);
-    for (let i = 0; i < buf.length; i += 4) {
-      if (buf[i] > gradCos) gradCos = buf[i];
-      if (buf[i + 1] > gradSin) gradSin = buf[i + 1];
-      if (buf[i + 2] < vMin) vMin = buf[i + 2];
-      if (buf[i + 2] > vMax) vMax = buf[i + 2];
-      n++;
-    }
-  }
-  return { samples: n, maxGradCos: gradCos, maxGradSin: gradSin, minCos: vMin, maxCos: vMax };
-};
diff --git a/src/app/features/scene/README.md b/src/app/features/scene/README.md
deleted file mode 100644
index be117a0a..00000000
--- a/src/app/features/scene/README.md
+++ /dev/null
@@ -1,69 +0,0 @@
-# Background scene
-
-A two-pass WebGL2 scene for the client's background canvas: an infinite terrain of CultMath
-noise with a world tree at its centre, dusk atmosphere and clouds, and a camera that pulls back
-from the tree on login. It is a self-contained module; nothing in the client imports it yet.
-Integration (a canvas under the app, `startBackgroundScene`, `login()` when the session starts,
-`dispose()`) is Void's cut `terrain-background`; the personas (`orbiting-personas`) and the squirrel
-are later cuts. This PR is the render core plus the contract the host needs: flag, tier, failure
-callbacks and the creature sizing rule. Nothing has drawn a creature.
-
-## Entry points
-
-- `index.ts` `startBackgroundScene(config.backgroundScene, capabilities, options)` is the host's
-  door. The client config's `backgroundScene.tier` (`off` default, `still`, `low`, `full`) is the
-  feature flag and the ceiling; `tier.ts` lowers it for `saveData`, low memory or few cores. At
-  `off` nothing is imported and no canvas context is requested; otherwise `Scene.ts` loads on
-  demand, so it stays out of the main chunk; if that chunk fails to load the error goes to
-  `onCompileFail` and the door returns null, it does not throw.
-- `Scene.ts` `createScene({ canvas, tier, onCompileFail, onContextLost, ... })` returns
-  `{ login, dispose }`, or `null` (keep the CSS ground then) when the tier is `off`, WebGL2 or
-  `EXT_color_buffer_float` is missing, or a shader fails to compile (`onCompileFail` gets the
-  `ShaderCompileError`; programs already linked are freed). `still` is a live rendered frame, not a
-  baked image: it runs the full pipeline once at the top level and stops; `low` starts the ladder at level 2; `full` at level 0. A lost WebGL context
-  stops the scene for good and calls `onContextLost`; nothing rebuilds it, the host decides what to
-  show. It caps at 30 fps, pauses when
-  the tab is hidden, renders 32 frames and stops under `prefers-reduced-motion` (a change of the
-  preference while it runs freezes or thaws it), and steps down a
-  quality ladder (`budget.ts`) against a 4 ms GPU budget when timer queries exist.
-- `creatures.ts` the creature record and `creatureScale`: a neutral creature is one fixed size and
-  overrides `sizeBucket`. The bucket names and scales are placeholders until the persona cut owns them.
-- `camera.ts` the pull-back path as pure functions (`pullProgress`, `cameraPose`).
-- `world.ts` every world number, and the Lipschitz bounds the sphere trace steps by. The GLSL
-  `#define`s are generated from it; no number is written twice.
-- `shaders/` pass 1 `terrain.frag.glsl`, pass 2 `atmosphere.frag.glsl`, `resolve.frag.glsl` (TAA),
-  `composite.frag.glsl`, plus CultLib's vendored GLSL (`shaders/README.md`).
-
-## How it renders
-
-1. **Solid pass** (`terrain.frag.glsl`, 0.4-0.75 of canvas resolution): sphere trace of
-   `min(terrain, tree)`. Terrain height is `mask(r) * (A * fbm + E * phacelle)`, with
-   `cultmath_fbm_grad(...).w` and `cultmath_phacelle(...).cos.w`. It writes lit colour with
-   coverage and the hit distance (second render target).
-2. **Atmosphere pass** (0.25-0.5 of canvas): closed-form exponential height fog plus a cloud
-   slab marched with a few jittered steps, both only up to the hit distance from pass 1.
-3. **Resolve**: TAA on the atmosphere (Halton jitter, history reprojected by the pass-1 depth,
-   3x3 neighbourhood clamp, 1/8 blend; reset on resize, level change and wake).
-4. **Composite** at canvas resolution: solid over analytic sky, then the atmosphere, ACES
-   tonemap, dither.
-
-## The step bound, and what is not proven
-
-The trace steps by `(y - h(x, z)) / sqrt(1 + G^2)`, `G` the Lipschitz bound of the height field,
-computed from `SNOISE_LIPSCHITZ` (CultMath's constant for `snoise`) in `world.ts`. Above the
-envelope (fbm plus the erosion amplitude) the step uses the envelope's bound alone and Phacelle is
-not evaluated.
-
-- The Phacelle gradient bound `phacelleGradBound` (7.0) is Libby's measured sup (6.63 at
-  |side| = 1.5, n = 0, CultLib PR #1 head 990521b3) plus margin: a measurement, not a proof.
-  The shader fixes roughness n = 0; a nonzero n needs the bound divided by (1 - n).
-- The bound makes grazing rays crawl. A ray that exhausts its steps while still below the highest
-  terrain is ended as a distant surface (fog hides it). That is a visible approximation, not a
-  hit proven by the march.
-- The low-resolution atmosphere samples pass-1 depth nearest, so silhouettes of near objects
-  carry a thin fog halo.
-
-## Measured and not measured
-
-See the pull request or `harness/scene/README.md` for the numbers and how they were taken. They
-come from a software rasterizer, not a GPU, and nothing has been run on a phone.
diff --git a/src/app/features/scene/Scene.test.ts b/src/app/features/scene/Scene.test.ts
deleted file mode 100644
index 25b7f08d..00000000
--- a/src/app/features/scene/Scene.test.ts
+++ /dev/null
@@ -1,305 +0,0 @@
-import { afterEach, beforeEach, describe, expect, it, Mock, vi } from 'vitest';
-import { createScene, ShaderCompileError } from './Scene';
-import { LEVELS } from './budget';
-import { startBackgroundScene } from './index';
-
-type Fn = Mock;
-
-/** A GL context where every call is a spy and every constant is 1. Compiles succeed until `failFrom`. */
-function fakeGl(failFrom = Infinity) {
-  let compiles = 0;
-  const calls: Record<string, Fn> = {};
-  const spy = (name: string, impl: () => unknown = () => ({})): Fn => {
-    if (!calls[name]) calls[name] = vi.fn(impl);
-    return calls[name];
-  };
-  const gl = new Proxy({} as Record<string, unknown>, {
-    get(_, prop: string) {
-      if (/^[A-Z][A-Z0-9_]*$/.test(prop)) return 1;
-      if (prop === 'compileShader') {
-        return spy(prop, () => {
-          compiles += 1;
-        });
-      }
-      if (prop === 'getShaderParameter') return spy(prop, () => compiles < failFrom);
-      if (prop === 'getShaderInfoLog') return spy(prop, () => 'ERROR: 0:1: bad');
-      if (prop === 'getProgramParameter') return spy(prop, () => true);
-      return spy(prop);
-    },
-  });
-  return { gl: gl as unknown as WebGL2RenderingContext, calls };
-}
-
-function fakeCanvas(gl: WebGL2RenderingContext | null) {
-  const canvas = new EventTarget() as EventTarget & {
-    clientWidth: number;
-    clientHeight: number;
-    width: number;
-    height: number;
-    getContext: Fn;
-  };
-  canvas.clientWidth = 400;
-  canvas.clientHeight = 300;
-  canvas.width = 0;
-  canvas.height = 0;
-  canvas.getContext = vi.fn(() => gl);
-  return canvas;
-}
-
-let rafQueue: Array<(t: number) => void>;
-let cancelled: number;
-let win: EventTarget;
-let motion: EventTarget & { matches: boolean };
-let doc: EventTarget & { visibilityState: string };
-
-beforeEach(() => {
-  rafQueue = [];
-  cancelled = 0;
-  motion = Object.assign(new EventTarget(), { matches: false });
-  win = Object.assign(new EventTarget(), {
-    devicePixelRatio: 1,
-    matchMedia: () => motion,
-  });
-  doc = Object.assign(new EventTarget(), { visibilityState: 'visible' });
-  vi.stubGlobal('window', win);
-  vi.stubGlobal('document', doc);
-  vi.stubGlobal('requestAnimationFrame', (cb: (t: number) => void) => rafQueue.push(cb));
-  vi.stubGlobal('cancelAnimationFrame', () => {
-    cancelled += 1;
-  });
-});
-
-afterEach(() => {
-  vi.unstubAllGlobals();
-});
-
-const runFrame = (now: number) => {
-  const cb = rafQueue.shift();
-  if (!cb) throw new Error('no frame was scheduled');
-  cb(now);
-};
-const asCanvas = (c: ReturnType<typeof fakeCanvas>) => c as unknown as HTMLCanvasElement;
-
-describe('createScene tiers', () => {
-  it("'off' returns null without asking the canvas for a context", () => {
-    const { gl } = fakeGl();
-    const canvas = fakeCanvas(gl);
-    expect(createScene({ canvas: asCanvas(canvas), tier: 'off' })).toBeNull();
-    expect(canvas.getContext).not.toHaveBeenCalled();
-    expect(rafQueue).toHaveLength(0);
-  });
-
-  it("'still' draws one frame and schedules no more", () => {
-    const { gl, calls } = fakeGl();
-    const scene = createScene({ canvas: asCanvas(fakeCanvas(gl)), tier: 'still' });
-    expect(scene).not.toBeNull();
-    runFrame(1000);
-    expect(calls.drawArrays).toHaveBeenCalledTimes(4); // four passes, one frame
-    expect(rafQueue).toHaveLength(0);
-  });
-
-  it("'still' ignores login(): the pull-back is for a moving scene", () => {
-    const { gl } = fakeGl();
-    const scene = createScene({ canvas: asCanvas(fakeCanvas(gl)), tier: 'still' });
-    runFrame(1000);
-    scene?.login();
-    expect(rafQueue).toHaveLength(0);
-  });
-
-  it("'full' keeps scheduling frames", () => {
-    const { gl } = fakeGl();
-    createScene({ canvas: asCanvas(fakeCanvas(gl)), tier: 'full' });
-    runFrame(1000);
-    expect(rafQueue).toHaveLength(1);
-  });
-
-  it("'low' traces with a cheaper level than 'full'", () => {
-    const traceSteps = (tier: 'low' | 'full') => {
-      rafQueue.length = 0; // each call is a fresh scene
-      const { gl, calls } = fakeGl();
-      createScene({ canvas: asCanvas(fakeCanvas(gl)), tier });
-      runFrame(1000);
-      // u_maxSteps is the only uniform1i whose value is a trace-step count
-      return calls.uniform1i.mock.calls.map((c) => c[1]).filter((v) => v >= 40);
-    };
-    expect(traceSteps('full')).toContain(LEVELS[0].traceSteps);
-    expect(traceSteps('low')).toContain(LEVELS[2].traceSteps);
-    expect(traceSteps('low')).not.toContain(LEVELS[0].traceSteps);
-  });
-
-  it('returns null when WebGL2 is missing, so the host keeps its ground', () => {
-    expect(createScene({ canvas: asCanvas(fakeCanvas(null)) })).toBeNull();
-  });
-});
-
-describe('shader compile failure', () => {
-  it('reports through onCompileFail, returns null, and frees the programs already linked', () => {
-    const { gl, calls } = fakeGl(4); // terrain compiles both shaders; atmosphere's fragment is the 4th and fails
-    const onCompileFail = vi.fn();
-    const scene = createScene({ canvas: asCanvas(fakeCanvas(gl)), onCompileFail });
-    expect(scene).toBeNull();
-    expect(onCompileFail).toHaveBeenCalledTimes(1);
-    const err = onCompileFail.mock.calls[0][0] as ShaderCompileError;
-    expect(err).toBeInstanceOf(ShaderCompileError);
-    expect(err.stage).toBe('atmosphere');
-    expect(err.log).toContain('bad');
-    expect(calls.deleteProgram).toHaveBeenCalled(); // the terrain program that did link
-    expect(rafQueue).toHaveLength(0);
-  });
-
-  it('does not throw out of createScene when no callback is given', () => {
-    const { gl } = fakeGl(0);
-    expect(() => createScene({ canvas: asCanvas(fakeCanvas(gl)) })).not.toThrow();
-  });
-});
-
-describe('context loss', () => {
-  it('stops the loop, tells the host, and detaches every listener', () => {
-    const { gl } = fakeGl();
-    const canvas = fakeCanvas(gl);
-    const onContextLost = vi.fn();
-    createScene({ canvas: asCanvas(canvas), onContextLost });
-    const lost = new Event('webglcontextlost', { cancelable: true });
-    canvas.dispatchEvent(lost);
-    expect(lost.defaultPrevented).toBe(true);
-    expect(onContextLost).toHaveBeenCalledTimes(1);
-    expect(cancelled).toBe(1);
-    // listeners are gone: a second loss, a resize and a visibility change do nothing
-    canvas.dispatchEvent(new Event('webglcontextlost', { cancelable: true }));
-    win.dispatchEvent(new Event('resize'));
-    doc.dispatchEvent(new Event('visibilitychange'));
-    expect(onContextLost).toHaveBeenCalledTimes(1);
-    expect(rafQueue.length).toBe(1); // only the frame queued before the loss, never run
-  });
-
-  it('does not render a queued frame after the loss', () => {
-    const { gl, calls } = fakeGl();
-    const canvas = fakeCanvas(gl);
-    createScene({ canvas: asCanvas(canvas) });
-    canvas.dispatchEvent(new Event('webglcontextlost', { cancelable: true }));
-    runFrame(1000);
-    expect(calls.drawArrays).toBeUndefined();
-  });
-});
-
-describe('prefers-reduced-motion', () => {
-  const runAll = (t0: number) => {
-    let t = t0;
-    let n = 0;
-    while (rafQueue.length && n < 200) {
-      runFrame(t);
-      t += 40;
-      n += 1;
-    }
-    return n;
-  };
-
-  it('freezes to a bounded run when the preference turns on mid-flight', () => {
-    const { gl } = fakeGl();
-    createScene({ canvas: asCanvas(fakeCanvas(gl)) });
-    runFrame(1000);
-    expect(rafQueue).toHaveLength(1); // moving: keeps going
-    motion.matches = true;
-    motion.dispatchEvent(new Event('change'));
-    expect(runAll(1040)).toBeLessThan(200); // ends
-    expect(rafQueue).toHaveLength(0);
-  });
-
-  it('thaws a frozen scene when the preference turns off', () => {
-    motion.matches = true;
-    const { gl } = fakeGl();
-    createScene({ canvas: asCanvas(fakeCanvas(gl)) });
-    runAll(1000);
-    expect(rafQueue).toHaveLength(0);
-    motion.matches = false;
-    motion.dispatchEvent(new Event('change'));
-    expect(rafQueue).toHaveLength(1);
-    runFrame(5000);
-    expect(rafQueue).toHaveLength(1); // unbounded again
-  });
-
-  it('removes the listener on dispose and on context loss', () => {
-    const { gl } = fakeGl();
-    const scene = createScene({ canvas: asCanvas(fakeCanvas(gl)) });
-    scene?.dispose();
-    rafQueue.length = 0;
-    motion.dispatchEvent(new Event('change'));
-    expect(rafQueue).toHaveLength(0);
-
-    const lostCanvas = fakeCanvas(fakeGl().gl);
-    createScene({ canvas: asCanvas(lostCanvas) });
-    lostCanvas.dispatchEvent(new Event('webglcontextlost', { cancelable: true }));
-    rafQueue.length = 0;
-    motion.matches = true;
-    motion.dispatchEvent(new Event('change'));
-    expect(rafQueue).toHaveLength(0);
-  });
-
-  it('a still does not listen: one frame stays one frame', () => {
-    const { gl } = fakeGl();
-    createScene({ canvas: asCanvas(fakeCanvas(gl)), tier: 'still' });
-    runFrame(1000);
-    motion.matches = false;
-    motion.dispatchEvent(new Event('change'));
-    expect(rafQueue).toHaveLength(0);
-  });
-});
-
-describe('startBackgroundScene', () => {
-  it("does not request a context when the config leaves the tier 'off'", async () => {
-    const { gl } = fakeGl();
-    const canvas = fakeCanvas(gl);
-    expect(await startBackgroundScene(undefined, {}, { canvas: asCanvas(canvas) })).toBeNull();
-    expect(
-      await startBackgroundScene({ tier: 'off' }, {}, { canvas: asCanvas(canvas) })
-    ).toBeNull();
-    expect(canvas.getContext).not.toHaveBeenCalled();
-  });
-
-  it('applies the device ceiling: saveData runs a still, one frame', async () => {
-    const { gl, calls } = fakeGl();
-    const scene = await startBackgroundScene(
-      { tier: 'full' },
-      { saveData: true },
-      { canvas: asCanvas(fakeCanvas(gl)) }
-    );
-    expect(scene).not.toBeNull();
-    runFrame(1000);
-    expect(calls.drawArrays).toHaveBeenCalledTimes(4);
-    expect(rafQueue).toHaveLength(0);
-  });
-
-  it('reports a failed scene chunk to onCompileFail and returns null instead of throwing', async () => {
-    vi.resetModules();
-    vi.doMock('./Scene', () => {
-      throw new Error('Failed to fetch dynamically imported module');
-    });
-    try {
-      const { startBackgroundScene: start } = await import('./index');
-      const onCompileFail = vi.fn();
-      const canvas = fakeCanvas(fakeGl().gl);
-      const scene = await start({ tier: 'full' }, {}, { canvas: asCanvas(canvas), onCompileFail });
-      expect(scene).toBeNull();
-      expect(onCompileFail).toHaveBeenCalledTimes(1);
-      expect(onCompileFail.mock.calls[0][0]).toBeInstanceOf(Error);
-      expect(canvas.getContext).not.toHaveBeenCalled();
-      // and with no callback it still does not throw
-      expect(await start({ tier: 'full' }, {}, { canvas: asCanvas(canvas) })).toBeNull();
-    } finally {
-      vi.doUnmock('./Scene');
-      vi.resetModules();
-    }
-  });
-
-  it('hands compile failure to the host and returns null, the fall to the CSS ground', async () => {
-    const { gl } = fakeGl(0);
-    const onCompileFail = vi.fn();
-    const scene = await startBackgroundScene(
-      { tier: 'full' },
-      {},
-      { canvas: asCanvas(fakeCanvas(gl)), onCompileFail }
-    );
-    expect(scene).toBeNull();
-    expect(onCompileFail).toHaveBeenCalledTimes(1);
-  });
-});
diff --git a/src/app/features/scene/Scene.ts b/src/app/features/scene/Scene.ts
deleted file mode 100644
index 40ce300d..00000000
--- a/src/app/features/scene/Scene.ts
+++ /dev/null
@@ -1,476 +0,0 @@
-import { fragmentSource, vertexSource, Stage } from './shaderSource';
-import { cameraPose, pullProgress, CameraPose } from './camera';
-import { BudgetLadder, Level, LEVELS } from './budget';
-import type { SceneTier } from './tier';
-import { PALETTE } from './palette';
-
-/** Phone GPU budget for the whole scene, from the ground-cut doc's budget table. */
-export const GPU_BUDGET_MS = 4.0;
-const FRAME_INTERVAL_MS = 1000 / 30;
-const REDUCED_MOTION_FRAMES = 32;
-const MAX_DPR = 1.5;
-
-export type PassName = 'terrain' | 'atmosphere' | 'resolve' | 'composite';
-const PASSES: PassName[] = ['terrain', 'atmosphere', 'resolve', 'composite'];
-
-export interface SceneStats {
-  /** GPU milliseconds per pass for one finished frame (timer queries; absent without the extension). */
-  passMs: Record<PassName, number>;
-  level: number;
-  solidSize: [number, number];
-  atmosphereSize: [number, number];
-}
-
-/** Measurement seam: the harness rewrites a stage's source to time a variant. Never set in the client. */
-export type SourcePatch = (stage: Stage, source: string) => string;
-
-export class ShaderCompileError extends Error {
-  constructor(readonly stage: Stage | 'vertex', readonly log: string) {
-    super(`${stage} shader failed to compile:\n${log}`);
-  }
-}
-
-/** Ladder level a 'low' scene starts at: the cost of a weak device's first 45 frames is never paid at full. */
-const LOW_START_LEVEL = 2;
-/** The 'still' tier draws one frame at this level and stops. */
-const STILL_LEVEL = LEVELS[0];
-
-export interface SceneOptions {
-  canvas: HTMLCanvasElement;
-  /**
-   * 'off' returns null without touching the canvas. 'still' draws one frame and stops. 'low' starts
-   * the adaptive ladder low. 'full' starts it at the top. Default 'full'.
-   */
-  tier?: SceneTier;
-  /** A shader failed to compile or link. createScene frees what it built and returns null. */
-  onCompileFail?: (e: ShaderCompileError) => void;
-  /** The WebGL context was lost. The scene stops for good; the host keeps its ground. */
-  onContextLost?: () => void;
-  /** Called per finished frame when timer queries exist. */
-  onStats?: (s: SceneStats) => void;
-  /** Weather knob, 0 clear .. 1 overcast. */
-  coverage?: number;
-  /** Fixed level instead of the adaptive ladder (measurement). */
-  fixedLevel?: Level;
-  /** Ignore the 30 fps cap and the visibility pause (measurement). */
-  unthrottled?: boolean;
-  patchSource?: SourcePatch;
-}
-
-export interface Scene {
-  /** Start the camera pull-back from the tree. */
-  login(): void;
-  dispose(): void;
-}
-
-function compile(
-  gl: WebGL2RenderingContext,
-  type: number,
-  source: string,
-  stage: Stage | 'vertex'
-): WebGLShader {
-  const sh = gl.createShader(type)!;
-  gl.shaderSource(sh, source);
-  gl.compileShader(sh);
-  if (!gl.getShaderParameter(sh, gl.COMPILE_STATUS)) {
-    const log = gl.getShaderInfoLog(sh) ?? '';
-    gl.deleteShader(sh);
-    throw new ShaderCompileError(stage, log);
-  }
-  return sh;
-}
-
-export function linkStage(
-  gl: WebGL2RenderingContext,
-  stage: Stage,
-  patch?: SourcePatch
-): WebGLProgram {
-  const vs = compile(gl, gl.VERTEX_SHADER, vertexSource, 'vertex');
-  const fs = compile(
-    gl,
-    gl.FRAGMENT_SHADER,
-    patch ? patch(stage, fragmentSource(stage)) : fragmentSource(stage),
-    stage
-  );
-  const prog = gl.createProgram()!;
-  gl.attachShader(prog, vs);
-  gl.attachShader(prog, fs);
-  gl.linkProgram(prog);
-  gl.deleteShader(vs);
-  gl.deleteShader(fs);
-  if (!gl.getProgramParameter(prog, gl.LINK_STATUS)) {
-    const log = gl.getProgramInfoLog(prog) ?? '';
-    gl.deleteProgram(prog);
-    throw new ShaderCompileError(stage, log);
-  }
-  return prog;
-}
-
-interface Target {
-  tex: WebGLTexture;
-  w: number;
-  h: number;
-}
-
-function halton(i: number, base: number): number {
-  let f = 1;
-  let r = 0;
-  let n = i;
-  while (n > 0) {
-    f /= base;
-    r += f * (n % base);
-    n = Math.floor(n / base);
-  }
-  return r;
-}
-
-/** Null when WebGL2 or float colour buffers are missing; the host keeps its CSS ground. */
-export function createScene(opts: SceneOptions): Scene | null {
-  const { canvas } = opts;
-  const tier = opts.tier ?? 'full';
-  if (tier === 'off') return null;
-  const gl = canvas.getContext('webgl2', {
-    antialias: false,
-    alpha: false,
-    depth: false,
-    stencil: false,
-    powerPreference: 'low-power',
-  });
-  if (!gl || !gl.getExtension('EXT_color_buffer_float')) return null;
-  gl.getExtension('OES_texture_float_linear');
-  const timer = gl.getExtension('EXT_disjoint_timer_query_webgl2') as {
-    TIME_ELAPSED_EXT: number;
-    GPU_DISJOINT_EXT: number;
-  } | null;
-
-  const programs = {} as Record<PassName, WebGLProgram>;
-  try {
-    PASSES.forEach((p) => {
-      programs[p] = linkStage(gl, p, opts.patchSource);
-    });
-  } catch (e) {
-    PASSES.forEach((p) => {
-      if (programs[p]) gl.deleteProgram(programs[p]);
-    });
-    if (!(e instanceof ShaderCompileError)) throw e;
-    opts.onCompileFail?.(e);
-    return null;
-  }
-  const uniforms = new Map<WebGLProgram, Map<string, WebGLUniformLocation | null>>();
-  const loc = (p: WebGLProgram, name: string) => {
-    let m = uniforms.get(p);
-    if (!m) uniforms.set(p, (m = new Map()));
-    if (!m.has(name)) m.set(name, gl.getUniformLocation(p, name));
-    return m.get(name) ?? null;
-  };
-
-  const vao = gl.createVertexArray();
-  gl.bindVertexArray(vao);
-
-  const makeTarget = (w: number, h: number, format: number, filter: number): Target => {
-    const tex = gl.createTexture()!;
-    gl.bindTexture(gl.TEXTURE_2D, tex);
-    gl.texStorage2D(gl.TEXTURE_2D, 1, format, w, h);
-    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, filter);
-    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, filter);
-    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
-    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
-    return { tex, w, h };
-  };
-
-  const fbos = {
-    solid: gl.createFramebuffer()!,
-    atm: gl.createFramebuffer()!,
-    hist: [gl.createFramebuffer()!, gl.createFramebuffer()!],
-  };
-  let solid: Target;
-  let depth: Target;
-  let atm: Target;
-  let hist: [Target, Target];
-  const freeTargets = () => {
-    [solid, depth, atm, hist?.[0], hist?.[1]].forEach((t) => {
-      if (t) gl.deleteTexture(t.tex);
-    });
-  };
-
-  const attach = (fbo: WebGLFramebuffer, targets: Target[]) => {
-    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
-    targets.forEach((t, i) =>
-      gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0 + i, gl.TEXTURE_2D, t.tex, 0)
-    );
-    gl.drawBuffers(targets.map((_, i) => gl.COLOR_ATTACHMENT0 + i));
-  };
-
-  const still = tier === 'still';
-  const ladder = new BudgetLadder(GPU_BUDGET_MS, 45, tier === 'low' ? LOW_START_LEVEL : 0);
-  const level = (): Level => opts.fixedLevel ?? (still ? STILL_LEVEL : ladder.current);
-
-  let canvasW = 0;
-  let canvasH = 0;
-  let sizedFor: Level | undefined;
-  let resetHistory = true;
-
-  const ensureSize = () => {
-    const dpr = Math.min(window.devicePixelRatio || 1, MAX_DPR);
-    const w = Math.max(2, Math.round(canvas.clientWidth * dpr));
-    const h = Math.max(2, Math.round(canvas.clientHeight * dpr));
-    const lv = level();
-    if (w === canvasW && h === canvasH && lv === sizedFor) return;
-    canvasW = w;
-    canvasH = h;
-    sizedFor = lv;
-    canvas.width = w;
-    canvas.height = h;
-    freeTargets();
-    const sw = Math.max(2, Math.round(w * lv.solidScale));
-    const sh = Math.max(2, Math.round(h * lv.solidScale));
-    const aw = Math.max(2, Math.round(w * lv.atmosphereScale));
-    const ah = Math.max(2, Math.round(h * lv.atmosphereScale));
-    solid = makeTarget(sw, sh, gl.RGBA16F, gl.LINEAR);
-    depth = makeTarget(sw, sh, gl.R16F, gl.NEAREST);
-    atm = makeTarget(aw, ah, gl.RGBA16F, gl.LINEAR);
-    hist = [makeTarget(aw, ah, gl.RGBA16F, gl.LINEAR), makeTarget(aw, ah, gl.RGBA16F, gl.LINEAR)];
-    attach(fbos.solid, [solid, depth]);
-    attach(fbos.atm, [atm]);
-    attach(fbos.hist[0], [hist[0]]);
-    attach(fbos.hist[1], [hist[1]]);
-    resetHistory = true;
-  };
-
-  const reducedMotion = window.matchMedia?.('(prefers-reduced-motion: reduce)');
-  const start = performance.now();
-  let loginAt: number | undefined;
-  let frame = 0;
-  let histIndex = 0;
-  let prev: CameraPose | undefined;
-  let raf = 0;
-  let lastRendered = -Infinity;
-  let framesLeft = still ? 1 : Infinity; // a still frame, or reduced motion, bounds this
-  let disposed = false;
-
-  // Timer queries in flight: each holds one pass's query.
-  const pending: Array<{ q: WebGLQuery; pass: PassName; frame: number }> = [];
-  const finished = new Map<number, Partial<Record<PassName, number>>>();
-
-  const timed = (pass: PassName, f: number, body: () => void) => {
-    if (!timer || !opts.onStats) {
-      body();
-      return;
-    }
-    const q = gl.createQuery()!;
-    gl.beginQuery(timer.TIME_ELAPSED_EXT, q);
-    body();
-    gl.endQuery(timer.TIME_ELAPSED_EXT);
-    pending.push({ q, pass, frame: f });
-  };
-
-  const collect = () => {
-    if (!timer) return;
-    while (pending.length && gl.getQueryParameter(pending[0].q, gl.QUERY_RESULT_AVAILABLE)) {
-      const { q, pass, frame: f } = pending.shift()!;
-      const disjoint = gl.getParameter(timer.GPU_DISJOINT_EXT);
-      const ns = gl.getQueryParameter(q, gl.QUERY_RESULT) as number;
-      gl.deleteQuery(q);
-      const row = finished.get(f) ?? {};
-      if (!disjoint) row[pass] = ns / 1e6;
-      finished.set(f, row);
-      if (Object.keys(row).length === PASSES.length) {
-        finished.delete(f);
-        const passMs = row as Record<PassName, number>;
-        const total = PASSES.reduce((s, p) => s + passMs[p], 0);
-        if (!opts.fixedLevel && ladder.push(total)) sizedFor = undefined;
-        opts.onStats?.({
-          passMs,
-          level: ladder.index,
-          solidSize: [solid.w, solid.h],
-          atmosphereSize: [atm.w, atm.h],
-        });
-      }
-    }
-  };
-
-  const setCommon = (p: WebGLProgram, pose: CameraPose, time: number) => {
-    const aspect = canvasW / canvasH;
-    const th = Math.tan(pose.fov / 2);
-    gl.uniform3fv(loc(p, 'u_camPos'), pose.position as unknown as number[]);
-    gl.uniformMatrix3fv(loc(p, 'u_camBasis'), false, pose.basis as unknown as number[]);
-    gl.uniform2f(loc(p, 'u_tanHalf'), th * aspect, th);
-    gl.uniform1f(loc(p, 'u_time'), time);
-    gl.uniform3fv(loc(p, 'u_sunDir'), PALETTE.sunDir as unknown as number[]);
-    gl.uniform3fv(loc(p, 'u_sunColor'), PALETTE.sunColor as unknown as number[]);
-    gl.uniform3fv(loc(p, 'u_skyTop'), PALETTE.skyTop as unknown as number[]);
-    gl.uniform3fv(loc(p, 'u_skyHorizon'), PALETTE.skyHorizon as unknown as number[]);
-    gl.uniform3fv(loc(p, 'u_fogColor'), PALETTE.fogColor as unknown as number[]);
-  };
-
-  const bindTex = (unit: number, t: Target, p: WebGLProgram, name: string) => {
-    gl.activeTexture(gl.TEXTURE0 + unit);
-    gl.bindTexture(gl.TEXTURE_2D, t.tex);
-    gl.uniform1i(loc(p, name), unit);
-  };
-
-  const draw = () => gl.drawArrays(gl.TRIANGLES, 0, 3);
-
-  const render = (now: number) => {
-    ensureSize();
-    const lv = level();
-    const frozen = reducedMotion?.matches ?? false;
-    const time = frozen ? 0 : (now - start) / 1000;
-    let elapsed: number | undefined;
-    if (loginAt !== undefined) elapsed = frozen ? 1e9 : (now - loginAt) / 1000;
-    const pose = cameraPose(pullProgress(elapsed), time);
-    const f = frame;
-    frame += 1;
-    const jx = halton((f % 16) + 1, 2) - 0.5;
-    const jy = halton((f % 16) + 1, 3) - 0.5;
-
-    // Pass 1: solid surfaces, writes colour and depth.
-    timed('terrain', f, () => {
-      gl.bindFramebuffer(gl.FRAMEBUFFER, fbos.solid);
-      gl.viewport(0, 0, solid.w, solid.h);
-      const p = programs.terrain;
-      gl.useProgram(p);
-      setCommon(p, pose, time);
-      gl.uniform3fv(loc(p, 'u_grass'), PALETTE.grass as unknown as number[]);
-      gl.uniform3fv(loc(p, 'u_rock'), PALETTE.rock as unknown as number[]);
-      gl.uniform3fv(loc(p, 'u_bark'), PALETTE.bark as unknown as number[]);
-      gl.uniform3fv(loc(p, 'u_leaf'), PALETTE.leaf as unknown as number[]);
-      gl.uniform1i(loc(p, 'u_maxSteps'), lv.traceSteps);
-      draw();
-    });
-
-    // Pass 2: atmosphere up to pass 1's depth, low-res.
-    timed('atmosphere', f, () => {
-      gl.bindFramebuffer(gl.FRAMEBUFFER, fbos.atm);
-      gl.viewport(0, 0, atm.w, atm.h);
-      const p = programs.atmosphere;
-      gl.useProgram(p);
-      setCommon(p, pose, time);
-      bindTex(0, depth, p, 'u_depth');
-      gl.uniform1i(loc(p, 'u_steps'), lv.cloudSteps);
-      gl.uniform1f(loc(p, 'u_frame'), f);
-      gl.uniform2f(loc(p, 'u_jitter'), jx, jy);
-      gl.uniform2f(loc(p, 'u_size'), atm.w, atm.h);
-      gl.uniform1f(loc(p, 'u_coverage'), opts.coverage ?? 0.45);
-      draw();
-    });
-
-    // TAA resolve into the history that is not being read.
-    const write = histIndex === 0 ? 1 : 0;
-    timed('resolve', f, () => {
-      gl.bindFramebuffer(gl.FRAMEBUFFER, fbos.hist[write]);
-      gl.viewport(0, 0, atm.w, atm.h);
-      const p = programs.resolve;
-      gl.useProgram(p);
-      setCommon(p, pose, time);
-      bindTex(0, atm, p, 'u_cur');
-      bindTex(1, hist[histIndex], p, 'u_history');
-      bindTex(2, depth, p, 'u_depth');
-      const pp = prev ?? pose;
-      const th = Math.tan(pp.fov / 2);
-      gl.uniform3fv(loc(p, 'u_prevPos'), pp.position as unknown as number[]);
-      gl.uniformMatrix3fv(loc(p, 'u_prevBasis'), false, pp.basis as unknown as number[]);
-      gl.uniform2f(loc(p, 'u_prevTanHalf'), th * (canvasW / canvasH), th);
-      gl.uniform1f(loc(p, 'u_blend'), resetHistory ? 1 : 0.125);
-      gl.uniform2f(loc(p, 'u_curSize'), atm.w, atm.h);
-      draw();
-    });
-
-    // Full-resolution composite to the canvas.
-    timed('composite', f, () => {
-      gl.bindFramebuffer(gl.FRAMEBUFFER, null);
-      gl.viewport(0, 0, canvasW, canvasH);
-      const p = programs.composite;
-      gl.useProgram(p);
-      setCommon(p, pose, time);
-      bindTex(0, solid, p, 'u_solid');
-      bindTex(1, hist[write], p, 'u_atm');
-      gl.uniform1f(loc(p, 'u_frame'), f);
-      draw();
-    });
-
-    histIndex = write;
-    prev = pose;
-    resetHistory = false;
-    collect();
-  };
-
-  const tick = (now: number) => {
-    raf = 0;
-    if (disposed) return;
-    const due = opts.unthrottled || now - lastRendered >= FRAME_INTERVAL_MS - 2;
-    if (due) {
-      if (
-        !opts.fixedLevel &&
-        !timer &&
-        lastRendered > 0 &&
-        now - lastRendered > FRAME_INTERVAL_MS * 1.5
-      ) {
-        // no timer: a missed cap counts as over budget
-        if (ladder.push(GPU_BUDGET_MS * 2)) sizedFor = undefined;
-      }
-      lastRendered = now;
-      render(now);
-      framesLeft -= 1;
-    }
-    if (framesLeft > 0 && (opts.unthrottled || document.visibilityState === 'visible'))
-      raf = requestAnimationFrame(tick);
-  };
-
-  const wake = () => {
-    if (disposed || raf) return;
-    if (reducedMotion?.matches && framesLeft <= 0) return;
-    resetHistory = true; // the first frame after a pause has a real elapsed dt
-    raf = requestAnimationFrame(tick);
-  };
-  const undo: Array<() => void> = [];
-  const listen = (target: EventTarget, type: string, handler: (e: Event) => void) => {
-    target.addEventListener(type, handler);
-    undo.push(() => target.removeEventListener(type, handler));
-  };
-  const stop = () => {
-    disposed = true;
-    if (raf) cancelAnimationFrame(raf);
-    undo.forEach((f) => f());
-  };
-  if (!opts.unthrottled) {
-    listen(document, 'visibilitychange', () => {
-      if (document.visibilityState === 'visible') wake();
-    });
-  }
-  listen(window, 'resize', () => wake());
-  // A lost context takes every texture and program with it and nothing here rebuilds them, so the
-  // scene ends and the host decides what to show. preventDefault: otherwise the browser never
-  // restores the context, which is what we want, and a restore would find a dead scene.
-  listen(canvas, 'webglcontextlost', (e) => {
-    e.preventDefault();
-    stop();
-    opts.onContextLost?.();
-  });
-  if (reducedMotion?.matches && !still) framesLeft = REDUCED_MOTION_FRAMES;
-  // The preference can flip while the scene lives: freeze to a bounded run, or thaw to a free one.
-  if (reducedMotion && !still) {
-    listen(reducedMotion, 'change', () => {
-      framesLeft = reducedMotion.matches ? REDUCED_MOTION_FRAMES : Infinity;
-      wake();
-    });
-  }
-  wake();
-
-  return {
-    login() {
-      if (still || disposed) return; // a still has no pull-back
-      loginAt = performance.now();
-      if (reducedMotion?.matches) framesLeft = REDUCED_MOTION_FRAMES;
-      wake();
-    },
-    dispose() {
-      if (disposed) return;
-      stop();
-      freeTargets();
-      PASSES.forEach((p) => gl.deleteProgram(programs[p]));
-      gl.deleteVertexArray(vao);
-      [fbos.solid, fbos.atm, ...fbos.hist].forEach((fb) => gl.deleteFramebuffer(fb));
-    },
-  };
-}
diff --git a/src/app/features/scene/budget.test.ts b/src/app/features/scene/budget.test.ts
deleted file mode 100644
index 9ac8f0af..00000000
--- a/src/app/features/scene/budget.test.ts
+++ /dev/null
@@ -1,41 +0,0 @@
-import { describe, expect, it } from 'vitest';
-import { BudgetLadder, LEVELS } from './budget';
-
-describe('budget ladder', () => {
-  it('steps down after a whole window over budget and never back up', () => {
-    const ladder = new BudgetLadder(4, 5);
-    Array.from({ length: 4 }).forEach(() => expect(ladder.push(9)).toBe(false));
-    expect(ladder.push(9)).toBe(true);
-    expect(ladder.index).toBe(1);
-    Array.from({ length: 100 }).forEach(() => ladder.push(0.1)); // fast frames never raise the level
-    expect(ladder.index).toBe(1);
-  });
-
-  it('judges the median, so one slow frame does not step down', () => {
-    const ladder = new BudgetLadder(4, 5);
-    [1, 1, 50, 1, 1].forEach((ms) => ladder.push(ms));
-    expect(ladder.index).toBe(0);
-  });
-
-  it('stops at the last level', () => {
-    const ladder = new BudgetLadder(4, 1);
-    Array.from({ length: 20 }).forEach(() => ladder.push(99));
-    expect(ladder.index).toBe(LEVELS.length - 1);
-  });
-
-  it('every level is cheaper than the one before in each cost axis', () => {
-    LEVELS.slice(1).forEach((lv, i) => {
-      const before = LEVELS[i];
-      expect(lv.solidScale).toBeLessThan(before.solidScale);
-      expect(lv.atmosphereScale).toBeLessThan(before.atmosphereScale);
-      expect(lv.cloudSteps).toBeLessThan(before.cloudSteps);
-      expect(lv.traceSteps).toBeLessThan(before.traceSteps);
-    });
-  });
-
-  it('starts at the level it is given, clamped into the ladder', () => {
-    expect(new BudgetLadder(4, 5, 2).index).toBe(2);
-    expect(new BudgetLadder(4, 5, 99).index).toBe(LEVELS.length - 1);
-    expect(new BudgetLadder(4, 5, -3).index).toBe(0);
-  });
-});
diff --git a/src/app/features/scene/budget.ts b/src/app/features/scene/budget.ts
deleted file mode 100644
index 3b373d86..00000000
--- a/src/app/features/scene/budget.ts
+++ /dev/null
@@ -1,59 +0,0 @@
-// The adaptive step-down. The ladder only descends within a session; nothing here ever steps up.
-
-export interface Level {
-  /** Pass 1 resolution as a fraction of the canvas. */
-  solidScale: number;
-  /** Pass 2 resolution as a fraction of the canvas. */
-  atmosphereScale: number;
-  /** Cloud march steps. */
-  cloudSteps: number;
-  /** Sphere-trace step cap. */
-  traceSteps: number;
-}
-
-export const LEVELS: readonly Level[] = [
-  { solidScale: 0.75, atmosphereScale: 0.5, cloudSteps: 12, traceSteps: 96 },
-  { solidScale: 0.6, atmosphereScale: 0.4, cloudSteps: 8, traceSteps: 80 },
-  { solidScale: 0.5, atmosphereScale: 0.33, cloudSteps: 6, traceSteps: 64 },
-  { solidScale: 0.4, atmosphereScale: 0.25, cloudSteps: 4, traceSteps: 48 },
-];
-
-/** Median of the last `window` frame times above `budgetMs` for a whole window steps down one level. */
-export class BudgetLadder {
-  private level: number;
-
-  private recent: number[] = [];
-
-  private readonly budgetMs: number;
-
-  private readonly window: number;
-
-  /** `startLevel` lets a weak device begin below level 0; it is clamped into the ladder. */
-  constructor(budgetMs: number, window = 45, startLevel = 0) {
-    this.budgetMs = budgetMs;
-    this.window = window;
-    this.level = Math.min(Math.max(startLevel, 0), LEVELS.length - 1);
-  }
-
-  get current(): Level {
-    return LEVELS[this.level];
-  }
-
-  get index(): number {
-    return this.level;
-  }
-
-  /** Feed one frame's GPU (or cadence) time. Returns true when the level changed. */
-  push(ms: number): boolean {
-    this.recent.push(ms);
-    if (this.recent.length < this.window) return false;
-    const sorted = [...this.recent].sort((a, b) => a - b);
-    const median = sorted[Math.floor(sorted.length / 2)];
-    this.recent = [];
-    if (median > this.budgetMs && this.level < LEVELS.length - 1) {
-      this.level += 1;
-      return true;
-    }
-    return false;
-  }
-}
diff --git a/src/app/features/scene/camera.test.ts b/src/app/features/scene/camera.test.ts
deleted file mode 100644
index f7199a65..00000000
--- a/src/app/features/scene/camera.test.ts
+++ /dev/null
@@ -1,42 +0,0 @@
-import { describe, expect, it } from 'vitest';
-import { cameraPose, pullProgress, PULL_BACK_SECONDS } from './camera';
-import { WORLD } from './world';
-
-const dist = (p: readonly [number, number, number]) => Math.hypot(p[0], p[2]);
-
-describe('login pull-back', () => {
-  it('is at rest before login and complete after PULL_BACK_SECONDS', () => {
-    expect(pullProgress(undefined)).toBe(0);
-    expect(pullProgress(0)).toBe(0);
-    expect(pullProgress(PULL_BACK_SECONDS)).toBe(1);
-    expect(pullProgress(PULL_BACK_SECONDS * 10)).toBe(1);
-  });
-
-  it('only moves away from the tree and never reverses', () => {
-    let last = -1;
-    for (let s = 0; s <= PULL_BACK_SECONDS; s += 0.1) {
-      const d = dist(cameraPose(pullProgress(s), 0).position);
-      expect(d).toBeGreaterThanOrEqual(last);
-      last = d;
-    }
-  });
-
-  it('ends over the flat ground so it cannot be inside the terrain, whatever the orbit angle', () => {
-    for (let t = 0; t < 2000; t += 37) {
-      expect(dist(cameraPose(1, t).position)).toBeLessThan(WORLD.plateauInner);
-    }
-  });
-
-  it('looks at the tree: forward points at the axis and the basis is orthonormal', () => {
-    const pose = cameraPose(0.5, 12);
-    const [rx, ry, rz, ux, uy, uz, fx, fy, fz] = pose.basis;
-    const dot = (a: number[], b: number[]) => a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
-    expect(dot([rx, ry, rz], [ux, uy, uz])).toBeCloseTo(0, 6);
-    expect(dot([rx, ry, rz], [fx, fy, fz])).toBeCloseTo(0, 6);
-    expect(dot([ux, uy, uz], [fx, fy, fz])).toBeCloseTo(0, 6);
-    expect(Math.hypot(fx, fy, fz)).toBeCloseTo(1, 6);
-    // Forward points back across the tree axis, not away from it.
-    const [px, , pz] = pose.position;
-    expect(fx * px + fz * pz).toBeLessThan(0);
-  });
-});
diff --git a/src/app/features/scene/camera.ts b/src/app/features/scene/camera.ts
deleted file mode 100644
index 2b08f0d1..00000000
--- a/src/app/features/scene/camera.ts
+++ /dev/null
@@ -1,56 +0,0 @@
-// The scene's camera: close under the tree at rest, pulled back on login, drifting after.
-// Pure functions of time so the pull-back is testable without a GL context.
-
-export type Vec3 = readonly [number, number, number];
-
-export interface CameraPose {
-  position: Vec3;
-  /** Column-major right, up, forward: the layout of the shader's mat3 uniform. */
-  basis: readonly [number, number, number, number, number, number, number, number, number];
-  /** Vertical field of view in radians. */
-  fov: number;
-}
-
-export const PULL_BACK_SECONDS = 6;
-
-// Keep the end distance inside WORLD.plateauInner so the camera is always over flat ground.
-const NEAR = { radius: 20, camY: 5, targetY: 34, fov: 1.15 };
-const FAR = { radius: 110, camY: 50, targetY: 36, fov: 0.82 };
-const DRIFT_RAD_PER_SEC = 0.025;
-
-const smoother = (x: number) => x * x * x * (x * (x * 6 - 15) + 10);
-const lerp = (a: number, b: number, t: number) => a + (b - a) * t;
-
-/** 0 before login, easing to 1 over PULL_BACK_SECONDS. `elapsed` is seconds since login. */
-export function pullProgress(elapsed: number | undefined): number {
-  if (elapsed === undefined || elapsed <= 0) return 0;
-  return smoother(Math.min(1, elapsed / PULL_BACK_SECONDS));
-}
-
-function norm(v: Vec3): Vec3 {
-  const l = Math.hypot(v[0], v[1], v[2]) || 1;
-  return [v[0] / l, v[1] / l, v[2] / l];
-}
-function cross(a: Vec3, b: Vec3): Vec3 {
-  return [a[1] * b[2] - a[2] * b[1], a[2] * b[0] - a[0] * b[2], a[0] * b[1] - a[1] * b[0]];
-}
-
-/**
- * @param pull 0..1 from pullProgress
- * @param time seconds since the scene started, for the slow orbit
- */
-export function cameraPose(pull: number, time: number): CameraPose {
-  const radius = lerp(NEAR.radius, FAR.radius, pull);
-  const camY = lerp(NEAR.camY, FAR.camY, pull);
-  const targetY = lerp(NEAR.targetY, FAR.targetY, pull);
-  const azimuth = 0.9 + time * DRIFT_RAD_PER_SEC;
-  const position: Vec3 = [radius * Math.cos(azimuth), camY, radius * Math.sin(azimuth)];
-  const forward = norm([-position[0], targetY - position[1], -position[2]]);
-  const right = norm(cross([0, 1, 0], forward));
-  const up = cross(forward, right);
-  return {
-    position,
-    basis: [...right, ...up, ...forward] as unknown as CameraPose['basis'],
-    fov: lerp(NEAR.fov, FAR.fov, pull),
-  };
-}
diff --git a/src/app/features/scene/creatures.test.ts b/src/app/features/scene/creatures.test.ts
deleted file mode 100644
index 938c217f..00000000
--- a/src/app/features/scene/creatures.test.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-import { describe, expect, it } from 'vitest';
-import { BUCKET_SCALE, creatureScale, SizeBucket } from './creatures';
-
-const buckets: SizeBucket[] = ['small', 'medium', 'large'];
-
-describe('creature scale', () => {
-  it('follows sizeBucket for a creature with an estate', () => {
-    buckets.forEach((sizeBucket) =>
-      expect(creatureScale({ sizeBucket, neutral: false })).toBe(BUCKET_SCALE[sizeBucket])
-    );
-  });
-
-  it('draws nothing for a neutral creature, whatever sizeBucket it was sent', () => {
-    expect(creatureScale({ neutral: true })).toBeNull();
-    buckets.forEach((sizeBucket) => expect(creatureScale({ sizeBucket, neutral: true })).toBeNull());
-  });
-
-  it('does not crash or default to medium when a non-neutral creature has no sizeBucket', () => {
-    expect(creatureScale({ neutral: false })).toBeNull();
-    expect(creatureScale({ sizeBucket: undefined, neutral: false })).toBeNull();
-  });
-
-  it('draws nothing for an unknown bucket, including inherited property names', () => {
-    expect(creatureScale({ sizeBucket: 'huge' as SizeBucket, neutral: false })).toBeNull();
-    expect(creatureScale({ sizeBucket: 'toString' as SizeBucket, neutral: false })).toBeNull();
-  });
-});
diff --git a/src/app/features/scene/creatures.ts b/src/app/features/scene/creatures.ts
deleted file mode 100644
index a0b2bd29..00000000
--- a/src/app/features/scene/creatures.ts
+++ /dev/null
@@ -1,37 +0,0 @@
-// Creature sizing for the orbiting personas. Only the rule lives here; drawing them is a later cut.
-//
-// Props contract: heimdall-body:follow_up:ratatoskr-creature-projection-v2 (against GameCult/Bifrost; supersedes heimdall-body/ratatoskr-creature-projection).
-// Nothing here is binding until Bifrost's steward cuts that contract.
-//
-// Shape: {id, estate, neutral, activity} plus sizeBucket when neutral is false.
-// Invariants:
-//   - Exact vote weights stay in Bifrost; Ratatoskr only ever sees a bucket.
-//   - neutral=true means Bifrost publishes no sizeBucket, no kind and no energy. A received value is
-//     ignored, and a neutral creature is not drawn.
-//   - A missing or unknown sizeBucket is not drawn either; no size is ever defaulted.
-//   - activity comes from the Heimdall session.
-// Consent: humans get a coarse bucket by default plus a typed opt-out; Minds and Personas may show finer buckets.
-// Humans have three coarse buckets. The scales below (0.7 / 1 / 1.4) are placeholders, not fixed.
-
-export type SizeBucket = 'small' | 'medium' | 'large';
-
-export interface Creature {
-  id: string;
-  estate: string;
-  /** Absent when neutral. Read it only through creatureScale. */
-  sizeBucket?: SizeBucket;
-  neutral: boolean;
-  activity: 'idle' | 'active';
-}
-
-export const BUCKET_SCALE: Readonly<Record<SizeBucket, number>> = {
-  small: 0.7,
-  medium: 1,
-  large: 1.4,
-};
-
-/** The draw scale, or null when nothing is drawn: a neutral creature, or a bucket that is absent or unknown. */
-export function creatureScale(c: Pick<Creature, 'sizeBucket' | 'neutral'>): number | null {
-  if (c.neutral || c.sizeBucket === undefined) return null;
-  return Object.prototype.hasOwnProperty.call(BUCKET_SCALE, c.sizeBucket) ? BUCKET_SCALE[c.sizeBucket] : null;
-}
diff --git a/src/app/features/scene/cultmathTrim.test.ts b/src/app/features/scene/cultmathTrim.test.ts
deleted file mode 100644
index cef6b281..00000000
--- a/src/app/features/scene/cultmathTrim.test.ts
+++ /dev/null
@@ -1,82 +0,0 @@
-import { describe, expect, it } from 'vitest';
-import { trimGlsl } from './cultmathTrim';
-import { fragmentSource, Stage } from './shaderSource';
-import cultmath from './shaders/CultMath.glsl?raw';
-
-const LIB = `// header
-#ifndef LIB_GLSL
-#define LIB_GLSL
-const float LIB_PI = 3.14;
-
-float lib_half(float v) { return v * 0.5; }
-vec2 lib_half(vec2 v) { return v * 0.5; }
-
-// uses the constant and an overload set
-float lib_pi_half(float v) { return lib_half(v) * LIB_PI; }
-
-struct LibPair { float a; float b; };
-
-LibPair lib_pair(float v) { LibPair p; p.a = v; p.b = lib_half(v); return p; }
-float lib_unused(float v) { return v; }
-#endif
-`;
-
-describe('trimGlsl', () => {
-  it('keeps what a root names and what that reaches, and drops the rest', () => {
-    const out = trimGlsl(LIB, ['float x = lib_pi_half(1.0);']);
-    expect(out).toContain('lib_pi_half');
-    expect(out).toContain('LIB_PI');
-    expect(out).toContain('float lib_half');
-    expect(out).toContain('vec2 lib_half'); // overloads stay together
-    expect(out).not.toContain('lib_unused');
-    expect(out).not.toContain('LibPair');
-    expect(out).not.toContain('lib_pair');
-  });
-
-  it('keeps a struct that a kept function returns', () => {
-    const out = trimGlsl(LIB, ['LibPair p = lib_pair(1.0);']);
-    expect(out).toContain('struct LibPair');
-    expect(out).toContain('lib_half');
-    expect(out).not.toContain('lib_pi_half');
-  });
-
-  it('keeps the include guard balanced', () => {
-    const out = trimGlsl(LIB, ['lib_half(1.0)']);
-    expect(out).toMatch(/^#ifndef LIB_GLSL\n#define LIB_GLSL\n/);
-    expect(out.trimEnd().endsWith('#endif')).toBe(true);
-  });
-
-  it('keeps nothing but the guard for a root that names nothing', () => {
-    const out = trimGlsl(LIB, ['void main() {}']);
-    expect(out).not.toContain('lib_');
-    expect(out).toContain('#ifndef LIB_GLSL');
-  });
-});
-
-describe('CultMath per shader stage', () => {
-  const stages: Stage[] = ['terrain', 'atmosphere', 'resolve', 'composite'];
-  const cultmathNames = (text: string) => new Set(text.match(/\bcultmath_\w+/g) ?? []);
-  const defined = (src: string, name: string) =>
-    new RegExp(`^\\s*(?:float|vec[234]|mat3|int|\\w+)\\s+${name}\\s*\\(`, 'm').test(src);
-
-  it.each(stages)('%s defines every CultMath function it, or Phacelle, calls', (stage) => {
-    const src = fragmentSource(stage);
-    cultmathNames(src).forEach((n) => expect(defined(src, n), n).toBe(true));
-  });
-
-  it.each(stages)('%s is smaller than the whole library', (stage) => {
-    expect(fragmentSource(stage).length).toBeLessThan(cultmath.length / 2);
-  });
-
-  it('puts the noise a stage calls in that stage and not in the others', () => {
-    expect(fragmentSource('terrain')).toContain('cultmath_snoise');
-    expect(fragmentSource('composite')).not.toContain('cultmath_snoise');
-  });
-
-  it('adds Phacelle to terrain alone, as its own file', () => {
-    expect(fragmentSource('terrain')).toContain('cultmath_phacelle');
-    stages
-      .filter((s) => s !== 'terrain')
-      .forEach((s) => expect(fragmentSource(s)).not.toContain('cultmath_phacelle'));
-  });
-});
diff --git a/src/app/features/scene/cultmathTrim.ts b/src/app/features/scene/cultmathTrim.ts
deleted file mode 100644
index fc246e5c..00000000
--- a/src/app/features/scene/cultmathTrim.ts
+++ /dev/null
@@ -1,81 +0,0 @@
-/**
- * Keeps the part of CultMath's GLSL that a stage can reach. The vendored file is whole and never
- * edited; each stage compiles only the declarations its own source (and the source concatenated
- * beside it) names, directly or through other kept declarations. Overloads share a name and are
- * kept together.
- */
-
-interface Decl {
-  name: string;
-  text: string;
-}
-
-const GUARD_OPEN = /^#ifndef\s+\w+\s*\n#define\s+\w+\s*\n/m;
-const GUARD_CLOSE = /\n#endif\s*$/;
-
-/** Name a top-level declaration defines: function, struct or const. */
-function declName(text: string): string | undefined {
-  const code = text.replace(/\/\/.*$/gm, '');
-  if (!code.includes('{')) return /\b(\w+)\s*=/.exec(code)?.[1];
-  return /\bstruct\s+(\w+)/.exec(code)?.[1] ?? /\b(\w+)\s*\(/.exec(code)?.[1];
-}
-
-/** Splits at brace depth 0: a declaration ends at the `;` or `}` that returns to depth 0. */
-function declarations(body: string): Decl[] {
-  const out: Decl[] = [];
-  let depth = 0;
-  let start = 0;
-  let i = 0;
-  while (i < body.length) {
-    const c = body[i];
-    if (c === '/' && body[i + 1] === '/') {
-      const eol = body.indexOf('\n', i);
-      i = eol < 0 ? body.length : eol;
-    } else if (c === '{') {
-      depth += 1;
-    } else if ((c === '}' || c === ';') && depth - (c === '}' ? 1 : 0) === 0) {
-      if (c === '}') depth -= 1;
-      // a struct's closing brace is followed by `;`
-      const end = c === '}' && /^\s*;/.test(body.slice(i + 1)) ? body.indexOf(';', i) : i;
-      const text = body.slice(start, end + 1);
-      const name = declName(text);
-      if (name) out.push({ name, text });
-      start = end + 1;
-      i = end;
-    } else if (c === '}') {
-      depth -= 1;
-    }
-    i += 1;
-  }
-  return out;
-}
-
-const idents = (text: string): string[] => text.match(/\b[A-Za-z_]\w*\b/g) ?? [];
-
-/** `library` trimmed to what `roots` reach; the include guard is kept. */
-export function trimGlsl(library: string, roots: string[]): string {
-  const open = GUARD_OPEN.exec(library)?.[0] ?? '';
-  const close = GUARD_CLOSE.test(library) ? '\n#endif\n' : '';
-  const body = library
-    .slice(open ? library.indexOf(open) + open.length : 0)
-    .replace(GUARD_CLOSE, '');
-  const decls = declarations(body);
-  const byName = new Map<string, Decl[]>();
-  decls.forEach((d) => byName.set(d.name, [...(byName.get(d.name) ?? []), d]));
-
-  const kept = new Set<Decl>();
-  const queue = roots.flatMap(idents);
-  while (queue.length) {
-    const group = byName.get(queue.pop() ?? '');
-    group?.forEach((d) => {
-      if (kept.has(d)) return;
-      kept.add(d);
-      queue.push(...idents(d.text));
-    });
-  }
-  const text = decls
-    .filter((d) => kept.has(d))
-    .map((d) => d.text.replace(/^\s*\n/, ''))
-    .join('\n');
-  return `${open}${text}${close}`;
-}
diff --git a/src/app/features/scene/index.ts b/src/app/features/scene/index.ts
deleted file mode 100644
index c896649e..00000000
--- a/src/app/features/scene/index.ts
+++ /dev/null
@@ -1,33 +0,0 @@
-import type { Scene, SceneOptions } from './Scene';
-import { BackgroundSceneConfig, Capabilities, resolveTier } from './tier';
-
-export type { Scene, SceneStats } from './Scene';
-export type { SceneTier } from './tier';
-
-export type StartOptions = Omit<SceneOptions, 'tier' | 'patchSource' | 'onCompileFail'> & {
-  /** A shader failed to compile, or the scene chunk failed to load. The host keeps its ground. */
-  onCompileFail?: (e: Error) => void;
-};
-
-/**
- * The client's one door to the scene. When the tier resolves to 'off' nothing is imported and no
- * canvas context is requested; otherwise the scene code loads on demand, so it stays out of the
- * main chunk. Null means "keep the CSS ground", including when that chunk fails to load (offline,
- * stale deploy): the failure goes to onCompileFail and nothing throws.
- */
-export async function startBackgroundScene(
-  config: BackgroundSceneConfig | undefined,
-  capabilities: Capabilities,
-  options: StartOptions
-): Promise<Scene | null> {
-  const tier = resolveTier(config, capabilities);
-  if (tier === 'off') return null;
-  let createScene: typeof import('./Scene').createScene;
-  try {
-    ({ createScene } = await import('./Scene'));
-  } catch (e) {
-    options.onCompileFail?.(e instanceof Error ? e : new Error(String(e)));
-    return null;
-  }
-  return createScene({ ...options, tier });
-}
diff --git a/src/app/features/scene/palette.ts b/src/app/features/scene/palette.ts
deleted file mode 100644
index 54a84ad3..00000000
--- a/src/app/features/scene/palette.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-// The scene's colours, as linear RGB uniforms. The sky tints are GameCult's three nebula inputs
-// (orange 255 138 42, violet 109 96 255, sky 89 183 255) over the brand base #07111a, so the
-// background reads as the same dusk as gamecult.org. The shaders hold no colour literal.
-
-export type Rgb = readonly [number, number, number];
-
-const srgb = (r: number, g: number, b: number): Rgb => [
-  (r / 255) ** 2.2,
-  (g / 255) ** 2.2,
-  (b / 255) ** 2.2,
-];
-
-export const PALETTE = {
-  sunColor: srgb(255, 150, 70).map((c) => c * 3.2) as unknown as Rgb,
-  skyTop: srgb(30, 36, 92),
-  skyHorizon: srgb(255, 138, 42).map((c) => c * 0.55) as unknown as Rgb,
-  fogColor: srgb(109, 96, 255).map((c) => c * 0.12) as unknown as Rgb,
-  grass: srgb(72, 112, 86),
-  rock: srgb(112, 104, 122),
-  bark: srgb(62, 46, 40),
-  leaf: srgb(89, 183, 255).map((c) => c * 0.7) as unknown as Rgb,
-  sunDir: (() => {
-    const v = [0.55, 0.16, -0.82];
-    const l = Math.hypot(v[0], v[1], v[2]);
-    return [v[0] / l, v[1] / l, v[2] / l] as Rgb;
-  })(),
-} as const;
diff --git a/src/app/features/scene/shaderSource.ts b/src/app/features/scene/shaderSource.ts
deleted file mode 100644
index c7a2a03f..00000000
--- a/src/app/features/scene/shaderSource.ts
+++ /dev/null
@@ -1,34 +0,0 @@
-import cultmath from './shaders/CultMath.glsl?raw';
-import phacelle from './shaders/CultMath.Phacelle.glsl?raw';
-import common from './shaders/common.glsl?raw';
-import fullscreenVert from './shaders/fullscreen.vert.glsl?raw';
-import terrainFrag from './shaders/terrain.frag.glsl?raw';
-import atmosphereFrag from './shaders/atmosphere.frag.glsl?raw';
-import resolveFrag from './shaders/resolve.frag.glsl?raw';
-import compositeFrag from './shaders/composite.frag.glsl?raw';
-import { WORLD, worldDefines } from './world';
-import { trimGlsl } from './cultmathTrim';
-
-export type Stage = 'terrain' | 'atmosphere' | 'resolve' | 'composite';
-
-const HEADER =
-  '#version 300 es\nprecision highp float;\nprecision highp int;\nprecision highp sampler2D;\n';
-
-export const vertexSource = HEADER + fullscreenVert;
-
-const stages: Record<Stage, string> = {
-  terrain: terrainFrag,
-  atmosphere: atmosphereFrag,
-  resolve: resolveFrag,
-  composite: compositeFrag,
-};
-
-/**
- * Fragment source for a stage: header, world defines, the part of CultMath the stage reaches, the
- * shared block, the stage. Phacelle stays a separate file, added only where it is called.
- */
-export function fragmentSource(stage: Stage): string {
-  const erosion = stage === 'terrain' && WORLD.phacelleGradBound > 0 ? phacelle : '';
-  const math = trimGlsl(cultmath, [erosion, common, stages[stage]]);
-  return `${HEADER}${worldDefines()}\n${math}\n${erosion}\n${common}\n${stages[stage]}`;
-}
diff --git a/src/app/features/scene/shaders/CultMath.Phacelle.glsl b/src/app/features/scene/shaders/CultMath.Phacelle.glsl
deleted file mode 100644
index 11405fa2..00000000
--- a/src/app/features/scene/shaders/CultMath.Phacelle.glsl
+++ /dev/null
@@ -1,99 +0,0 @@
-// Generated from shaders/CultMath.Phacelle.hlsl by GlslLowering (packages/cultmath/tests/CultMath.Tests/GlslLowering.cs). Do not edit; regenerate with CULTMATH_WRITE_GLSL=1 dotnet test --filter GlslMirrorTests. MPL-2.0; requires CultMath.glsl before it.
-#ifndef CULTMATH_PHACELLE_GLSL
-#define CULTMATH_PHACELLE_GLSL
-// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of
-// the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
-//
-// Phacelle noise. Copyright (c) 2025 Rune Skovbo Johansen (Shadertoy t3dyWl; MPL-2.0), read from the
-// C# port PhacelleNoise in lpmitchell/AdvancedTerrainErosion, converted to burstable C# by Luke
-// Mitchell (2026). Modified by GameCult: 3D cells, a caller-supplied stripe wave vector, an exact
-// gradient and exact pruning. This file is an MPL-2.0 file; CultMath.hlsl, which includes it after
-// its own definitions of CULTMATH_TAU and cultmath_pcg3d, is MIT (see THIRD-PARTY-NOTICES.md).
-
-// Invariant 8's struct return shape for cultmath_phacelle, compared field by field and bit for bit
-// against CultMath.CultPhasor, same field order.
-struct CultPhasor
-{
-    vec4 cos;
-    vec4 sin;
-};
-
-// Johansen's Phacelle noise on 3D cells. See math.phacelle's comment (math.Phacelle.cs) for the stripe wave
-// vector, the weight, the normalization, the exact gradient and why the prune is exact. Mirrors
-// the C# body operation for operation; the C#-only internal overload that switches the prune off
-// has no shader twin.
-CultPhasor cultmath_phacelle(vec3 p, vec3 side, float offset, float normalization)
-{
-    vec3 cell = floor(p);
-    vec3 local = p - cell;
-    float phaseOffset = offset * CULTMATH_TAU;
-    float sumW = 0.0;
-    float sumCos = 0.0;
-    float sumSin = 0.0;
-    vec3 gradW = vec3(0.0, 0.0, 0.0);
-    vec3 gradCos = vec3(0.0, 0.0, 0.0);
-    vec3 gradSin = vec3(0.0, 0.0, 0.0);
-
-    for (int dz = -1; dz <= 2; dz++)
-    {
-        float gz = max(0.0, abs(local.z - float(dz)) - 0.5);
-        for (int dy = -1; dy <= 2; dy++)
-        {
-            float gy = max(0.0, abs(local.y - float(dy)) - 0.5);
-            for (int dx = -1; dx <= 2; dx++)
-            {
-                float gx = max(0.0, abs(local.x - float(dx)) - 0.5);
-                if (gx * gx + gy * gy + gz * gz >= 2.25)
-                    continue;
-
-                vec3 gridStep = vec3(dx, dy, dz);
-                ivec3 hash = cultmath_pcg3d(ivec3(cell + gridStep));
-                vec3 jitter = vec3(
-                    float(uint(hash.x) >> 8) * (1.0 / 16777216.0) - 0.5,
-                    float(uint(hash.y) >> 8) * (1.0 / 16777216.0) - 0.5,
-                    float(uint(hash.z) >> 8) * (1.0 / 16777216.0) - 0.5);
-                vec3 v = local - gridStep - jitter;
-                float falloff = exp(-2.0 * dot(v, v));
-                float w = max(0.0, falloff - 0.01111);
-                vec3 dw = w > 0.0 ? (-4.0 * falloff) * v : vec3(0.0, 0.0, 0.0);
-                float phase = dot(v, side) + phaseOffset;
-                float c = cos(phase);
-                float s = sin(phase);
-
-                sumW += w;
-                sumCos += w * c;
-                sumSin += w * s;
-                gradW += dw;
-                gradCos += dw * c - (w * s) * side;
-                gradSin += dw * s + (w * c) * side;
-            }
-        }
-    }
-
-    float invW = 1.0 / sumW;
-    float rawCos = sumCos * invW;
-    float rawSin = sumSin * invW;
-    vec3 gradRawCos = (gradCos - rawCos * gradW) * invW;
-    vec3 gradRawSin = (gradSin - rawSin * gradW) * invW;
-    float rawLength = sqrt(rawCos * rawCos + rawSin * rawSin);
-    float floorLength = 1.0 - normalization;
-
-    CultPhasor result;
-    if (rawLength > floorLength)
-    {
-        float outCos = rawCos / rawLength;
-        float outSin = rawSin / rawLength;
-        vec3 gradLength = (rawCos * gradRawCos + rawSin * gradRawSin) / rawLength;
-        result.cos = vec4((gradRawCos - outCos * gradLength) / rawLength, outCos);
-        result.sin = vec4((gradRawSin - outSin * gradLength) / rawLength, outSin);
-    }
-    else
-    {
-        result.cos = vec4(gradRawCos / floorLength, rawCos / floorLength);
-        result.sin = vec4(gradRawSin / floorLength, rawSin / floorLength);
-    }
-
-    return result;
-}
-
-#endif
diff --git a/src/app/features/scene/shaders/CultMath.glsl b/src/app/features/scene/shaders/CultMath.glsl
deleted file mode 100644
index 8a380a96..00000000
--- a/src/app/features/scene/shaders/CultMath.glsl
+++ /dev/null
@@ -1,1035 +0,0 @@
-// Generated from shaders/CultMath.hlsl and CultMath.Interval.hlsl and CultMath.Affine.hlsl by GlslLowering (packages/cultmath/tests/CultMath.Tests/GlslLowering.cs). Do not edit; regenerate with CULTMATH_WRITE_GLSL=1 dotnet test --filter GlslMirrorTests. MIT. cultmath_phacelle is in CultMath.Phacelle.glsl, to be concatenated after this file by consumers that call it. cultmath_cycles_divide, cultmath_cycles_power, cultmath_cycles_logarithm, cultmath_cycles_sqrt, cultmath_cycles_inverse_sqrt, cultmath_cycles_modulo, cultmath_cycles_floored_modulo, cultmath_cycles_wrap, cultmath_cycles_snap, cultmath_cycles_pingpong, cultmath_cycles_smooth_min, cultmath_cycles_smooth_max, cultmath_cycles_compare, cultmath_cycles_round, cultmath_cycles_trunc, cultmath_cycles_fract, cultmath_cycles_sign, cultmath_cycles_arcsine, cultmath_cycles_arccosine, cultmath_cycles_arctan2, cultmath_cycles_map_range_linear, cultmath_cycles_map_range_stepped, cultmath_cycles_map_range_smoothstep, cultmath_cycles_map_range_smootherstep, cultmath_cycles_clamp_minmax, cultmath_cycles_clamp_range, cultmath_cycles_mix_float, cultmath_cycles_mix_vector, cultmath_cycles_mix_blend, cultmath_cycles_mix_add, cultmath_cycles_mix_mul, cultmath_cycles_mix_screen, cultmath_cycles_mix_overlay, cultmath_cycles_mix_sub, cultmath_cycles_mix_div, cultmath_cycles_mix_diff, cultmath_cycles_mix_exclusion, cultmath_cycles_mix_dark, cultmath_cycles_mix_light, cultmath_cycles_mix_dodge, cultmath_cycles_mix_burn, cultmath_cycles_rgb_to_hsv, cultmath_cycles_hsv_to_rgb, cultmath_cycles_mix_hue, cultmath_cycles_mix_sat, cultmath_cycles_mix_val, cultmath_cycles_mix_color, cultmath_cycles_mix_soft, cultmath_cycles_mix_linear, cultmath_cycles_rgb_to_bw, cultmath_cycles_ramp_index is in CultMath.Cycles.glsl, to be concatenated after this file by consumers that call it.
-#ifndef CULTMATH_GLSL
-#define CULTMATH_GLSL
-// CultMath HLSL mirror.
-//
-// HLSL already owns the vec2/vec3/vec4 type names and most primitive
-// intrinsics. This include names the CultMath semantic surface explicitly so
-// shader code, C# wrappers, and Rust/native parity fixtures can share the same
-// small vocabulary without local helper drift.
-
-const float CULTMATH_PI = 3.14159265358979323846;
-const float CULTMATH_TAU = 6.28318530717958647692;
-const float CULTMATH_HALF_PI = 1.57079632679489661923;
-
-float cultmath_radians(float degrees_value) { return degrees_value * (CULTMATH_PI / 180.0); }
-float cultmath_degrees(float radians_value) { return radians_value * (180.0 / CULTMATH_PI); }
-
-float cultmath_frac(float value) { return value - floor(value); }
-vec2 cultmath_frac(vec2 value) { return value - floor(value); }
-vec3 cultmath_frac(vec3 value) { return value - floor(value); }
-vec4 cultmath_frac(vec4 value) { return value - floor(value); }
-
-float cultmath_clamp(float value, float minimum, float maximum) { return min(max(value, minimum), maximum); }
-vec2 cultmath_clamp(vec2 value, vec2 minimum, vec2 maximum) { return min(max(value, minimum), maximum); }
-vec3 cultmath_clamp(vec3 value, vec3 minimum, vec3 maximum) { return min(max(value, minimum), maximum); }
-vec4 cultmath_clamp(vec4 value, vec4 minimum, vec4 maximum) { return min(max(value, minimum), maximum); }
-
-// DXIL Saturate is FMin(1, FMax(0, x)); dxc lowers min/max to the same FMin/FMax, NaN rules included.
-float cultmath_saturate(float value) { return min(1.0, max(0.0, value)); }
-vec2 cultmath_saturate(vec2 value) { return min(vec2(1.0, 1.0), max(vec2(0.0, 0.0), value)); }
-vec3 cultmath_saturate(vec3 value) { return min(vec3(1.0, 1.0, 1.0), max(vec3(0.0, 0.0, 0.0), value)); }
-vec4 cultmath_saturate(vec4 value) { return min(vec4(1.0, 1.0, 1.0, 1.0), max(vec4(0.0, 0.0, 0.0, 0.0), value)); }
-
-float cultmath_lerp(float start, float end, float amount) { return start + (end - start) * amount; }
-vec2 cultmath_lerp(vec2 start, vec2 end, vec2 amount) { return start + (end - start) * amount; }
-vec3 cultmath_lerp(vec3 start, vec3 end, vec3 amount) { return start + (end - start) * amount; }
-vec4 cultmath_lerp(vec4 start, vec4 end, vec4 amount) { return start + (end - start) * amount; }
-
-float cultmath_step(float edge, float value) { return value < edge ? 0.0 : 1.0; }
-vec2 cultmath_step(vec2 edge, vec2 value) { return vec2(cultmath_step(edge.x, value.x), cultmath_step(edge.y, value.y)); }
-vec3 cultmath_step(vec3 edge, vec3 value) { return vec3(cultmath_step(edge.x, value.x), cultmath_step(edge.y, value.y), cultmath_step(edge.z, value.z)); }
-vec4 cultmath_step(vec4 edge, vec4 value) { return vec4(cultmath_step(edge.x, value.x), cultmath_step(edge.y, value.y), cultmath_step(edge.z, value.z), cultmath_step(edge.w, value.w)); }
-
-float cultmath_smoothstep(float minimum, float maximum, float value)
-{
-    float t = cultmath_saturate((value - minimum) / (maximum - minimum));
-    return t * t * (3.0 - 2.0 * t);
-}
-
-vec2 cultmath_smoothstep(vec2 minimum, vec2 maximum, vec2 value)
-{
-    vec2 t = cultmath_saturate((value - minimum) / (maximum - minimum));
-    return t * t * (vec2(3.0, 3.0) - vec2(2.0, 2.0) * t);
-}
-
-vec3 cultmath_smoothstep(vec3 minimum, vec3 maximum, vec3 value)
-{
-    vec3 t = cultmath_saturate((value - minimum) / (maximum - minimum));
-    return t * t * (vec3(3.0, 3.0, 3.0) - vec3(2.0, 2.0, 2.0) * t);
-}
-
-vec4 cultmath_smoothstep(vec4 minimum, vec4 maximum, vec4 value)
-{
-    vec4 t = cultmath_saturate((value - minimum) / (maximum - minimum));
-    return t * t * (vec4(3.0, 3.0, 3.0, 3.0) - vec4(2.0, 2.0, 2.0, 2.0) * t);
-}
-
-float cultmath_smoothstep01(float value) { return cultmath_smoothstep(0.0, 1.0, value); }
-
-float cultmath_smootherstep(float value)
-{
-    value = cultmath_saturate(value);
-    return value * value * value * (value * (value * 6.0 - 15.0) + 10.0);
-}
-
-vec2 cultmath_snoise_mod289(vec2 value) { return value - floor(value * (1.0 / 289.0)) * 289.0; }
-vec3 cultmath_snoise_mod289(vec3 value) { return value - floor(value * (1.0 / 289.0)) * 289.0; }
-vec4 cultmath_snoise_mod289(vec4 value) { return value - floor(value * (1.0 / 289.0)) * 289.0; }
-vec3 cultmath_snoise_permute(vec3 value) { return cultmath_snoise_mod289(((value * 34.0) + 10.0) * value); }
-vec4 cultmath_snoise_permute(vec4 value) { return cultmath_snoise_mod289(((value * 34.0) + 10.0) * value); }
-
-// Ashima Arts / Ian McEwan 3D simplex noise (MIT), same float32 evaluation
-// order as the C# math.snoise(vec3) mirror. Ties resolve in simplexnoise1234's
-// total order; see math.snoise.
-float cultmath_snoise(vec3 value)
-{
-    vec2 c = vec2(1.0 / 6.0, 1.0 / 3.0);
-    vec3 i = floor(value + dot(value, c.yyy));
-    vec3 x0 = value - i + dot(i, c.xxx);
-    vec3 g = vec3(step(x0.y, x0.x), step(x0.z, x0.y), 1.0 - step(x0.z, x0.x));
-    vec3 l = 1.0 - g;
-    vec3 i1 = min(g.xyz, l.zxy);
-    vec3 i2 = max(g.xyz, l.zxy);
-    vec3 x1 = x0 - i1 + c.xxx;
-    vec3 x2 = x0 - i2 + c.yyy;
-    vec3 x3 = x0 - 0.5;
-
-    i = cultmath_snoise_mod289(i);
-    vec4 p = cultmath_snoise_permute(cultmath_snoise_permute(cultmath_snoise_permute(
-        i.z + vec4(0.0, i1.z, i2.z, 1.0)) + i.y + vec4(0.0, i1.y, i2.y, 1.0)) + i.x + vec4(0.0, i1.x, i2.x, 1.0));
-
-    const float n_ = 0.142857142857;
-    vec3 ns = vec3(2.0 * n_, 0.5 * n_ - 1.0, n_);
-    vec4 j = p - 49.0 * floor(p * ns.z * ns.z);
-    vec4 x_ = floor(j * ns.z);
-    vec4 y_ = floor(j - 7.0 * x_);
-    vec4 x = x_ * ns.x + ns.yyyy;
-    vec4 y = y_ * ns.x + ns.yyyy;
-    vec4 h = 1.0 - abs(x) - abs(y);
-
-    vec4 b0 = vec4(x.xy, y.xy);
-    vec4 b1 = vec4(x.zw, y.zw);
-    vec4 s0 = floor(b0) * 2.0 + 1.0;
-    vec4 s1 = floor(b1) * 2.0 + 1.0;
-    vec4 sh = -step(h, vec4(0.0, 0.0, 0.0, 0.0));
-    vec4 a0 = b0.xzyw + s0.xzyw * sh.xxyy;
-    vec4 a1 = b1.xzyw + s1.xzyw * sh.zzww;
-
-    vec3 p0 = vec3(a0.xy, h.x);
-    vec3 p1 = vec3(a0.zw, h.y);
-    vec3 p2 = vec3(a1.xy, h.z);
-    vec3 p3 = vec3(a1.zw, h.w);
-    vec4 norm = 1.79284291400159 - 0.85373472095314 * vec4(dot(p0, p0), dot(p1, p1), dot(p2, p2), dot(p3, p3));
-    p0 *= norm.x;
-    p1 *= norm.y;
-    p2 *= norm.z;
-    p3 *= norm.w;
-
-    vec4 m = max(0.5 - vec4(dot(x0, x0), dot(x1, x1), dot(x2, x2), dot(x3, x3)), 0.0);
-    m = m * m;
-    return 105.0 * dot(m * m, vec4(dot(p0, x0), dot(p1, x1), dot(p2, x2), dot(p3, x3)));
-}
-
-float cultmath_snoise(vec2 value)
-{
-    vec4 c = vec4(
-        0.211324865405187,
-        0.366025403784439,
-        -0.577350269189626,
-        0.024390243902439);
-    vec2 i = floor(value + dot(value, c.yy));
-    vec2 x0 = value - i + dot(i, c.xx);
-    vec2 i1 = x0.x > x0.y ? vec2(1.0, 0.0) : vec2(0.0, 1.0);
-    vec4 x12 = vec4(x0.x + c.x - i1.x, x0.y + c.x - i1.y, x0.x + c.z, x0.y + c.z);
-
-    i = cultmath_snoise_mod289(i);
-    vec3 p = cultmath_snoise_permute(
-        cultmath_snoise_permute(i.y + vec3(0.0, i1.y, 1.0)) + i.x + vec3(0.0, i1.x, 1.0));
-    vec3 m = max(0.5 - vec3(dot(x0, x0), dot(x12.xy, x12.xy), dot(x12.zw, x12.zw)), 0.0);
-    m *= m;
-    m *= m;
-
-    vec3 x = 2.0 * fract(p * c.w) - 1.0;
-    vec3 h = abs(x) - 0.5;
-    vec3 ox = floor(x + 0.5);
-    vec3 a0 = x - ox;
-    m *= 1.79284291400159 - 0.85373472095314 * (a0 * a0 + h * h);
-
-    vec3 g = vec3(
-        a0.x * x0.x + h.x * x0.y,
-        a0.y * x12.x + h.y * x12.y,
-        a0.z * x12.z + h.z * x12.w);
-    return 130.0 * dot(m, g);
-}
-
-// Analytic gradient of cultmath_snoise(vec3) (invariant 8), following webgl-noise
-// src/noise3Dgrad.glsl (Ashima Arts / McEwan, MIT); same kernel, permutation and scale as
-// cultmath_snoise(vec3) (stegu/webgl-noise 22434e04d7). See the C# math.snoise_grad comment for the
-// derivation. Every local up through p0..p3 and x0..x3 is cultmath_snoise(vec3)'s own derivation
-// verbatim.
-vec4 cultmath_snoise_grad(vec3 value)
-{
-    vec2 c = vec2(1.0 / 6.0, 1.0 / 3.0);
-    vec3 i = floor(value + dot(value, c.yyy));
-    vec3 x0 = value - i + dot(i, c.xxx);
-    vec3 g = vec3(step(x0.y, x0.x), step(x0.z, x0.y), 1.0 - step(x0.z, x0.x));
-    vec3 l = 1.0 - g;
-    vec3 i1 = min(g.xyz, l.zxy);
-    vec3 i2 = max(g.xyz, l.zxy);
-    vec3 x1 = x0 - i1 + c.xxx;
-    vec3 x2 = x0 - i2 + c.yyy;
-    vec3 x3 = x0 - 0.5;
-
-    i = cultmath_snoise_mod289(i);
-    vec4 p = cultmath_snoise_permute(cultmath_snoise_permute(cultmath_snoise_permute(
-        i.z + vec4(0.0, i1.z, i2.z, 1.0)) + i.y + vec4(0.0, i1.y, i2.y, 1.0)) + i.x + vec4(0.0, i1.x, i2.x, 1.0));
-
-    const float n_ = 0.142857142857;
-    vec3 ns = vec3(2.0 * n_, 0.5 * n_ - 1.0, n_);
-    vec4 j = p - 49.0 * floor(p * ns.z * ns.z);
-    vec4 x_ = floor(j * ns.z);
-    vec4 y_ = floor(j - 7.0 * x_);
-    vec4 x = x_ * ns.x + ns.yyyy;
-    vec4 y = y_ * ns.x + ns.yyyy;
-    vec4 h = 1.0 - abs(x) - abs(y);
-
-    vec4 b0 = vec4(x.xy, y.xy);
-    vec4 b1 = vec4(x.zw, y.zw);
-    vec4 s0 = floor(b0) * 2.0 + 1.0;
-    vec4 s1 = floor(b1) * 2.0 + 1.0;
-    vec4 sh = -step(h, vec4(0.0, 0.0, 0.0, 0.0));
-    vec4 a0 = b0.xzyw + s0.xzyw * sh.xxyy;
-    vec4 a1 = b1.xzyw + s1.xzyw * sh.zzww;
-
-    vec3 p0 = vec3(a0.xy, h.x);
-    vec3 p1 = vec3(a0.zw, h.y);
-    vec3 p2 = vec3(a1.xy, h.z);
-    vec3 p3 = vec3(a1.zw, h.w);
-    vec4 norm = 1.79284291400159 - 0.85373472095314 * vec4(dot(p0, p0), dot(p1, p1), dot(p2, p2), dot(p3, p3));
-    p0 *= norm.x;
-    p1 *= norm.y;
-    p2 *= norm.z;
-    p3 *= norm.w;
-
-    vec4 m0 = max(0.5 - vec4(dot(x0, x0), dot(x1, x1), dot(x2, x2), dot(x3, x3)), 0.0);
-    vec4 m2 = m0 * m0;
-    vec4 m3 = m2 * m0;
-    vec4 m4 = m2 * m2;
-
-    vec4 px = vec4(dot(p0, x0), dot(p1, x1), dot(p2, x2), dot(p3, x3));
-    float value2 = 105.0 * dot(m4, px);
-    vec3 grad = -8.0 * m3.x * x0 * px.x + m4.x * p0
-        + -8.0 * m3.y * x1 * px.y + m4.y * p1
-        + -8.0 * m3.z * x2 * px.z + m4.z * p2
-        + -8.0 * m3.w * x3 * px.w + m4.w * p3;
-    grad *= 105.0;
-
-    return vec4(grad, value2);
-}
-
-// Analytic Hessian of cultmath_snoise(vec3); see the C# math.snoise_hessian comment for the
-// derivation. Every local up through p0..p3 and x0..x3 is cultmath_snoise_grad's own. The matrix is
-// built from nine scalars, which read as rows in HLSL and as columns in GLSL; it is symmetric, so the
-// two agree.
-mat3 cultmath_snoise_hessian(vec3 value)
-{
-    vec2 c = vec2(1.0 / 6.0, 1.0 / 3.0);
-    vec3 i = floor(value + dot(value, c.yyy));
-    vec3 x0 = value - i + dot(i, c.xxx);
-    vec3 g = vec3(step(x0.y, x0.x), step(x0.z, x0.y), 1.0 - step(x0.z, x0.x));
-    vec3 l = 1.0 - g;
-    vec3 i1 = min(g.xyz, l.zxy);
-    vec3 i2 = max(g.xyz, l.zxy);
-    vec3 x1 = x0 - i1 + c.xxx;
-    vec3 x2 = x0 - i2 + c.yyy;
-    vec3 x3 = x0 - 0.5;
-
-    i = cultmath_snoise_mod289(i);
-    vec4 p = cultmath_snoise_permute(cultmath_snoise_permute(cultmath_snoise_permute(
-        i.z + vec4(0.0, i1.z, i2.z, 1.0)) + i.y + vec4(0.0, i1.y, i2.y, 1.0)) + i.x + vec4(0.0, i1.x, i2.x, 1.0));
-
-    const float n_ = 0.142857142857;
-    vec3 ns = vec3(2.0 * n_, 0.5 * n_ - 1.0, n_);
-    vec4 j = p - 49.0 * floor(p * ns.z * ns.z);
-    vec4 x_ = floor(j * ns.z);
-    vec4 y_ = floor(j - 7.0 * x_);
-    vec4 x = x_ * ns.x + ns.yyyy;
-    vec4 y = y_ * ns.x + ns.yyyy;
-    vec4 h = 1.0 - abs(x) - abs(y);
-
-    vec4 b0 = vec4(x.xy, y.xy);
-    vec4 b1 = vec4(x.zw, y.zw);
-    vec4 s0 = floor(b0) * 2.0 + 1.0;
-    vec4 s1 = floor(b1) * 2.0 + 1.0;
-    vec4 sh = -step(h, vec4(0.0, 0.0, 0.0, 0.0));
-    vec4 a0 = b0.xzyw + s0.xzyw * sh.xxyy;
-    vec4 a1 = b1.xzyw + s1.xzyw * sh.zzww;
-
-    vec3 p0 = vec3(a0.xy, h.x);
-    vec3 p1 = vec3(a0.zw, h.y);
-    vec3 p2 = vec3(a1.xy, h.z);
-    vec3 p3 = vec3(a1.zw, h.w);
-    vec4 norm = 1.79284291400159 - 0.85373472095314 * vec4(dot(p0, p0), dot(p1, p1), dot(p2, p2), dot(p3, p3));
-    p0 *= norm.x;
-    p1 *= norm.y;
-    p2 *= norm.z;
-    p3 *= norm.w;
-
-    vec4 m0 = max(0.5 - vec4(dot(x0, x0), dot(x1, x1), dot(x2, x2), dot(x3, x3)), 0.0);
-    vec4 m2 = m0 * m0;
-    vec4 m3 = m2 * m0;
-    vec4 px = vec4(dot(p0, x0), dot(p1, x1), dot(p2, x2), dot(p3, x3));
-    vec4 wide = 48.0 * m2 * px;
-    vec4 narrow = 8.0 * m3;
-
-    vec4 cxx = vec4(x0.x, x1.x, x2.x, x3.x);
-    vec4 cxy = vec4(x0.y, x1.y, x2.y, x3.y);
-    vec4 cxz = vec4(x0.z, x1.z, x2.z, x3.z);
-    vec4 cpx = vec4(p0.x, p1.x, p2.x, p3.x);
-    vec4 cpy = vec4(p0.y, p1.y, p2.y, p3.y);
-    vec4 cpz = vec4(p0.z, p1.z, p2.z, p3.z);
-
-    float hxx = 105.0 * (dot(wide * cxx, cxx) - dot(narrow, 2.0 * cpx * cxx + px));
-    float hyy = 105.0 * (dot(wide * cxy, cxy) - dot(narrow, 2.0 * cpy * cxy + px));
-    float hzz = 105.0 * (dot(wide * cxz, cxz) - dot(narrow, 2.0 * cpz * cxz + px));
-    float hxy = 105.0 * (dot(wide * cxx, cxy) - dot(narrow, cpx * cxy + cpy * cxx));
-    float hxz = 105.0 * (dot(wide * cxx, cxz) - dot(narrow, cpx * cxz + cpz * cxx));
-    float hyz = 105.0 * (dot(wide * cxy, cxz) - dot(narrow, cpy * cxz + cpz * cxy));
-    return mat3(hxx, hxy, hxz, hxy, hyy, hyz, hxz, hyz, hzz);
-}
-
-// The integral over [t0, t1] of clamp(a + b t, lo, hi); see the C# math.integral_clamp_linear comment.
-float cultmath_integral_clamp_linear(float a, float b, float lo, float hi, float t0, float t1)
-{
-    lo = min(lo, hi);
-    if (b == 0.0)
-        return t1 != t0 ? clamp(a, lo, hi) * (t1 - t0) : 0.0;
-
-    float direction = t1 < t0 ? -1.0 : 1.0;
-    float start = min(t0, t1);
-    float stop = max(t0, t1);
-    float atLo = (lo - a) / b;
-    float atHi = (hi - a) / b;
-    float enter = clamp(min(atLo, atHi), start, stop);
-    float leave = clamp(max(atLo, atHi), start, stop);
-    float before = b > 0.0 ? lo : hi;
-    float after = b > 0.0 ? hi : lo;
-    float held = enter > start ? before * (enter - start) : 0.0;
-    float kept = stop > leave ? after * (stop - leave) : 0.0;
-    float total = held + (a + b * (0.5 * (enter + leave))) * (leave - enter) + kept;
-    return direction * total;
-}
-
-// Octave sum of cultmath_snoise_grad (invariant 8); see the C# math.fbm_grad comment for the
-// per-octave frequency/amplitude derivation and why octaves is clamped.
-vec4 cultmath_fbm_grad(vec3 p, int octaves, float lacunarity, float gain)
-{
-    octaves = clamp(octaves, 0, 16);
-    float amplitude = 1.0;
-    float frequency = 1.0;
-    float value = 0.0;
-    vec3 gradient = vec3(0.0, 0.0, 0.0);
-    for (int i = 0; i < octaves; i++)
-    {
-        vec4 n = cultmath_snoise_grad(p * frequency);
-        value += amplitude * n.w;
-        gradient += amplitude * frequency * n.xyz;
-        frequency *= lacunarity;
-        amplitude *= gain;
-    }
-
-    return vec4(gradient, value);
-}
-
-// Ridged multifractal noise (Musgrave, Texturing and Modeling, ch. 16); see the C# math.ridged_grad
-// comment for the fold/sign derivation, the deliberate crease at n = 0, and why octaves is clamped.
-vec4 cultmath_ridged_grad(vec3 p, int octaves, float lacunarity, float gain)
-{
-    octaves = clamp(octaves, 0, 16);
-    float amplitude = 1.0;
-    float frequency = 1.0;
-    float value = 0.0;
-    vec3 gradient = vec3(0.0, 0.0, 0.0);
-    for (int i = 0; i < octaves; i++)
-    {
-        vec4 n = cultmath_snoise_grad(p * frequency);
-        float s = sign(n.w);
-        value += amplitude * (1.0 - abs(n.w));
-        gradient += -amplitude * frequency * s * n.xyz;
-        frequency *= lacunarity;
-        amplitude *= gain;
-    }
-
-    return vec4(gradient, value);
-}
-
-float cultmath_lengthsq(vec2 value) { return dot(value, value); }
-float cultmath_lengthsq(vec3 value) { return dot(value, value); }
-float cultmath_lengthsq(vec4 value) { return dot(value, value); }
-
-float cultmath_distance(vec2 left, vec2 right) { return length(left - right); }
-float cultmath_distance(vec3 left, vec3 right) { return length(left - right); }
-float cultmath_distance(vec4 left, vec4 right) { return length(left - right); }
-
-vec2 cultmath_reflect(vec2 incident, vec2 normal_value)
-{
-    return incident - 2.0 * dot(normal_value, incident) * normal_value;
-}
-
-vec3 cultmath_reflect(vec3 incident, vec3 normal_value)
-{
-    return incident - 2.0 * dot(normal_value, incident) * normal_value;
-}
-
-vec2 cultmath_rotate(vec2 value, float radians_value)
-{
-    float s = sin(radians_value);
-    float c = cos(radians_value);
-    return vec2(value.x * c - value.y * s, value.x * s + value.y * c);
-}
-
-vec2 cultmath_rotate_degrees(vec2 value, float degrees_value)
-{
-    return cultmath_rotate(value, cultmath_radians(degrees_value));
-}
-
-float cultmath_csum(vec2 value) { return value.x + value.y; }
-float cultmath_csum(vec3 value) { return value.x + value.y + value.z; }
-float cultmath_csum(vec4 value) { return value.x + value.y + value.z + value.w; }
-
-float cultmath_decay(float source, float lambda_value, float dt) { return source * exp(-lambda_value * dt); }
-vec2 cultmath_decay(vec2 source, float lambda_value, float dt) { return source * exp(-lambda_value * dt); }
-vec3 cultmath_decay(vec3 source, float lambda_value, float dt) { return source * exp(-lambda_value * dt); }
-vec4 cultmath_decay(vec4 source, float lambda_value, float dt) { return source * exp(-lambda_value * dt); }
-
-float cultmath_damp(float start, float end, float lambda_value, float dt)
-{
-    return cultmath_lerp(start, end, 1.0 - exp(-lambda_value * dt));
-}
-
-vec2 cultmath_damp(vec2 start, vec2 end, float lambda_value, float dt)
-{
-    float amount = 1.0 - exp(-lambda_value * dt);
-    return cultmath_lerp(start, end, vec2(amount, amount));
-}
-
-vec3 cultmath_damp(vec3 start, vec3 end, float lambda_value, float dt)
-{
-    float amount = 1.0 - exp(-lambda_value * dt);
-    return cultmath_lerp(start, end, vec3(amount, amount, amount));
-}
-
-vec4 cultmath_damp(vec4 start, vec4 end, float lambda_value, float dt)
-{
-    float amount = 1.0 - exp(-lambda_value * dt);
-    return cultmath_lerp(start, end, vec4(amount, amount, amount, amount));
-}
-
-float cultmath_catmullrom(float p0, float p1, float p2, float p3, float t)
-{
-    float t2 = t * t;
-    float t3 = t2 * t;
-    return 0.5 * ((2.0 * p1) + (p2 - p0) * t + (2.0 * p0 - 5.0 * p1 + 4.0 * p2 - p3) * t2 + (-p0 + 3.0 * p1 - 3.0 * p2 + p3) * t3);
-}
-
-vec2 cultmath_catmullrom(vec2 p0, vec2 p1, vec2 p2, vec2 p3, float t)
-{
-    float t2 = t * t;
-    float t3 = t2 * t;
-    return 0.5 * ((2.0 * p1) + (p2 - p0) * t + (2.0 * p0 - 5.0 * p1 + 4.0 * p2 - p3) * t2 + (-p0 + 3.0 * p1 - 3.0 * p2 + p3) * t3);
-}
-
-vec3 cultmath_catmullrom(vec3 p0, vec3 p1, vec3 p2, vec3 p3, float t)
-{
-    float t2 = t * t;
-    float t3 = t2 * t;
-    return 0.5 * ((2.0 * p1) + (p2 - p0) * t + (2.0 * p0 - 5.0 * p1 + 4.0 * p2 - p3) * t2 + (-p0 + 3.0 * p1 - 3.0 * p2 + p3) * t3);
-}
-
-vec4 cultmath_catmullrom(vec4 p0, vec4 p1, vec4 p2, vec4 p3, float t)
-{
-    float t2 = t * t;
-    float t3 = t2 * t;
-    return 0.5 * ((2.0 * p1) + (p2 - p0) * t + (2.0 * p0 - 5.0 * p1 + 4.0 * p2 - p3) * t2 + (-p0 + 3.0 * p1 - 3.0 * p2 + p3) * t3);
-}
-
-float cultmath_quadratic_bezier(float p0, float p1, float p2, float t)
-{
-    t = cultmath_saturate(t);
-    float inv = 1.0 - t;
-    return inv * inv * p0 + 2.0 * inv * t * p1 + t * t * p2;
-}
-
-vec3 cultmath_quadratic_bezier(vec3 p0, vec3 p1, vec3 p2, float t)
-{
-    t = cultmath_saturate(t);
-    float inv = 1.0 - t;
-    return inv * inv * p0 + 2.0 * inv * t * p1 + t * t * p2;
-}
-
-float cultmath_cubic_bezier(float p0, float p1, float p2, float p3, float t)
-{
-    t = cultmath_saturate(t);
-    float inv = 1.0 - t;
-    return inv * inv * inv * p0 + 3.0 * inv * inv * t * p1 + 3.0 * inv * t * t * p2 + t * t * t * p3;
-}
-
-vec3 cultmath_cubic_bezier(vec3 p0, vec3 p1, vec3 p2, vec3 p3, float t)
-{
-    t = cultmath_saturate(t);
-    float inv = 1.0 - t;
-    return inv * inv * inv * p0 + 3.0 * inv * inv * t * p1 + 3.0 * inv * t * t * p2 + t * t * t * p3;
-}
-
-float cultmath_hash(float value) { return cultmath_frac(sin(value) * 43758.5453); }
-float cultmath_hash(vec2 value) { return cultmath_hash(dot(value, vec2(127.1, 311.7))); }
-float cultmath_hash(vec3 value) { return cultmath_hash(dot(value, vec3(127.1, 311.7, 74.7))); }
-
-// PCG hashes (Jarzynski and Olano, JCGT 2020), written over scalar uints so CultMath's ivec3/ivec4 carry the bits.
-uint cultmath_pcg(uint value)
-{
-    uint state = value * 747796405u + 2891336453u;
-    uint word = ((state >> int((state >> 28) + 4u)) ^ state) * 277803737u;
-    return (word >> 22) ^ word;
-}
-
-ivec3 cultmath_pcg3d(ivec3 value)
-{
-    uint x = uint(value.x) * 1664525u + 1013904223u, y = uint(value.y) * 1664525u + 1013904223u, z = uint(value.z) * 1664525u + 1013904223u;
-    x += y * z; y += z * x; z += x * y;
-    x ^= x >> 16; y ^= y >> 16; z ^= z >> 16;
-    x += y * z; y += z * x; z += x * y;
-    return ivec3(int(x), int(y), int(z));
-}
-
-ivec3 cultmath_pcg3d(vec3 value) { return cultmath_pcg3d(ivec3(int(floatBitsToUint(value.x)), int(floatBitsToUint(value.y)), int(floatBitsToUint(value.z)))); }
-ivec3 cultmath_pcg3d(vec2 value) { return cultmath_pcg3d(vec3(value, 0.0)); }
-
-ivec4 cultmath_pcg4d(ivec4 value)
-{
-    uint x = uint(value.x) * 1664525u + 1013904223u, y = uint(value.y) * 1664525u + 1013904223u;
-    uint z = uint(value.z) * 1664525u + 1013904223u, w = uint(value.w) * 1664525u + 1013904223u;
-    x += y * w; y += z * x; z += x * y; w += y * z;
-    x ^= x >> 16; y ^= y >> 16; z ^= z >> 16; w ^= w >> 16;
-    x += y * w; y += z * x; z += x * y; w += y * z;
-    return ivec4(int(x), int(y), int(z), int(w));
-}
-
-ivec4 cultmath_pcg4d(vec4 value) { return cultmath_pcg4d(ivec4(int(floatBitsToUint(value.x)), int(floatBitsToUint(value.y)), int(floatBitsToUint(value.z)), int(floatBitsToUint(value.w)))); }
-
-// Inigo Quilez, "smooth minimum": quadratic-polynomial smin carried to value-and-gradient form. See
-// math.smin_grad's comment (math.cs) for why the gradient blend is exact, not an approximation.
-vec4 cultmath_smin_grad(vec4 a, vec4 b, float k)
-{
-    float h = clamp(0.5 + 0.5 * (b.w - a.w) / k, 0.0, 1.0);
-    float value = mix(b.w, a.w, h) - k * h * (1.0 - h);
-    vec3 gradient = mix(b.xyz, a.xyz, h);
-    return vec4(gradient, value);
-}
-
-// Invariant 8's one struct return shape (design.md, "HLSL Target: Source Transformations"):
-// compared field by field and bit for bit against CultMath.CultCellular, same field order.
-struct CultCellular
-{
-    vec4 nearest;
-    vec4 edge;
-    float id;
-};
-
-// Worley, "A Cellular Texture Basis Function" (SIGGRAPH 1996). See math.cellular's comment
-// (math.cs) for the hashing, gradient, search-radius exactness proof, id source and
-// degenerate-point conventions this mirrors exactly, including the 5x5x5 lower-bound prune.
-CultCellular cultmath_cellular(vec3 p)
-{
-    vec3 cell = floor(p);
-    float f1 = 1.0e30;
-    float f2 = 1.0e30;
-    vec3 c1 = vec3(0.0, 0.0, 0.0);
-    vec3 c2 = vec3(0.0, 0.0, 0.0);
-    vec3 cellId = vec3(0.0, 0.0, 0.0);
-
-    for (int dz = -2; dz <= 2; dz++)
-    {
-        float lz = max(0.0, abs(float(dz)) - 1.0);
-        for (int dy = -2; dy <= 2; dy++)
-        {
-            float ly = max(0.0, abs(float(dy)) - 1.0);
-            for (int dx = -2; dx <= 2; dx++)
-            {
-                float lx = max(0.0, abs(float(dx)) - 1.0);
-                float lowerBound = sqrt(lx * lx + ly * ly + lz * lz);
-                if (lowerBound >= f2)
-                    continue;
-
-                vec3 neighbor = cell + vec3(dx, dy, dz);
-                ivec3 hash = cultmath_pcg3d(ivec3(neighbor));
-                vec3 jitter = vec3(
-                    float(uint(hash.x) >> 8) * (1.0 / 16777216.0),
-                    float(uint(hash.y) >> 8) * (1.0 / 16777216.0),
-                    float(uint(hash.z) >> 8) * (1.0 / 16777216.0));
-                vec3 feature = neighbor + jitter;
-                float d = cultmath_distance(p, feature);
-
-                if (d < f1)
-                {
-                    f2 = f1; c2 = c1;
-                    f1 = d; c1 = feature; cellId = neighbor;
-                }
-                else if (d < f2)
-                {
-                    f2 = d; c2 = feature;
-                }
-            }
-        }
-    }
-
-    // F1 = 0 and F2 = 0 share the same degenerate-gradient guard; see math.cellular's comment
-    // (math.cs) for why F2 = 0 is reachable past roughly |p| = 2^23.
-    vec3 grad1 = f1 > 0.0 ? (p - c1) / f1 : vec3(0.0, 0.0, 0.0);
-    vec3 grad2 = f2 > 0.0 ? (p - c2) / f2 : vec3(0.0, 0.0, 0.0);
-
-    // id comes from pcg4d over the winning cell's integer coordinate alone (same int-hashing rule
-    // as the jitter above), never from the pcg3d hash that produced its jitter (F4).
-    ivec4 idHash = cultmath_pcg4d(ivec4(ivec3(cellId), 0));
-
-    CultCellular result;
-    result.nearest = vec4(grad1, f1);
-    result.edge = vec4(grad2 - grad1, f2 - f1);
-    result.id = float(uint(idHash.w) >> 8) * (1.0 / 16777216.0);
-    return result;
-}
-
-
-
-
-// Interval arithmetic over vec2(lo, hi), lo <= hi, both finite. Every cultmath_iv_* function returns
-// an interval containing f(x) for every x in its input intervals, mirroring math.Interval.cs bit for
-// bit; see that file and docs/design.md ("Intervals") for each op's enclosure and its ulp widening.
-// Included by CultMath.hlsl after its own definitions of cultmath_smoothstep and cultmath_snoise.
-
-// Lipschitz constant of cultmath_snoise(vec3); provenance in math.Interval.cs (SNOISE_LIPSCHITZ).
-const float CULTMATH_SNOISE_LIPSCHITZ = 7.9640074;
-
-// Lipschitz constant of cultmath_snoise(vec2); provenance in math.Interval.cs (SNOISE2_LIPSCHITZ).
-const float CULTMATH_SNOISE2_LIPSCHITZ = 8.117002;
-
-vec2 cultmath_iv_point(float value) { return vec2(value, value); }
-vec2 cultmath_iv_add(vec2 a, vec2 b) { return vec2(a.x + b.x, a.y + b.y); }
-vec2 cultmath_iv_sub(vec2 a, vec2 b) { return vec2(a.x - b.y, a.y - b.x); }
-vec2 cultmath_iv_neg(vec2 a) { return vec2(-a.y, -a.x); }
-
-vec2 cultmath_iv_mul(vec2 a, vec2 b)
-{
-    float p0 = a.x * b.x;
-    float p1 = a.x * b.y;
-    float p2 = a.y * b.x;
-    float p3 = a.y * b.y;
-    return vec2(min(min(p0, p1), min(p2, p3)), max(max(p0, p1), max(p2, p3)));
-}
-
-vec2 cultmath_iv_scale(vec2 a, float s) { return s >= 0.0 ? vec2(a.x * s, a.y * s) : vec2(a.y * s, a.x * s); }
-
-vec2 cultmath_iv_abs(vec2 a)
-{
-    if (a.x >= 0.0)
-        return a;
-    if (a.y <= 0.0)
-        return vec2(-a.y, -a.x);
-    return vec2(0.0, max(-a.x, a.y));
-}
-
-vec2 cultmath_iv_min(vec2 a, vec2 b) { return vec2(min(a.x, b.x), min(a.y, b.y)); }
-vec2 cultmath_iv_max(vec2 a, vec2 b) { return vec2(max(a.x, b.x), max(a.y, b.y)); }
-
-vec2 cultmath_iv_sqr(vec2 a)
-{
-    float l = a.x * a.x;
-    float h = a.y * a.y;
-    if (a.x >= 0.0)
-        return vec2(l, h);
-    if (a.y <= 0.0)
-        return vec2(h, l);
-    return vec2(0.0, max(l, h));
-}
-
-vec2 cultmath_iv_sqrt(vec2 a) { return vec2(sqrt(max(a.x, 0.0)), sqrt(max(a.y, 0.0))); }
-
-// Widened by one ulp on each side: exp is not required to be correctly rounded.
-vec2 cultmath_iv_exp(vec2 a)
-{
-    float lo = exp(a.x);
-    float hi = exp(a.y);
-    return vec2(lo > 0.0 ? uintBitsToFloat(floatBitsToUint(lo) - 1u) : 0.0, uintBitsToFloat(floatBitsToUint(hi) + 1u));
-}
-
-vec2 cultmath_iv_clamp(vec2 a, float minimum, float maximum)
-{
-    return vec2(cultmath_clamp(a.x, minimum, maximum), cultmath_clamp(a.y, minimum, maximum));
-}
-
-vec2 cultmath_iv_saturate(vec2 a) { return vec2(cultmath_saturate(a.x), cultmath_saturate(a.y)); }
-
-// The endpoints, ordered, widened by one ulp inside [0, 1]: the float32 evaluation of smoothstep is
-// monotone only to within one ulp.
-vec2 cultmath_iv_smoothstep(float minimum, float maximum, vec2 a)
-{
-    float s0 = cultmath_smoothstep(minimum, maximum, a.x);
-    float s1 = cultmath_smoothstep(minimum, maximum, a.y);
-    float lo = min(s0, s1);
-    float hi = max(s0, s1);
-    return vec2(lo > 0.0 ? uintBitsToFloat(floatBitsToUint(lo) - 1u) : 0.0, hi < 1.0 ? uintBitsToFloat(floatBitsToUint(hi) + 1u) : 1.0);
-}
-
-// The natural interval extension of x + (y - x) * amount, which is how cultmath_lerp evaluates.
-vec2 cultmath_iv_lerp(vec2 a, vec2 b, float amount) { return cultmath_iv_add(a, cultmath_iv_scale(cultmath_iv_sub(b, a), amount)); }
-
-// [n - L r, n + L r] intersected with [-1, 1], n = cultmath_snoise(centre). One snoise, value only.
-vec2 cultmath_iv_snoise_ball(vec3 centre, float radius)
-{
-    float n = cultmath_snoise(centre);
-    float e = CULTMATH_SNOISE_LIPSCHITZ * radius;
-    return vec2(max(n - e, -1.0), min(n + e, 1.0));
-}
-
-// The 2D overload: [n - L2 r, n + L2 r] intersected with [-1, 1], n = cultmath_snoise(centre). One snoise, value only.
-vec2 cultmath_iv_snoise_ball(vec2 centre, float radius)
-{
-    float n = cultmath_snoise(centre);
-    float e = CULTMATH_SNOISE2_LIPSCHITZ * radius;
-    return vec2(max(n - e, -1.0), min(n + e, 1.0));
-}
-
-// Octave sum of cultmath_iv_snoise_ball, compounding frequency and amplitude as the value-and-gradient fBm does.
-vec2 cultmath_iv_fbm_ball(vec3 centre, float radius, int octaves, float lacunarity, float gain)
-{
-    octaves = clamp(octaves, 0, 16);
-    float amplitude = 1.0;
-    float frequency = 1.0;
-    vec2 sum = vec2(0.0, 0.0);
-    for (int i = 0; i < octaves; i++)
-    {
-        sum = cultmath_iv_add(sum, cultmath_iv_scale(cultmath_iv_snoise_ball(centre * frequency, radius * abs(frequency)), amplitude));
-        frequency *= lacunarity;
-        amplitude *= gain;
-    }
-
-    return sum;
-}
-
-// A ball (xyz centre, w radius) enclosing every point of every ray of a screen tile over the depth segment
-// [z0, z1], warped by at most warp. Camera frame: pinhole at the origin looking down +z, ray (m z, z).
-// footprintPerDepth = N / (sqrt(2) f) for an N x N tile at focal length f. The radius is widened by
-// (|c|_1 + radius) 2^-20, which covers the ball's own float32 rounding. Derivation in math.Interval.cs.
-vec4 cultmath_iv_frustum_ball(vec2 centreSlope, float z0, float z1, float footprintPerDepth, float warp)
-{
-    float zm = (z0 + z1) * 0.5;
-    float axis = sqrt(centreSlope.x * centreSlope.x + centreSlope.y * centreSlope.y + 1.0);
-    float cx = centreSlope.x * zm;
-    float cy = centreSlope.y * zm;
-    float radius = (z1 - z0) * 0.5 * axis + z1 * footprintPerDepth + warp;
-    radius += (abs(cx) + abs(cy) + abs(zm) + radius) * 9.5367431640625e-7;
-    return vec4(cx, cy, zm, radius);
-}
-
-
-
-
-
-
-// Reduced affine forms with one shared symbol over vec3(x0, a, e): the set { x0 + a eps + e delta :
-// delta in [-1, 1] } at the region's shared eps in [-1, 1], e >= 0. Every cultmath_af_* function mirrors
-// math.Affine.cs bit for bit; see that file and docs/design.md ("Affine forms") for each op's enclosure
-// and the float32 rounding allowance it folds into e. Included by CultMath.hlsl after
-// CultMath.Interval.hlsl, whose CULTMATH_SNOISE_LIPSCHITZ it shares, and after its own
-// definition of cultmath_snoise_grad.
-
-// An upper bound on the spectral norm of the Hessian of cultmath_snoise(vec3); provenance in
-// math.Affine.cs (SNOISE_HESSIAN).
-const float CULTMATH_SNOISE_HESSIAN = 55.642143;
-
-// The absolute rounding of one float32 read of cultmath_snoise_grad, value and gradient; the owner is
-// math.Affine.cs (SNOISE_READ_VALUE, SNOISE_READ_GRADIENT), read here by cultmath_af_snoise and in
-// CultMath.hlsl by cultmath_span_slack.
-const float CULTMATH_SNOISE_READ_VALUE = 6.103515625e-5;
-const float CULTMATH_SNOISE_READ_GRADIENT = 2.44140625e-4;
-
-// An upper bound on the operator norm of the third-derivative tensor of cultmath_snoise(vec3), the
-// next order after CULTMATH_SNOISE_HESSIAN; provenance in math.Span.cs (SNOISE_THIRD).
-const float CULTMATH_SNOISE_THIRD = 535.8009;
-
-vec3 cultmath_af_point(float value) { return vec3(value, 0.0, 0.0); }
-vec3 cultmath_af_symbol(float x0, float a) { return vec3(x0, a, 0.0); }
-
-vec3 cultmath_af_from_iv(vec2 interval)
-{
-    float x0 = interval.x * 0.5 + interval.y * 0.5;
-    float e = interval.y * 0.5 - interval.x * 0.5;
-    return vec3(x0, 0.0, e + (abs(x0) + e) * 9.5367431640625e-7 + 1.17549435e-38);
-}
-
-// An endpoint that would be NaN is the infinity on its side. NaN is found by its bit pattern: dxc marks
-// compares fast, so a test that needs NaN to make `lo == lo` false is deleted under its default flags.
-vec2 cultmath_af_range(vec3 x)
-{
-    float r = abs(x.y) + x.z;
-    float w = abs(x.x) * 9.5367431640625e-7 + r * 9.5367431640625e-7;
-    float lo = x.x - r - w;
-    float hi = x.x + r + w;
-    return vec2((floatBitsToUint(lo) & 0x7fffffffu) > 0x7f800000u ? uintBitsToFloat(0xff800000u) : lo,
-        (floatBitsToUint(hi) & 0x7fffffffu) > 0x7f800000u ? uintBitsToFloat(0x7f800000u) : hi);
-}
-
-vec3 cultmath_af_add(vec3 x, vec3 y)
-{
-    float x0 = x.x + y.x;
-    float a = x.y + y.y;
-    float e = x.z + y.z;
-    return vec3(x0, a, e + (abs(x0) + abs(a) + e) * 9.5367431640625e-7);
-}
-
-vec3 cultmath_af_sub(vec3 x, vec3 y)
-{
-    float x0 = x.x - y.x;
-    float a = x.y - y.y;
-    float e = x.z + y.z;
-    return vec3(x0, a, e + (abs(x0) + abs(a) + e) * 9.5367431640625e-7);
-}
-
-vec3 cultmath_af_neg(vec3 x) { return vec3(-x.x, -x.y, x.z); }
-
-vec3 cultmath_af_scale(vec3 x, float s)
-{
-    float x0 = x.x * s;
-    float a = x.y * s;
-    float e = x.z * abs(s);
-    return vec3(x0, a, e + (abs(x0) + abs(a) + e) * 9.5367431640625e-7 + 1.17549435e-38);
-}
-
-vec3 cultmath_af_add_iv(vec3 x, vec2 interval) { return cultmath_af_add(x, cultmath_af_from_iv(interval)); }
-
-vec3 cultmath_af_mul(vec3 x, vec3 y)
-{
-    float x0 = x.x * y.x;
-    float p = x.x * y.y;
-    float q = y.x * x.y;
-    float a = p + q;
-    float e = abs(x.x) * y.z + abs(y.x) * x.z + (abs(x.y) + x.z) * (abs(y.y) + y.z);
-    return vec3(x0, a, e + (abs(x0) + abs(p) + abs(q) + e) * 9.5367431640625e-7 + 1.17549435e-38);
-}
-
-// The narrower of the Lipschitz form and the centred (Taylor) form over every p = centre + axis eps + w,
-// |w| <= radius, from one cultmath_snoise_grad at the centre; the allowance for the float32 evaluation is
-// in math.Affine.cs.
-vec3 cultmath_af_snoise(vec3 centre, vec3 axis, float radius)
-{
-    vec4 g = cultmath_snoise_grad(centre);
-    vec3 gradient = vec3(g.x, g.y, g.z);
-    float reach = length(axis) + radius;
-    float lipschitz = CULTMATH_SNOISE_LIPSCHITZ * reach;
-    float a = dot(gradient, axis);
-    float remainder = length(gradient) * radius + 0.5 * CULTMATH_SNOISE_HESSIAN * reach * reach;
-    float allowance = CULTMATH_SNOISE_READ_VALUE + CULTMATH_SNOISE_READ_GRADIENT * reach
-        + CULTMATH_SNOISE_LIPSCHITZ * 9.5367431640625e-7 * (abs(centre.x) + abs(centre.y) + abs(centre.z) + reach);
-    bool centred = abs(a) + remainder < lipschitz;
-    float slope = centred ? a : 0.0;
-    float e = (centred ? remainder : lipschitz) + allowance;
-    return vec3(g.w, slope, e + (abs(g.w) + abs(slope) + e) * 9.5367431640625e-7);
-}
-
-// Octave sum of cultmath_af_snoise, compounding frequency and amplitude as the value-and-gradient fBm does.
-vec3 cultmath_af_fbm(vec3 centre, vec3 axis, float radius, int octaves, float lacunarity, float gain)
-{
-    octaves = clamp(octaves, 0, 16);
-    float amplitude = 1.0;
-    float frequency = 1.0;
-    vec3 sum = vec3(0.0, 0.0, 0.0);
-    for (int i = 0; i < octaves; i++)
-    {
-        sum = cultmath_af_add(sum, cultmath_af_scale(cultmath_af_snoise(centre * frequency, axis * frequency, radius * abs(frequency)), amplitude));
-        frequency *= lacunarity;
-        amplitude *= gain;
-    }
-
-    return sum;
-}
-
-// The axis of a screen tile's slice over the depth segment [z0, z1]; camera frame of
-// cultmath_iv_frustum_ball.
-vec3 cultmath_af_frustum_axis(vec2 centreSlope, float z0, float z1)
-{
-    float h = (z1 - z0) * 0.5;
-    return vec3(centreSlope.x * h, centreSlope.y * h, h);
-}
-
-// The affine slice of a screen tile over [z0, z1]: centre xyz, radius w. Derivation in math.Affine.cs.
-vec4 cultmath_af_frustum_ball(vec2 centreSlope, float z0, float z1, float footprintPerDepth, float warpVariation)
-{
-    float zm = (z0 + z1) * 0.5;
-    float h = (z1 - z0) * 0.5;
-    float cx = centreSlope.x * zm;
-    float cy = centreSlope.y * zm;
-    float spread = (abs(centreSlope.x) + abs(centreSlope.y) + 1.0) * h;
-    float radius = z1 * footprintPerDepth + warpVariation;
-    radius += (abs(cx) + abs(cy) + abs(zm) + spread + radius) * 9.5367431640625e-7;
-    return vec4(cx, cy, zm, radius);
-}
-
-
-
-
-// Span stages (invariant 8): the SpanPath, SpanStage and SpanNoise of math.Span.cs, field for field in
-// C#'s order, and cultmath_span_stage, its octave stage, statement for statement so the text is a bit-for-bit
-// mirror. They follow the includes because the bounds read CULTMATH_SNOISE_LIPSCHITZ, _HESSIAN and _THIRD.
-// A shader caller builds a SpanStage itself (SpanStage(1.0, 1.0, vec3(0.0), vec3(0.0), vec3(0.0), vec3(0.0))
-// is the identity of math.SpanStage.Identity, which has no shader form); see math.span_stage's comments for
-// the span, the transform, the bounds and the allowances. cultmath_span_rounding and cultmath_span_slack
-// are math.span_rounding and math.span_slack, the owners of S_o and of the three allowances.
-struct SpanPath
-{
-    vec3 midpoint;
-    vec3 velocity;
-    float speed;
-    float acceleration;
-    float halfLength;
-};
-
-struct SpanStage
-{
-    float frequency;
-    float stretch;
-    vec3 axis;
-    vec3 shift;
-    vec3 offset;
-    vec3 octaveStep;
-};
-
-struct SpanNoise
-{
-    vec4 field;
-    float curvature;
-    float fold;
-};
-
-float cultmath_span_rounding(float scale, vec3 mq, SpanStage stage, vec3 octaveShift, float nu, float halfLength)
-{
-    return 9.5367431640625e-7 * (abs(scale) * (cultmath_csum(abs(mq)) + cultmath_csum(abs(stage.shift))) + cultmath_csum(abs(stage.offset)) + cultmath_csum(abs(octaveShift)) + 1.7320508 * nu * halfLength);
-}
-
-vec3 cultmath_span_slack(float rounding)
-{
-    return vec3(CULTMATH_SNOISE_READ_VALUE + CULTMATH_SNOISE_LIPSCHITZ * rounding,
-        CULTMATH_SNOISE_READ_GRADIENT + CULTMATH_SNOISE_HESSIAN * rounding,
-        9.765625e-4 + CULTMATH_SNOISE_THIRD * rounding);
-}
-
-// The octave stage behind cultmath_span_fbm and cultmath_span_ridged, as math.span_stage is behind span_fbm
-// and span_ridged. The Frobenius norm of the Hessian is written out in C#'s order (GLSL has no _mRC member
-// access); the C# local named step is octaveShift here (it would shadow GLSL's step()).
-SpanNoise cultmath_span_stage(bool ridged, SpanPath path, SpanStage stage, int octaves, float lacunarity, float gain)
-{
-    vec3 q = path.midpoint;
-    float halfLength = path.halfLength;
-    octaves = clamp(octaves, 0, 16);
-    bool stretched = dot(stage.axis, stage.axis) > 0.0 && stage.stretch != 1.0;
-    vec3 direction = stretched ? normalize(stage.axis) : vec3(0.0, 0.0, 0.0);
-    float squeeze = stretched ? 1.0 / stage.stretch - 1.0 : 0.0;
-    float norm = abs(stage.frequency) * (stretched ? max(1.0, 1.0 / stage.stretch) : 1.0);
-    vec3 mq = stretched ? stage.frequency * (q + squeeze * dot(direction, q) * direction) : stage.frequency * q;
-    vec3 mv = stretched ? stage.frequency * (path.velocity + squeeze * dot(direction, path.velocity) * direction) : stage.frequency * path.velocity;
-    float amplitude = 1.0;
-    float scale = 1.0;
-    float value = 0.0;
-    vec3 gradient = vec3(0.0, 0.0, 0.0);
-    float curvature = 0.0;
-    float fold = 0.0;
-    for (int i = 0; i < octaves; i++)
-    {
-        vec3 octaveShift = float(i) * stage.octaveStep;
-        vec3 x = scale * (mq + stage.shift) + (stage.offset + octaveShift);
-        vec4 n = cultmath_snoise_grad(x);
-        vec3 g = vec3(n.x, n.y, n.z);
-        vec3 mg = stretched ? stage.frequency * (g + squeeze * dot(direction, g) * direction) : stage.frequency * g;
-        if (ridged)
-        {
-            float s = sign(n.w);
-            value += amplitude * (1.0 - abs(n.w));
-            gradient += -amplitude * scale * s * mg;
-        }
-        else
-        {
-            value += amplitude * n.w;
-            gradient += amplitude * scale * mg;
-        }
-
-        float weight = abs(amplitude);
-        float factor = abs(scale) * norm;
-        float nu = factor * path.speed;
-        float rounding = cultmath_span_rounding(scale, mq, stage, octaveShift, nu, halfLength);
-        vec3 slack = cultmath_span_slack(rounding);
-        float valueSlack = slack.x;
-        float gradientSlack = slack.y;
-        float hessianSlack = slack.z;
-        mat3 hm = cultmath_snoise_hessian(x);
-        float frobenius = sqrt(hm[0][0] * hm[0][0] + hm[0][1] * hm[0][1] + hm[0][2] * hm[0][2] + hm[1][0] * hm[1][0] + hm[1][1] * hm[1][1] + hm[1][2] * hm[1][2]
-            + hm[2][0] * hm[2][0] + hm[2][1] * hm[2][1] + hm[2][2] * hm[2][2]);
-        float hessianBound = min(CULTMATH_SNOISE_HESSIAN, frobenius + hessianSlack + CULTMATH_SNOISE_THIRD * nu * halfLength);
-        curvature += weight * factor * factor * hessianBound;
-        if (ridged)
-        {
-            vec3 w = scale * mv;
-            float reach = hessianBound * nu * halfLength;
-            float gl = min(CULTMATH_SNOISE_LIPSCHITZ, length(g) + gradientSlack + reach);
-            float travel = (abs(dot(g, w)) + gradientSlack * length(w)) * halfLength + (hessianBound * nu * length(w) + gl * factor * path.acceleration) * (0.5 * halfLength * halfLength) + 2.0 * valueSlack;
-            fold += 2.0 * weight * max(travel - abs(n.w), 0.0);
-        }
-
-        scale *= lacunarity;
-        amplitude *= gain;
-    }
-
-    SpanNoise result;
-    result.field = vec4(gradient, value);
-    result.curvature = curvature;
-    result.fold = fold;
-    return result;
-}
-
-SpanNoise cultmath_span_fbm(SpanPath path, SpanStage stage, int octaves, float lacunarity, float gain)
-{
-    return cultmath_span_stage(false, path, stage, octaves, lacunarity, gain);
-}
-
-SpanNoise cultmath_span_ridged(SpanPath path, SpanStage stage, int octaves, float lacunarity, float gain)
-{
-    return cultmath_span_stage(true, path, stage, octaves, lacunarity, gain);
-}
-
-float cultmath_value_noise(vec2 position)
-{
-    vec2 cell = floor(position);
-    vec2 local = cultmath_frac(position);
-    vec2 u = local * local * (vec2(3.0, 3.0) - vec2(2.0, 2.0) * local);
-
-    float a = cultmath_hash(cell);
-    float b = cultmath_hash(cell + vec2(1.0, 0.0));
-    float c = cultmath_hash(cell + vec2(0.0, 1.0));
-    float d = cultmath_hash(cell + vec2(1.0, 1.0));
-
-    return cultmath_lerp(cultmath_lerp(a, b, u.x), cultmath_lerp(c, d, u.x), u.y);
-}
-
-float cultmath_value_noise_bicubic(vec2 position)
-{
-    vec2 cell = floor(position);
-    vec2 local = cultmath_frac(position);
-
-    float y0 = cultmath_catmullrom(cultmath_hash(cell + vec2(-1.0, -1.0)), cultmath_hash(cell + vec2(0.0, -1.0)), cultmath_hash(cell + vec2(1.0, -1.0)), cultmath_hash(cell + vec2(2.0, -1.0)), local.x);
-    float y1 = cultmath_catmullrom(cultmath_hash(cell + vec2(-1.0, 0.0)), cultmath_hash(cell + vec2(0.0, 0.0)), cultmath_hash(cell + vec2(1.0, 0.0)), cultmath_hash(cell + vec2(2.0, 0.0)), local.x);
-    float y2 = cultmath_catmullrom(cultmath_hash(cell + vec2(-1.0, 1.0)), cultmath_hash(cell + vec2(0.0, 1.0)), cultmath_hash(cell + vec2(1.0, 1.0)), cultmath_hash(cell + vec2(2.0, 1.0)), local.x);
-    float y3 = cultmath_catmullrom(cultmath_hash(cell + vec2(-1.0, 2.0)), cultmath_hash(cell + vec2(0.0, 2.0)), cultmath_hash(cell + vec2(1.0, 2.0)), cultmath_hash(cell + vec2(2.0, 2.0)), local.x);
-
-    return cultmath_catmullrom(y0, y1, y2, y3, local.y);
-}
-
-#endif
diff --git a/src/app/features/scene/shaders/README.md b/src/app/features/scene/shaders/README.md
deleted file mode 100644
index b970f82b..00000000
--- a/src/app/features/scene/shaders/README.md
+++ /dev/null
@@ -1,19 +0,0 @@
-# Vendored CultMath GLSL
-
-`CultMath.glsl` and `CultMath.Phacelle.glsl` are CultLib's generated WebGL2
-lowering of `packages/cultmath/shaders/CultMath.hlsl` and
-`CultMath.Phacelle.hlsl`, copied unedited from CultLib branch
-`eureka/cultmath-tapes-interval-ops-r5` at `658c09e` (the branch that carries
-the interval ops and `CULTMATH_SNOISE2_LIPSCHITZ`; the repo default branch
-does not carry the GLSL yet). Never edit them here: regenerate in CultLib and
-re-copy. `CultMath.glsl` is MIT; `CultMath.Phacelle.glsl` is MPL-2.0 (Rune
-Skovbo Johansen's Phacelle noise, see its header), so that file keeps its
-header and any change to it is published under MPL-2.0.
-
-The other `*.glsl` files here are the scene's own stages. They are
-concatenated by `../shaderSource.ts` after a prelude; they use no colour
-literal (the palette is uniforms) and define no noise.
-
-`../shaderSource.ts` compiles each stage with only the part of `CultMath.glsl` that stage reaches
-(`../cultmathTrim.ts`); the vendored file itself stays whole. Phacelle is added to the terrain stage
-alone.
diff --git a/src/app/features/scene/shaders/atmosphere.frag.glsl b/src/app/features/scene/shaders/atmosphere.frag.glsl
deleted file mode 100644
index adbf1b5b..00000000
--- a/src/app/features/scene/shaders/atmosphere.frag.glsl
+++ /dev/null
@@ -1,90 +0,0 @@
-// Pass 2: atmosphere, marched only up to pass 1's depth. Height fog is closed-form; the cloud
-// slab is marched with a few jittered steps. Output: rgb in-scattered light, a transmittance.
-uniform sampler2D u_depth;     // pass 1 hit distance, nearest
-uniform int u_steps;           // cloud march steps
-uniform float u_frame;
-uniform vec2 u_jitter;         // sub-pixel jitter in pixels of this target
-uniform vec2 u_size;           // this target's size in pixels
-uniform float u_coverage;      // weather knob: 0 clear .. 1 overcast
-
-in vec2 v_uv;
-layout(location = 0) out vec4 o_atm;
-
-float hg(float cosTheta, float g)
-{
-    float g2 = g * g;
-    return (1.0 - g2) / (12.566370614 * pow(1.0 + g2 - 2.0 * g * cosTheta, 1.5));
-}
-
-float cloudDensity(vec3 p)
-{
-    float wind = u_time * 2.5;
-    float f = cultmath_fbm_grad(vec3(p.x * 0.0042 + wind * 0.0042, p.y * 0.0075, p.z * 0.0042), 3, 2.0, 0.5).w;
-    float h = (p.y - W_CLOUD_Y0) / (W_CLOUD_Y1 - W_CLOUD_Y0);
-    float profile = smoothstep(0.0, 0.2, h) * smoothstep(1.0, 0.55, h);
-    return clamp((f + 0.55 * u_coverage - 0.25) * 2.4, 0.0, 1.0) * profile;
-}
-
-void main()
-{
-    vec2 jittered = (gl_FragCoord.xy + u_jitter) / u_size;
-    vec3 rd = camRay(jittered);
-    vec3 ro = u_camPos;
-    float depth = texture(u_depth, v_uv).r;
-    float tEnd = min(depth, W_ATM_FAR);
-
-    // Exponential height fog, closed form: optical depth of density d0 * exp(-k y) along the ray.
-    float k = W_FOG_FALLOFF;
-    float dy = rd.y * tEnd;
-    float tau = W_FOG_DENSITY * exp(-k * ro.y) * (abs(dy) > 1e-3 ? (1.0 - exp(-k * dy)) / (k * rd.y) : tEnd);
-    float fogT = exp(-max(tau, 0.0));
-    float cosSun = dot(rd, u_sunDir);
-    vec3 fogLight = u_fogColor + u_sunColor * hg(cosSun, 0.55) * 0.9;
-    vec3 inscatter = fogLight * (1.0 - fogT);
-    float trans = fogT;
-
-    // Clouds: only the part of the ray inside the slab and in front of the surface.
-    float ta = 0.0;
-    float tb = tEnd;
-    if (abs(rd.y) > 1e-4)
-    {
-        float t0 = (W_CLOUD_Y0 - ro.y) / rd.y;
-        float t1 = (W_CLOUD_Y1 - ro.y) / rd.y;
-        ta = max(0.0, min(t0, t1));
-        tb = min(tEnd, max(t0, t1));
-    }
-    else if (ro.y < W_CLOUD_Y0 || ro.y > W_CLOUD_Y1)
-        tb = 0.0;
-
-    if (tb > ta && u_steps > 0)
-    {
-        float dt = (tb - ta) / float(u_steps);
-        float t = ta + dt * ign(gl_FragCoord.xy, u_frame);
-        float T = 1.0;
-        vec3 L = vec3(0.0);
-        float phase = hg(cosSun, 0.6) + 0.35 * hg(cosSun, -0.2);
-        for (int i = 0; i < u_steps; i++)
-        {
-            vec3 p = ro + rd * t;
-            float d = cloudDensity(p);
-            if (d > 0.01)
-            {
-                // One sample toward the sun stands in for self-shadowing.
-                float shade = exp(-cloudDensity(p + u_sunDir * 38.0) * 2.2);
-                vec3 light = u_sunColor * (phase * 6.0) * shade + mix(u_skyHorizon, u_skyTop, 0.6) * 0.35;
-                float ext = d * dt * 0.035;
-                float stepT = exp(-ext);
-                L += T * (1.0 - stepT) * light;
-                T *= stepT;
-                if (T < 0.03)
-                    break;
-            }
-            t += dt;
-        }
-        // Fog in front of the slab is already in `inscatter`; clouds sit behind it.
-        inscatter += trans * L;
-        trans *= T;
-    }
-
-    o_atm = vec4(inscatter, trans);
-}
diff --git a/src/app/features/scene/shaders/common.glsl b/src/app/features/scene/shaders/common.glsl
deleted file mode 100644
index 6378a2e6..00000000
--- a/src/app/features/scene/shaders/common.glsl
+++ /dev/null
@@ -1,31 +0,0 @@
-// Shared by every fragment stage; concatenated after the prelude, CultMath and the world defines.
-uniform vec3 u_camPos;
-uniform mat3 u_camBasis;   // columns: right, up, forward
-uniform vec2 u_tanHalf;    // x: tan(fov/2) * aspect, y: tan(fov/2)
-uniform float u_time;
-uniform vec3 u_sunDir;     // unit, towards the sun
-uniform vec3 u_sunColor;
-uniform vec3 u_skyTop;
-uniform vec3 u_skyHorizon;
-uniform vec3 u_fogColor;
-
-vec3 camRay(vec2 uv)
-{
-    vec2 ndc = uv * 2.0 - 1.0;
-    return normalize(u_camBasis * vec3(ndc * u_tanHalf, 1.0));
-}
-
-float ign(vec2 p, float frame)
-{
-    p += 5.588238 * mod(frame, 64.0);
-    return fract(52.9829189 * fract(dot(p, vec2(0.06711056, 0.00583715))));
-}
-
-vec3 skyColor(vec3 rd)
-{
-    float h = clamp(rd.y, 0.0, 1.0);
-    vec3 c = mix(u_skyHorizon, u_skyTop, pow(h, 0.45));
-    float s = max(dot(rd, u_sunDir), 0.0);
-    c += u_sunColor * (1.5 * pow(s, 256.0));
-    return c;
-}
diff --git a/src/app/features/scene/shaders/composite.frag.glsl b/src/app/features/scene/shaders/composite.frag.glsl
deleted file mode 100644
index 9dce31f1..00000000
--- a/src/app/features/scene/shaders/composite.frag.glsl
+++ /dev/null
@@ -1,26 +0,0 @@
-// Full-resolution composite to the canvas: solid over sky, then the accumulated atmosphere.
-uniform sampler2D u_solid;   // rgb lit, a coverage (bilinear)
-uniform sampler2D u_atm;     // TAA'd atmosphere (bilinear)
-uniform float u_frame;
-
-in vec2 v_uv;
-out vec4 o_frag;
-
-vec3 tonemap(vec3 x)
-{
-    // Narkowicz ACES fit.
-    return clamp((x * (2.51 * x + 0.03)) / (x * (2.43 * x + 0.59) + 0.14), 0.0, 1.0);
-}
-
-void main()
-{
-    vec3 rd = camRay(v_uv);
-    vec4 solid = texture(u_solid, v_uv);
-    vec4 atm = texture(u_atm, v_uv);
-    vec3 base = mix(skyColor(rd), solid.rgb, solid.a);
-    vec3 col = base * atm.a + atm.rgb;
-    col = tonemap(col);
-    col = pow(col, vec3(1.0 / 2.2));
-    col += (ign(gl_FragCoord.xy, u_frame) - 0.5) / 255.0;
-    o_frag = vec4(col, 1.0);
-}
diff --git a/src/app/features/scene/shaders/fullscreen.vert.glsl b/src/app/features/scene/shaders/fullscreen.vert.glsl
deleted file mode 100644
index cab0e527..00000000
--- a/src/app/features/scene/shaders/fullscreen.vert.glsl
+++ /dev/null
@@ -1,8 +0,0 @@
-out vec2 v_uv;
-void main()
-{
-    // One oversized triangle; uv spans 0..1 over the visible part.
-    vec2 p = vec2(float((gl_VertexID << 1) & 2), float(gl_VertexID & 2));
-    v_uv = p;
-    gl_Position = vec4(p * 2.0 - 1.0, 0.0, 1.0);
-}
diff --git a/src/app/features/scene/shaders/resolve.frag.glsl b/src/app/features/scene/shaders/resolve.frag.glsl
deleted file mode 100644
index cc6dd2e0..00000000
--- a/src/app/features/scene/shaders/resolve.frag.glsl
+++ /dev/null
@@ -1,41 +0,0 @@
-// TAA resolve for the atmosphere target: reproject history by the pass-1 depth, clamp it to the
-// current frame's 3x3 neighbourhood, blend.
-uniform sampler2D u_cur;
-uniform sampler2D u_history;
-uniform sampler2D u_depth;
-uniform vec3 u_prevPos;
-uniform mat3 u_prevBasis;
-uniform vec2 u_prevTanHalf;
-uniform float u_blend;        // weight of the current frame; 1 resets
-uniform vec2 u_curSize;
-
-in vec2 v_uv;
-layout(location = 0) out vec4 o_hist;
-
-void main()
-{
-    vec2 px = 1.0 / u_curSize;
-    vec4 cur = texture(u_cur, v_uv);
-    vec4 lo = cur;
-    vec4 hi = cur;
-    for (int y = -1; y <= 1; y++)
-        for (int x = -1; x <= 1; x++)
-        {
-            vec4 s = texture(u_cur, v_uv + vec2(float(x), float(y)) * px);
-            lo = min(lo, s);
-            hi = max(hi, s);
-        }
-
-    // Where this pixel's ray ended, reprojected into last frame's camera.
-    vec3 rd = camRay(v_uv);
-    float t = min(texture(u_depth, v_uv).r, 600.0);
-    vec3 v = u_camPos + rd * t - u_prevPos;
-    vec3 local = transpose(u_prevBasis) * v;
-    vec2 prevNdc = local.z > 0.0 ? local.xy / (local.z * u_prevTanHalf) : vec2(2.0);
-    vec2 prevUv = prevNdc * 0.5 + 0.5;
-    bool inside = all(greaterThanEqual(prevUv, vec2(0.0))) && all(lessThanEqual(prevUv, vec2(1.0)));
-
-    float a = (inside && u_blend < 1.0) ? u_blend : 1.0;
-    vec4 hist = clamp(texture(u_history, prevUv), lo, hi);
-    o_hist = mix(hist, cur, a);
-}
diff --git a/src/app/features/scene/shaders/terrain.frag.glsl b/src/app/features/scene/shaders/terrain.frag.glsl
deleted file mode 100644
index b8f2f718..00000000
--- a/src/app/features/scene/shaders/terrain.frag.glsl
+++ /dev/null
@@ -1,184 +0,0 @@
-// Pass 1: solid surfaces (terrain + world tree), sphere-traced. Writes lit colour with coverage
-// and, separately, the hit distance that bounds pass 2.
-uniform vec3 u_grass;
-uniform vec3 u_rock;
-uniform vec3 u_bark;
-uniform vec3 u_leaf;
-uniform int u_maxSteps;
-
-in vec2 v_uv;
-layout(location = 0) out vec4 o_color;   // rgb lit, a coverage
-layout(location = 1) out float o_depth;  // hit distance along the ray, W_FAR on a miss
-
-// ---- terrain -------------------------------------------------------------------------------
-
-float terrainMask(vec2 xz) { return smoothstep(W_PLATEAU_IN, W_PLATEAU_OUT, length(xz)); }
-
-// Value only; cultmath_fbm_grad is the shipped fbm, a public value-only fbm is Libby's gap.
-float terrainFbm(vec2 xz) { return cultmath_fbm_grad(vec3(xz * W_FREQ, 0.0), W_OCTAVES, W_LACUNARITY, W_GAIN).w; }
-
-#if W_ERODE_ENABLED
-CultPhasor terrainPhacelle(vec2 xz)
-{
-    // A fixed stripe wave vector: ridges across the sheet, not slope-aligned erosion.
-    return cultmath_phacelle(vec3(xz * W_ERODE_FREQ, 0.0), W_ERODE_SIDE, 0.0, W_ERODE_NORM);
-}
-#endif
-
-// Conservative distance to the terrain graph. Above the envelope (fbm + erosion amplitude) the
-// cheap envelope bound is exact enough to step by; only within it is the eroded field evaluated.
-float terrainDistance(vec3 p)
-{
-    float m = terrainMask(p.xz);
-    // Flat plateau: the height is exactly 0, so neither noise is evaluated. Sky rays spend most
-    // of their steps here.
-    if (m <= 0.0)
-        return p.y * W_SLOPE_ENV_INV;
-    float hb = m * W_AMP * terrainFbm(p.xz);
-    float above = p.y - (hb + m * W_ERODE_AMP);
-    if (above > 0.0)
-        return above * W_SLOPE_ENV_INV;
-#if W_ERODE_ENABLED
-    hb += m * W_ERODE_AMP * terrainPhacelle(p.xz).cos.w;
-#endif
-    return (p.y - hb) * W_SLOPE_FULL_INV;
-}
-
-vec3 terrainNormal(vec2 xz)
-{
-    float r = length(xz);
-    float m = smoothstep(W_PLATEAU_IN, W_PLATEAU_OUT, r);
-    float s = clamp((r - W_PLATEAU_IN) / (W_PLATEAU_OUT - W_PLATEAU_IN), 0.0, 1.0);
-    float dm = r > 0.0 ? 6.0 * s * (1.0 - s) / (W_PLATEAU_OUT - W_PLATEAU_IN) : 0.0;
-    vec2 dir = r > 0.0 ? xz / r : vec2(0.0);
-    vec4 fg = cultmath_fbm_grad(vec3(xz * W_FREQ, 0.0), W_OCTAVES, W_LACUNARITY, W_GAIN);
-    float f = fg.w;
-    vec2 g = m * W_AMP * W_FREQ * fg.xz + dm * W_AMP * f * dir;
-#if W_ERODE_ENABLED
-    CultPhasor ph = terrainPhacelle(xz);
-    g += m * W_ERODE_AMP * W_ERODE_FREQ * ph.cos.xz + dm * W_ERODE_AMP * ph.cos.w * dir;
-#endif
-    return normalize(vec3(-g.x, 1.0, -g.y));
-}
-
-// ---- world tree ----------------------------------------------------------------------------
-
-float smin(float a, float b, float k)
-{
-    float h = max(k - abs(a - b), 0.0) / k;
-    return min(a, b) - h * h * k * 0.25;
-}
-
-// Not an exact SDF: the flare, ellipsoid and displacement are all scaled to stay under 1-Lipschitz.
-float treeDistance(vec3 p, out float leafness)
-{
-    vec3 c = vec3(0.0, 0.5 * (W_CANOPY_Y + W_CANOPY_R.y), 0.0);
-    float bound = length(p - c) - (W_CANOPY_Y + W_CANOPY_R.y);
-    leafness = 0.0;
-    if (bound > 8.0)
-        return bound;
-
-    float ang = atan(p.z, p.x);
-    float y01 = clamp(p.y / W_TRUNK_H, 0.0, 1.0);
-    float radius = mix(W_TRUNK_R0, W_TRUNK_R1, y01) + 6.0 * exp(-p.y * 0.2) * (1.0 + 0.35 * sin(6.0 * ang + p.y * 0.15));
-    float trunk = max(length(p.xz) - radius, p.y - W_TRUNK_H * 1.2) * 0.7;
-
-    vec3 q = (p - vec3(0.0, W_CANOPY_Y, 0.0)) / W_CANOPY_R;
-    float disp = cultmath_snoise(p * 0.05 + vec3(0.0, u_time * 0.015, 0.0));
-    float canopy = (length(q) - 1.0) * min(W_CANOPY_R.x, W_CANOPY_R.y) - 3.0 * disp;
-    canopy *= 0.45; // 1 / (1 + 3 * 0.05 * L)
-
-    float d = smin(trunk, canopy, 6.0);
-    leafness = clamp(0.5 + (trunk - canopy) * 0.15, 0.0, 1.0);
-    return d;
-}
-
-// ---- trace ---------------------------------------------------------------------------------
-
-float sceneDistance(vec3 p, out float leafness, out bool onTree)
-{
-    float dt = terrainDistance(p);
-    float dr = treeDistance(p, leafness);
-    onTree = dr < dt;
-    return min(dt, dr);
-}
-
-void main()
-{
-    vec3 ro = u_camPos;
-    vec3 rd = camRay(v_uv);
-
-    float t = 0.0;
-    // Nothing is above W_MAX_HEIGHT: skip the empty air above it, or miss outright.
-    if (ro.y > W_MAX_HEIGHT)
-    {
-        if (rd.y >= 0.0)
-        {
-            o_color = vec4(0.0);
-            o_depth = W_FAR;
-            return;
-        }
-        t = (W_MAX_HEIGHT - ro.y) / rd.y;
-    }
-
-    bool hit = false;
-    bool onTree = false;
-    float leafness = 0.0;
-    int i = 0;
-    for (; i < u_maxSteps; i++)
-    {
-        vec3 p = ro + rd * t;
-        float d = sceneDistance(p, leafness, onTree);
-        if (d < 0.0006 * t + 0.01)
-        {
-            hit = true;
-            break;
-        }
-        t += d;
-        if (t > W_FAR || (p.y > W_MAX_HEIGHT && rd.y > 0.0))
-            break;
-    }
-    // The conservative bound makes grazing rays crawl: a ray that ran out of steps while still
-    // below the highest terrain is a distant surface under thick fog, so it ends there.
-    if (!hit && i == u_maxSteps && t < W_FAR)
-    {
-        hit = true;
-        sceneDistance(ro + rd * t, leafness, onTree);
-    }
-
-    if (!hit)
-    {
-        o_color = vec4(0.0);
-        o_depth = W_FAR;
-        return;
-    }
-
-    vec3 p = ro + rd * t;
-    vec3 n;
-    vec3 albedo;
-    if (onTree)
-    {
-        float e = 0.35;
-        float l;
-        n = normalize(vec3(
-            treeDistance(p + vec3(e, 0.0, 0.0), l) - treeDistance(p - vec3(e, 0.0, 0.0), l),
-            treeDistance(p + vec3(0.0, e, 0.0), l) - treeDistance(p - vec3(0.0, e, 0.0), l),
-            treeDistance(p + vec3(0.0, 0.0, e), l) - treeDistance(p - vec3(0.0, 0.0, e), l)));
-        float speckle = 0.75 + 0.25 * cultmath_snoise(p * 0.8);
-        albedo = mix(u_bark, u_leaf * speckle, leafness);
-    }
-    else
-    {
-        n = terrainNormal(p.xz);
-        float rockness = smoothstep(0.78, 0.55, n.y);
-        albedo = mix(u_grass, u_rock, rockness);
-    }
-
-    float ndl = dot(n, u_sunDir);
-    float wrap = clamp(ndl * 0.6 + 0.4, 0.0, 1.0); // half-lambert: no shadow ray in the cheap pass
-    vec3 ambient = mix(u_skyHorizon, u_skyTop, 0.5 + 0.5 * n.y) * 0.45;
-    vec3 col = albedo * (u_sunColor * wrap * wrap + ambient);
-
-    o_color = vec4(col, 1.0);
-    o_depth = t;
-}
diff --git a/src/app/features/scene/tier.test.ts b/src/app/features/scene/tier.test.ts
deleted file mode 100644
index d35b6bb6..00000000
--- a/src/app/features/scene/tier.test.ts
+++ /dev/null
@@ -1,26 +0,0 @@
-import { describe, expect, it } from 'vitest';
-import { resolveTier } from './tier';
-
-describe('scene tier', () => {
-  it('is off unless the config turns it on, which is the feature flag', () => {
-    expect(resolveTier(undefined)).toBe('off');
-    expect(resolveTier({})).toBe('off');
-    expect(resolveTier({ tier: 'off' }, { deviceMemory: 16 })).toBe('off');
-    expect(resolveTier({ tier: 'full' })).toBe('full');
-  });
-
-  it('lets the device lower the configured tier and never raise it', () => {
-    expect(resolveTier({ tier: 'full' }, { saveData: true })).toBe('still');
-    expect(resolveTier({ tier: 'full' }, { deviceMemory: 2 })).toBe('low');
-    expect(resolveTier({ tier: 'full' }, { hardwareConcurrency: 4 })).toBe('low');
-    expect(resolveTier({ tier: 'low' }, { saveData: true })).toBe('still');
-    expect(resolveTier({ tier: 'still' }, { deviceMemory: 16, hardwareConcurrency: 16 })).toBe(
-      'still'
-    );
-    expect(resolveTier({ tier: 'low' }, { deviceMemory: 16, hardwareConcurrency: 16 })).toBe('low');
-  });
-
-  it('treats unknown capabilities as capable', () => {
-    expect(resolveTier({ tier: 'full' }, {})).toBe('full');
-  });
-});
diff --git a/src/app/features/scene/tier.ts b/src/app/features/scene/tier.ts
deleted file mode 100644
index 1c1668c7..00000000
--- a/src/app/features/scene/tier.ts
+++ /dev/null
@@ -1,49 +0,0 @@
-// Which quality the background scene runs at. The client config's `backgroundScene.tier` is both
-// the feature flag (absent or 'off' means the scene is not even imported) and the ceiling; the
-// device can only lower it.
-
-export type SceneTier = 'off' | 'still' | 'low' | 'full';
-
-/** Cheapest first. */
-export const TIERS: readonly SceneTier[] = ['off', 'still', 'low', 'full'];
-
-export interface Capabilities {
-  /** `navigator.connection.saveData`. */
-  saveData?: boolean;
-  /** `navigator.deviceMemory` in GiB (Chromium only). */
-  deviceMemory?: number;
-  hardwareConcurrency?: number;
-}
-
-export interface BackgroundSceneConfig {
-  tier?: SceneTier;
-}
-
-export function readCapabilities(nav: Navigator): Capabilities {
-  const n = nav as Navigator & {
-    deviceMemory?: number;
-    connection?: { saveData?: boolean };
-  };
-  return {
-    saveData: n.connection?.saveData,
-    deviceMemory: n.deviceMemory,
-    hardwareConcurrency: n.hardwareConcurrency,
-  };
-}
-
-/** The most the device is allowed to run, before the configured ceiling is applied. */
-function deviceCeiling(c: Capabilities): SceneTier {
-  if (c.saveData) return 'still';
-  if ((c.deviceMemory ?? Infinity) <= 2 || (c.hardwareConcurrency ?? Infinity) <= 4) return 'low';
-  return 'full';
-}
-
-/** The tier to run: the configured one (default 'off'), lowered by what the device can carry. */
-export function resolveTier(
-  config: BackgroundSceneConfig | undefined,
-  capabilities: Capabilities = {}
-): SceneTier {
-  const configured = config?.tier ?? 'off';
-  const ceiling = deviceCeiling(capabilities);
-  return TIERS.indexOf(configured) <= TIERS.indexOf(ceiling) ? configured : ceiling;
-}
diff --git a/src/app/features/scene/world.test.ts b/src/app/features/scene/world.test.ts
deleted file mode 100644
index caa04fad..00000000
--- a/src/app/features/scene/world.test.ts
+++ /dev/null
@@ -1,40 +0,0 @@
-import { describe, expect, it } from 'vitest';
-import common from './shaders/common.glsl?raw';
-import terrain from './shaders/terrain.frag.glsl?raw';
-import atmosphere from './shaders/atmosphere.frag.glsl?raw';
-import resolve from './shaders/resolve.frag.glsl?raw';
-import composite from './shaders/composite.frag.glsl?raw';
-import { terrainBounds, WORLD, worldDefines } from './world';
-
-describe('world defines', () => {
-  it('define every W_ name any scene shader uses', () => {
-    const defined = new Set([...worldDefines().matchAll(/#define (W_\w+)/g)].map((m) => m[1]));
-    [common, terrain, atmosphere, resolve, composite]
-      .flatMap((src) => [...src.matchAll(/\bW_[A-Z0-9_]+\b/g)])
-      .forEach((m) => expect(defined, m[0]).toContain(m[0]));
-  });
-
-  it('emit only valid GLSL numbers', () => {
-    expect(worldDefines()).not.toMatch(/NaN|Infinity|undefined/);
-  });
-});
-
-describe('terrain step bound', () => {
-  it('is more conservative with erosion than without, and without erosion carries no phacelle term', () => {
-    const b = terrainBounds();
-    expect(b.slopeFull).toBeGreaterThan(b.slopeEnvelope);
-    const off = terrainBounds({ ...WORLD, phacelleGradBound: 0 });
-    expect(off.slopeFull).toBe(off.slopeEnvelope);
-  });
-
-  it('puts every surface under the height the tracer skips to', () => {
-    const maxHeight = Number(/#define W_MAX_HEIGHT (\S+)/.exec(worldDefines())![1]);
-    expect(maxHeight).toBeGreaterThanOrEqual(terrainBounds().maxHeight);
-    expect(maxHeight).toBeGreaterThanOrEqual(WORLD.tree.canopyY + WORLD.tree.canopyRadius[1]);
-  });
-
-  it('leaves the erosion bound turned on only when a bound exists', () => {
-    expect(worldDefines()).toContain('#define W_ERODE_ENABLED 1');
-    expect(worldDefines({ ...WORLD, phacelleGradBound: 0 })).toContain('#define W_ERODE_ENABLED 0');
-  });
-});
diff --git a/src/app/features/scene/world.ts b/src/app/features/scene/world.ts
deleted file mode 100644
index e9594a68..00000000
--- a/src/app/features/scene/world.ts
+++ /dev/null
@@ -1,117 +0,0 @@
-// The scene's world constants. One owner: the shader prelude below is generated from this
-// object, so a number lives here and nowhere else, and the Lipschitz bounds that make the
-// sphere-trace step safe are computed beside the numbers they bound.
-
-// Lipschitz constant of cultmath_snoise(vec3), CULTMATH_SNOISE_LIPSCHITZ in the vendored
-// CultMath.glsl (provenance in CultLib math.Interval.cs).
-export const SNOISE_LIPSCHITZ = 7.9640074;
-
-export const WORLD = {
-  far: 1400,
-  // Terrain: height = mask(r) * (amp * fbm(xz * freq) + erodeAmp * phacelle(xz * erodeFreq)).
-  amp: 70,
-  freq: 1 / 520,
-  octaves: 4,
-  lacunarity: 2.0,
-  gain: 0.45,
-  // Flat ground (height 0) out to plateauInner, full terrain from plateauOuter. The login
-  // camera stays inside plateauInner, so it can never end up inside the terrain.
-  plateauInner: 135,
-  plateauOuter: 380,
-  erodeAmp: 2.5,
-  erodeFreq: 1 / 38,
-  // The stripe wave vector and normalization the terrain feeds cultmath_phacelle.
-  erodeSide: [1.7, 0, 1] as const,
-  erodeNorm: 0.5,
-  // Bound on |grad| of the phasor's cos component for the side and norm above. Libby measured a
-  // sup of 6.63 at |side| = 1.5, n = 0 (CultLib PR #1 head 990521b3); 7.0 adds margin.
-  // The sup was measured, not proved. The shader passes roughness n = 0 as a literal, so the doc
-  // envelope max(10, 1.25|side|)/(1-n) needs no 1/(1-n) factor here; if n ever becomes nonzero,
-  // divide this bound by (1 - n).
-  // |value| <= 1 holds by construction (the output is a normalized phasor).
-  // Typed number, not the literal 7, so callers can build variants such as { ...WORLD, phacelleGradBound: 0 }.
-  phacelleGradBound: 7.0 as number,
-  // World tree at the origin.
-  tree: {
-    trunkHeight: 38,
-    baseRadius: 3.4,
-    topRadius: 1.9,
-    canopyY: 52,
-    canopyRadius: [30, 17, 30] as const,
-  },
-  // Atmosphere.
-  atmosphereFar: 1400,
-  cloudBase: 130,
-  cloudTop: 230,
-  fogDensity: 0.0028,
-  fogFalloff: 0.011,
-} as const;
-
-const f = (n: number) => (Number.isInteger(n) ? `${n}.0` : `${n}`);
-
-/** Sum over octaves of (lacunarity * gain)^i: the slope bound's octave factor. */
-function slopeSum(octaves: number, lacunarity: number, gain: number): number {
-  let s = 0;
-  for (let i = 0; i < octaves; i += 1) s += (lacunarity * gain) ** i;
-  return s;
-}
-
-/** Sum over octaves of gain^i: the fbm value bound. */
-function valueSum(octaves: number, gain: number): number {
-  let s = 0;
-  for (let i = 0; i < octaves; i += 1) s += gain ** i;
-  return s;
-}
-
-export interface TerrainBounds {
-  /** Lipschitz bound of the envelope surface (no erosion). */
-  slopeEnvelope: number;
-  /** Lipschitz bound of the eroded surface. */
-  slopeFull: number;
-  /** Highest point the terrain can reach. */
-  maxHeight: number;
-}
-
-export function terrainBounds(w: typeof WORLD = WORLD): TerrainBounds {
-  const fbmMax = valueSum(w.octaves, w.gain);
-  const maskSlope = 1.5 / (w.plateauOuter - w.plateauInner); // smoothstep's max slope
-  const fbmSlope = w.amp * w.freq * SNOISE_LIPSCHITZ * slopeSum(w.octaves, w.lacunarity, w.gain);
-  const slopeEnvelope = fbmSlope + (w.amp * fbmMax + w.erodeAmp) * maskSlope;
-  const slopeFull = slopeEnvelope + w.erodeAmp * w.erodeFreq * w.phacelleGradBound;
-  return { slopeEnvelope, slopeFull, maxHeight: w.amp * fbmMax + w.erodeAmp };
-}
-
-/** The #defines every stage sees. */
-export function worldDefines(w: typeof WORLD = WORLD): string {
-  const b = terrainBounds(w);
-  const t = w.tree;
-  const lines: Array<[string, string]> = [
-    ['W_FAR', f(w.far)],
-    ['W_AMP', f(w.amp)],
-    ['W_FREQ', f(w.freq)],
-    ['W_OCTAVES', String(w.octaves)],
-    ['W_LACUNARITY', f(w.lacunarity)],
-    ['W_GAIN', f(w.gain)],
-    ['W_PLATEAU_IN', f(w.plateauInner)],
-    ['W_PLATEAU_OUT', f(w.plateauOuter)],
-    ['W_ERODE_AMP', f(w.erodeAmp)],
-    ['W_ERODE_FREQ', f(w.erodeFreq)],
-    ['W_ERODE_SIDE', `vec3(${w.erodeSide.map(f).join(', ')})`],
-    ['W_ERODE_NORM', f(w.erodeNorm)],
-    ['W_ERODE_ENABLED', w.phacelleGradBound > 0 ? '1' : '0'],
-    ['W_SLOPE_ENV_INV', f(1 / Math.sqrt(1 + b.slopeEnvelope ** 2))],
-    ['W_SLOPE_FULL_INV', f(1 / Math.sqrt(1 + b.slopeFull ** 2))],
-    ['W_MAX_HEIGHT', f(Math.max(b.maxHeight, t.canopyY + t.canopyRadius[1] + 6))],
-    ['W_TRUNK_H', f(t.trunkHeight)],
-    ['W_TRUNK_R0', f(t.baseRadius)],
-    ['W_TRUNK_R1', f(t.topRadius)],
-    ['W_CANOPY_Y', f(t.canopyY)],
-    ['W_CANOPY_R', `vec3(${t.canopyRadius.map(f).join(', ')})`],
-    ['W_ATM_FAR', f(w.atmosphereFar)],
-    ['W_CLOUD_Y0', f(w.cloudBase)],
-    ['W_CLOUD_Y1', f(w.cloudTop)],
-    ['W_FOG_DENSITY', f(w.fogDensity)],
-    ['W_FOG_FALLOFF', f(w.fogFalloff)],
-  ];
-  return lines.map(([k, v]) => `#define ${k} ${v}`).join('\n');
-}
diff --git a/src/app/features/soundscape/device.ts b/src/app/features/soundscape/device.ts
deleted file mode 100644
index ecdf1593..00000000
--- a/src/app/features/soundscape/device.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-export interface DeviceHints {
-  deviceMemory?: number;
-  hardwareConcurrency?: number;
-}
-
-/**
- * Off on weak phones. The thresholds are placeholders: no phone has been measured (grammar
- * section 7, item 4). Unknown hints (Safari reports neither) do not count as weak.
- */
-export const isWeakDevice = ({ deviceMemory, hardwareConcurrency }: DeviceHints): boolean =>
-  (deviceMemory !== undefined && deviceMemory < 4) ||
-  (hardwareConcurrency !== undefined && hardwareConcurrency < 4);
diff --git a/src/app/features/soundscape/frame.ts b/src/app/features/soundscape/frame.ts
deleted file mode 100644
index 947d2bb5..00000000
--- a/src/app/features/soundscape/frame.ts
+++ /dev/null
@@ -1,108 +0,0 @@
-// The activity frame of Aqua's soundscape grammar (AquaSynth docs/soundscape-grammar, grammar head
-// 0091d01, section 2). The Heimdall session produces it; this file only reads it. Shape follows
-// heimdall-body:follow_up:ratatoskr-creature-projection-v2 as the grammar relays it. The human
-// kind subset (Idle/Working/Speaking) below is PROVISIONAL: still proposed, not ruled, until
-// Bifrost's steward cuts the list.
-
-export type Estate = 'human' | 'mind' | 'persona';
-export type Kind = 'Idle' | 'Reading' | 'Thinking' | 'Working' | 'Speaking' | 'Waiting' | 'Alert';
-export type Energy = 'Low' | 'Mid' | 'High' | 'Peak';
-export type Size = 'S' | 'M' | 'L';
-export type Override = 'None' | 'Muted';
-
-interface FrameBase {
-  mind: string;
-  estate: Estate;
-  override: Override;
-  seq: number;
-  /** Producer observation time, whole seconds (grammar: 1 s resolution). */
-  at: number;
-}
-/** O1: a neutral frame carries no size, kind or energy; it is not an Idle and nothing reads one. */
-export interface NeutralFrame extends FrameBase {
-  neutral: true;
-  size?: undefined;
-  kind?: undefined;
-  energy?: undefined;
-}
-export interface LiveFrame extends FrameBase {
-  neutral: false;
-  size: Size;
-  kind: Kind;
-  energy: Energy;
-}
-export type ActivityFrame = NeutralFrame | LiveFrame;
-
-const ESTATES: readonly Estate[] = ['human', 'mind', 'persona'];
-const KINDS: readonly Kind[] = [
-  'Idle',
-  'Reading',
-  'Thinking',
-  'Working',
-  'Speaking',
-  'Waiting',
-  'Alert',
-];
-const ENERGIES: readonly Energy[] = ['Low', 'Mid', 'High', 'Peak'];
-const SIZES: readonly Size[] = ['S', 'M', 'L'];
-
-/** Grammar S2 (proposed, unmeasured): a frame older than this is absent. */
-export const STALE_AFTER_S = 10;
-
-const oneOf = <T extends string>(set: readonly T[], v: unknown): T | undefined =>
-  set.find((s) => s === v);
-
-/** PROVISIONAL (grammar section 2, awaiting the projection-v2 field list): a human's kinds. */
-export const HUMAN_KINDS: readonly Kind[] = ['Idle', 'Working', 'Speaking'];
-
-/** Estate clamp, only ever revealing less: a human's out-of-subset or omitted kind is Idle. */
-const clampKind = (estate: Estate, kind: unknown): Kind | undefined =>
-  estate === 'human' ? oneOf(HUMAN_KINDS, kind) ?? 'Idle' : oneOf(KINDS, kind);
-
-/** A human's energy is three buckets: Peak reads as High. */
-const clampEnergy = (estate: Estate, energy: Energy): Energy =>
-  estate === 'human' && energy === 'Peak' ? 'High' : energy;
-
-/**
- * Read an untrusted frame. Only the grammar's fields survive: any other key (a weight, a vote, a
- * room id) is dropped, so a consumer cannot be steered by data the grammar does not define (A3).
- * `neutral` is read first: a neutral frame yields no size, kind or energy even if the producer sent
- * them (O1). Returns undefined for anything malformed; the caller treats that as no frame (A4).
- */
-export const readFrame = (raw: unknown): ActivityFrame | undefined => {
-  if (typeof raw !== 'object' || raw === null) return undefined;
-  const r = raw as Record<string, unknown>;
-  if (typeof r.neutral !== 'boolean') return undefined;
-  const estate = oneOf(ESTATES, r.estate);
-  const override =
-    r.override === undefined ? 'None' : oneOf(['None', 'Muted'] as const, r.override);
-  if (!estate || !override) return undefined;
-  if (typeof r.mind !== 'string' || r.mind === '') return undefined;
-  if (!Number.isInteger(r.seq) || !Number.isFinite(r.at)) return undefined;
-  const base = { mind: r.mind, estate, override, seq: r.seq as number, at: r.at as number };
-  if (r.neutral) return { ...base, neutral: true };
-  const kind = clampKind(estate, r.kind);
-  const energy = oneOf(ENERGIES, r.energy);
-  const size = oneOf(SIZES, r.size);
-  if (!kind || !energy || !size) return undefined;
-  return { ...base, neutral: false, size, kind, energy: clampEnergy(estate, energy) };
-};
-
-/** Latest frame per mind (S1: consumers drop seq <= last). */
-export class FrameTable {
-  private frames = new Map<string, ActivityFrame>();
-
-  offer(raw: unknown): boolean {
-    const f = readFrame(raw);
-    if (!f) return false;
-    const last = this.frames.get(f.mind);
-    if (last && f.seq <= last.seq) return false;
-    this.frames.set(f.mind, f);
-    return true;
-  }
-
-  /** Frames not stale at `nowS`; a missing or stale frame is simply absent (A4), not neutral. */
-  fresh(nowS: number): ActivityFrame[] {
-    return [...this.frames.values()].filter((f) => nowS - f.at <= STALE_AFTER_S);
-  }
-}
diff --git a/src/app/features/soundscape/scene.ts b/src/app/features/soundscape/scene.ts
deleted file mode 100644
index 027cc27a..00000000
--- a/src/app/features/soundscape/scene.ts
+++ /dev/null
@@ -1,8 +0,0 @@
-import type { ActivityFrame, Size } from './frame';
-
-/** Placeholders owned by the orbit renderer, not the frame (grammar, Estate section). Unmeasured. */
-export const PLACEHOLDER_SIZE_SCALE: Record<Size, number> = { S: 0.7, M: 1, L: 1.4 };
-
-/** O1: a neutral participant gets no orbit. There is no neutral pose; it is not in the list. */
-export const drawnCreatures = (frames: readonly ActivityFrame[]): ActivityFrame[] =>
-  frames.filter((f) => !f.neutral);
diff --git a/src/app/features/soundscape/socket.ts b/src/app/features/soundscape/socket.ts
deleted file mode 100644
index e1d23010..00000000
--- a/src/app/features/soundscape/socket.ts
+++ /dev/null
@@ -1,47 +0,0 @@
-import { FrameTable } from './frame';
-import { drawnCreatures } from './scene';
-import { planVoices, type SoundscapePrefs, type VoiceCommand } from './voices';
-import { isWeakDevice, type DeviceHints } from './device';
-
-/**
- * Where frames come from is `ratatoskr:question:activity-feed-source`, still open. Until the
- * Heimdall session feed exists the only source is `silentSource`. A source never reads a room's
- * member list (A1): being in a room says nothing about being active.
- */
-export interface ActivitySource {
-  subscribe(onFrame: (raw: unknown) => void): () => void;
-}
-const noop = () => undefined;
-export const silentSource: ActivitySource = { subscribe: () => noop };
-
-/** Receives the plan. No audio assets exist yet, so nothing in this repo sounds. */
-export interface VoiceSink {
-  play(commands: readonly VoiceCommand[]): void;
-}
-
-export interface AudioSocketDeps {
-  source: ActivitySource;
-  sink: VoiceSink;
-  prefs: () => SoundscapePrefs;
-  device: () => DeviceHints;
-  /** Whole seconds. */
-  nowS: () => number;
-}
-
-export const createAudioSocket = (deps: AudioSocketDeps) => {
-  const table = new FrameTable();
-  const unsubscribe = deps.source.subscribe((raw) => table.offer(raw));
-  return {
-    /** Called by the scheduler tick; a hidden page simply stops calling it (S5). */
-    tick(): VoiceCommand[] {
-      const prefs = deps.prefs();
-      const effective = { ...prefs, enabled: prefs.enabled && !isWeakDevice(deps.device()) };
-      const commands = planVoices(table.fresh(deps.nowS()), effective);
-      deps.sink.play(commands);
-      return commands;
-    },
-    /** What the orbit renderer draws: the same table, neutral removed. */
-    drawn: () => drawnCreatures(table.fresh(deps.nowS())),
-    close: unsubscribe,
-  };
-};
diff --git a/src/app/features/soundscape/soundscape.test.ts b/src/app/features/soundscape/soundscape.test.ts
deleted file mode 100644
index 294456a1..00000000
--- a/src/app/features/soundscape/soundscape.test.ts
+++ /dev/null
@@ -1,233 +0,0 @@
-import { describe, expect, it, vi } from 'vitest';
-import { FrameTable, readFrame, STALE_AFTER_S, type ActivityFrame, type LiveFrame } from './frame';
-import { drawnCreatures, PLACEHOLDER_SIZE_SCALE } from './scene';
-import { DEFAULT_VOICE_CAP, planVoices, type SoundscapePrefs } from './voices';
-import { isWeakDevice } from './device';
-import { createAudioSocket, silentSource, type ActivitySource } from './socket';
-
-const frame = (o: Partial<LiveFrame> = {}): LiveFrame => ({
-  mind: 'void',
-  estate: 'mind',
-  kind: 'Working',
-  energy: 'Mid',
-  size: 'M',
-  neutral: false,
-  override: 'None',
-  seq: 1,
-  at: 100,
-  ...o,
-});
-const neutralFrame = (o: Partial<ActivityFrame> = {}): ActivityFrame =>
-  ({ ...frame(), ...o, neutral: true } as unknown as ActivityFrame);
-/** A raw frame as a producer sends it, with the named keys omitted. */
-const without = (f: object, ...keys: string[]) =>
-  Object.fromEntries(Object.entries(f).filter(([k]) => !keys.includes(k)));
-const noop = () => undefined;
-const on: SoundscapePrefs = { enabled: true, muted: false, volume: 0.5, voiceCap: 4 };
-
-describe('neutral overrides everything', () => {
-  it('draws nothing and sounds nothing for any kind, energy, size or estate', () => {
-    const cases = (['human', 'mind', 'persona'] as const).flatMap((estate) =>
-      (['Speaking', 'Alert', 'Working'] as const).flatMap((kind) =>
-        (['High', 'Peak'] as const).flatMap((energy) =>
-          (['S', 'M', 'L'] as const).map((size) => neutralFrame({ estate, kind, energy, size }))
-        )
-      )
-    );
-    expect(cases).toHaveLength(54);
-    cases.forEach((f) => {
-      expect(drawnCreatures([f])).toEqual([]);
-      expect(planVoices([f], on)).toEqual([]);
-    });
-  });
-  it('is not the same as an absent frame: absent reads as idle, neutral as hidden', () => {
-    const t = new FrameTable();
-    t.offer(frame({ at: 100 }));
-    expect(drawnCreatures(t.fresh(100 + STALE_AFTER_S + 1))).toEqual([]);
-    expect(drawnCreatures(t.fresh(100)).length).toBe(1);
-  });
-});
-
-describe('neutral is read first', () => {
-  it('yields no size, kind or energy, even when the producer sent them', () => {
-    (['human', 'mind', 'persona'] as const).forEach((estate) => {
-      const f = readFrame({
-        ...frame({ estate, kind: 'Speaking', energy: 'High' }),
-        neutral: true,
-      });
-      expect(f).toBeDefined();
-      expect(f?.neutral).toBe(true);
-      expect(f?.size).toBeUndefined();
-      expect(Object.keys(f ?? {})).not.toContain('size');
-      expect(f?.kind).toBeUndefined();
-      expect(f?.energy).toBeUndefined();
-      expect(Object.keys(f ?? {})).not.toContain('kind');
-      expect(Object.keys(f ?? {})).not.toContain('energy');
-    });
-  });
-  it('a neutral human with kind omitted is not an Idle', () => {
-    const bare = without(frame({ estate: 'human' }), 'kind', 'energy');
-    const f = readFrame({ ...bare, neutral: true });
-    expect(f?.kind).toBeUndefined();
-    expect(drawnCreatures([f as ActivityFrame])).toEqual([]);
-    expect(planVoices([f as ActivityFrame], on)).toEqual([]);
-  });
-});
-
-describe('human kinds are the provisional subset', () => {
-  it.each(['Reading', 'Thinking', 'Waiting', 'Alert'] as const)('clamps %s to Idle', (kind) => {
-    expect(readFrame(frame({ estate: 'human', kind }))?.kind).toBe('Idle');
-  });
-  it('keeps Idle, Working and Speaking', () => {
-    (['Idle', 'Working', 'Speaking'] as const).forEach((kind) =>
-      expect(readFrame(frame({ estate: 'human', kind }))?.kind).toBe(kind)
-    );
-  });
-  it('an omitted kind is Idle for a non-neutral human only', () => {
-    const noKind = without(frame({ estate: 'human' }), 'kind');
-    expect(readFrame(noKind)?.kind).toBe('Idle');
-    expect(readFrame({ ...noKind, neutral: true })?.kind).toBeUndefined();
-  });
-  it('minds and personas keep all seven kinds, and omitted is malformed for them', () => {
-    (['mind', 'persona'] as const).forEach((estate) => {
-      (['Idle', 'Reading', 'Thinking', 'Working', 'Speaking', 'Waiting', 'Alert'] as const).forEach(
-        (kind) => expect(readFrame(frame({ estate, kind }))?.kind).toBe(kind)
-      );
-      const noKind = without(frame({ estate }), 'kind');
-      expect(readFrame(noKind)).toBeUndefined();
-    });
-  });
-});
-
-describe('human energy is clamped to three buckets by the consumer', () => {
-  it('turns Peak into High for humans only', () => {
-    expect(readFrame(frame({ estate: 'human', energy: 'Peak' }))?.energy).toBe('High');
-    expect(readFrame(frame({ estate: 'mind', energy: 'Peak' }))?.energy).toBe('Peak');
-    expect(readFrame(frame({ estate: 'persona', energy: 'Peak' }))?.energy).toBe('Peak');
-  });
-  it('keeps the clamp through the voice plan', () => {
-    const t = new FrameTable();
-    t.offer(frame({ estate: 'human', energy: 'Peak' }));
-    expect(planVoices(t.fresh(100), on)[0].energy).toBe('High');
-  });
-});
-
-describe('activity is a stub, never the room member list', () => {
-  it('the silent source and the socket yield nothing, however many members a room has', () => {
-    const members = ['@a:x', '@b:x', '@c:x'];
-    const sock = createAudioSocket({
-      source: silentSource,
-      sink: { play: noop },
-      prefs: () => on,
-      device: () => ({}),
-      nowS: () => 100,
-    });
-    expect(members.length).toBeGreaterThan(0);
-    expect(sock.tick()).toEqual([]);
-    expect(sock.drawn()).toEqual([]);
-  });
-  it('only frames the source pushes produce voices', () => {
-    const pushes: ((raw: unknown) => void)[] = [];
-    const source: ActivitySource = {
-      subscribe: (cb) => {
-        pushes.push(cb);
-        return noop;
-      },
-    };
-    const sock = createAudioSocket({
-      source,
-      sink: { play: noop },
-      prefs: () => on,
-      device: () => ({}),
-      nowS: () => 100,
-    });
-    pushes[0](frame({ mind: 'aqua' }));
-    expect(sock.tick().map((v) => v.mind)).toEqual(['aqua']);
-  });
-});
-
-describe('no vote weights', () => {
-  it('drops fields the grammar does not define, and the plan carries only user volume as gain', () => {
-    const f = readFrame({ ...frame(), weight: 9, votes: 40, roomId: '!r:x', brief: 'secret' });
-    expect(Object.keys(f ?? {}).sort()).toEqual(
-      ['at', 'energy', 'estate', 'kind', 'mind', 'neutral', 'override', 'seq', 'size'].sort()
-    );
-    const t = new FrameTable();
-    t.offer({ ...frame(), weight: 9 });
-    expect(planVoices(t.fresh(100), on)[0].gain).toBe(0.5);
-  });
-});
-
-describe('size scales are placeholders', () => {
-  it('live in the renderer table, not in the frame, and change nothing about voices', () => {
-    expect(PLACEHOLDER_SIZE_SCALE).toEqual({ S: 0.7, M: 1, L: 1.4 });
-    const s = planVoices([frame({ size: 'S' })], on);
-    const l = planVoices([frame({ size: 'L' })], on);
-    expect(s).toEqual(l);
-  });
-});
-
-describe('socket defaults and limits', () => {
-  it('ships off, muted, with the proposed cap', async () => {
-    vi.stubGlobal('localStorage', { getItem: () => null });
-    const { getSettings } = await import('../../state/settings');
-    const s = getSettings();
-    expect(s.soundscapeEnabled).toBe(false);
-    expect(s.soundscapeMuted).toBe(true);
-    expect(s.soundscapeVoiceCap).toBe(DEFAULT_VOICE_CAP);
-  });
-  it('master mute, disabled flag and zero volume all silence', () => {
-    const f = [frame()];
-    expect(planVoices(f, { ...on, muted: true })).toEqual([]);
-    expect(planVoices(f, { ...on, enabled: false })).toEqual([]);
-    expect(planVoices(f, { ...on, volume: 0 })).toEqual([]);
-  });
-  it('caps voices, dropping the lowest energy first', () => {
-    const f = ['a', 'b', 'c', 'd', 'e'].map((mind, i) =>
-      frame({ mind, energy: (['Low', 'Mid', 'High', 'Peak', 'Mid'] as const)[i] })
-    );
-    const voices = planVoices(f, { ...on, voiceCap: 4 }).map((v) => v.mind);
-    expect(voices).toHaveLength(4);
-    expect(voices).not.toContain('a');
-  });
-  it('Muted silences the voice but the creature is still drawn; Idle/Waiting are silent', () => {
-    const f = [frame({ override: 'Muted' }), frame({ mind: 'x', kind: 'Idle' })];
-    expect(planVoices(f, on)).toEqual([]);
-    expect(drawnCreatures(f)).toHaveLength(2);
-  });
-  it('is off on weak phones even when the flag is on, and unknown hints are not weak', () => {
-    expect(isWeakDevice({ deviceMemory: 2 })).toBe(true);
-    expect(isWeakDevice({ hardwareConcurrency: 2 })).toBe(true);
-    expect(isWeakDevice({})).toBe(false);
-    const played: number[] = [];
-    const sock = createAudioSocket({
-      source: {
-        subscribe: (cb) => {
-          cb(frame());
-          return noop;
-        },
-      },
-      sink: { play: (c) => played.push(c.length) },
-      prefs: () => on,
-      device: () => ({ deviceMemory: 1 }),
-      nowS: () => 100,
-    });
-    expect(sock.tick()).toEqual([]);
-    expect(played).toEqual([0]);
-  });
-  it('drops frames with seq <= last, and malformed frames', () => {
-    const t = new FrameTable();
-    expect(t.offer(frame({ seq: 5 }))).toBe(true);
-    expect(t.offer(frame({ seq: 5 }))).toBe(false);
-    expect(t.offer(frame({ seq: 4 }))).toBe(false);
-    expect(t.offer({ ...frame(), kind: 'Dancing' })).toBe(false);
-  });
-});
-
-describe('neutral carries no size', () => {
-  it('reads without a size, and a live frame without one is malformed', () => {
-    const raw = frame();
-    expect(readFrame({ ...without(raw, 'size', 'kind', 'energy'), neutral: true })).toBeDefined();
-    expect(readFrame(without(raw, 'size'))).toBeUndefined();
-  });
-});
diff --git a/src/app/features/soundscape/voices.ts b/src/app/features/soundscape/voices.ts
deleted file mode 100644
index 676ae853..00000000
--- a/src/app/features/soundscape/voices.ts
+++ /dev/null
@@ -1,51 +0,0 @@
-import type { ActivityFrame, Energy, Kind, LiveFrame } from './frame';
-
-/** Grammar V3 (proposed, unmeasured): voices audible at once. */
-export const DEFAULT_VOICE_CAP = 4;
-
-/** Local listener preferences. Never written back into a frame (O3). */
-export interface SoundscapePrefs {
-  /** The feature flag. Default off. */
-  enabled: boolean;
-  /** Master mute. Default on. */
-  muted: boolean;
-  /** 0..1 */
-  volume: number;
-  voiceCap: number;
-}
-
-export interface VoiceCommand {
-  mind: string;
-  kind: Kind;
-  energy: Energy;
-  gain: number;
-}
-
-const ENERGY_RANK: Record<Energy, number> = { Low: 0, Mid: 1, High: 2, Peak: 3 };
-/** Grammar section 3: Idle and Waiting default silent. */
-const SILENT_KINDS: ReadonlySet<Kind> = new Set<Kind>(['Idle', 'Waiting']);
-
-const clamp01 = (v: number) => (Number.isFinite(v) ? Math.min(1, Math.max(0, v)) : 0);
-
-/**
- * Which voices speak now. Neutral overrides everything (O1); `Muted` silences one Mind (O2);
- * over the cap the lowest energy drops first (V3, ties by mind id so the result is stable).
- * Identity is the mind id only (V1); `gain` is the user's volume, not a vote weight.
- * Lead exemption in V3 is not implemented: the grammar does not say how a lead is chosen.
- */
-export const planVoices = (
-  frames: readonly ActivityFrame[],
-  prefs: SoundscapePrefs
-): VoiceCommand[] => {
-  if (!prefs.enabled || prefs.muted) return [];
-  const gain = clamp01(prefs.volume);
-  if (gain === 0) return [];
-  const cap = Math.max(0, Math.floor(prefs.voiceCap));
-  return frames
-    .filter(
-      (f): f is LiveFrame => !f.neutral && f.override !== 'Muted' && !SILENT_KINDS.has(f.kind)
-    )
-    .sort((a, b) => ENERGY_RANK[b.energy] - ENERGY_RANK[a.energy] || a.mind.localeCompare(b.mind))
-    .slice(0, cap)
-    .map((f) => ({ mind: f.mind, kind: f.kind, energy: f.energy, gain }));
-};
diff --git a/src/app/hooks/useClientConfig.ts b/src/app/hooks/useClientConfig.ts
index 7a0586eb..e5fc6cc6 100644
--- a/src/app/hooks/useClientConfig.ts
+++ b/src/app/hooks/useClientConfig.ts
@@ -1,5 +1,4 @@
 import { createContext, useContext } from 'react';
-import type { BackgroundSceneConfig } from '../features/scene/tier';
 
 export type HashRouterConfig = {
   enabled?: boolean;
@@ -19,8 +18,6 @@ export type ClientConfig = {
   };
 
   hashRouter?: HashRouterConfig;
-
-  backgroundScene?: BackgroundSceneConfig;
 };
 
 const ClientConfigContext = createContext<ClientConfig | null>(null);
diff --git a/src/app/state/settings.ts b/src/app/state/settings.ts
index d4deb39c..6a894350 100644
--- a/src/app/state/settings.ts
+++ b/src/app/state/settings.ts
@@ -47,12 +47,6 @@ export interface Settings {
   dateFormatString: string;
 
   developerTools: boolean;
-
-  /** Soundscape flag: default off, and muted by default even when on. */
-  soundscapeEnabled: boolean;
-  soundscapeMuted: boolean;
-  soundscapeVolume: number;
-  soundscapeVoiceCap: number;
 }
 
 const defaultSettings: Settings = {
@@ -87,11 +81,6 @@ const defaultSettings: Settings = {
   dateFormatString: 'D MMM YYYY',
 
   developerTools: false,
-
-  soundscapeEnabled: false,
-  soundscapeMuted: true,
-  soundscapeVolume: 0.5,
-  soundscapeVoiceCap: 4,
 };
 
 export const getSettings = () => {
diff --git a/src/client/initMatrix.ts b/src/client/initMatrix.ts
index 871a7625..498d4f75 100644
--- a/src/client/initMatrix.ts
+++ b/src/client/initMatrix.ts
@@ -3,7 +3,6 @@ import { createClient, MatrixClient, IndexedDBStore, IndexedDBCryptoStore } from
 import { cryptoCallbacks } from './secretStorageKeys';
 import { clearNavToActivePathStore } from '../app/state/navToActivePath';
 import { pushSessionToSW } from '../sw-session';
-import { startResumeSync } from './resumeSync';
 
 type Session = {
   baseUrl: string;
@@ -41,14 +40,10 @@ export const initClient = async (session: Session): Promise<MatrixClient> => {
   return mx;
 };
 
-const startSync = (mx: MatrixClient) =>
-  mx.startClient({
+export const startClient = async (mx: MatrixClient) => {
+  await mx.startClient({
     lazyLoadMembers: true,
   });
-
-export const startClient = async (mx: MatrixClient) => {
-  await startSync(mx);
-  startResumeSync(mx, { restart: startSync });
 };
 
 export const clearCacheAndReload = async (mx: MatrixClient) => {
diff --git a/src/client/resumeSync.test.ts b/src/client/resumeSync.test.ts
deleted file mode 100644
index eada97af..00000000
--- a/src/client/resumeSync.test.ts
+++ /dev/null
@@ -1,132 +0,0 @@
-import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
-import { HEALTH_CHECK_MS, MIN_HIDDEN_MS, RESUME_DEBOUNCE_MS, startResumeSync } from './resumeSync';
-
-class Target extends EventTarget {
-  visibilityState: 'visible' | 'hidden' = 'visible';
-}
-
-const setup = (state: string | null = 'SYNCING') => {
-  const doc = new Target();
-  const win = new Target();
-  const mx = {
-    state,
-    getSyncState: () => mx.state,
-    retryImmediately: vi.fn(() => true),
-    stopClient: vi.fn(),
-  };
-  const restart = vi.fn(async () => {});
-  const stop = startResumeSync(mx, {
-    restart,
-    doc: doc as never,
-    win: win as never,
-  });
-  const hide = () => {
-    doc.visibilityState = 'hidden';
-    doc.dispatchEvent(new Event('visibilitychange'));
-  };
-  const show = () => {
-    doc.visibilityState = 'visible';
-    doc.dispatchEvent(new Event('visibilitychange'));
-  };
-  return { doc, win, mx, restart, stop, hide, show };
-};
-
-const settle = () => vi.advanceTimersByTimeAsync(RESUME_DEBOUNCE_MS);
-
-describe('startResumeSync', () => {
-  beforeEach(() => {
-    vi.useFakeTimers();
-  });
-  afterEach(() => {
-    vi.useRealTimers();
-  });
-
-  it('nudges the poll when the tab returns after a real absence', async () => {
-    const t = setup();
-    t.hide();
-    await vi.advanceTimersByTimeAsync(MIN_HIDDEN_MS);
-    t.show();
-    expect(t.mx.retryImmediately).not.toHaveBeenCalled();
-    await settle();
-    expect(t.mx.retryImmediately).toHaveBeenCalledTimes(1);
-  });
-
-  it('ignores a hide shorter than the minimum', async () => {
-    const t = setup();
-    t.hide();
-    await vi.advanceTimersByTimeAsync(MIN_HIDDEN_MS - 1);
-    t.show();
-    await vi.advanceTimersByTimeAsync(RESUME_DEBOUNCE_MS + HEALTH_CHECK_MS);
-    expect(t.mx.retryImmediately).not.toHaveBeenCalled();
-  });
-
-  it('handles pageshow only when restored from bfcache, and online always', async () => {
-    const t = setup();
-    t.win.dispatchEvent(Object.assign(new Event('pageshow'), { persisted: false }));
-    await settle();
-    expect(t.mx.retryImmediately).not.toHaveBeenCalled();
-    t.win.dispatchEvent(Object.assign(new Event('pageshow'), { persisted: true }));
-    await settle();
-    expect(t.mx.retryImmediately).toHaveBeenCalledTimes(1);
-    await vi.advanceTimersByTimeAsync(HEALTH_CHECK_MS);
-    t.win.dispatchEvent(new Event('online'));
-    await settle();
-    expect(t.mx.retryImmediately).toHaveBeenCalledTimes(2);
-  });
-
-  it('debounces a burst of triggers into one nudge', async () => {
-    const t = setup();
-    t.win.dispatchEvent(new Event('online'));
-    t.win.dispatchEvent(new Event('online'));
-    t.win.dispatchEvent(Object.assign(new Event('pageshow'), { persisted: true }));
-    await settle();
-    expect(t.mx.retryImmediately).toHaveBeenCalledTimes(1);
-  });
-
-  it('does not restart when sync is healthy after the check window', async () => {
-    for (const state of ['PREPARED', 'SYNCING', 'CATCHUP']) {
-      const t = setup(state);
-      t.win.dispatchEvent(new Event('online'));
-      await vi.advanceTimersByTimeAsync(RESUME_DEBOUNCE_MS + HEALTH_CHECK_MS);
-      expect(t.restart).not.toHaveBeenCalled();
-      t.stop();
-    }
-  });
-
-  it('does one stop/start when sync is still unhealthy, never overlapping', async () => {
-    const t = setup('RECONNECTING');
-    let release!: () => void;
-    t.restart.mockImplementation(
-      () =>
-        new Promise<void>((r) => {
-          release = r;
-        })
-    );
-    t.win.dispatchEvent(new Event('online'));
-    await vi.advanceTimersByTimeAsync(RESUME_DEBOUNCE_MS + HEALTH_CHECK_MS);
-    expect(t.mx.stopClient).toHaveBeenCalledTimes(1);
-    expect(t.restart).toHaveBeenCalledTimes(1);
-    // a trigger while the restart is in flight does nothing
-    t.win.dispatchEvent(new Event('online'));
-    await vi.advanceTimersByTimeAsync(RESUME_DEBOUNCE_MS + HEALTH_CHECK_MS);
-    expect(t.mx.retryImmediately).toHaveBeenCalledTimes(1);
-    expect(t.restart).toHaveBeenCalledTimes(1);
-    release();
-    await vi.advanceTimersByTimeAsync(0);
-    t.win.dispatchEvent(new Event('online'));
-    await settle();
-    expect(t.mx.retryImmediately).toHaveBeenCalledTimes(2);
-  });
-
-  it('removes listeners and cancels pending work on dispose', async () => {
-    const t = setup('ERROR');
-    t.win.dispatchEvent(new Event('online'));
-    await settle();
-    t.stop();
-    await vi.advanceTimersByTimeAsync(HEALTH_CHECK_MS);
-    expect(t.restart).not.toHaveBeenCalled();
-    t.win.dispatchEvent(new Event('online'));
-    await settle();
-    expect(t.mx.retryImmediately).toHaveBeenCalledTimes(1);
-  });
-});
diff --git a/src/client/resumeSync.ts b/src/client/resumeSync.ts
deleted file mode 100644
index 5f81547b..00000000
--- a/src/client/resumeSync.ts
+++ /dev/null
@@ -1,86 +0,0 @@
-/** The slice of MatrixClient this module drives; a MatrixClient satisfies it. */
-export type SyncHost = {
-  getSyncState(): string | null;
-  retryImmediately(): boolean;
-  stopClient(): void;
-};
-
-// matrix-js-sdk SyncState values for a live sync loop.
-const HEALTHY: ReadonlySet<string | null> = new Set(['PREPARED', 'SYNCING', 'CATCHUP']);
-
-export const RESUME_DEBOUNCE_MS = 250;
-export const MIN_HIDDEN_MS = 5000;
-export const HEALTH_CHECK_MS = 3000;
-
-type ResumeSyncOptions<Host> = {
-  /** Event sources and visibility; default to the browser globals. */
-  doc?: Pick<Document, 'addEventListener' | 'removeEventListener' | 'visibilityState'>;
-  win?: Pick<Window, 'addEventListener' | 'removeEventListener'>;
-  /** Restart the client after stopClient; must resolve once startClient has been issued. */
-  restart: (mx: Host) => Promise<void>;
-};
-
-/**
- * A backgrounded tab or PWA leaves the sync long-poll dead until its 30 s timeout.
- * On return (visible after a real absence, pageshow from bfcache, online) nudge the
- * poll with retryImmediately; if sync is still unhealthy after HEALTH_CHECK_MS, do one
- * stop/start. Returns a disposer that removes every listener and timer.
- */
-export const startResumeSync = <Host extends SyncHost>(
-  mx: Host,
-  { restart, doc = document, win = window }: ResumeSyncOptions<Host>
-): (() => void) => {
-  let hiddenAt: number | undefined;
-  let debounce: ReturnType<typeof setTimeout> | undefined;
-  let healthCheck: ReturnType<typeof setTimeout> | undefined;
-  let restarting = false;
-  let disposed = false;
-
-  const check = async () => {
-    healthCheck = undefined;
-    if (disposed || restarting || HEALTHY.has(mx.getSyncState())) return;
-    restarting = true;
-    try {
-      mx.stopClient();
-      await restart(mx);
-    } finally {
-      restarting = false;
-    }
-  };
-
-  const resume = () => {
-    if (debounce !== undefined) clearTimeout(debounce);
-    debounce = setTimeout(() => {
-      debounce = undefined;
-      if (disposed || restarting || healthCheck !== undefined) return;
-      mx.retryImmediately();
-      healthCheck = setTimeout(check, HEALTH_CHECK_MS);
-    }, RESUME_DEBOUNCE_MS);
-  };
-
-  const onVisibility = () => {
-    if (doc.visibilityState === 'hidden') {
-      hiddenAt = Date.now();
-      return;
-    }
-    const away = hiddenAt === undefined ? Infinity : Date.now() - hiddenAt;
-    hiddenAt = undefined;
-    if (away >= MIN_HIDDEN_MS) resume();
-  };
-  const onPageShow = (e: Event) => {
-    if ((e as PageTransitionEvent).persisted) resume();
-  };
-
-  doc.addEventListener('visibilitychange', onVisibility);
-  win.addEventListener('pageshow', onPageShow);
-  win.addEventListener('online', resume);
-
-  return () => {
-    disposed = true;
-    if (debounce !== undefined) clearTimeout(debounce);
-    if (healthCheck !== undefined) clearTimeout(healthCheck);
-    doc.removeEventListener('visibilitychange', onVisibility);
-    win.removeEventListener('pageshow', onPageShow);
-    win.removeEventListener('online', resume);
-  };
-};