Merge pull request 'ci: drop Cinny-upstream workflows that cannot run on the forge' (#25) from void/ci-drop-cinny-leftovers into main

Remove cla, pr-title, deploy-pull-request, netlify-dev and prod-deploy;
drop the deleted prod-deploy path from docker-pr's trigger filter.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.github/workflows/cla.yml

@@ -1,36 +0,0 @@
-name: 'CLA Assistant'
-on:
-  issue_comment:
-    types: [created]
-  pull_request_target:
-    types: [opened, closed, synchronize]
-
-jobs:
-  CLAssistant:
-    runs-on: ubuntu-latest
-    steps:
-      - name: 'CLA Assistant'
-        if: (github.event.comment.body == 'recheck' || github.event.comment.body == 'I have read the CLA Document and I hereby sign the CLA') || github.event_name == 'pull_request_target'
-        # Beta Release
-        uses: cla-assistant/github-action@ca4a40a7d1004f18d9960b404b97e5f30a505a08 # v2.6.1
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          # the below token should have repo scope and must be manually added by you in the repository's secret
-          PERSONAL_ACCESS_TOKEN: ${{ secrets.CLA_PAT }}
-        with:
-          path-to-signatures: 'signatures.json'
-          path-to-document: 'https://github.com/cinnyapp/cla/blob/main/cla.md' # e.g. a CLA or a DCO document
-          # branch should not be protected
-          branch: 'main'
-          allowlist: ajbura,bot*
-
-          #below are the optional inputs - If the optional inputs are not given, then default values will be taken
-          remote-organization-name: cinnyapp
-          remote-repository-name: cla
-          #create-file-commit-message: 'For example: Creating file for storing CLA Signatures'
-          #signed-commit-message: 'For example: $contributorName has signed the CLA in #$pullRequestNo'
-          #custom-notsigned-prcomment: 'pull request comment with Introductory message to ask new contributors to sign'
-          #custom-pr-sign-comment: 'The signature to be committed in order to sign the CLA'
-          #custom-allsigned-prcomment: 'pull request comment when all contributors has signed, defaults to **CLA Assistant Lite bot** All Contributors have signed the CLA.'
-          #lock-pullrequest-aftermerge: false - if you don't want this bot to automatically lock the pull request after merging (default - true)
-          #use-dco-flag: true - If you are using DCO instead of CLA

.github/workflows/deploy-pull-request.yml

@@ -1,60 +0,0 @@
-name: Deploy PR to Netlify
-run-name: "Deploy PR to Netlify (${{ github.event.workflow_run.head_branch }})"
-
-on:
-  workflow_run:
-      workflows: ["Build pull request"]
-      types: [completed]
-
-jobs:
-  deploy-pull-request:
-    name: Deploy pull request
-    runs-on: ubuntu-latest
-    permissions:
-      contents: read
-      pull-requests: write
-    if: ${{ github.event.workflow_run.conclusion == 'success' }}
-    steps:
-      - name: Download pr number
-        uses: dawidd6/action-download-artifact@d63b86af1b34672e53c440b1b83979861906bad7 # v24
-        with:
-          workflow: ${{ github.event.workflow.id }}
-          run_id: ${{ github.event.workflow_run.id }}
-          name: pr
-      - name: Validate and output pr number
-        id: pr
-        run: |
-          PR_ID=$(<pr.txt)
-          if ! [[ "${PR_ID}" =~ ^[0-9]+$ ]]; then
-            echo "::error::pr.txt contains non-numeric content: ${PR_ID}"
-            exit 1
-          fi
-          echo "id=${PR_ID}" >> "${GITHUB_OUTPUT}"
-      - name: Download artifact
-        uses: dawidd6/action-download-artifact@d63b86af1b34672e53c440b1b83979861906bad7 # v24
-        with:
-          workflow: ${{ github.event.workflow.id }}
-          run_id: ${{ github.event.workflow_run.id }}
-          name: preview
-          path: dist
-      - name: Deploy to Netlify
-        id: netlify
-        uses: nwtgck/actions-netlify@d22a32a27c918fe470bbc562e984f80ec48c2668 # v4.0.0
-        with:
-          publish-dir: dist
-          deploy-message: "Deploy PR ${{ steps.pr.outputs.id }}"
-          alias: ${{ steps.pr.outputs.id }}
-          # These don't work because we're in workflow_run
-          enable-pull-request-comment: false
-          enable-commit-comment: false
-        env:
-          NETLIFY_AUTH_TOKEN: ${{ secrets.NETLIFY_AUTH_TOKEN_PR }}
-          NETLIFY_SITE_ID: ${{ secrets.NETLIFY_SITE_ID_PR_CINNY }}
-        timeout-minutes: 1
-      - name: Comment preview on PR
-        uses: marocchino/sticky-pull-request-comment@5770ad5eb8f42dd2c4f34da00c94c5381e49af88 # v3.0.5
-        with:
-          number: ${{ steps.pr.outputs.id }}
-          message: |
-            Preview: ${{ steps.netlify.outputs.deploy-url }}
-            ⚠️ Exercise caution. Use test accounts. ⚠️

.github/workflows/docker-pr.yml

@@ -5,7 +5,6 @@ on:
     paths:
       - 'Dockerfile'
       - '.github/workflows/docker-pr.yml'
-      - '.github/workflows/prod-deploy.yml'
 
 jobs:
   docker-build:

.github/workflows/netlify-dev.yml

@@ -1,39 +0,0 @@
-name: Deploy to Netlify (dev)
-
-on:
-  push:
-    branches:
-      - dev
-
-jobs:
-  deploy-to-netlify:
-    name: Deploy to Netlify
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-      - name: Setup node
-        uses: actions/setup-node@949feb2413d6458794dcd2491c4babbbce0c15c1 # v7.1.0
-        with:
-          node-version-file: ".node-version"
-          package-manager-cache: false
-      - name: Install dependencies
-        run: npm ci
-      - name: Build app
-        env:
-          NODE_OPTIONS: '--max_old_space_size=4096'
-        run: npm run build
-      - name: Deploy to Netlify
-        uses: nwtgck/actions-netlify@d22a32a27c918fe470bbc562e984f80ec48c2668 # v4.0.0
-        with:
-          publish-dir: dist
-          deploy-message: 'Dev deploy ${{ github.sha }}'
-          enable-commit-comment: false
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          production-deploy: true
-          github-deployment-environment: nightly
-          github-deployment-description: 'Nightly deployment on each commit to dev branch'
-        env:
-          NETLIFY_AUTH_TOKEN: ${{ secrets.NETLIFY_AUTH_TOKEN }}
-          NETLIFY_SITE_ID: ${{ secrets.NETLIFY_SITE_ID_DEV }}
-        timeout-minutes: 1

.github/workflows/pr-title.yml

@@ -1,15 +0,0 @@
-name: Check PR title
-
-on:
-  pull_request_target:
-    types:
-      - opened
-      - edited
-
-jobs:
-  lint:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: amannn/action-semantic-pull-request@48f256284bd46cdaab1048c3721360e808335d50 # v6.1.1
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/prod-deploy.yml

@@ -1,100 +0,0 @@
-name: Production deploy
-
-on:
-  release:
-    types: [published]
-
-jobs:
-  deploy-and-tarball:
-    name: Netlify deploy and tarball
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-      - name: Setup node
-        uses: actions/setup-node@949feb2413d6458794dcd2491c4babbbce0c15c1 # v7.1.0
-        with:
-          node-version-file: '.node-version'
-          package-manager-cache: false
-      - name: Install dependencies
-        run: npm ci
-      - name: Build app
-        env:
-          NODE_OPTIONS: '--max_old_space_size=4096'
-        run: npm run build
-      - name: Deploy to Netlify
-        uses: nwtgck/actions-netlify@d22a32a27c918fe470bbc562e984f80ec48c2668 # v4.0.0
-        with:
-          publish-dir: dist
-          deploy-message: 'Prod deploy ${{ github.ref_name }}'
-          enable-commit-comment: false
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          production-deploy: true
-          github-deployment-environment: stable
-          github-deployment-description: 'Stable deployment on each release'
-        env:
-          NETLIFY_AUTH_TOKEN: ${{ secrets.NETLIFY_AUTH_TOKEN }}
-          NETLIFY_SITE_ID: ${{ secrets.NETLIFY_SITE_ID_APP }}
-        timeout-minutes: 1
-      - name: Get version from tag
-        id: vars
-        run: echo "tag=${GITHUB_REF#refs/*/}" >> $GITHUB_OUTPUT
-      - name: Create tar.gz
-        run: tar -czvf cinny-${{ steps.vars.outputs.tag }}.tar.gz dist
-      - name: Sign tar.gz
-        run: |
-          echo '${{ secrets.GNUPG_KEY }}' | gpg --batch --import
-          # Sadly a few lines in the private key match a few lines in the public key,
-          # As a result just --export --armor gives us a few lines replaced with ***
-          # making it useless for importing the signing key. Instead, we dump it as
-          # non-armored and hex-encode it so that its printable.
-          echo "PGP Signing key, in raw PGP format in hex. Import with cat ... | xxd -r -p - | gpg --import"
-          gpg --export | xxd -p
-          echo '${{ secrets.GNUPG_PASSPHRASE }}' | gpg --batch --yes --pinentry-mode loopback --passphrase-fd 0 --armor --detach-sign cinny-${{ steps.vars.outputs.tag }}.tar.gz
-      - name: Upload tagged release
-        uses: softprops/action-gh-release@efb35369e0ad2afab669f228072c1b0d510eae64 # v3.0.3
-        with:
-          tag_name: ${{ github.ref_name }}
-          files: |
-            cinny-${{ steps.vars.outputs.tag }}.tar.gz
-            cinny-${{ steps.vars.outputs.tag }}.tar.gz.asc
-
-  publish-image:
-    name: Push Docker image to Docker Hub, GHCR
-    runs-on: ubuntu-latest
-    permissions:
-      contents: read
-      packages: write
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@1f40c72289eff860ee54a304f1438e3cff362e0a # v4.3.0
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e # v4.3.0
-      - name: Login to Docker Hub #Do not update this action from a outside PR
-        uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
-        with:
-          username: ${{ secrets.DOCKER_USERNAME }}
-          password: ${{ secrets.DOCKER_PASSWORD }}
-      - name: Login to the Github Container registry #Do not update this action from a outside PR
-        uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
-        with:
-          registry: ghcr.io
-          username: ${{ github.actor }}
-          password: ${{ secrets.GITHUB_TOKEN }}
-      - name: Extract metadata (tags, labels) for Docker, GHCR
-        id: meta
-        uses: docker/metadata-action@dc802804100637a589fabce1cb79ff13a1411302 # v6.2.0
-        with:
-          images: |
-            ${{ secrets.DOCKER_USERNAME }}/cinny
-            ghcr.io/${{ github.repository }}
-      - name: Build and push Docker image
-        uses: docker/build-push-action@53b7df96c91f9c12dcc8a07bcb9ccacbed38856a # v7.3.0
-        with:
-          context: .
-          platforms: linux/amd64,linux/arm64
-          push: true
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}

config.json

@@ -17,5 +17,9 @@
   "hashRouter": {
     "enabled": false,
     "basename": "/"
+  },
+
+  "backgroundScene": {
+    "tier": "off"
   }
 }

harness/scene/README.md

@@ -0,0 +1,21 @@
+# 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> trace             # mean trace steps per pixel and pass ms at three camera poses, PREPASS=0,1 arms
+    node drive.cjs <outdir> diff <pngdir>     # one frozen frame with and without the prepass, pixel diff and both PNGs
+    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.

harness/scene/bundle.cjs

@@ -0,0 +1,40 @@
+// Bundles entry.ts with the scene's ?raw GLSL imports into $OUT/bundle.js plus an index.html.
+// usage: node bundle.cjs <outdir> [demo]     (esbuild from NODE_PATH). `demo` bundles the standalone page.
+const esbuild = require('esbuild');
+const fs = require('fs');
+const path = require('path');
+const out = process.argv[2];
+const demo = process.argv[3] === 'demo';
+fs.mkdirSync(out, { recursive: true });
+const rawPlugin = {
+  name: 'raw',
+  setup(b) {
+    b.onResolve({ filter: /\?raw$/ }, (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, demo ? 'demo.ts' : '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><title>Ratatoskr scene: trace prepass</title><body style="margin:0;background:#000"><canvas id=c style="width:100vw;height:100vh;display:block"></canvas>' +
+        (demo
+          ? '<div style="position:fixed;left:8px;top:8px;padding:6px 8px;background:#000a;color:#ddd;font:12px monospace"><label><input id=prepass type=checkbox checked> cone prepass</label> <label><input id=half type=checkbox> half-float start</label> <label>pull-back <input id=pull type=range min=0 max=1 step=0.05 value=0.6></label><pre id=out style="margin:4px 0 0;white-space:pre-wrap"></pre><details id=dev><summary>device</summary><pre id=info style="margin:4px 0 0;white-space:pre-wrap;max-height:50vh;overflow:auto"></pre></details></div>'
+          : '') +
+        '<script src=bundle.js></script>'
+    );
+  });

harness/scene/demo.ts

@@ -0,0 +1,102 @@
+// Standalone page: the scene full-window with a readout of pass ms and trace steps per pixel, and
+// a switch for the cone prepass. Not shipped.
+import {
+  createScene,
+  Scene,
+  SceneStats,
+  SceneUnavailable,
+  TraceStats,
+} from '../../src/app/features/scene/Scene';
+import { LEVELS } from '../../src/app/features/scene/budget';
+
+let canvas = document.getElementById('c') as HTMLCanvasElement;
+const out = document.getElementById('out') as HTMLPreElement;
+const box = document.getElementById('prepass') as HTMLInputElement;
+const pull = document.getElementById('pull') as HTMLInputElement;
+const half = document.getElementById('half') as HTMLInputElement;
+const dev = document.getElementById('dev') as HTMLDetailsElement;
+const info = document.getElementById('info') as HTMLPreElement;
+const timerless = (() => {
+  const g = document.createElement('canvas').getContext('webgl2');
+  return !g?.getExtension('EXT_disjoint_timer_query_webgl2');
+})();
+
+const WHY: Record<SceneUnavailable, string> = {
+  'no-webgl2': 'this browser gave no WebGL2 context',
+  'no-float-or-half-float-colour-buffer':
+    'WebGL2 is there, but neither EXT_color_buffer_float nor EXT_color_buffer_half_float is',
+};
+
+// What the browser says about itself, read from a scratch context so it shows even when the scene
+// could not start. A canvas that never got a WebGL2 context is asked for WebGL1 to name the GPU.
+function describeDevice(): string {
+  const c = document.createElement('canvas');
+  const gl2 = c.getContext('webgl2');
+  const gl = gl2 ?? (document.createElement('canvas').getContext('webgl') as WebGLRenderingContext | null);
+  const lines = [`webgl2 context: ${gl2 ? 'yes' : 'NO'}`];
+  if (!gl) return [...lines, 'webgl1 context: NO'].join('\n');
+  const dbg = gl.getExtension('WEBGL_debug_renderer_info');
+  lines.push(
+    `renderer: ${gl.getParameter(dbg ? dbg.UNMASKED_RENDERER_WEBGL : gl.RENDERER)}`,
+    `vendor: ${gl.getParameter(dbg ? dbg.UNMASKED_VENDOR_WEBGL : gl.VENDOR)}`,
+    `version: ${gl.getParameter(gl.VERSION)}`,
+    `user agent: ${navigator.userAgent}`
+  );
+  const ext = gl.getSupportedExtensions() ?? [];
+  for (const n of ['EXT_color_buffer_float', 'EXT_color_buffer_half_float', 'OES_texture_float_linear', 'EXT_disjoint_timer_query_webgl2'])
+    lines.push(`${n}: ${ext.includes(n) ? 'yes' : 'NO'}`);
+  lines.push(`extensions (${ext.length}): ${ext.join(' ')}`);
+  return lines.join('\n');
+}
+info.textContent = describeDevice();
+
+let scene: Scene | null = null;
+let stats: SceneStats | undefined;
+let trace: TraceStats | undefined;
+
+function start() {
+  scene?.dispose();
+  stats = trace = undefined;
+  // A fresh canvas: a context cannot change its attributes, and dispose leaves the old one bound.
+  const fresh = canvas.cloneNode() as HTMLCanvasElement;
+  canvas.replaceWith(fresh);
+  canvas = fresh;
+  scene = createScene({
+    canvas: fresh,
+    unthrottled: true,
+    fixedLevel: LEVELS[0],
+    fixedPull: +pull.value,
+    prepass: box.checked,
+    halfStart: half.checked,
+    onUnavailable: (r) => (out.textContent = `createScene returned null: ${WHY[r]}`),
+    onCompileFail: (e) => (out.textContent = `createScene returned null: ${e.message}`),
+    onStats: (s) => (stats = s),
+    onTraceStats: (t) => (trace = t),
+  });
+  dev.open = !scene;
+}
+
+setInterval(() => {
+  if (!scene) return;
+  const lines = [`prepass ${box.checked ? 'on' : 'off'}   start target ${scene.startFormat}   pull ${pull.value}`];
+  if (stats) {
+    const ms = stats.passMs;
+    const total = Object.values(ms).reduce((a, b) => a + b, 0);
+    lines.push(
+      `gpu ms  prepass ${ms.prepass.toFixed(2)}  terrain ${ms.terrain.toFixed(2)}  atmosphere ${ms.atmosphere.toFixed(2)}  resolve ${ms.resolve.toFixed(2)}  composite ${ms.composite.toFixed(2)}  total ${total.toFixed(2)}`,
+      `solid ${stats.solidSize.join('x')}`
+    );
+  } else if (timerless) {
+    lines.push('gpu ms: this browser has no EXT_disjoint_timer_query_webgl2');
+  }
+  if (trace)
+    lines.push(
+      `steps/pixel ${trace.stepsPerPixel.toFixed(2)}  (pass 1 ${trace.traceSteps.toFixed(2)}, prepass ${trace.prepassSteps.toFixed(1)} per tile)`
+    );
+  out.textContent = lines.join('\n');
+}, 500);
+
+box.addEventListener('change', start);
+half.addEventListener('change', start);
+pull.addEventListener('input', start);
+start();

harness/scene/drive.cjs

@@ -0,0 +1,309 @@
+// 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 fs = require('fs');
+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('pageerror', (e) => process.stderr.write(`[pageerror] ${e}\n`));
+  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 });
+      }
+    }
+  }
+
+  if (mode === 'trace') {
+    // Steps per pixel and pass ms at fixed camera poses, one scene per run. PREPASS=0,1 picks the arms.
+    const arms = (process.env.PREPASS || '1').split(',').map((x) => x === '1');
+    report.runs = [];
+    for (const [w, h] of process.env.PORTRAIT === '0'
+      ? [[960, 540]]
+      : [
+          [960, 540],
+          [540, 1200],
+        ]) {
+      for (const pull of (process.env.PULLS || '0,0.5,1').split(',').map(Number)) {
+        for (const prepass of arms) {
+          await page.setViewportSize({ width: w, height: h });
+          const r = await page.evaluate(
+            ({ pull, prepass, FRAMES }) =>
+              new Promise((res) => {
+                const rows = [];
+                const trace = [];
+                let done = false;
+                const finish = () => {
+                  if (done || rows.length < FRAMES || trace.length < 4) return;
+                  done = true;
+                  s.dispose();
+                  const keep = rows.slice(FRAMES >> 2);
+                  const med = (xs) => xs.sort((a, b) => a - b)[xs.length >> 1];
+                  const tk = trace.slice(1);
+                  const mean = (k) => tk.reduce((a, t) => a + t[k], 0) / tk.length;
+                  res({
+                    solid: keep[0].solidSize,
+                    readbacks: tk.length,
+                    traceSteps: +mean('traceSteps').toFixed(2),
+                    prepassSteps: +mean('prepassSteps').toFixed(2),
+                    stepsPerPixel: +mean('stepsPerPixel').toFixed(2),
+                    medianMs: Object.fromEntries(
+                      Object.keys(keep[0].passMs).map((k) => [k, +med(keep.map((x) => x.passMs[k])).toFixed(2)])
+                    ),
+                  });
+                };
+                const s = window.__scene.createScene({
+                  canvas: document.getElementById('c'),
+                  unthrottled: true,
+                  fixedLevel: window.__scene.LEVELS[0],
+                  fixedPull: pull,
+                  prepass,
+                  onTraceStats: (t) => {
+                    trace.push(t);
+                    finish();
+                  },
+                  onStats: (st) => {
+                    rows.push(st);
+                    finish();
+                  },
+                });
+                if (!s) res({ error: 'createScene returned null' });
+              }),
+            { pull, prepass, FRAMES: +(process.env.FRAMES || 64) }
+          );
+          report.runs.push({ viewport: [w, h], pull, prepass, ...r });
+        }
+      }
+    }
+  }
+
+  if (mode === 'diff') {
+    // Same frozen frame (reduced motion: time 0, 32 frames) with and without the prepass, compared
+    // pixel by pixel. The prepass is meant to change cost, not the picture.
+    await page.emulateMedia({ reducedMotion: 'reduce' });
+    await page.setViewportSize({ width: 640, height: 360 });
+    const shoot = async (pull, prepass, steps) => {
+      await page.evaluate(
+        ({ pull, prepass, steps }) => {
+          // Reduced motion bounds the scene to 32 frames; each asks for the next with rAF, so the
+          // count stops moving when it is done. Timer-query callbacks lag too far to count on.
+          window.__raf = 0;
+          if (!window.__rafPatched) {
+            window.__rafPatched = true;
+            const raf = window.requestAnimationFrame.bind(window);
+            window.requestAnimationFrame = (cb) => (window.__raf++, raf(cb));
+          }
+          window.__d = window.__scene.createScene({
+            canvas: document.getElementById('c'),
+            fixedLevel: { ...window.__scene.LEVELS[0], traceSteps: steps },
+            fixedPull: pull,
+            prepass,
+          });
+        },
+        { pull, prepass, steps }
+      );
+      for (let last = -1, still = 0; still < 3; await page.waitForTimeout(1000)) {
+        const n = await page.evaluate(() => window.__raf);
+        still = n === last ? still + 1 : 0;
+        last = n;
+      }
+      const png = await page.screenshot();
+      await page.evaluate(() => window.__d.dispose());
+      return png.toString('base64');
+    };
+    // The step cap makes a grazing ray give up and count as a hit, so the baseline is compared
+    // with a 512-step render of the same frame as well: whichever is closer to it is the more
+    // faithful one.
+    const decode = (x) =>
+      page.evaluate(
+        (x) =>
+          new Promise((r) => {
+            const i = new Image();
+            i.onload = () => {
+              const c = document.createElement('canvas');
+              c.width = i.width;
+              c.height = i.height;
+              const g = c.getContext('2d');
+              g.drawImage(i, 0, 0);
+              r(Array.from(g.getImageData(0, 0, i.width, i.height).data));
+            };
+            i.src = 'data:image/png;base64,' + x;
+          }),
+        x
+      );
+    const compare = (da, db) => {
+      let max = 0, over = 0, sum = 0;
+      const px = da.length / 4;
+      for (let i = 0; i < da.length; i += 4) {
+        let m = 0;
+        for (let k = 0; k < 3; k++) m = Math.max(m, Math.abs(da[i + k] - db[i + k]));
+        sum += m;
+        if (m > max) max = m;
+        if (m > 2) over++;
+      }
+      return { maxChannelDiff: max, pixelsOver2of255: over, ofPixels: px, meanMaxChannelDiff: +(sum / px).toFixed(3) };
+    };
+    report.diffs = [];
+    for (const pull of (process.env.PULLS || '0,0.5,1').split(',').map(Number)) {
+      const png = {
+        off: await shoot(pull, false, 96),
+        on: await shoot(pull, true, 96),
+        ref: await shoot(pull, false, 512),
+        off2: await shoot(pull, false, 96),
+      };
+      for (const k of Object.keys(png)) fs.writeFileSync(path.join(outdir, `diff-${k}-${pull}.png`), Buffer.from(png[k], 'base64'));
+      const [off, on, ref, off2] = [await decode(png.off), await decode(png.on), await decode(png.ref), await decode(png.off2)];
+      report.diffs.push({ pull, offVsOffAgain: compare(off, off2), offVsOn: compare(off, on), offVsRef512: compare(off, ref), onVsRef512: compare(on, ref) });
+    }
+  }
+
+  console.log(JSON.stringify(report, null, 1));
+  await b.close();
+})().catch((e) => {
+  console.log('ERR', String(e).slice(0, 2000));
+  process.exit(1);
+});

harness/scene/entry.ts

@@ -0,0 +1,87 @@
+// 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 };
+};

index.html

@@ -4,21 +4,17 @@
     <meta charset="UTF-8" />
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0" />
-    <title>Cinny</title>
-    <meta name="name" content="Cinny" />
-    <meta name="author" content="Ajay Bura" />
+    <title>Ratatoskr</title>
+    <meta name="name" content="Ratatoskr" />
+    <meta name="author" content="GameCult" />
     <meta
       name="description"
       content="A Matrix client where you can enjoy the conversation using simple, elegant and secure interface protected by e2ee with the power of open source."
     />
-    <meta
-      name="keywords"
-      content="cinny, cinnyapp, cinnychat, matrix, matrix client, matrix.org, element"
-    />
+    <meta name="keywords" content="ratatoskr, gamecult, matrix, matrix client, matrix.org" />
 
-    <meta property="og:title" content="Cinny" />
-    <meta property="og:url" content="https://cinny.in" />
-    <meta property="og:image" content="https://cinny.in/assets/favicon-48x48.png" />
+    <meta property="og:title" content="Ratatoskr" />
+    <meta property="og:url" content="https://gamecult.org" />
     <meta
       property="og:description"
       content="A Matrix client where you can enjoy the conversation using simple, elegant and secure interface protected by e2ee with the power of open source."
@@ -29,8 +25,8 @@
 
     <link rel="manifest" href="/manifest.json" />
     <meta name="mobile-web-app-capable" content="yes" />
-    <meta name="application-name" content="Cinny" />
-    <meta name="apple-mobile-web-app-title" content="Cinny" />
+    <meta name="application-name" content="Ratatoskr" />
+    <meta name="apple-mobile-web-app-title" content="Ratatoskr" />
     <meta name="apple-mobile-web-app-capable" content="yes" />
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
 

public/manifest.json

@@ -1,7 +1,7 @@
 {
-  "name": "Cinny",
-  "short_name": "Cinny",
-  "description": "Yet another matrix client",
+  "name": "Ratatoskr",
+  "short_name": "Ratatoskr",
+  "description": "GameCult's Matrix client",
   "dir": "auto",
   "lang": "en-US",
   "display": "standalone",

public/res/svg/cinny-highlight.svg

@@ -1,13 +0,0 @@
-<svg width="18" height="18" viewBox="0 0 18 18" fill="none" xmlns="http://www.w3.org/2000/svg">
-<g clip-path="url(#clip0_2707_1961)">
-<path d="M10.5867 17.3522C10.0727 17.4492 9.54226 17.5 9 17.5C4.30558 17.5 0.5 13.6944 0.5 9C0.5 4.30558 4.30558 0.5 9 0.5C13.6944 0.5 17.5 4.30558 17.5 9C17.5 9.54226 17.4492 10.0727 17.3522 10.5867C16.6511 10.2123 15.8503 10 15 10C12.2386 10 10 12.2386 10 15C10 15.8503 10.2123 16.6511 10.5867 17.3522Z" fill="white"/>
-<path d="M10 6.39999C10 6.67614 9.77614 6.89999 9.5 6.89999C9.22386 6.89999 9 6.67614 9 6.39999C9 6.12385 9.22386 5.89999 9.5 5.89999C9.77614 5.89999 10 6.12385 10 6.39999Z" fill="black"/>
-<path fill-rule="evenodd" clip-rule="evenodd" d="M9 0C4 0 0 4 0 9C0 14 4 18 9 18C9.63967 18 10.263 17.9345 10.8636 17.8099C10.3186 17.0091 10 16.0417 10 15C10 12.2386 12.2386 10 15 10C16.0417 10 17.0091 10.3186 17.8099 10.8636C17.9345 10.263 18 9.63967 18 9C18 4 14 0 9 0ZM1.2 10.8L4.7 8.5V8.2C4.7 6.4 6 5 7.8 4.8H8.2C9.4 4.8 10.5 5.4 11.1 6.4C11.4 6.3 11.7 6.3 12 6.3C12.4 6.3 12.8 6.3 13.2 6.4C13.9 6.6 14.6 6.9 15.2 7.3C14.6 7.1 14 7 13.3 7C12.1 7 11.1 7.4 10.4 8.4C9.7 9.3 9.3 10.4 9.3 11.6C9.3 13.1 8.9 14.5 8 15.8C7.93744 15.8834 7.87923 15.9625 7.82356 16.0381C7.6123 16.325 7.43739 16.5626 7.2 16.8C4.2 16.1 1.9 13.8 1.2 10.8Z" fill="black"/>
-<path d="M18 15C18 16.6569 16.6569 18 15 18C13.3431 18 12 16.6569 12 15C12 13.3431 13.3431 12 15 12C16.6569 12 18 13.3431 18 15Z" fill="#45B83B"/>
-</g>
-<defs>
-<clipPath id="clip0_2707_1961">
-<rect width="18" height="18" fill="white"/>
-</clipPath>
-</defs>
-</svg>

public/res/svg/cinny-unread.svg

@@ -1,13 +0,0 @@
-<svg width="18" height="18" viewBox="0 0 18 18" fill="none" xmlns="http://www.w3.org/2000/svg">
-<g clip-path="url(#clip0_2707_2015)">
-<path d="M10.5867 17.3522C10.0727 17.4492 9.54226 17.5 9 17.5C4.30558 17.5 0.5 13.6944 0.5 9C0.5 4.30558 4.30558 0.5 9 0.5C13.6944 0.5 17.5 4.30558 17.5 9C17.5 9.54226 17.4492 10.0727 17.3522 10.5867C16.6511 10.2123 15.8503 10 15 10C12.2386 10 10 12.2386 10 15C10 15.8503 10.2123 16.6511 10.5867 17.3522Z" fill="white"/>
-<path d="M10 6.39999C10 6.67614 9.77614 6.89999 9.5 6.89999C9.22386 6.89999 9 6.67614 9 6.39999C9 6.12385 9.22386 5.89999 9.5 5.89999C9.77614 5.89999 10 6.12385 10 6.39999Z" fill="black"/>
-<path fill-rule="evenodd" clip-rule="evenodd" d="M9 0C4 0 0 4 0 9C0 14 4 18 9 18C9.63967 18 10.263 17.9345 10.8636 17.8099C10.3186 17.0091 10 16.0417 10 15C10 12.2386 12.2386 10 15 10C16.0417 10 17.0091 10.3186 17.8099 10.8636C17.9345 10.263 18 9.63967 18 9C18 4 14 0 9 0ZM1.2 10.8L4.7 8.5V8.2C4.7 6.4 6 5 7.8 4.8H8.2C9.4 4.8 10.5 5.4 11.1 6.4C11.4 6.3 11.7 6.3 12 6.3C12.4 6.3 12.8 6.3 13.2 6.4C13.9 6.6 14.6 6.9 15.2 7.3C14.6 7.1 14 7 13.3 7C12.1 7 11.1 7.4 10.4 8.4C9.7 9.3 9.3 10.4 9.3 11.6C9.3 13.1 8.9 14.5 8 15.8C7.93744 15.8834 7.87923 15.9625 7.82356 16.0381C7.6123 16.325 7.43739 16.5626 7.2 16.8C4.2 16.1 1.9 13.8 1.2 10.8Z" fill="black"/>
-<path d="M18 15C18 16.6569 16.6569 18 15 18C13.3431 18 12 16.6569 12 15C12 13.3431 13.3431 12 15 12C16.6569 12 18 13.3431 18 15Z" fill="#989898"/>
-</g>
-<defs>
-<clipPath id="clip0_2707_2015">
-<rect width="18" height="18" fill="white"/>
-</clipPath>
-</defs>
-</svg>

public/res/svg/cinny.svg

@@ -1,19 +0,0 @@
-<!-- Generator: Adobe Illustrator 18.0.0, SVG Export Plug-In  -->
-<svg version="1.1"
-	 xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:a="http://ns.adobe.com/AdobeSVGViewerExtensions/3.0/"
-	 x="0px" y="0px" width="18px" height="18px" viewBox="0 0 18 18" enable-background="new 0 0 18 18" xml:space="preserve">
-<defs>
-</defs>
-<g>
-	<g>
-		<circle fill="#FFFFFF" cx="9" cy="9" r="8.5"/>
-	</g>
-	<g>
-		<path d="M9,0C4,0,0,4,0,9c0,5,4,9,9,9c5,0,9-4,9-9C18,4,14,0,9,0z M1.2,10.8l3.5-2.3c0-0.1,0-0.2,0-0.3c0-1.8,1.3-3.2,3.1-3.4
-			c0.1,0,0.2,0,0.4,0c1.2,0,2.3,0.6,2.9,1.6c0.3-0.1,0.6-0.1,0.9-0.1c0.4,0,0.8,0,1.2,0.1c0.7,0.2,1.4,0.5,2,0.9
-			C14.6,7.1,14,7,13.3,7c-1.2,0-2.2,0.4-2.9,1.4c-0.7,0.9-1.1,2-1.1,3.2c0,1.5-0.4,2.9-1.3,4.2c-0.3,0.4-0.5,0.7-0.8,1
-			C4.2,16.1,1.9,13.8,1.2,10.8z"/>
-		<circle cx="9.5" cy="6.4" r="0.5"/>
-	</g>
-</g>
-</svg>

public/res/svg/ratatoskr-highlight.svg

@@ -0,0 +1,17 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="64" height="64" viewBox="0 0 64 64">
+<ellipse cx="19" cy="33" rx="13" ry="22" transform="rotate(-15 19 33)" fill="#d9742b"/>
+<ellipse cx="21" cy="33" rx="7" ry="15" transform="rotate(-15 21 33)" fill="#f0a45d"/>
+<ellipse cx="36" cy="43" rx="11" ry="14" transform="rotate(0 36 43)" fill="#e0833a"/>
+<ellipse cx="40" cy="46" rx="6" ry="9" transform="rotate(0 40 46)" fill="#f6dcb8"/>
+<polygon points="35,19 36,7 43,15" fill="#c9672a"/>
+<polygon points="44,15 50,7 52,19" fill="#c9672a"/>
+<circle cx="43" cy="25" r="10" fill="#e0833a"/>
+<ellipse cx="47" cy="29" rx="5" ry="3.5" transform="rotate(0 47 29)" fill="#f6dcb8"/>
+<circle cx="46.5" cy="23.5" r="1.8" fill="#1a1a1a"/>
+<circle cx="47" cy="23" r="0.6" fill="#ffffff"/>
+<circle cx="52" cy="27.5" r="1.5" fill="#1a1a1a"/>
+<ellipse cx="33" cy="56" rx="5" ry="2.5" transform="rotate(0 33 56)" fill="#c9672a"/>
+<ellipse cx="44" cy="56" rx="4.5" ry="2.5" transform="rotate(0 44 56)" fill="#c9672a"/>
+<circle cx="52" cy="52" r="11" fill="#ffffff"/>
+<circle cx="52" cy="52" r="8" fill="#45B83B"/>
+</svg>

public/res/svg/ratatoskr-unread.svg

@@ -0,0 +1,17 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="64" height="64" viewBox="0 0 64 64">
+<ellipse cx="19" cy="33" rx="13" ry="22" transform="rotate(-15 19 33)" fill="#d9742b"/>
+<ellipse cx="21" cy="33" rx="7" ry="15" transform="rotate(-15 21 33)" fill="#f0a45d"/>
+<ellipse cx="36" cy="43" rx="11" ry="14" transform="rotate(0 36 43)" fill="#e0833a"/>
+<ellipse cx="40" cy="46" rx="6" ry="9" transform="rotate(0 40 46)" fill="#f6dcb8"/>
+<polygon points="35,19 36,7 43,15" fill="#c9672a"/>
+<polygon points="44,15 50,7 52,19" fill="#c9672a"/>
+<circle cx="43" cy="25" r="10" fill="#e0833a"/>
+<ellipse cx="47" cy="29" rx="5" ry="3.5" transform="rotate(0 47 29)" fill="#f6dcb8"/>
+<circle cx="46.5" cy="23.5" r="1.8" fill="#1a1a1a"/>
+<circle cx="47" cy="23" r="0.6" fill="#ffffff"/>
+<circle cx="52" cy="27.5" r="1.5" fill="#1a1a1a"/>
+<ellipse cx="33" cy="56" rx="5" ry="2.5" transform="rotate(0 33 56)" fill="#c9672a"/>
+<ellipse cx="44" cy="56" rx="4.5" ry="2.5" transform="rotate(0 44 56)" fill="#c9672a"/>
+<circle cx="52" cy="52" r="11" fill="#ffffff"/>
+<circle cx="52" cy="52" r="8" fill="#989898"/>
+</svg>

public/res/svg/ratatoskr.svg

@@ -0,0 +1,15 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="64" height="64" viewBox="0 0 64 64">
+<ellipse cx="19" cy="33" rx="13" ry="22" transform="rotate(-15 19 33)" fill="#d9742b"/>
+<ellipse cx="21" cy="33" rx="7" ry="15" transform="rotate(-15 21 33)" fill="#f0a45d"/>
+<ellipse cx="36" cy="43" rx="11" ry="14" transform="rotate(0 36 43)" fill="#e0833a"/>
+<ellipse cx="40" cy="46" rx="6" ry="9" transform="rotate(0 40 46)" fill="#f6dcb8"/>
+<polygon points="35,19 36,7 43,15" fill="#c9672a"/>
+<polygon points="44,15 50,7 52,19" fill="#c9672a"/>
+<circle cx="43" cy="25" r="10" fill="#e0833a"/>
+<ellipse cx="47" cy="29" rx="5" ry="3.5" transform="rotate(0 47 29)" fill="#f6dcb8"/>
+<circle cx="46.5" cy="23.5" r="1.8" fill="#1a1a1a"/>
+<circle cx="47" cy="23" r="0.6" fill="#ffffff"/>
+<circle cx="52" cy="27.5" r="1.5" fill="#1a1a1a"/>
+<ellipse cx="33" cy="56" rx="5" ry="2.5" transform="rotate(0 33 56)" fill="#c9672a"/>
+<ellipse cx="44" cy="56" rx="4.5" ry="2.5" transform="rotate(0 44 56)" fill="#c9672a"/>
+</svg>

scripts/gen-brand.mjs

@@ -0,0 +1,202 @@
+// Draws the Ratatoskr squirrel once, as shapes, and writes the SVG logos plus the
+// favicon and app-icon PNGs from the same shapes (no image tools needed).
+// Run: node scripts/gen-brand.mjs
+import { deflateSync } from 'node:zlib';
+import { mkdirSync, writeFileSync } from 'node:fs';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const root = join(dirname(fileURLToPath(import.meta.url)), '..');
+const BG = '#1c1b22';
+
+// Squirrel facing right on a 64x64 grid. Later shapes draw over earlier ones.
+const squirrel = [
+  { t: 'ellipse', cx: 19, cy: 33, rx: 13, ry: 22, rot: -15, fill: '#d9742b' },
+  { t: 'ellipse', cx: 21, cy: 33, rx: 7, ry: 15, rot: -15, fill: '#f0a45d' },
+  { t: 'ellipse', cx: 36, cy: 43, rx: 11, ry: 14, rot: 0, fill: '#e0833a' },
+  { t: 'ellipse', cx: 40, cy: 46, rx: 6, ry: 9, rot: 0, fill: '#f6dcb8' },
+  {
+    t: 'poly',
+    pts: [
+      [35, 19],
+      [36, 7],
+      [43, 15],
+    ],
+    fill: '#c9672a',
+  },
+  {
+    t: 'poly',
+    pts: [
+      [44, 15],
+      [50, 7],
+      [52, 19],
+    ],
+    fill: '#c9672a',
+  },
+  { t: 'circle', cx: 43, cy: 25, r: 10, fill: '#e0833a' },
+  { t: 'ellipse', cx: 47, cy: 29, rx: 5, ry: 3.5, rot: 0, fill: '#f6dcb8' },
+  { t: 'circle', cx: 46.5, cy: 23.5, r: 1.8, fill: '#1a1a1a' },
+  { t: 'circle', cx: 47, cy: 23, r: 0.6, fill: '#ffffff' },
+  { t: 'circle', cx: 52, cy: 27.5, r: 1.5, fill: '#1a1a1a' },
+  { t: 'ellipse', cx: 33, cy: 56, rx: 5, ry: 2.5, rot: 0, fill: '#c9672a' },
+  { t: 'ellipse', cx: 44, cy: 56, rx: 4.5, ry: 2.5, rot: 0, fill: '#c9672a' },
+];
+const badge = (fill) => [
+  { t: 'circle', cx: 52, cy: 52, r: 11, fill: '#ffffff' },
+  { t: 'circle', cx: 52, cy: 52, r: 8, fill },
+];
+const background = [{ t: 'rect', x: 0, y: 0, w: 64, h: 64, fill: BG }];
+
+const f = (n) => +n.toFixed(2);
+const svgOf = (shapes) =>
+  shapes
+    .map((s) => {
+      if (s.t === 'circle')
+        return `<circle cx="${s.cx}" cy="${s.cy}" r="${s.r}" fill="${s.fill}"/>`;
+      if (s.t === 'rect') return `<rect width="${s.w}" height="${s.h}" fill="${s.fill}"/>`;
+      if (s.t === 'poly')
+        return `<polygon points="${s.pts.map((p) => p.join(',')).join(' ')}" fill="${s.fill}"/>`;
+      return `<ellipse cx="${s.cx}" cy="${s.cy}" rx="${s.rx}" ry="${s.ry}" transform="rotate(${s.rot} ${s.cx} ${s.cy})" fill="${s.fill}"/>`;
+    })
+    .join('\n');
+const writeSvg = (name, shapes) =>
+  writeFileSync(
+    join(root, 'public/res/svg', name),
+    `<svg xmlns="http://www.w3.org/2000/svg" width="64" height="64" viewBox="0 0 64 64">\n${svgOf(
+      shapes
+    )}\n</svg>\n`
+  );
+
+const hex = (h) => [1, 3, 5].map((i) => parseInt(h.slice(i, i + 2), 16));
+const inside = (s, x, y) => {
+  if (s.t === 'rect') return x >= s.x && x < s.x + s.w && y >= s.y && y < s.y + s.h;
+  if (s.t === 'circle') return (x - s.cx) ** 2 + (y - s.cy) ** 2 <= s.r ** 2;
+  if (s.t === 'ellipse') {
+    const a = (-s.rot * Math.PI) / 180;
+    const dx = x - s.cx;
+    const dy = y - s.cy;
+    const u = dx * Math.cos(a) - dy * Math.sin(a);
+    const v = dx * Math.sin(a) + dy * Math.cos(a);
+    return (u / s.rx) ** 2 + (v / s.ry) ** 2 <= 1;
+  }
+  let c = false;
+  for (let i = 0, j = s.pts.length - 1; i < s.pts.length; j = i++) {
+    const [xi, yi] = s.pts[i];
+    const [xj, yj] = s.pts[j];
+    if (yi > y !== yj > y && x < ((xj - xi) * (y - yi)) / (yj - yi) + xi) c = !c;
+  }
+  return c;
+};
+
+const crcTable = Array.from({ length: 256 }, (_, n) => {
+  let c = n;
+  for (let k = 0; k < 8; k += 1) c = c & 1 ? 0xedb88320 ^ (c >>> 1) : c >>> 1;
+  return c >>> 0;
+});
+const crc = (b) => {
+  let c = 0xffffffff;
+  for (const x of b) c = crcTable[(c ^ x) & 255] ^ (c >>> 8);
+  return (c ^ 0xffffffff) >>> 0;
+};
+const chunk = (type, data) => {
+  const out = Buffer.alloc(12 + data.length);
+  out.writeUInt32BE(data.length, 0);
+  out.write(type, 4, 'ascii');
+  data.copy(out, 8);
+  out.writeUInt32BE(crc(out.subarray(4, 8 + data.length)), 8 + data.length);
+  return out;
+};
+
+// Rasterise with 4x4 supersampling; `scale` shrinks the drawing about the centre.
+const png = (shapes, size, scale = 1) => {
+  const rgba = Buffer.alloc(size * size * 4);
+  const SS = 4;
+  const colours = shapes.map((s) => hex(s.fill));
+  for (let py = 0; py < size; py += 1) {
+    for (let px = 0; px < size; px += 1) {
+      let r = 0;
+      let g = 0;
+      let b = 0;
+      let a = 0;
+      for (let sy = 0; sy < SS; sy += 1) {
+        for (let sx = 0; sx < SS; sx += 1) {
+          const gx = ((px + (sx + 0.5) / SS) / size) * 64;
+          const gy = ((py + (sy + 0.5) / SS) / size) * 64;
+          // the background rect covers the whole canvas and ignores `scale`
+          let hit = -1;
+          shapes.forEach((s, i) => {
+            const x = s.t === 'rect' ? gx : (gx - 32) / scale + 32;
+            const y = s.t === 'rect' ? gy : (gy - 32) / scale + 32;
+            if (inside(s, x, y)) hit = i;
+          });
+          if (hit >= 0) {
+            [r, g, b] = [r + colours[hit][0], g + colours[hit][1], b + colours[hit][2]];
+            a += 1;
+          }
+        }
+      }
+      const o = (py * size + px) * 4;
+      if (a > 0) {
+        rgba[o] = Math.round(r / a);
+        rgba[o + 1] = Math.round(g / a);
+        rgba[o + 2] = Math.round(b / a);
+      }
+      rgba[o + 3] = Math.round((a / (SS * SS)) * 255);
+    }
+  }
+  const raw = Buffer.alloc(size * (size * 4 + 1));
+  for (let y = 0; y < size; y += 1) {
+    raw[y * (size * 4 + 1)] = 0;
+    rgba.copy(raw, y * (size * 4 + 1) + 1, y * size * 4, (y + 1) * size * 4);
+  }
+  const ihdr = Buffer.alloc(13);
+  ihdr.writeUInt32BE(size, 0);
+  ihdr.writeUInt32BE(size, 4);
+  ihdr.set([8, 6, 0, 0, 0], 8);
+  return Buffer.concat([
+    Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]),
+    chunk('IHDR', ihdr),
+    chunk('IDAT', deflateSync(raw)),
+    chunk('IEND', Buffer.alloc(0)),
+  ]);
+};
+
+// ICO container holding PNG images.
+const ico = (images) => {
+  const head = Buffer.alloc(6 + images.length * 16);
+  head.writeUInt16LE(1, 2);
+  head.writeUInt16LE(images.length, 4);
+  let offset = head.length;
+  images.forEach(({ size, data }, i) => {
+    const e = 6 + i * 16;
+    head[e] = size;
+    head[e + 1] = size;
+    head.writeUInt16LE(1, e + 4);
+    head.writeUInt16LE(32, e + 6);
+    head.writeUInt32LE(data.length, e + 8);
+    head.writeUInt32LE(offset, e + 12);
+    offset += data.length;
+  });
+  return Buffer.concat([head, ...images.map((i) => i.data)]);
+};
+
+writeSvg('ratatoskr.svg', squirrel);
+writeSvg('ratatoskr-unread.svg', [...squirrel, ...badge('#989898')]);
+writeSvg('ratatoskr-highlight.svg', [...squirrel, ...badge('#45B83B')]);
+
+const icon = [...background, ...squirrel];
+const put = (dir, name, size) => {
+  mkdirSync(join(root, 'public/res', dir), { recursive: true });
+  writeFileSync(join(root, 'public/res', dir, name), png(icon, size, 0.82));
+};
+[36, 48, 72, 96, 144, 192, 256, 384, 512].forEach((s) =>
+  put('android', `android-chrome-${s}x${s}.png`, s)
+);
+[57, 60, 72, 76, 114, 120, 144, 152, 167, 180].forEach((s) =>
+  put('apple', `apple-touch-icon-${s}x${s}.png`, s)
+);
+writeFileSync(
+  join(root, 'public/favicon.ico'),
+  ico([16, 32, 48].map((size) => ({ size, data: png(icon, size, 0.9) })))
+);
+console.log('wrote svg logos, favicon.ico, android and apple icons');

src/app/components/splash-screen/SplashScreen.tsx

@@ -21,7 +21,7 @@ export function SplashScreen({ children }: SplashScreenProps) {
         justifyContent="Center"
       >
         <Text size="H2" align="Center">
-          Cinny
+          Ratatoskr
         </Text>
       </Box>
     </Box>

src/app/features/scene/README.md

@@ -0,0 +1,79 @@
+# 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 is missing, neither
+  `EXT_color_buffer_float` nor `EXT_color_buffer_half_float` exists (`onUnavailable` says which; with
+  only the half extension the prepass start target is RGBA16F, written rounded down), 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/` `sdf.glsl` (the distance bound pass 0 and pass 1 share), pass 0 `prepass.frag.glsl`, 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
+
+0. **Cone prepass** (`prepass.frag.glsl`, one texel per 8x8 tile of pass 1): marches one ray per
+   tile, shrinking each step by the widest any ray of the tile strays from it, so every step is
+   free for the whole tile. It stores the distance no ray of the tile can have hit before, or
+   `W_FAR` when the whole tile climbs out above the highest geometry. Pass 1 starts its rays
+   there. `createScene({ prepass: false })` skips it (the measurement baseline).
+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.
+
+`createScene({ onTraceStats })` measures the trace: pass 1 gets a step-count output and an extra
+render target, read back every 8th frame through a pixel-pack buffer and a fence (never waited
+on), and reports mean steps per pixel. Unset, neither the output nor the target exists.
+
+## 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.

src/app/features/scene/Scene.test.ts

@@ -0,0 +1,443 @@
+import { afterEach, beforeEach, describe, expect, it, Mock, vi } from 'vitest';
+import { createScene, ShaderCompileError, HALF_START_BIAS, HALF_START_SCALE } from './Scene';
+import { WORLD } from './world';
+import { LEVELS } from './budget';
+import { fragmentSource } from './shaderSource';
+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, missing: string[] = []) {
+  let compiles = 0;
+  const calls: Record<string, Fn> = {};
+  const spy = (name: string, impl: (...a: any[]) => unknown = () => ({})): Fn => {
+    if (!calls[name]) calls[name] = vi.fn(impl);
+    return calls[name];
+  };
+  const gl = new Proxy({} as Record<string, unknown>, {
+    get(_, prop: string) {
+      // the two start-target formats must be told apart; every other constant is 1
+      if (prop === 'RGBA32F') return 32;
+      if (prop === 'RGBA16F') return 16;
+      if (/^[A-Z][A-Z0-9_]*$/.test(prop)) return 1;
+      if (prop === 'getExtension')
+        return spy(prop, (n: string) => (missing.includes(n) ? null : {}));
+      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(5); // prepass and 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('cone prepass', () => {
+  const programsFor = (prepass?: boolean) => {
+    rafQueue.length = 0;
+    const { gl, calls } = fakeGl();
+    createScene({ canvas: asCanvas(fakeCanvas(gl)), prepass });
+    return calls.createProgram.mock.calls.length;
+  };
+
+  it('is one more program than the baseline, and off means off', () => {
+    expect(programsFor(true)).toBe(programsFor(false) + 1);
+    expect(programsFor(undefined)).toBe(programsFor(true));
+  });
+
+  it('draws before pass 1 and only when on', () => {
+    const drawsFor = (prepass: boolean) => {
+      rafQueue.length = 0;
+      const { gl, calls } = fakeGl();
+      createScene({ canvas: asCanvas(fakeCanvas(gl)), prepass });
+      runFrame(1000);
+      return calls.drawArrays.mock.calls.length;
+    };
+    expect(drawsFor(true)).toBe(drawsFor(false) + 1);
+  });
+
+  it('the trace-step output exists in pass 1 only when the host asked to measure', () => {
+    expect(fragmentSource('terrain')).not.toContain('TRACE_STATS 1');
+    expect(fragmentSource('terrain', '#define TRACE_STATS 1\n')).toContain('#define TRACE_STATS 1');
+  });
+
+  it('reads the step bytes tightly packed, whatever the width', () => {
+    rafQueue.length = 0;
+    const { gl, calls } = fakeGl();
+    createScene({ canvas: asCanvas(fakeCanvas(gl)), onTraceStats: () => {} });
+    runFrame(1000);
+    // fake constants are all 1: PACK_ALIGNMENT is 1, so a restore to 4 is the only other call
+    const packs = calls.pixelStorei.mock.calls.map((c) => c[1]);
+    expect(packs[0]).toBe(1);
+    expect(packs).toContain(4);
+    expect(calls.readPixels.mock.invocationCallOrder[0]).toBeGreaterThan(
+      calls.pixelStorei.mock.invocationCallOrder[0]
+    );
+  });
+
+  it('shares one distance bound between pass 1 and the prepass', () => {
+    const bound = (stage: 'terrain' | 'prepass') =>
+      fragmentSource(stage).match(/float sceneDistance\([^)]*\)\s*\{[^}]*\}/)?.[0];
+    expect(bound('prepass')).toBeDefined();
+    expect(bound('prepass')).toBe(bound('terrain'));
+    expect(fragmentSource('atmosphere')).not.toContain('sceneDistance');
+  });
+});
+
+describe('device without EXT_color_buffer_float', () => {
+  const FLOAT = 'EXT_color_buffer_float';
+  const HALF = 'EXT_color_buffer_half_float';
+  const build = (missing: string[], extra: Partial<Parameters<typeof createScene>[0]> = {}) => {
+    rafQueue.length = 0;
+    const { gl, calls } = fakeGl(Infinity, missing);
+    const onUnavailable = vi.fn();
+    const scene = createScene({ canvas: asCanvas(fakeCanvas(gl)), onUnavailable, ...extra });
+    if (scene) runFrame(1000); // targets are allocated on the first frame
+    const formats = calls.texStorage2D?.mock.calls.map((c) => c[2]) ?? [];
+    const sources = (calls.shaderSource?.mock.calls ?? []).map((c) => c[1] as string);
+    return {
+      scene,
+      onUnavailable,
+      formats,
+      prepassSource: sources.find((x) => x.includes('o_start')),
+    };
+  };
+
+  it('names why the scene is unavailable: no WebGL2, or neither float nor half-float colour buffers', () => {
+    const none = vi.fn();
+    createScene({ canvas: asCanvas(fakeCanvas(null)), onUnavailable: none });
+    expect(none).toHaveBeenCalledTimes(1);
+    expect(none).toHaveBeenCalledWith('no-webgl2');
+    const r = build([FLOAT, HALF]);
+    expect(r.scene).toBeNull();
+    expect(r.onUnavailable).toHaveBeenCalledTimes(1);
+    expect(r.onUnavailable).toHaveBeenCalledWith('no-float-or-half-float-colour-buffer');
+    expect(build([]).onUnavailable).not.toHaveBeenCalled();
+  });
+
+  it('with only half-float colour buffers, starts the prepass in an RGBA16F target with the rounding-down write', () => {
+    const r = build([FLOAT]);
+    expect(r.scene?.startFormat).toBe('RGBA16F');
+    expect(r.formats).not.toContain(32);
+    expect(r.prepassSource).toContain('#define START_HALF 1');
+    expect(r.prepassSource).toContain(`#define START_HALF_SCALE ${HALF_START_SCALE}`);
+  });
+
+  it('keeps RGBA32F and the plain write where it is renderable, unless asked for half', () => {
+    const wide = build([HALF]);
+    expect(wide.scene?.startFormat).toBe('RGBA32F');
+    expect(wide.formats).toContain(32);
+    expect(wide.prepassSource).not.toContain('#define START_HALF');
+    expect(build([], { halfStart: true }).scene?.startFormat).toBe('RGBA16F');
+  });
+
+  // The shader writes max(0, t*SCALE - BIAS) into a half, which rounds to nearest (even); this is
+  // that rounding. The GPU's rounding of a half write is the unknown a phone must confirm.
+  const toHalf = (x: number) => {
+    if (x === 0) return 0;
+    let e = Math.max(Math.floor(Math.log2(x)), -14);
+    if (2 ** e > x) e -= 1;
+    const ulp = 2 ** (e - 10);
+    const q = x / ulp;
+    let r = Math.floor(q);
+    const d = q - r;
+    if (d > 0.5 || (d === 0.5 && r % 2 === 1)) r += 1;
+    return r * ulp;
+  };
+  const stored = (t: number) => toHalf(Math.max(0, t * HALF_START_SCALE - HALF_START_BIAS));
+
+  it('stores a start distance never past the true one, and not much short of it', () => {
+    let seed = 7;
+    const rand = () => (seed = (seed * 16807) % 2147483647) / 2147483647;
+    const ts = [0, 1e-6, 1e-4, 6.1e-5, 0.01, 1, 1023.9, 1024, 2047.9];
+    for (let i = 0; i < 20000; i++) ts.push(rand() * WORLD.far, rand() * rand() * 4);
+    for (let t = 0; t <= WORLD.far; t += 0.37) ts.push(t);
+    for (const t of ts) {
+      expect(stored(t)).toBeLessThanOrEqual(t);
+      expect(t - stored(t)).toBeLessThanOrEqual(t * 0.0021 + 6e-5);
+    }
+  });
+
+  it('holds the miss sentinel W_FAR exactly, so pass 1 still skips a tile the prepass proved empty', () => {
+    expect(toHalf(WORLD.far)).toBe(WORLD.far);
+  });
+});
+
+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(5);
+    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);
+  });
+});

src/app/features/scene/Scene.ts

@@ -0,0 +1,638 @@
+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' | 'prepass';
+const PASSES: PassName[] = ['terrain', 'atmosphere', 'resolve', 'composite', 'prepass'];
+/** Pass 1 pixels per prepass tile edge. */
+const TILE = 8;
+
+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];
+}
+
+/** Trace cost over one finished readback: mean distance evaluations per pass-1 pixel. */
+export interface TraceStats {
+  /** Mean pass-1 steps per pixel. */
+  traceSteps: number;
+  /** Mean prepass steps per tile; 0 without the prepass. */
+  prepassSteps: number;
+  /** traceSteps plus the prepass's steps spread over the pixels of each tile. */
+  stepsPerPixel: 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}`);
+  }
+}
+
+/**
+ * Why createScene returned null for want of a device feature. Rendering to half floats needs
+ * EXT_color_buffer_float or EXT_color_buffer_half_float; the prepass start target is RGBA32F with
+ * the first and RGBA16F with only the second.
+ */
+export type SceneUnavailable = 'no-webgl2' | 'no-float-or-half-float-colour-buffer';
+
+/**
+ * The RGBA16F prepass start is written as `t * HALF_START_SCALE - HALF_START_BIAS`. A half rounds
+ * to nearest with relative error at most 2^-11, so shaving 2^-10 of t leaves the stored value
+ * below t, and the bias covers the absolute error where halves go subnormal. The shader reads both
+ * through #defines, so this is the one copy.
+ */
+export const HALF_START_SCALE = 1 - 1 / 1024;
+export const HALF_START_BIAS = 1 / 32768;
+const HALF_START_DEFINES = `#define START_HALF 1\n#define START_HALF_SCALE ${HALF_START_SCALE}\n#define START_HALF_BIAS ${HALF_START_BIAS}\n`;
+
+/** 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;
+  /** createScene is about to return null because the device lacks a feature, and which one. */
+  onUnavailable?: (reason: SceneUnavailable) => void;
+  /** Force the RGBA16F prepass start target even where RGBA32F is renderable (measurement, tests). */
+  halfStart?: boolean;
+  /** 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;
+  /**
+   * Measurement: mean sphere-trace steps per pass-1 pixel, read back every few frames. Setting it
+   * compiles pass 1 with a step-count output and an extra render target; unset, neither exists.
+   */
+  onTraceStats?: (s: TraceStats) => void;
+  /** Weather knob, 0 clear .. 1 overcast. */
+  coverage?: number;
+  /** Fixed level instead of the adaptive ladder (measurement). */
+  fixedLevel?: Level;
+  /** Cone prepass that starts pass-1 rays past empty space. Default true; false is the measurement baseline. */
+  prepass?: boolean;
+  /** Hold the camera at this pull-back progress, 0..1, instead of following login (measurement). */
+  fixedPull?: number;
+  /** Ignore the 30 fps cap and the visibility pause (measurement). */
+  unthrottled?: boolean;
+  patchSource?: SourcePatch;
+}
+
+export interface Scene {
+  /** Texture format of the prepass start target. */
+  readonly startFormat: 'RGBA32F' | 'RGBA16F';
+  /** 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,
+  defines?: string
+): WebGLProgram {
+  const vs = compile(gl, gl.VERTEX_SHADER, vertexSource, 'vertex');
+  const fs = compile(
+    gl,
+    gl.FRAGMENT_SHADER,
+    patch ? patch(stage, fragmentSource(stage, defines)) : fragmentSource(stage, defines),
+    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 a float colour buffer is missing (`onUnavailable` says which); 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) {
+    opts.onUnavailable?.('no-webgl2');
+    return null;
+  }
+  const wide = !!gl.getExtension('EXT_color_buffer_float');
+  if (!wide && !gl.getExtension('EXT_color_buffer_half_float')) {
+    opts.onUnavailable?.('no-float-or-half-float-colour-buffer');
+    return null;
+  }
+  // Every other target is a half; only the prepass start can ask for 32 bits.
+  const halfStart = opts.halfStart || !wide;
+  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 usePrepass = opts.prepass ?? true;
+  const passes = usePrepass ? PASSES : PASSES.filter((p) => p !== 'prepass');
+  const programs = {} as Record<PassName, WebGLProgram>;
+  try {
+    passes.forEach((p) => {
+      const defines =
+        p === 'terrain' && opts.onTraceStats
+          ? '#define TRACE_STATS 1\n'
+          : p === 'prepass' && halfStart
+          ? HALF_START_DEFINES
+          : undefined;
+      programs[p] = linkStage(gl, p, opts.patchSource, defines);
+    });
+  } 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 startFormat = halfStart ? gl.RGBA16F : gl.RGBA32F;
+
+  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()!,
+    pre: gl.createFramebuffer()!,
+    atm: gl.createFramebuffer()!,
+    hist: [gl.createFramebuffer()!, gl.createFramebuffer()!],
+  };
+  let solid: Target;
+  let depth: Target;
+  let steps: Target | undefined;
+  let startTex: Target;
+  let atm: Target;
+  let hist: [Target, Target];
+  const freeTargets = () => {
+    [solid, depth, steps, startTex, 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);
+
+  // Trace-step readback: one pixel-pack read in flight at a time, polled by fence, never waited on.
+  // Pass 1's step bytes and the prepass's RGBA floats (g: steps) come back together.
+  const READBACK_EVERY = 8;
+  interface Readback {
+    fence: WebGLSync;
+    pixels: number;
+    tiles: number;
+  }
+  let readback: Readback | undefined;
+  const packSteps = opts.onTraceStats ? gl.createBuffer() : null;
+  const packStart = opts.onTraceStats && usePrepass ? gl.createBuffer() : null;
+  const discardReadback = () => {
+    if (readback) gl.deleteSync(readback.fence);
+    readback = undefined;
+  };
+  const startReadback = () => {
+    if (!steps || readback) return;
+    gl.pixelStorei(gl.PACK_ALIGNMENT, 1); // R8 rows are not 4-byte multiples at every width
+    gl.bindBuffer(gl.PIXEL_PACK_BUFFER, packSteps);
+    gl.bufferData(gl.PIXEL_PACK_BUFFER, steps.w * steps.h, gl.STREAM_READ);
+    gl.bindFramebuffer(gl.FRAMEBUFFER, fbos.solid);
+    gl.readBuffer(gl.COLOR_ATTACHMENT0 + 2);
+    gl.readPixels(0, 0, steps.w, steps.h, gl.RED, gl.UNSIGNED_BYTE, 0);
+    let tiles = 0;
+    if (packStart) {
+      tiles = startTex.w * startTex.h;
+      gl.bindBuffer(gl.PIXEL_PACK_BUFFER, packStart);
+      gl.bufferData(gl.PIXEL_PACK_BUFFER, tiles * 16, gl.STREAM_READ);
+      gl.bindFramebuffer(gl.FRAMEBUFFER, fbos.pre);
+      gl.readPixels(0, 0, startTex.w, startTex.h, gl.RGBA, gl.FLOAT, 0);
+    }
+    gl.bindBuffer(gl.PIXEL_PACK_BUFFER, null);
+    gl.pixelStorei(gl.PACK_ALIGNMENT, 4);
+    readback = {
+      fence: gl.fenceSync(gl.SYNC_GPU_COMMANDS_COMPLETE, 0)!,
+      pixels: steps.w * steps.h,
+      tiles,
+    };
+  };
+  const pollReadback = () => {
+    if (!readback) return;
+    const status = gl.clientWaitSync(readback.fence, 0, 0);
+    if (status !== gl.ALREADY_SIGNALED && status !== gl.CONDITION_SATISFIED) return;
+    const { pixels, tiles } = readback;
+    const bytes = new Uint8Array(pixels);
+    gl.bindBuffer(gl.PIXEL_PACK_BUFFER, packSteps);
+    gl.getBufferSubData(gl.PIXEL_PACK_BUFFER, 0, bytes);
+    let preSum = 0;
+    if (packStart) {
+      const floats = new Float32Array(tiles * 4);
+      gl.bindBuffer(gl.PIXEL_PACK_BUFFER, packStart);
+      gl.getBufferSubData(gl.PIXEL_PACK_BUFFER, 0, floats);
+      for (let i = 1; i < floats.length; i += 4) preSum += floats[i];
+    }
+    gl.bindBuffer(gl.PIXEL_PACK_BUFFER, null);
+    let sum = 0;
+    for (let i = 0; i < bytes.length; i += 1) sum += bytes[i];
+    discardReadback();
+    const traceSteps = sum / pixels;
+    const prepassSteps = tiles ? preSum / tiles : 0;
+    opts.onTraceStats?.({
+      traceSteps,
+      prepassSteps,
+      stepsPerPixel: traceSteps + (prepassSteps * tiles) / pixels,
+    });
+  };
+
+  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);
+    // Without the prepass pass 1 reads a 1x1 zero start: every ray from the camera, as before.
+    startTex = usePrepass
+      ? makeTarget(Math.ceil(sw / TILE), Math.ceil(sh / TILE), startFormat, gl.NEAREST)
+      : makeTarget(1, 1, startFormat, gl.NEAREST);
+    steps = opts.onTraceStats ? makeTarget(sw, sh, gl.R8, gl.NEAREST) : undefined;
+    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, steps ? [solid, depth, steps] : [solid, depth]);
+    discardReadback();
+    attach(fbos.pre, [startTex]);
+    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 = { prepass: 0, ...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(opts.fixedPull ?? 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 0: cone march at one ray per 8x8 tile of pass 1, the start distance for its rays.
+    if (usePrepass) {
+      timed('prepass', f, () => {
+        gl.bindFramebuffer(gl.FRAMEBUFFER, fbos.pre);
+        gl.viewport(0, 0, startTex.w, startTex.h);
+        const p = programs.prepass;
+        gl.useProgram(p);
+        setCommon(p, pose, time);
+        gl.uniform1i(loc(p, 'u_maxSteps'), lv.traceSteps);
+        gl.uniform2f(loc(p, 'u_tileHalf'), 0.5 / startTex.w, 0.5 / startTex.h);
+        draw();
+      });
+    }
+
+    // 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);
+      bindTex(0, startTex, p, 'u_start');
+      draw();
+    });
+    if (f % READBACK_EVERY === 0) startReadback(); // outside the timed span: not pass 1's cost
+
+    // 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();
+    pollReadback();
+  };
+
+  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 {
+    startFormat: halfStart ? 'RGBA16F' : 'RGBA32F',
+    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]));
+      discardReadback();
+      [packSteps, packStart].forEach((b) => b && gl.deleteBuffer(b));
+      gl.deleteVertexArray(vao);
+      [fbos.solid, fbos.pre, fbos.atm, ...fbos.hist].forEach((fb) => gl.deleteFramebuffer(fb));
+    },
+  };
+}

src/app/features/scene/budget.test.ts

@@ -0,0 +1,41 @@
+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);
+  });
+});

src/app/features/scene/budget.ts

@@ -0,0 +1,59 @@
+// 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;
+  }
+}

src/app/features/scene/camera.test.ts

@@ -0,0 +1,42 @@
+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);
+  });
+});

src/app/features/scene/camera.ts

@@ -0,0 +1,56 @@
+// 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),
+  };
+}

src/app/features/scene/creatures.test.ts

@@ -0,0 +1,27 @@
+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();
+  });
+});

src/app/features/scene/creatures.ts

@@ -0,0 +1,37 @@
+// 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;
+}

src/app/features/scene/cultmathTrim.test.ts

@@ -0,0 +1,82 @@
+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'));
+  });
+});

src/app/features/scene/cultmathTrim.ts

@@ -0,0 +1,81 @@
+/**
+ * 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}`;
+}

src/app/features/scene/index.ts

@@ -0,0 +1,33 @@
+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 });
+}

src/app/features/scene/palette.ts

@@ -0,0 +1,27 @@
+// 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;

src/app/features/scene/shaderSource.ts

@@ -0,0 +1,41 @@
+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 sdf from './shaders/sdf.glsl?raw';
+import prepassFrag from './shaders/prepass.frag.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 = 'prepass' | '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> = {
+  prepass: prepassFrag,
+  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 distance bound (stages that trace), the stage. `defines` is whole `#define`
+ * lines (measurement flags) ahead of the world's. Phacelle stays a separate file, added only where
+ * it is called.
+ */
+export function fragmentSource(stage: Stage, defines = ''): string {
+  const solid = stage === 'terrain' || stage === 'prepass';
+  const erosion = solid && WORLD.phacelleGradBound > 0 ? phacelle : '';
+  const world = solid ? sdf : '';
+  const math = trimGlsl(cultmath, [erosion, common, world, stages[stage]]);
+  return `${HEADER}${defines}${worldDefines()}\n${math}\n${erosion}\n${common}\n${world}\n${stages[stage]}`;
+}

src/app/features/scene/shaders/CultMath.Phacelle.glsl

@@ -0,0 +1,99 @@
+// 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

src/app/features/scene/shaders/README.md

@@ -0,0 +1,19 @@
+# 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.

src/app/features/scene/shaders/atmosphere.frag.glsl

@@ -0,0 +1,90 @@
+// 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);
+}

src/app/features/scene/shaders/common.glsl

@@ -0,0 +1,31 @@
+// 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;
+}

src/app/features/scene/shaders/composite.frag.glsl

@@ -0,0 +1,26 @@
+// 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);
+}

src/app/features/scene/shaders/fullscreen.vert.glsl

@@ -0,0 +1,8 @@
+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);
+}

src/app/features/scene/shaders/prepass.frag.glsl

@@ -0,0 +1,57 @@
+// Pass 0: a cone march at one ray per tile of pass-1 pixels. Writes the distance along the tile's
+// centre ray that no ray in the tile can have hit before, so pass 1 starts there instead of at the
+// camera. Every step is safe for every ray of the tile: the cone's radius at t is the widest any
+// ray strays from the centre ray, and the centre's distance bound minus that radius is a free ball
+// around each ray's own point.
+uniform int u_maxSteps;
+uniform vec2 u_tileHalf;   // half a tile in uv: the footprint of this texel, as pass 1 samples it
+
+in vec2 v_uv;
+layout(location = 0) out vec4 o_start;   // r: start distance, W_FAR when the tile misses; g: steps spent (a half holds both)
+
+void main()
+{
+    vec3 ro = u_camPos;
+    vec3 rd = camRay(v_uv);
+
+    // Widest stray of any ray in the tile from the centre ray, per unit t. The rays are the unit
+    // directions through a rectangle on the view plane, whose sublevel sets about rd are convex, so
+    // the maximum sits at a corner. The margin is for float rounding.
+    float spread = 0.0;
+    for (int c = 0; c < 4; c++)
+    {
+        vec2 corner = vec2(c & 1, c >> 1) * 2.0 - 1.0;
+        spread = max(spread, length(camRay(v_uv + corner * u_tileHalf) - rd));
+    }
+    spread *= 1.05;
+
+    // Past tEnd every ray of the tile is above W_MAX_HEIGHT and still rising (or beyond W_FAR):
+    // none can hit anything.
+    float rise = rd.y - spread;
+    float tEnd = W_FAR;
+    if (rise > 0.0)
+        tEnd = min(W_FAR, max(0.0, (W_MAX_HEIGHT - ro.y) / rise));
+
+    float t = 0.0;
+    float leafness;
+    bool onTree;
+    int evals = 0;
+    for (int i = 0; i < u_maxSteps && t < tEnd; i++)
+    {
+        evals++;
+        // Pass 1's hit tolerance, 0.0006 t + 0.01, is kept clear at the far end of the step too, so
+        // no ray of the tile starts inside its own hit radius.
+        float s = (sceneDistance(ro + rd * t, leafness, onTree) - spread * t - (0.0006 * t + 0.01)) / 1.0006;
+        if (s <= 0.0)
+            break;
+        t += s;
+    }
+    float start = t;
+#ifdef START_HALF
+    // The target is RGBA16F: the write rounds to a half, and the round may go up. Any start past
+    // the true one is a ray that could skip a surface, so shave more than half a ulp off first
+    // (START_HALF_SCALE, START_HALF_BIAS: Scene.ts). W_FAR stays exact, an integer a half holds.
+    start = max(0.0, t * START_HALF_SCALE - START_HALF_BIAS);
+#endif
+    o_start = vec4(t >= tEnd ? W_FAR : start, float(evals), 0.0, 0.0);
+}

src/app/features/scene/shaders/resolve.frag.glsl

@@ -0,0 +1,41 @@
+// 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);
+}

src/app/features/scene/shaders/sdf.glsl

@@ -0,0 +1,95 @@
+// The solid world as a distance bound: terrain graph plus tree. Shared by the pass-1 trace and the
+// cone prepass, so both step by the same bound.
+
+// ---- 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);
+}

src/app/features/scene/shaders/terrain.frag.glsl

@@ -0,0 +1,108 @@
+// 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;
+uniform sampler2D u_start;   // prepass: r = distance no ray of this pixel's tile hits before; W_FAR = tile misses
+
+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
+#ifdef TRACE_STATS
+layout(location = 2) out float o_steps;  // distance evaluations this ray spent, over 255 (measurement only)
+#endif
+
+// ---- trace ---------------------------------------------------------------------------------
+
+void main()
+{
+    vec3 ro = u_camPos;
+    vec3 rd = camRay(v_uv);
+
+    float t = texture(u_start, v_uv).r;
+    // Nothing is above W_MAX_HEIGHT: skip the empty air above it, or miss outright. A tile the
+    // prepass proved empty arrives as W_FAR.
+    bool missAtOnce = t >= W_FAR;
+    if (ro.y > W_MAX_HEIGHT)
+    {
+        missAtOnce = missAtOnce || rd.y >= 0.0;
+        t = max(t, (W_MAX_HEIGHT - ro.y) / rd.y);
+    }
+    if (missAtOnce)
+    {
+        o_color = vec4(0.0);
+        o_depth = W_FAR;
+#ifdef TRACE_STATS
+        o_steps = 0.0;
+#endif
+        return;
+    }
+
+    bool hit = false;
+    bool onTree = false;
+    float leafness = 0.0;
+    int i = 0;
+    int evals = 0;
+    for (; i < u_maxSteps; i++)
+    {
+        evals++;
+        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);
+    }
+#ifdef TRACE_STATS
+    o_steps = float(evals) / 255.0;
+#endif
+
+    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;
+}

src/app/features/scene/tier.test.ts

@@ -0,0 +1,26 @@
+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');
+  });
+});

src/app/features/scene/tier.ts

@@ -0,0 +1,49 @@
+// 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;
+}

src/app/features/scene/world.test.ts

@@ -0,0 +1,40 @@
+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');
+  });
+});

src/app/features/scene/world.ts

@@ -0,0 +1,117 @@
+// 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');
+}

src/app/features/settings/about/About.tsx

@@ -4,7 +4,7 @@ import { Page, PageContent, PageHeader } from '../../../components/page';
 import { SequenceCard } from '../../../components/sequence-card';
 import { SequenceCardStyle } from '../styles.css';
 import { SettingTile } from '../../../components/setting-tile';
-import CinnySVG from '../../../../../public/res/svg/cinny.svg';
+import RatatoskrSVG from '../../../../../public/res/svg/ratatoskr.svg';
 import { clearCacheAndReload } from '../../../../client/initMatrix';
 import { useMatrixClient } from '../../../hooks/useMatrixClient';
 
@@ -38,23 +38,23 @@ export function About({ requestClose }: AboutProps) {
                 <Box shrink="No">
                   <img
                     style={{ width: toRem(60), height: toRem(60) }}
-                    src={CinnySVG}
-                    alt="Cinny logo"
+                    src={RatatoskrSVG}
+                    alt="Ratatoskr logo"
                   />
                 </Box>
                 <Box direction="Column" gap="300">
                   <Box direction="Column" gap="100">
                     <Box gap="100" alignItems="End">
-                      <Text size="H3">Cinny</Text>
+                      <Text size="H3">Ratatoskr</Text>
                       <Text size="T200">v4.12.8</Text>
                     </Box>
-                    <Text>Yet another matrix client.</Text>
+                    <Text>GameCult&apos;s Matrix client.</Text>
                   </Box>
 
                   <Box gap="200" wrap="Wrap">
                     <Button
                       as="a"
-                      href="https://github.com/cinnyapp/cinny"
+                      href="https://eureka.gamecult.org/forge/GameCult/Ratatoskr"
                       rel="noreferrer noopener"
                       target="_blank"
                       variant="Secondary"
@@ -65,20 +65,19 @@ export function About({ requestClose }: AboutProps) {
                     >
                       <Text size="B300">Source Code</Text>
                     </Button>
-                    <Button
-                      as="a"
-                      href="https://cinny.in/#sponsor"
-                      rel="noreferrer noopener"
-                      target="_blank"
-                      variant="Critical"
-                      fill="Soft"
-                      size="300"
-                      radii="300"
-                      before={<Icon src={Icons.Heart} size="100" filled />}
-                    >
-                      <Text size="B300">Support</Text>
-                    </Button>
                   </Box>
+                  <Text size="T300">
+                    Based on{' '}
+                    <a
+                      href="https://github.com/cinnyapp/cinny"
+                      target="_blank"
+                      rel="noreferrer noopener"
+                    >
+                      Cinny
+                    </a>{' '}
+                    4.12.8 by Ajay Bura and contributors. Ratatoskr is free software under the GNU
+                    Affero General Public License v3; its source is at the Source Code link above.
+                  </Text>
                 </Box>
               </Box>
               <Box direction="Column" gap="100">

src/app/features/settings/devices/LocalBackup.tsx

@@ -28,7 +28,7 @@ function ExportKeys() {
         const blob = new Blob([encKeys], {
           type: 'text/plain;charset=us-ascii',
         });
-        FileSaver.saveAs(blob, 'cinny-keys.txt');
+        FileSaver.saveAs(blob, 'ratatoskr-keys.txt');
       },
       [mx]
     )

src/app/features/settings/notifications/SystemNotification.tsx

@@ -27,7 +27,7 @@ function EmailNotification() {
             device_display_name: email,
             lang: 'en',
             data: {
-              brand: 'Cinny',
+              brand: 'Ratatoskr',
             },
             append: true,
           });

src/app/features/soundscape/device.ts

@@ -0,0 +1,12 @@
+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);

src/app/features/soundscape/frame.ts

@@ -0,0 +1,108 @@
+// 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);
+  }
+}

src/app/features/soundscape/scene.ts

@@ -0,0 +1,8 @@
+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);

src/app/features/soundscape/socket.ts

@@ -0,0 +1,47 @@
+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,
+  };
+};

src/app/features/soundscape/soundscape.test.ts

@@ -0,0 +1,233 @@
+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();
+  });
+});

src/app/features/soundscape/voices.ts

@@ -0,0 +1,51 @@
+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 }));
+};

src/app/hooks/useClientConfig.ts

@@ -1,4 +1,5 @@
 import { createContext, useContext } from 'react';
+import type { BackgroundSceneConfig } from '../features/scene/tier';
 
 export type HashRouterConfig = {
   enabled?: boolean;
@@ -18,6 +19,8 @@ export type ClientConfig = {
   };
 
   hashRouter?: HashRouterConfig;
+
+  backgroundScene?: BackgroundSceneConfig;
 };
 
 const ClientConfigContext = createContext<ClientConfig | null>(null);

src/app/pages/auth/AuthFooter.tsx

@@ -5,20 +5,26 @@ import * as css from './styles.css';
 export function AuthFooter() {
   return (
     <Box className={css.AuthFooter} justifyContent="Center" gap="400" wrap="Wrap">
-      <Text as="a" size="T300" href="https://cinny.in" target="_blank" rel="noreferrer">
+      <Text as="a" size="T300" href="https://gamecult.org" target="_blank" rel="noreferrer">
         About
       </Text>
       <Text
         as="a"
         size="T300"
-        href="https://github.com/ajbura/cinny/releases"
+        href="https://eureka.gamecult.org/forge/GameCult/Ratatoskr"
         target="_blank"
         rel="noreferrer"
       >
-        v4.12.8
+        Source
       </Text>
-      <Text as="a" size="T300" href="https://twitter.com/cinnyapp" target="_blank" rel="noreferrer">
-        Twitter
+      <Text
+        as="a"
+        size="T300"
+        href="https://github.com/cinnyapp/cinny"
+        target="_blank"
+        rel="noreferrer"
+      >
+        Based on Cinny
       </Text>
       <Text as="a" size="T300" href="https://matrix.org" target="_blank" rel="noreferrer">
         Powered by Matrix

src/app/pages/auth/AuthLayout.tsx

@@ -20,7 +20,7 @@ import {
 } from '../../hooks/useClientConfig';
 import { AsyncStatus, useAsyncCallback } from '../../hooks/useAsyncCallback';
 import { LOGIN_PATH, REGISTER_PATH, RESET_PASSWORD_PATH } from '../paths';
-import CinnySVG from '../../../../public/res/svg/cinny.svg';
+import RatatoskrSVG from '../../../../public/res/svg/ratatoskr.svg';
 import { ServerPicker } from './ServerPicker';
 import { AutoDiscoveryAction, autoDiscovery } from '../../cs-api';
 import { SpecVersionsLoader } from '../../components/SpecVersionsLoader';
@@ -134,8 +134,8 @@ export function AuthLayout() {
         <Box direction="Column" className={css.AuthCard}>
           <Header className={css.AuthHeader} size="600" variant="Surface">
             <Box grow="Yes" direction="Row" gap="300" alignItems="Center">
-              <img className={css.AuthLogo} src={CinnySVG} alt="Cinny Logo" />
-              <Text size="H3">Cinny</Text>
+              <img className={css.AuthLogo} src={RatatoskrSVG} alt="Ratatoskr logo" />
+              <Text size="H3">Ratatoskr</Text>
             </Box>
           </Header>
           <Box className={css.AuthCardContent} direction="Column">

src/app/pages/auth/login/PasswordLoginForm.tsx

@@ -133,7 +133,7 @@ export function PasswordLoginForm({ defaultUsername, defaultEmail }: PasswordLog
         user: username,
       },
       password,
-      initial_device_display_name: 'Cinny Web',
+      initial_device_display_name: 'Ratatoskr Web',
     });
   };
 
@@ -151,7 +151,7 @@ export function PasswordLoginForm({ defaultUsername, defaultEmail }: PasswordLog
         user: mxIdUsername,
       },
       password,
-      initial_device_display_name: 'Cinny Web',
+      initial_device_display_name: 'Ratatoskr Web',
     });
   };
   const handleEmailLogin = (email: string, password: string) => {
@@ -163,7 +163,7 @@ export function PasswordLoginForm({ defaultUsername, defaultEmail }: PasswordLog
         address: email,
       },
       password,
-      initial_device_display_name: 'Cinny Web',
+      initial_device_display_name: 'Ratatoskr Web',
     });
   };
 

src/app/pages/auth/login/TokenLogin.tsx

@@ -57,7 +57,7 @@ export function TokenLogin({ token }: TokenLoginProps) {
     startLogin(baseUrl, {
       type: 'm.login.token',
       token,
-      initial_device_display_name: 'Cinny Web',
+      initial_device_display_name: 'Ratatoskr Web',
     });
   }, [baseUrl, token, startLogin]);
 

src/app/pages/auth/register/PasswordRegisterForm.tsx

@@ -109,7 +109,7 @@ function RegisterUIAFlow({
         auth: authDict,
         password,
         username,
-        initial_device_display_name: 'Cinny Web',
+        initial_device_display_name: 'Ratatoskr Web',
       });
     },
     [onRegister, formData]
@@ -250,7 +250,7 @@ export function PasswordRegisterForm({
       auth: {
         session: authData.session,
       },
-      initial_device_display_name: 'Cinny Web',
+      initial_device_display_name: 'Ratatoskr Web',
     });
   };
 

src/app/pages/client/ClientNonUIFeatures.tsx

@@ -3,9 +3,9 @@ import React, { ReactNode, useCallback, useEffect, useRef } from 'react';
 import { useNavigate } from 'react-router-dom';
 import { RoomEvent, RoomEventHandlerMap } from 'matrix-js-sdk';
 import { roomToUnreadAtom, unreadEqual, unreadInfoToUnread } from '../../state/room/roomToUnread';
-import LogoSVG from '../../../../public/res/svg/cinny.svg';
-import LogoUnreadSVG from '../../../../public/res/svg/cinny-unread.svg';
-import LogoHighlightSVG from '../../../../public/res/svg/cinny-highlight.svg';
+import LogoSVG from '../../../../public/res/svg/ratatoskr.svg';
+import LogoUnreadSVG from '../../../../public/res/svg/ratatoskr-unread.svg';
+import LogoHighlightSVG from '../../../../public/res/svg/ratatoskr-highlight.svg';
 import NotificationSound from '../../../../public/sound/notification.ogg';
 import InviteSound from '../../../../public/sound/invite.ogg';
 import { notificationPermission, setFavicon } from '../../utils/dom';

src/app/pages/client/WelcomePage.tsx

@@ -1,7 +1,7 @@
 import React from 'react';
 import { Box, Button, Icon, Icons, Text, config, toRem } from 'folds';
 import { Page, PageHero, PageHeroSection } from '../../components/page';
-import CinnySVG from '../../../../public/res/svg/cinny.svg';
+import RatatoskrSVG from '../../../../public/res/svg/ratatoskr.svg';
 
 export function WelcomePage() {
   return (
@@ -14,17 +14,17 @@ export function WelcomePage() {
       >
         <PageHeroSection>
           <PageHero
-            icon={<img width="70" height="70" src={CinnySVG} alt="Cinny Logo" />}
-            title="Welcome to Cinny"
+            icon={<img width="70" height="70" src={RatatoskrSVG} alt="Ratatoskr logo" />}
+            title="Welcome to Ratatoskr"
             subTitle={
               <span>
-                Yet another matrix client.{' '}
+                GameCult&apos;s Matrix client, based on{' '}
                 <a
-                  href="https://github.com/cinnyapp/cinny/releases"
+                  href="https://github.com/cinnyapp/cinny"
                   target="_blank"
                   rel="noreferrer noopener"
                 >
-                  v4.12.8
+                  Cinny
                 </a>
               </span>
             }
@@ -33,7 +33,7 @@ export function WelcomePage() {
               <Box grow="Yes" style={{ maxWidth: toRem(300) }} direction="Column" gap="300">
                 <Button
                   as="a"
-                  href="https://github.com/cinnyapp/cinny"
+                  href="https://eureka.gamecult.org/forge/GameCult/Ratatoskr"
                   target="_blank"
                   rel="noreferrer noopener"
                   before={<Icon size="200" src={Icons.Code} />}
@@ -42,18 +42,6 @@ export function WelcomePage() {
                     Source Code
                   </Text>
                 </Button>
-                <Button
-                  as="a"
-                  href="https://cinny.in/#sponsor"
-                  target="_blank"
-                  rel="noreferrer noopener"
-                  fill="Soft"
-                  before={<Icon size="200" src={Icons.Heart} />}
-                >
-                  <Text as="span" size="B400" truncate>
-                    Support
-                  </Text>
-                </Button>
               </Box>
             </Box>
           </PageHero>

src/app/state/settings.ts

@@ -47,6 +47,12 @@ 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 = {
@@ -81,6 +87,11 @@ const defaultSettings: Settings = {
   dateFormatString: 'D MMM YYYY',
 
   developerTools: false,
+
+  soundscapeEnabled: false,
+  soundscapeMuted: true,
+  soundscapeVolume: 0.5,
+  soundscapeVoiceCap: 4,
 };
 
 export const getSettings = () => {