Metabolism: rule program, song-driven life, tribe VMs; M2.7 design (strains & allegiances, living wells)

metabolism/src/demo/catalog.js

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+// Catalog loading + display helpers for the demo page.
+// The catalog itself is computed by the vite plugin (node-side analysis of the
+// exact same pipeline the browser uses), so the library card and the player
+// can never disagree about a song's shape.
+
+const LAW_COLORS = {
+    intro: '#7d8fa3',
+    build: '#d8a24a',
+    drop: '#e2434b',
+    breakdown: '#4a8fe2',
+    sustain: '#3fbf9f',
+    outro: '#9a7fd6',
+};
+
+export function fetchCatalog() {
+    return fetch('/songs/catalog.json').then((r) => {
+        if (!r.ok) throw new Error(`catalog unavailable (${r.status})`);
+        return r.json();
+    });
+}
+
+export function lawColor(kind) {
+    return LAW_COLORS[kind] || '#5f6673';
+}
+
+/** A CSS accent (hue/sat from the track's palette, so the page wears the song). */
+export function accentFor(entry) {
+    const hue = Number(entry.hue) || 0.6;
+    const sat = Number(entry.sat) || 0.6;
+    return `hsl(${Math.round(hue * 360)}, ${Math.round(Math.min(1, sat) * 100)}%, 58%)`;
+}
+
+export function fmtTime(s) {
+    if (!Number.isFinite(s) || s < 0) return '0:00';
+    const m = Math.floor(s / 60);
+    const ss = String(Math.floor(s % 60)).padStart(2, '0');
+    return `${m}:${ss}`;
+}
+
+/** A one-line natural-language summary of what the track is. */
+export function tagsFor(entry) {
+    const q = entry.summary;
+    const bits = [];
+    if (q.bpm) bits.push(`${Math.round(q.bpm)} BPM`);
+    bits.push(q.centroid > 0.5 ? 'bright' : 'dark');
+    bits.push(q.flatness < 0.12 ? 'tonal' : q.flatness < 0.4 ? 'grained' : 'noisy');
+    bits.push(q.beatStrength > 0.5 ? 'pulsing' : 'beatless');
+    bits.push(`${entry.laws.length} ${entry.laws.length === 1 ? 'part' : 'parts'}`);
+    return bits.join(' · ');
+}
+
+/** Read the URL's song/seed/res and give safe defaults for the rest. */
+export function parseQuery() {
+    const p = new URLSearchParams(location.search);
+    const res = ['640x360', '960x540', '1280x720'].includes(p.get('res')) ? p.get('res') : '640x360';
+    return { song: p.get('song') || 'drone', seed: parseSeed(p.get('seed')), res };
+}
+
+function parseSeed(v) {
+    const n = parseInt(v ?? '', 10);
+    return Number.isFinite(n) && n > 0 ? n : 12345;
+}