feat: pure NPC generator over genre tables

src/npc/generator.js

@@ -0,0 +1,18 @@
+function pick(arr, rng) {
+  return arr[Math.floor(rng() * arr.length)];
+}
+
+export function generateNpc(pack, seed, rng) {
+  const t = pack.tables;
+  const name = `${pick(t.firstNames, rng)} ${pick(t.surnames, rng)}`;
+  return {
+    genre: pack.label,
+    seed: String(seed ?? '').trim(),
+    name,
+    look: pick(t.looks, rng),
+    manner: pick(t.manners, rng),
+    wants: pick(t.wants, rng),
+    secret: pick(t.secrets, rng),
+    voice: pick(t.voices, rng),
+  };
+}

tests/npc/generator.test.js

@@ -0,0 +1,35 @@
+import { describe, it, expect } from 'vitest';
+import { generateNpc } from '../../src/npc/generator.js';
+
+const pack = {
+  id: 'test', label: 'Test',
+  tables: {
+    firstNames: ['A', 'B'], surnames: ['X', 'Y'],
+    looks: ['look0', 'look1'], manners: ['man0', 'man1'],
+    wants: ['want0', 'want1'], secrets: ['sec0', 'sec1'], voices: ['voi0', 'voi1'],
+  },
+};
+// deterministic rng replaying a fixed sequence
+function seq(values) { let i = 0; return () => values[i++ % values.length]; }
+
+describe('generateNpc', () => {
+  it('assembles a character by picking from tables with the injected rng', () => {
+    // order of picks: firstName, surname, look, manner, wants, secret, voice
+    const rng = seq([0.0, 0.9, 0.9, 0.0, 0.9, 0.0, 0.9]);
+    const npc = generateNpc(pack, '  nervous foreman  ', rng);
+    expect(npc.name).toBe('A Y');       // 0.0->A, 0.9->Y
+    expect(npc.look).toBe('look1');     // 0.9
+    expect(npc.manner).toBe('man0');    // 0.0
+    expect(npc.wants).toBe('want1');    // 0.9
+    expect(npc.secret).toBe('sec0');    // 0.0
+    expect(npc.voice).toBe('voi1');     // 0.9
+    expect(npc.seed).toBe('nervous foreman'); // trimmed, echoed
+    expect(npc.genre).toBe('Test');
+  });
+
+  it('is fully determined by the rng (same sequence -> same npc)', () => {
+    const a = generateNpc(pack, 's', seq([0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7]));
+    const b = generateNpc(pack, 's', seq([0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7]));
+    expect(a).toEqual(b);
+  });
+});