Initial TTRPG character meta-builder with visual sheet editor.

Offline Electron app seeds 10 system presets, supports create-from-scratch designer with palette/drag/resize/bricks, and exports .ttrpg-system.json for the player.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/shared/core.test.ts

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+import assert from 'node:assert/strict';
+import { test } from 'node:test';
+
+import { evaluateFormula, buildFormulaContext } from './formula.ts';
+import { computeDerived, sortDerived, CycleError } from './derived.ts';
+import { validatePointBuy, validateArray, rollDice, sum, validateCreationRules } from './creation.ts';
+import { snapshotHash, canonicalJson } from './snapshot.ts';
+import { validateSystemDefinition } from './systemValidate.ts';
+import type { SystemDefinition } from './types.ts';
+import { FORMAT_VERSION, SYSTEM_FORMAT } from './types.ts';
+
+test('evaluateFormula: D&D ability modifier', () => {
+  const ctx = { 'attr.str': 16 };
+  assert.equal(evaluateFormula('floor((attr.str - 10) / 2)', ctx), 3);
+  assert.equal(evaluateFormula('(attr.str - 10) / 2', ctx, 'floor'), 3);
+});
+
+test('evaluateFormula: clamp min max', () => {
+  assert.equal(evaluateFormula('clamp(attr.str, 1, 20)', { 'attr.str': 25 }), 20);
+});
+
+test('computeDerived topo order', () => {
+  const derived = computeDerived(
+    [
+      {
+        key: 'strMod',
+        label: 'STR mod',
+        formula: 'floor((attr.str - 10) / 2)',
+        dependsOn: ['attr.str'],
+        round: 'none',
+      },
+      {
+        key: 'carry',
+        label: 'Carry',
+        formula: 'attr.str * 15',
+        dependsOn: ['attr.str'],
+      },
+    ],
+    { attributes: { str: 12 } },
+  );
+  assert.equal(derived.strMod, 1);
+  assert.equal(derived.carry, 180);
+});
+
+test('sortDerived detects cycles', () => {
+  assert.throws(
+    () =>
+      sortDerived([
+        { key: 'a', label: 'a', formula: 'derived.b', dependsOn: ['derived.b'] },
+        { key: 'b', label: 'b', formula: 'derived.a', dependsOn: ['derived.a'] },
+      ]),
+    CycleError,
+  );
+});
+
+test('point buy budget', () => {
+  const rule = {
+    id: 'pb',
+    type: 'point_buy' as const,
+    appliesTo: 'attribute' as const,
+    params: {
+      budget: 27,
+      keys: ['str', 'dex', 'con', 'int', 'wis', 'cha'],
+    },
+  };
+  const ok = validatePointBuy(rule, { str: 15, dex: 14, con: 13, int: 12, wis: 10, cha: 8 });
+  assert.equal(ok.length, 0);
+  const bad = validatePointBuy(rule, { str: 15, dex: 15, con: 15, int: 15, wis: 15, cha: 15 });
+  assert.ok(bad.some((e) => e.code === 'point_buy_budget'));
+});
+
+test('array permutation', () => {
+  const rule = {
+    id: 'arr',
+    type: 'array' as const,
+    appliesTo: 'attribute' as const,
+    params: { array: [15, 14, 13, 12, 10, 8], keys: ['str', 'dex', 'con', 'int', 'wis', 'cha'] },
+  };
+  assert.equal(
+    validateArray(rule, { str: 15, dex: 14, con: 13, int: 12, wis: 10, cha: 8 }).length,
+    0,
+  );
+  assert.ok(validateArray(rule, { str: 15, dex: 15, con: 13, int: 12, wis: 10, cha: 8 }).length > 0);
+});
+
+test('rollDice 4d6dl', () => {
+  let i = 0;
+  const seq = [0.0, 0.9, 0.5, 0.2]; // -> 1,6,4,2 drop 1 => 6+4+2=12
+  const rolls = rollDice('4d6dl', () => seq[i++] ?? 0);
+  assert.equal(sum(rolls), 12);
+});
+
+test('snapshotHash stable', () => {
+  const system = minimalSystem();
+  const a = snapshotHash(system);
+  const b = snapshotHash({ ...system, name: 'Other display name' });
+  // name is not part of hash payload — hash equal
+  assert.equal(a, b);
+  const c = snapshotHash({ ...system, revision: 2 });
+  assert.notEqual(a, c);
+});
+
+test('canonicalJson sorts keys', () => {
+  assert.equal(canonicalJson({ b: 1, a: 2 }), '{"a":2,"b":1}');
+});
+
+test('validateSystemDefinition', () => {
+  const r = validateSystemDefinition(minimalSystem());
+  assert.equal(r.ok, true);
+});
+
+test('validateCreationRules integrates point_buy', () => {
+  const system = minimalSystem();
+  const result = validateCreationRules(
+    system,
+    { attributes: { str: 15, dex: 14, con: 13, int: 12, wis: 10, cha: 8 } },
+    'point_buy',
+  );
+  assert.equal(result.ok, true);
+});
+
+test('buildFormulaContext', () => {
+  const ctx = buildFormulaContext({ attributes: { str: 10 }, resources: { hp: 8 } });
+  assert.equal(ctx['attr.str'], 10);
+  assert.equal(ctx['resource.hp'], 8);
+});
+
+function minimalSystem(): SystemDefinition {
+  return {
+    format: SYSTEM_FORMAT,
+    formatVersion: FORMAT_VERSION,
+    id: 'test',
+    name: 'Test',
+    schemaVersion: 1,
+    revision: 1,
+    bricks: {
+      attributes: [
+        { key: 'str', label: 'STR', scale: 'numeric', min: 8, max: 15, default: 10 },
+        { key: 'dex', label: 'DEX', scale: 'numeric', min: 8, max: 15, default: 10 },
+        { key: 'con', label: 'CON', scale: 'numeric', min: 8, max: 15, default: 10 },
+        { key: 'int', label: 'INT', scale: 'numeric', min: 8, max: 15, default: 10 },
+        { key: 'wis', label: 'WIS', scale: 'numeric', min: 8, max: 15, default: 10 },
+        { key: 'cha', label: 'CHA', scale: 'numeric', min: 8, max: 15, default: 10 },
+      ],
+      derived: [
+        {
+          key: 'strMod',
+          label: 'STR Mod',
+          formula: 'floor((attr.str - 10) / 2)',
+          dependsOn: ['attr.str'],
+        },
+      ],
+    },
+    creationRules: [
+      {
+        id: 'pb',
+        type: 'point_buy',
+        appliesTo: 'attribute',
+        params: {
+          budget: 27,
+          keys: ['str', 'dex', 'con', 'int', 'wis', 'cha'],
+        },
+      },
+    ],
+    sheetLayout: {
+      pageSize: 'fluid',
+      grid: { size: 8 },
+      pages: [{ id: 'main', label: 'Main', widgets: [] }],
+    },
+  };
+}