chore: ai, public course and other ui improvements

apps/api/src/__tests__/ai-credits-usage.test.ts

@@ -0,0 +1,55 @@
+import { describe, expect, it } from 'vitest';
+import { computePurchasedTokenOverflow } from '@api/services/agent/usage';
+
+describe('computePurchasedTokenOverflow', () => {
+  it('returns 0 when usage stays within allowance', () => {
+    expect(
+      computePurchasedTokenOverflow({
+        allowance: 1000,
+        monthlyUsageBefore: 500,
+        requestTokens: 400
+      })
+    ).toBe(0);
+  });
+
+  it('returns partial overflow when request crosses allowance boundary', () => {
+    expect(
+      computePurchasedTokenOverflow({
+        allowance: 1000,
+        monthlyUsageBefore: 900,
+        requestTokens: 200
+      })
+    ).toBe(100);
+  });
+
+  it('charges entire request against credits when allowance already exhausted', () => {
+    expect(
+      computePurchasedTokenOverflow({
+        allowance: 1000,
+        monthlyUsageBefore: 1200,
+        requestTokens: 50
+      })
+    ).toBe(50);
+  });
+
+  it('handles zero allowance', () => {
+    expect(
+      computePurchasedTokenOverflow({
+        allowance: 0,
+        monthlyUsageBefore: 0,
+        requestTokens: 10
+      })
+    ).toBe(10);
+  });
+});
+
+describe('leaderboard percentage split', () => {
+  it('allocates shares that sum to 1', () => {
+    const rows = [{ tokens: 30 }, { tokens: 70 }];
+    const total = rows.reduce((sum, row) => sum + row.tokens, 0);
+    const percentages = rows.map((row) => (total > 0 ? row.tokens / total : 0));
+
+    expect(percentages).toEqual([0.3, 0.7]);
+    expect(percentages.reduce((a, b) => a + b, 0)).toBeCloseTo(1);
+  });
+});