Days 5-10: From Code to Product (Testing, Landing Page, and the Cat Theme)

The first week was infrastructure. This week was about transforming a monorepo into something that looks and feels like a real product.

Days 5-8: The Testing Sprint — 147 Commits

Set up Vitest across the monorepo. My testing priority order was deliberate:

1. Shared packages first — the API streaming helper, Supabase client, credit management. These are load-bearing walls. If createAIStreamResponse() has a bug, all 15 streaming routes break. If credit deduction races, users get free readings or double-charged. 36 tests for the streaming helper alone, covering every code path: successful stream completion, mid-stream errors with credit refund, content filter truncation, SSE event formatting.

2. Domain calculation logic — BaZi calculations, tarot card draws, Liuren divination rolls. I can't personally verify correctness (zero domain knowledge), but I can verify deterministic behavior: same birth data always produces same chart, same deck shuffle always produces expected distribution, same hexagram always maps to same meaning.

3. API route integration tests — mock auth tokens, verify credit deduction, confirm SSE event format matches frontend expectations.

GitHub Actions CI pipeline: lint → type-check → build → test. Every PR gets the full treatment. This sounds standard, but for a solo developer it's the difference between "I think this works" and "I know this works."

147 commits across 4 days. Not glamorous. By the end I had confidence the platform wouldn't explode when I started making changes faster.

Days 9-10: Branding and Monetization — 100 Commits

The Cat Theme

PanPanMao (盼盼猫). The calculating cat. The fortune-telling cat.

Once the cat theme clicked, everything cascaded. Each app got a cat-themed treatment. The credit currency became dried fish treats (小鱼干). Because what else would you pay a fortune-telling cat with?

The brand decision was a product decision, not a marketing decision. Fortune-telling can feel intimidating or scammy. The cat makes it approachable. Users share results because they're fun, not because they're "accurate." This distinction matters for virality.

Stripe Integration

Four credit packages with the classic pricing psychology:

10 credits / $6.99 (entry tier)
50 credits / $24.99 (volume discount)
150 credits / $59.99 — Most Popular badge (anchor tier)
500 credits / $149.99 (power user)

The "Most Popular" badge isn't just a label — it's a pricing anchor. When I later tested removing it, conversion on that tier dropped noticeably. Bundle psychology is real.

I priced credits so each reading costs a fraction of the credit package price. The credit abstraction matters: people are more willing to spend 5 fish treats than a dollar amount. The currency rename from "credits" to "小鱼干" reduced perceived spending friction.

The Landing Page v1

Warm brown and gold tones. Mobile-first. "Thousand-year wisdom x Modern AI" tagline. Claude helped with Chinese copywriting — the tagline came from a brainstorming session where I evaluated 20 options.

This landing page would later be completely redesigned to dark luxury (Days 12-19) because "cozy" undermined the gravity users expected from a fortune-telling platform.

What I Learned This Week

Testing is an investment, not a cost. It paid for itself immediately during the branding refactors. Changing themes, renaming credit currencies, updating UI copy across 6 apps — the test suite caught three regression bugs I would have shipped.

Brand is a product decision. The cat theme made the platform approachable in a domain that can feel intimidating. It changed how users interacted with the product.

Pricing is psychology, not math. I spent more time on credit package naming than on the payment flow code.

AI for domain branding works. Claude generated Chinese copywriting I couldn't have written myself. The bilingual (zh-CN/zh-TW/en) i18n support across the entire platform was AI-translated and human-reviewed.