Notes on payment infrastructure and working with AI in high-stakes code — written by someone who isn't an expert yet, just paying close attention.https://taewoo.me/https://taewoo.me/posts/payment-integrations-with-claude-code/https://taewoo.me/posts/payment-integrations-with-claude-code/How I cut payment-provider integrations from a week to 1–2 days with Claude Code: goals first, high-risk logic first, review by a fresh agent.Thu, 22 Oct 2026 00:00:00 GMThttps://taewoo.me/posts/integrating-provider-without-sandbox/https://taewoo.me/posts/integrating-provider-without-sandbox/No sandbox and docs that don't match production? Simulate from the docs, send one tiny real payment, log every call, and fix the gaps before customers see them.Sun, 18 Oct 2026 00:00:00 GMThttps://taewoo.me/posts/why-sending-1-dollar-cost-15/https://taewoo.me/posts/why-sending-1-dollar-cost-15/A $1 wire cost me $15; $78 in USDT cost under $3. Fees belong to the rail, not the amount, and Vietnam's payment workarounds show what fintech could build.Sat, 03 Oct 2026 00:00:00 GMThttps://taewoo.me/posts/konbini-payments-japan/https://taewoo.me/posts/konbini-payments-japan/Konbini payment lets Japanese shoppers check out online and pay in cash at a convenience store. Why it works, and what it means for payment system design.Sun, 27 Sep 2026 00:00:00 GMThttps://taewoo.me/posts/designing-a-payout-system/https://taewoo.me/posts/designing-a-payout-system/Payouts fail in ways payment-in doesn't. Lessons on beneficiary verification, double sends, compliance-first routing, and reconciliation.Sun, 20 Sep 2026 00:00:00 GMThttps://taewoo.me/posts/confirming-customer-received-money/https://taewoo.me/posts/confirming-customer-received-money/Webhooks vs. polling: how a payment system actually confirms money has arrived, explained through a grocery-store QR code.Sun, 13 Sep 2026 00:00:00 GMThttps://taewoo.me/posts/evaluating-payment-api-before-adapter/https://taewoo.me/posts/evaluating-payment-api-before-adapter/Test the field mapping before frontend builds on top of it — a checklist for what to verify before writing adapter docs.Mon, 07 Sep 2026 00:00:00 GMThttps://taewoo.me/posts/design-patterns-predict-where-change-hurts/https://taewoo.me/posts/design-patterns-predict-where-change-hurts/A payment infrastructure engineer's notes on applying Chain of Responsibility, Adapter, Strategy, and Observer to a real virtual account creation flow.Tue, 25 Aug 2026 00:00:00 GMThttps://taewoo.me/posts/building-this-blog/https://taewoo.me/posts/building-this-blog/Domain, name, template, DNS — the small decisions that ate the time on a 'simple' blog setup.Mon, 24 Aug 2026 00:00:00 GMThttps://taewoo.me/posts/starting-here/https://taewoo.me/posts/starting-here/Why this blog exists, and what it's going to be about.Mon, 24 Aug 2026 00:00:00 GMT