AI Agents, DI Patterns, and the API That Broke Billing on a Friday Night

We built an org-wide AI agent in 4 days. Here's what broke in the weeks after.

TLDR: daily.dev shipped a 29,000-line TypeScript Slack AI agent in 4 days — and then spent weeks cleaning up credential leaks, token bleeding, and production incidents that the demo never mentioned.

We built an org-wide AI agent in 4 days. Here's what broke in the weeks after.

Dependency Injection in Node.js & TypeScript. The Part Nobody Teaches You

TLDR: Most Node.js devs hardwire their dependencies with direct imports, which quietly destroys testability. This post explains the difference between Dependency Injection and Dependency Inversion — and shows how to implement DI manually in TypeScript without reaching for a framework.

Dependency Injection in Node.js & TypeScript. The Part Nobody Teaches You

How a Silent API Update Broke Our Billing (And How to Prevent It)

TLDR: A silent Stripe API schema change caused 23 failed orders on a Friday night with no HTTP error. The author responded by building php-sentinel, a passive runtime API contract monitor that learns what APIs actually return and alerts when the shape drifts.

How a Silent API Update Broke Our Billing (And How to Prevent It)