How Solana Transactions Are Different from REST API Calls (And Why It Matters)

The Problem: Your Mental Model Is Broken You know how to build APIs. You understand request/response cycles. You know that a successful POST returns 200 OK, and a failed request returns 400 Bad Request. You've never been charged for a 400. Solana transactions will break every one of those assumptions. Last week, I sent a transaction that failed due to insufficient funds. The validator still charged me a fee. A 400 Bad Request just cost me real money. That's when I realized: I was thinking about