Coding agents are getting smarter. Their prompts aren't. Gemini CLI sends 4,096 tokens before you type a word. Zap sends only what the current task needs — Java skill for Java, React skill for React. A greeting costs 31 tokens, not 2,000. AST code index means it never writes files that already exist. Single Rust binary, no runtime, bring your own API key. Open source. Benchmarked.