I Benchmarked 5 File Editing Strategies for AI Coding Agents. Here's What Actually Works.

Yes, the title says "5 strategies" like every other listicle. The number isn't a framework. It's just how many I got through before my API bill made me pause. There are plenty more approaches worth testing. If you've benchmarked others or have a strategy that works well for you, I'd genuinely like to hear about it. Telling an agent to "edit the file" is easy. Being sure the result is correct is hard. I've been using Claude Code daily for months. One pattern kept showing up: the agent says "done," I commit, and later I find lines missing from the middle of the file. Or a formatter ran between edits and the next match fails silently. So I tested it systematically. 5 strategies, 20 scenarios, two file sizes (378 and 1053 lines), with 5 and 10 changes each. The 5 Strategies Sequential Edit: One Edit call per change, top to bottom. Simple, but line numbers drift after insertions. Atomic Write: Read once, rewrite entire file. Fewest tool calls, but token cost explodes on large files and midd