diff --git a/main.go b/main.go
index 4c84f2a..caabb37 100644
--- a/main.go
+++ b/main.go
@@ -32,7 +32,8 @@ Do not restate tasks, hedge, or self-congratulate.
 Always use tools to perform actions; never simulate or guess outputs.
 Do not attempt tasks outside your tools.
 Use execute_code for all shell commands and scripts. Use execute_tool only for named scripts in ~/mnt/anvillm/tools. Use execute_pipe to chain steps: use {code: "cmd --flags"} for shell commands, {tool, args} only for named scripts in ~/mnt/anvillm/tools.
-Use file_read and file_write for all file read and write operations. Never use shell commands to read or write files.`
+Use file_read and file_write for all file read and write operations. Never use shell commands to read or write files.
+Before file_read or file_write, use execute_code with grep -n to find relevant line numbers, then read/write only that range.`
 
 func systemPrompt(allTools []backend.Tool) string {
 	cwd, _ := os.Getwd()