diff --git a/AGENTS.md b/AGENTS.md
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@@ -35,6 +35,10 @@
 - Prefer small, direct Go code and standard library solutions.
 - Keep shell scripts strict with `set -euo pipefail`.
 - Use `gofmt` for Go formatting.
+- When a CLI accepts either an inline string or a file input, always prefer the file-based form.
+- For shell commands and AI/LLM tooling, prefer passing files as input whenever the CLI allows it.
+- Create temporary files as needed to follow the file-first rule.
+- Examples: use `git commit -F <file>` instead of `git commit -m <message>`, and use prompt files instead of inline prompt strings when invoking LLM CLIs.
 
 ## Testing Guidance