diff --git a/.huskies/AGENT.md b/.huskies/AGENT.md
index c6b2029d..69ee857d 100644
--- a/.huskies/AGENT.md
+++ b/.huskies/AGENT.md
@@ -20,5 +20,8 @@ The frontend is embedded into the Rust binary via `rust-embed`. Run `npm run bui
 
 Clippy is zero-tolerance: no warnings allowed. Fix every warning before committing.
 
+## File size
+Target a maximum of 800 lines per source file as a soft guide. If a file grows beyond 800 lines, decompose it by concern into smaller modules. Split at natural seams: group related types, functions, or handlers together and move each cohesive group to its own file. This keeps files readable and diffs focused.
+
 ## Runtime validation
 The `validate_agents` function in `server/src/config.rs` rejects unknown runtimes. Supported values: `"claude-code"` and `"gemini"`. Adding a new runtime requires updating that function.