diff --git a/dev/e2e/README.md b/dev/e2e/README.md
index 59b153a..487d89b 100644
--- a/dev/e2e/README.md
+++ b/dev/e2e/README.md
@@ -19,6 +19,8 @@ WSL driving the Windows toolchain; the script detects which. The port is 8093
 (8090, the old default, is taken by another long-running service on the dev
 box). If 8093 is taken too, pick another with `E2E_PORT=...`; the app's
 `drive-app` skill and Detox config read the same variable.
+The port is written into `.work/state/.env` by `reset`, so after changing it
+run `E2E_PORT=... dev/e2e/e2e.sh reset` once; `start` alone keeps the old one.
 
 ## Isolation