diff --git a/CLAUDE.md b/CLAUDE.md
index b30277f..f399dc2 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -21,6 +21,7 @@ and adds `bin/` to PATH. `$LWS` points to repo root.
 - `can_run <cmd>` — check if command is available
 - `is_slow_init` / `is_fast_init` — check `LWS_FAST` mode
 - `is_interactive_shell` — true when `[[ $- == *i* ]]`
+- `is_stdin_terminal` — true when stdin is a terminal (`tty` would return a device, not `not a tty`)
 - `is_wsl` — detect WSL environment
 - `is_ssh_session` — true when logged in over SSH
 - `true_false <val>` — normalize `1/true/yes` to boolean
diff --git a/functions.sh b/functions.sh
index 7a430ad..f835737 100644
--- a/functions.sh
+++ b/functions.sh
@@ -9,6 +9,10 @@ function is_interactive_shell() {
     [[ $- == *i* ]]
 }
 
+function is_stdin_terminal() {
+  [[ -t 0 ]]
+}
+
 function is_fast_init() {
     (( $LWS_FAST ))
 }
diff --git a/rc/gpg.sh b/rc/gpg.sh
new file mode 100644
index 0000000..672a24b
--- /dev/null
+++ b/rc/gpg.sh
@@ -0,0 +1,6 @@
+# shellcheck shell=bash
+
+if is_stdin_terminal && can_run gpg; then
+  GPG_TTY=$(tty)
+  export GPG_TTY
+fi