diff --git a/.jules/sentinel.md b/.jules/sentinel.md
new file mode 100644
index 0000000..272e219
--- /dev/null
+++ b/.jules/sentinel.md
@@ -0,0 +1,4 @@
+## 2025-02-02 - Secure File Creation with Shell Redirection
+**Vulnerability:** SSH private keys restored from 1Password via `op read > file` were created with default umask permissions before `chmod` was applied, creating a race condition.
+**Learning:** Shell redirection creates files before `chmod` can act. Even in "personal" dotfiles, this can expose secrets on multi-user systems (e.g., shared servers).
+**Prevention:** Use `(umask 077 && command > file)` to ensure files are born secure.
diff --git a/tools/setup-ssh-keys.sh b/tools/setup-ssh-keys.sh
index bde52fd..0286575 100755
--- a/tools/setup-ssh-keys.sh
+++ b/tools/setup-ssh-keys.sh
@@ -149,11 +149,16 @@ cmd_restore() {
     say "Restoring SSH key from 1Password..."
 
     # Create SSH directory
-    mkdir -p "$SSH_DIR"
+    # Use umask to ensure secure permissions on creation
+    (umask 077 && mkdir -p "$SSH_DIR")
     chmod 700 "$SSH_DIR"
 
     # Read private key from 1Password and save locally
-    op read "op://$VAULT/$KEY_NAME/private_key" > "$PRIVATE_KEY_FILE"
+    # Use umask in subshell to prevent race condition where file is briefly group-readable
+    (
+        umask 077
+        op read "op://$VAULT/$KEY_NAME/private_key" > "$PRIVATE_KEY_FILE"
+    )
     chmod 600 "$PRIVATE_KEY_FILE"
 
     # Read public key from 1Password and save locally