diff --git a/extension/identity.mjs b/extension/identity.mjs
new file mode 100644
index 0000000..cc4ad97
--- /dev/null
+++ b/extension/identity.mjs
@@ -0,0 +1,2 @@
+// Derived from manifest.key; keep in sync with the server exact Origin.
+export const EXTENSION_ID = 'kiolgjoohhgdohcafgelhikpgkbmckbg';