diff --git a/docs/examples/porch/middleware/idempotent.wo b/docs/examples/porch/middleware/idempotent.wo
index a8e55ee..c58e7ea 100644
--- a/docs/examples/porch/middleware/idempotent.wo
+++ b/docs/examples/porch/middleware/idempotent.wo
@@ -82,7 +82,11 @@ pub class Idempotent {
     let resp_json = json.encode(stored);
 
     let now = time.ticks();
-    try insert IdempotencyKey { key: key, response: resp_json, created_at: now } catch (e) nil;
+    -- Compute digest of method|path|body
+    let digest_input = "${req.method}|${req.path}|${req.body}";
+    let digest = sha256(bytes_of_text(digest_input));
+    let digest_hex = base64_encode(bytes_slice(digest, 0, 16));
+    try insert IdempotencyKey { key: key, response: resp_json, created_at: now, digest: digest_hex } catch (e) nil;
   }
 }
 
diff --git a/docs/examples/porch/middleware/store.wo b/docs/examples/porch/middleware/store.wo
index 79ca842..a18c71a 100644
--- a/docs/examples/porch/middleware/store.wo
+++ b/docs/examples/porch/middleware/store.wo
@@ -21,4 +21,5 @@ class IdempotencyKey {
   key:        Text @unique
   response:   Text
   created_at: Int
+  digest:     Text
 }
\ No newline at end of file