diff --git a/.changeset/restore-replayed-assertion-fresh-create-media-buy.md b/.changeset/restore-replayed-assertion-fresh-create-media-buy.md
new file mode 100644
index 0000000000..e42dee599b
--- /dev/null
+++ b/.changeset/restore-replayed-assertion-fresh-create-media-buy.md
@@ -0,0 +1,4 @@
+---
+---
+
+Restore positive `replayed` assertion on the fresh-path `create_media_buy_initial` step in `universal/idempotency.yaml`, now using the `field_value_or_absent` matcher (documented in #3032, shipped in `@adcp/client` 5.16.0). Fresh execution MAY omit `replayed` per `protocol-envelope.json`, but if present it MUST be `false` — this closes the coverage gap opened in #3013 without penalizing spec-correct agents that omit the field.
diff --git a/static/compliance/source/universal/idempotency.yaml b/static/compliance/source/universal/idempotency.yaml
index 2f97e4b3c0..9bed60fdb6 100644
--- a/static/compliance/source/universal/idempotency.yaml
+++ b/static/compliance/source/universal/idempotency.yaml
@@ -270,14 +270,10 @@ phases:
           - check: field_present
             path: "media_buy_id"
             description: "Agent returns a media_buy_id for the initial request"
-          # NOTE: intentionally NO assertion on `replayed` here. Per
-          # `protocol-envelope.json`, fresh execution MAY omit the field,
-          # and `@adcp/client` >= 5.14 omits it (see adcp-client#859).
-          # The replay step below asserts `replayed: true` on the
-          # cached replay, which is the real regression surface. A
-          # fresh-path `field_value allowed_values: [false]` assertion
-          # has no `field_absent`-tolerant form today and would fail
-          # spec-correct agents.
+          - check: field_value_or_absent
+            path: "replayed"
+            allowed_values: [false]
+            description: "If replayed is present on fresh execution, it MUST be false (protocol-envelope.json)"
 
           - check: field_present
             path: "context"