diff --git a/crates/e2e_test/src/replication_extension_test.rs b/crates/e2e_test/src/replication_extension_test.rs
index c5023d64c..1c0e64517 100644
--- a/crates/e2e_test/src/replication_extension_test.rs
+++ b/crates/e2e_test/src/replication_extension_test.rs
@@ -6975,3 +6975,87 @@ async fn test_replication_put_and_create_multipart_carry_source_version_id_query
     target.shutdown().await;
     Ok(())
 }
+
+/// P1-20: inbound replicas never cascade. An object replicated A->B carries
+/// x-amz-replication-status=REPLICA on B; `must_replicate` returns an empty
+/// decision for replicas, so even an ExistingObjectReplication=Enabled rule
+/// configured on B AFTER the replica landed (making it an "existing object"
+/// for that rule) must never push it onward — while B's own native objects
+/// flow to the onward bucket, proving B's outbound replication and scanner
+/// are live.
+#[tokio::test]
+#[serial]
+async fn test_scanner_never_cascades_inbound_replicas() -> TestResult {
+    init_logging();
+
+    let mut env_a = RustFSTestEnvironment::new().await?;
+    let mut env_a_vars = replication_fast_env();
+    env_a_vars.extend_from_slice(LOOPBACK_REPLICATION_TARGET_ENV);
+    env_a.start_rustfs_server_with_env(vec![], &env_a_vars).await?;
+
+    // B becomes a replication source itself, driven by its scanner.
+    let mut env_b = RustFSTestEnvironment::new().await?;
+    let mut env_b_vars = replication_fast_env();
+    env_b_vars.extend_from_slice(LOOPBACK_REPLICATION_TARGET_ENV);
+    env_b_vars.extend_from_slice(FAST_SCANNER_ENV);
+    env_b.start_rustfs_server_with_env(vec![], &env_b_vars).await?;
+
+    let bucket_a = "cascade-a-src";
+    let bucket_b = "cascade-b-mid";
+    let bucket_c = "cascade-a-third";
+    let client_a = env_a.create_s3_client();
+    let client_b = env_b.create_s3_client();
+    client_a.create_bucket().bucket(bucket_a).send().await?;
+    client_b.create_bucket().bucket(bucket_b).send().await?;
+    client_a.create_bucket().bucket(bucket_c).send().await?;
+    enable_bucket_versioning(&env_a, bucket_a).await?;
+    enable_bucket_versioning(&env_b, bucket_b).await?;
+    enable_bucket_versioning(&env_a, bucket_c).await?;
+
+    // A -> B first: the replica lands on B before B has any outbound rule.
+    let arn_ab = set_replication_target(&env_a, bucket_a, &env_b, bucket_b).await?;
+    put_bucket_replication(&env_a, bucket_a, &arn_ab).await?;
+
+    let replica_key = "replica-object.txt";
+    let replica_payload = "replica payload";
+    client_a
+        .put_object()
+        .bucket(bucket_a)
+        .key(replica_key)
+        .body(ByteStream::from_static(replica_payload.as_bytes()))
+        .send()
+        .await?;
+    wait_for_replicated_object(&client_b, bucket_b, replica_key, replica_payload).await?;
+
+    // Precondition for the anti-cascade contract: the inbound copy must carry
+    // REPLICA status on B. If this fails, the break is in inbound status
+    // stamping, not in the scanner guard.
+    let inbound = client_b.head_object().bucket(bucket_b).key(replica_key).send().await?;
+    assert_eq!(
+        inbound.replication_status().map(|status| status.as_str()),
+        Some("REPLICA"),
+        "inbound replica must be stamped REPLICA on the target"
+    );
+
+    // Now wire B's outbound rule; the replica is an "existing object" for it.
+    let arn_bc = set_replication_target(&env_b, bucket_b, &env_a, bucket_c).await?;
+    put_bucket_replication(&env_b, bucket_b, &arn_bc).await?;
+
+    // B's own native object flows onward through the live path.
+    let native_key = "native-control.txt";
+    let native_payload = "native control payload";
+    client_b
+        .put_object()
+        .bucket(bucket_b)
+        .key(native_key)
+        .body(ByteStream::from_static(native_payload.as_bytes()))
+        .send()
+        .await?;
+    wait_for_replicated_object(&client_a, bucket_c, native_key, native_payload).await?;
+
+    // With B's outbound proven, the inbound replica must stay put across
+    // multiple fast-scanner cycles.
+    assert_replication_key_absent(&client_a, bucket_c, replica_key, Duration::from_secs(6)).await?;
+
+    Ok(())
+}
diff --git a/rustfs/src/storage/options.rs b/rustfs/src/storage/options.rs
index b1df0f4db..e7fdd7120 100644
--- a/rustfs/src/storage/options.rs
+++ b/rustfs/src/storage/options.rs
@@ -450,6 +450,18 @@ fn apply_replica_status_from_headers(headers: &HeaderMap<HeaderValue>, opts: &mu
         .is_some_and(|status| status.eq_ignore_ascii_case(ReplicationStatusType::Replica.as_str()))
     {
         opts.set_replica_status(ReplicationStatusType::Replica);
+        // Persist REPLICA into the object metadata as well (mirrors the
+        // Snowball inbound path). The read side derives
+        // ObjectInfo::replication_status from this key, and must_replicate's
+        // anti-loop guard consumes it — without it, HEAD/GET report no
+        // status and the scanner's existing-object pass cascades the replica
+        // onward. `opts.delete_replication` alone only reaches delete flows.
+        opts.user_defined
+            .retain(|key, _| !key.eq_ignore_ascii_case(AMZ_BUCKET_REPLICATION_STATUS));
+        opts.user_defined.insert(
+            AMZ_BUCKET_REPLICATION_STATUS.to_string(),
+            ReplicationStatusType::Replica.as_str().to_string(),
+        );
     }
 }
 
@@ -1479,10 +1491,25 @@ mod tests {
         let opts = put_opts_from_headers(&headers, HashMap::new()).expect("replica status header should be ignored");
 
         assert_eq!(opts.delete_marker_replication_status(), ReplicationStatusType::Empty);
+        assert!(
+            !opts
+                .user_defined
+                .keys()
+                .any(|key| key.eq_ignore_ascii_case(AMZ_BUCKET_REPLICATION_STATUS)),
+            "an unauthorized client must not forge a persisted REPLICA status"
+        );
 
         let authorized = put_opts_from_headers_with_replication_authorization(&headers, HashMap::new(), true)
             .expect("authorized replica status header should parse");
         assert_eq!(authorized.delete_marker_replication_status(), ReplicationStatusType::Replica);
+        // The status must reach the object metadata: the read side derives
+        // ObjectInfo::replication_status from this key and the scanner's
+        // anti-cascade guard consumes it.
+        assert_eq!(
+            authorized.user_defined.get(AMZ_BUCKET_REPLICATION_STATUS).map(String::as_str),
+            Some(ReplicationStatusType::Replica.as_str()),
+            "authorized inbound replication must persist REPLICA into object metadata"
+        );
     }
 
     #[tokio::test]
@@ -1522,10 +1549,27 @@ mod tests {
         let opts = get_complete_multipart_upload_opts(&headers).expect("replica status header should be ignored");
 
         assert_eq!(opts.delete_marker_replication_status(), ReplicationStatusType::Empty);
+        assert!(
+            !opts
+                .user_defined
+                .keys()
+                .any(|key| key.eq_ignore_ascii_case(AMZ_BUCKET_REPLICATION_STATUS)),
+            "an unauthorized client must not forge a persisted REPLICA status"
+        );
 
         let authorized = get_complete_multipart_upload_opts_with_replication_authorization(&headers, true)
             .expect("authorized replica status header should parse");
         assert_eq!(authorized.delete_marker_replication_status(), ReplicationStatusType::Replica);
+        // For multipart the on-disk stamp actually comes from the SAME header
+        // at initiate time (create-multipart builds its options through
+        // put_opts_with_replication_authorization and persists user_defined
+        // into the upload's metadata); the completion-time insert asserted
+        // here feeds the anti-cascade must_replicate check on completion.
+        assert_eq!(
+            authorized.user_defined.get(AMZ_BUCKET_REPLICATION_STATUS).map(String::as_str),
+            Some(ReplicationStatusType::Replica.as_str()),
+            "authorized inbound multipart completion must carry REPLICA in its metadata"
+        );
     }
 
     #[test]