diff --git a/CHANGELOG.md b/CHANGELOG.md
index ebf882167..4f6601c07 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,7 +18,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - Read paths: an object at or below `policy.inline_max_bytes` (16 MiB by default) is teed to the client and to the local store in a single source read; a larger object or a Range read streams through and a background pull stores the whole object. A HEAD miss is proxied to the source and stores nothing (`policy.head = local_only` disables it). Every source-backed response carries `x-rustfs-on-demand-migration: source`
   - Protections: a per-source circuit breaker, a per-key negative cache, singleflight per key, a concurrency limit and a bounded pull queue shared by the inline and background paths, an optional bandwidth limit, an anti-loop request marker, and the shared outbound-endpoint (SSRF) policy
   - Metrics under `rustfs_on_demand_migration_*` (`requests_total`, `pulled_bytes_total`, `pulled_objects_total`, `pull_failures_total`, `inflight_pulls`, `queue_depth`, `source_latency_seconds_*`, `breaker_state`), mirrored per node by the admin status route
-  - Limitations: listings show only local objects (the source is not merged into `ListObjectsV2`); PUT and DELETE never reach the source; a source object updated after it was pulled is not re-fetched; SSE-C source objects are unsupported and answer 424; `Last-Modified` on a pulled object is the local write time, with the source timestamp kept in metadata
+  - Listings: `ListObjects` v1 remains local with ordinary key markers. `ListObjectsV2` can merge source objects when `policy.list_through = true`; this is off by default
+  - Upgrade and rollback: finish upgrading every node before enabling ODM. An rc.5 node that writes bucket configuration drops the ODM fields from metadata; neither a later restart nor moving the service out of ECStore recovers them. Before rollback, disable ODM and securely retain the original full configuration and credentials. After every node returns to a compatible version, restore and validate that configuration. Redacted exports cannot replace the credential backup; source-only objects are unavailable through RustFS while ODM is disabled. See the upgrade and rollback section of `docs/operations/on-demand-migration.md`
+  - Optional Google dependencies: default and `full` server builds retain native GCS support. `cargo build -p rustfs --no-default-features --features ftps,webdav` excludes Google SDKs while preserving configuration decoding and redaction; native GCS ODM and tier operations require the `gcs` feature. Do not use that build with existing GCS-tiered data
+  - Limitations: PUT and DELETE never reach the source; a source object updated after it was pulled is not re-fetched; SSE-C source objects are unsupported and answer 424; `Last-Modified` on a pulled object is the local write time, with the source timestamp kept in metadata
 - **NATS JetStream Publish Path**: Opt-in at-least-once delivery for the NATS notify and audit targets. A NATS Core publish flushes to the connection without awaiting a broker acknowledgement, so an event can be lost across a broker restart or a reconnect after the send queue has already cleared it. A queued event now clears only after the JetStream `PublishAck`, so bucket notifications survive those interruptions. Off by default and byte-identical to the NATS Core path when disabled.
   - Three configuration keys per target: `JETSTREAM_ENABLE`, `JETSTREAM_STREAM_NAME`, and `JETSTREAM_ACK_TIMEOUT_SECS`, under the `RUSTFS_NOTIFY_NATS_` and `RUSTFS_AUDIT_NATS_` prefixes
   - Durable store-and-forward with a stable dedup id sent as the `Nats-Msg-Id` header, so a replay after a crash is collapsed by the server duplicate window
diff --git a/rustfs/src/app/bucket_list_through.rs b/rustfs/src/app/bucket_list_through.rs
index 86497e36f..d4004c5bc 100644
--- a/rustfs/src/app/bucket_list_through.rs
+++ b/rustfs/src/app/bucket_list_through.rs
@@ -38,7 +38,6 @@ use crate::on_demand_migration::{
     SourceListRequest, SourceObject, SourcePage, decode_continuation_token, source_list_plan,
 };
 use futures::StreamExt;
-use http::HeaderMap;
 use rustfs_utils::http::{SUFFIX_SOURCE_PROXY_REQUEST, get_header};
 use std::sync::Arc;
 use std::time::Instant;
@@ -476,6 +475,7 @@ mod tests {
         FilterConfig, MAX_LIST_NO_PROGRESS_PAGES, OnDemandMigrationConfig, PathStyle, PolicyConfig, Provider, SourceConfig,
         SourceCredentials, TlsConfig,
     };
+    use http::HeaderMap;
     use std::time::Duration;
     use tokio::io::{AsyncReadExt, AsyncWriteExt};
 
diff --git a/rustfs/src/on_demand_migration/native_http.rs b/rustfs/src/on_demand_migration/native_http.rs
index ae084d084..9e1507ce1 100644
--- a/rustfs/src/on_demand_migration/native_http.rs
+++ b/rustfs/src/on_demand_migration/native_http.rs
@@ -133,6 +133,7 @@ impl NativeHttp {
         self.send_classified(request, error_code_header, false).await
     }
 
+    #[cfg(feature = "gcs")]
     pub(super) async fn send_object(
         &self,
         request: reqwest::Request,
@@ -210,6 +211,7 @@ pub(super) async fn read_text(response: reqwest::Response, max_bytes: usize) ->
 /// Base64 digest (`Content-MD5`, `md5Hash`, `x-goog-hash`) as lowercase hex.
 /// `None` when the value is not a 16-byte digest, so a CRC32C never passes as
 /// an MD5.
+#[cfg(any(test, feature = "gcs"))]
 pub(super) fn base64_md5_to_hex(value: &str) -> Option<String> {
     let raw = base64_simd::STANDARD.decode_to_vec(value.trim().as_bytes()).ok()?;
     (raw.len() == 16).then(|| faster_hex::hex_string(&raw))
diff --git a/rustfs/src/storage/access.rs b/rustfs/src/storage/access.rs
index faa98ad72..223a73383 100644
--- a/rustfs/src/storage/access.rs
+++ b/rustfs/src/storage/access.rs
@@ -4034,7 +4034,7 @@ mod tests {
             let enabled_before = sys.is_module_enabled();
             sys.set_module_enabled(true);
             let bucket = format!("odm-capture-failure-{}", uuid::Uuid::new_v4());
-            let mut config: crate::on_demand_migration::OnDemandMigrationConfig = serde_json::from_str(r#"{"source":{"provider":"minio","endpoint":"https://source.example.com","bucket":"source","credentials":{"access_key":"test","secret_key":"test"}}}"#).expect("source config");
+            let mut config: crate::on_demand_migration::OnDemandMigrationConfig = serde_json::from_str(r#"{"source":{"provider":"minio","endpoint":"https://source.example.com","region":"us-east-1","bucket":"source","credentials":{"access_key":"test","secret_key":"test"}}}"#).expect("source config");
             config.policy.list_through = true;
             sys.apply_for_incarnation(&bucket, uuid::Uuid::new_v4(), Some(&config)).await;
             let mut get = build_request(