From 300739208d21a76541e2b7841cc63f61d1ec06cf Mon Sep 17 00:00:00 2001
From: Daniel Madrid <105010181+dannimad@users.noreply.github.com>
Date: Tue, 12 May 2026 23:27:00 +0000
Subject: [PATCH] chore(container-loader): tighten snapshot refresh config flag
 gating

Drop the Fluid.Container.enableOfflineFull fallback from
SnapshotRefresher's #snapshotRefreshEnabled gating. Snapshot refresh
now requires Fluid.Container.enableOfflineSnapshotRefresh=true to be
opted into explicitly. Adds a unit test pinning the new behavior.
---
 .../container-loader/src/snapshotRefresher.ts |  3 +--
 .../src/test/snapshotRefresher.spec.ts        | 23 +++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/packages/loader/container-loader/src/snapshotRefresher.ts b/packages/loader/container-loader/src/snapshotRefresher.ts
index 66d880429456..25d427b7f0db 100644
--- a/packages/loader/container-loader/src/snapshotRefresher.ts
+++ b/packages/loader/container-loader/src/snapshotRefresher.ts
@@ -97,8 +97,7 @@ export class SnapshotRefresher implements IDisposable {
 
 		this.#snapshotRefreshEnabled =
 			this.offlineLoadEnabled &&
-			(this.mc.config.getBoolean("Fluid.Container.enableOfflineSnapshotRefresh") ??
-				this.mc.config.getBoolean("Fluid.Container.enableOfflineFull")) === true;
+			(this.mc.config.getBoolean("Fluid.Container.enableOfflineSnapshotRefresh") ?? false);
 
 		this.refreshTimer = this.#snapshotRefreshEnabled
 			? new Timer(this.snapshotRefreshTimeoutMs, () => this.tryRefreshSnapshot())
diff --git a/packages/loader/container-loader/src/test/snapshotRefresher.spec.ts b/packages/loader/container-loader/src/test/snapshotRefresher.spec.ts
index 690abedda409..3772fac60faf 100644
--- a/packages/loader/container-loader/src/test/snapshotRefresher.spec.ts
+++ b/packages/loader/container-loader/src/test/snapshotRefresher.spec.ts
@@ -60,6 +60,12 @@ function enableOfflineSnapshotRefresh(logger: ITelemetryBaseLogger): ITelemetryB
 	}).logger;
 }
 
+function enableOfflineFullOnly(logger: ITelemetryBaseLogger): ITelemetryBaseLogger {
+	return mixinMonitoringContext(logger, {
+		getRawConfig: (name) => (name === "Fluid.Container.enableOfflineFull" ? true : undefined),
+	}).logger;
+}
+
 class MockStorageAdapter implements ISerializedStateManagerDocumentStorageService {
 	public readonly blobs = new Map<string, ArrayBuffer>();
 	private snapshot: ISnapshotTree;
@@ -329,6 +335,23 @@ describe("SnapshotRefresher", () => {
 
 			refresher.dispose();
 		});
+
+		it("should not trigger refresh when only enableOfflineFull is set", () => {
+			const logger = enableOfflineFullOnly(mockLogger);
+			const timeout = 1000;
+			const refresher = createRefresher(true, () => true, timeout, logger);
+
+			refresher.startTimer();
+			clock.tick(timeout);
+
+			assert.strictEqual(
+				mockStorage.getVersionsCallCount,
+				0,
+				"getVersions should not be called when only enableOfflineFull is set (enableOfflineSnapshotRefresh must be opted in explicitly)",
+			);
+
+			refresher.dispose();
+		});
 	});
 
 	describe("tryRefreshSnapshot", () => {