diff --git a/src/ui/src/builder/BuilderApp.vue b/src/ui/src/builder/BuilderApp.vue
index 3da4b1fbb..006b2f3a6 100644
--- a/src/ui/src/builder/BuilderApp.vue
+++ b/src/ui/src/builder/BuilderApp.vue
@@ -84,16 +84,6 @@
 					<BuilderPanelSwitcher class="panelSwitcher" />
 				</template>
 			</ShareResizeVertical>
-			<div
-				v-if="showDeprecationBanner"
-				aria-hidden="true"
-				class="deprecationDimmer"
-			/>
-			<div
-				v-if="showDeprecationBanner"
-				aria-hidden="true"
-				class="deprecationBlocker"
-			/>
 		</div>
 
 		<!-- INSTANCE TRACKERS -->
@@ -603,27 +593,6 @@ onUnmounted(() => {
 	display: grid;
 }
 
-.deprecationDimmer {
-	pointer-events: none;
-	position: absolute;
-	inset: 0;
-	z-index: 6;
-	background-color: #e4e7ed;
-	opacity: 0.65;
-}
-
-.deprecationBlocker {
-	pointer-events: all;
-	cursor: not-allowed;
-	position: absolute;
-	top: var(--builderTopBarHeight);
-	left: 0;
-	right: 0;
-	bottom: 0;
-	z-index: 6;
-	background: transparent;
-}
-
 .builderHeader {
 	grid-column: 1 / 3;
 	grid-row: 1;
diff --git a/src/ui/src/builder/BuilderDeprecationBanner.vue b/src/ui/src/builder/BuilderDeprecationBanner.vue
index 9e08982de..f2133f9aa 100644
--- a/src/ui/src/builder/BuilderDeprecationBanner.vue
+++ b/src/ui/src/builder/BuilderDeprecationBanner.vue
@@ -165,7 +165,7 @@ const body = computed(() => {
 	}
 	return props.isOrganizationAdmin
 		? "This legacy agent editor will no longer be available - migrate your agent to the new Agent Builder now."
-		: "This legacy agent editor will no longer be available - create a Playbook instead.";
+		: "This legacy agent editor will no longer be available - work with your Admin to migrate your agent to the new Agent Builder now.";
 });
 
 const migrateLabel = computed(() =>
@@ -237,7 +237,7 @@ function onPlaybookClick() {
 
 .BuilderDeprecationBanner__copy {
 	min-width: 0;
-	max-width: 720px;
+	max-width: calc(100% - 200px);
 	color: white;
 }
 
diff --git a/src/writer/serve.py b/src/writer/serve.py
index bd0ed7a65..e0c5fb1d9 100644
--- a/src/writer/serve.py
+++ b/src/writer/serve.py
@@ -41,6 +41,7 @@
 from pydantic import ValidationError
 from starlette.websockets import WebSocket, WebSocketDisconnect, WebSocketState
 
+import writer
 from writer import VERSION, abstract
 from writer.ai import Graph
 from writer.app_runner import AppRunner
@@ -136,6 +137,12 @@ async def lifespan(asgi_app: FastAPI):
         app_runner.hook_to_running_event_loop()
         app_runner.load()
 
+        # Register platform-level deprecation flags so the LaunchDarkly client
+        # evaluates them for every agent builder session. These are merged with
+        # any flags already set by the user application's main.py.
+        _PLATFORM_FLAGS = {"beforeDeprecationCutoffAbv2", "afterDeprecationCutoffAbv2"}
+        writer.Config.feature_flags = list(set(writer.Config.feature_flags) | _PLATFORM_FLAGS)
+
         if (
             on_load is not None
             and hasattr(asgi_app.state, "is_server_static_mounted")
diff --git a/tests/backend/test_serve.py b/tests/backend/test_serve.py
index 244681269..7a0b1b26e 100644
--- a/tests/backend/test_serve.py
+++ b/tests/backend/test_serve.py
@@ -236,7 +236,16 @@ def test_feature_flags(self):
                 "Content-Type": "application/json"
             })
             feature_flags = res.json().get("featureFlags")
-            assert feature_flags == ["blueprints", "flag_one", "flag_two", "api_trigger", 'cron_trigger', 'journal']
+            assert set(feature_flags) == {
+                "blueprints",
+                "flag_one",
+                "flag_two",
+                "api_trigger",
+                "cron_trigger",
+                "journal",
+                "beforeDeprecationCutoffAbv2",
+                "afterDeprecationCutoffAbv2",
+            }
 
     def test_get_cron_triggers_api(self):
         """