diff --git a/dev_tools/catalog_gallery/linux/flutter/generated_plugins.cmake b/dev_tools/catalog_gallery/linux/flutter/generated_plugins.cmake
index 8e2a1900c..a2eef970f 100644
--- a/dev_tools/catalog_gallery/linux/flutter/generated_plugins.cmake
+++ b/dev_tools/catalog_gallery/linux/flutter/generated_plugins.cmake
@@ -8,6 +8,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  jni
 )
 
 set(PLUGIN_BUNDLED_LIBRARIES)
diff --git a/dev_tools/catalog_gallery/macos/Flutter/GeneratedPluginRegistrant.swift b/dev_tools/catalog_gallery/macos/Flutter/GeneratedPluginRegistrant.swift
index ad1073ab5..7b265476e 100644
--- a/dev_tools/catalog_gallery/macos/Flutter/GeneratedPluginRegistrant.swift
+++ b/dev_tools/catalog_gallery/macos/Flutter/GeneratedPluginRegistrant.swift
@@ -12,5 +12,5 @@ import video_player_avfoundation
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   AudioplayersDarwinPlugin.register(with: registry.registrar(forPlugin: "AudioplayersDarwinPlugin"))
   UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
-  FVPVideoPlayerPlugin.register(with: registry.registrar(forPlugin: "FVPVideoPlayerPlugin"))
+  VideoPlayerPlugin.register(with: registry.registrar(forPlugin: "VideoPlayerPlugin"))
 }
diff --git a/dev_tools/composer/linux/flutter/generated_plugins.cmake b/dev_tools/composer/linux/flutter/generated_plugins.cmake
index c085ca836..a1bc1781f 100644
--- a/dev_tools/composer/linux/flutter/generated_plugins.cmake
+++ b/dev_tools/composer/linux/flutter/generated_plugins.cmake
@@ -10,6 +10,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  jni
 )
 
 set(PLUGIN_BUNDLED_LIBRARIES)
diff --git a/dev_tools/composer/macos/Flutter/GeneratedPluginRegistrant.swift b/dev_tools/composer/macos/Flutter/GeneratedPluginRegistrant.swift
index 802a33c8d..4825c9db2 100644
--- a/dev_tools/composer/macos/Flutter/GeneratedPluginRegistrant.swift
+++ b/dev_tools/composer/macos/Flutter/GeneratedPluginRegistrant.swift
@@ -15,6 +15,6 @@ func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   AudioplayersDarwinPlugin.register(with: registry.registrar(forPlugin: "AudioplayersDarwinPlugin"))
   ScreenRetrieverMacosPlugin.register(with: registry.registrar(forPlugin: "ScreenRetrieverMacosPlugin"))
   UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
-  FVPVideoPlayerPlugin.register(with: registry.registrar(forPlugin: "FVPVideoPlayerPlugin"))
+  VideoPlayerPlugin.register(with: registry.registrar(forPlugin: "VideoPlayerPlugin"))
   WindowManagerPlugin.register(with: registry.registrar(forPlugin: "WindowManagerPlugin"))
 }
diff --git a/dev_tools/composer/windows/flutter/generated_plugins.cmake b/dev_tools/composer/windows/flutter/generated_plugins.cmake
index f74fccabd..79fabcfb8 100644
--- a/dev_tools/composer/windows/flutter/generated_plugins.cmake
+++ b/dev_tools/composer/windows/flutter/generated_plugins.cmake
@@ -11,6 +11,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  jni
 )
 
 set(PLUGIN_BUNDLED_LIBRARIES)
diff --git a/examples/simple_chat/linux/flutter/generated_plugins.cmake b/examples/simple_chat/linux/flutter/generated_plugins.cmake
index 8e2a1900c..a2eef970f 100644
--- a/examples/simple_chat/linux/flutter/generated_plugins.cmake
+++ b/examples/simple_chat/linux/flutter/generated_plugins.cmake
@@ -8,6 +8,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  jni
 )
 
 set(PLUGIN_BUNDLED_LIBRARIES)
diff --git a/examples/simple_chat/macos/Flutter/GeneratedPluginRegistrant.swift b/examples/simple_chat/macos/Flutter/GeneratedPluginRegistrant.swift
index ad1073ab5..7b265476e 100644
--- a/examples/simple_chat/macos/Flutter/GeneratedPluginRegistrant.swift
+++ b/examples/simple_chat/macos/Flutter/GeneratedPluginRegistrant.swift
@@ -12,5 +12,5 @@ import video_player_avfoundation
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   AudioplayersDarwinPlugin.register(with: registry.registrar(forPlugin: "AudioplayersDarwinPlugin"))
   UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
-  FVPVideoPlayerPlugin.register(with: registry.registrar(forPlugin: "FVPVideoPlayerPlugin"))
+  VideoPlayerPlugin.register(with: registry.registrar(forPlugin: "VideoPlayerPlugin"))
 }
diff --git a/examples/simple_chat/windows/flutter/generated_plugins.cmake b/examples/simple_chat/windows/flutter/generated_plugins.cmake
index 97b61367a..158064786 100644
--- a/examples/simple_chat/windows/flutter/generated_plugins.cmake
+++ b/examples/simple_chat/windows/flutter/generated_plugins.cmake
@@ -9,6 +9,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  jni
 )
 
 set(PLUGIN_BUNDLED_LIBRARIES)
diff --git a/examples/verdure/client/linux/flutter/generated_plugins.cmake b/examples/verdure/client/linux/flutter/generated_plugins.cmake
index 04f81f4b4..ac700e247 100644
--- a/examples/verdure/client/linux/flutter/generated_plugins.cmake
+++ b/examples/verdure/client/linux/flutter/generated_plugins.cmake
@@ -9,6 +9,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  jni
 )
 
 set(PLUGIN_BUNDLED_LIBRARIES)
diff --git a/examples/verdure/client/macos/Flutter/GeneratedPluginRegistrant.swift b/examples/verdure/client/macos/Flutter/GeneratedPluginRegistrant.swift
index 074b04b4c..46b142243 100644
--- a/examples/verdure/client/macos/Flutter/GeneratedPluginRegistrant.swift
+++ b/examples/verdure/client/macos/Flutter/GeneratedPluginRegistrant.swift
@@ -16,5 +16,5 @@ func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   DeviceInfoPlusMacosPlugin.register(with: registry.registrar(forPlugin: "DeviceInfoPlusMacosPlugin"))
   FileSelectorPlugin.register(with: registry.registrar(forPlugin: "FileSelectorPlugin"))
   UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
-  FVPVideoPlayerPlugin.register(with: registry.registrar(forPlugin: "FVPVideoPlayerPlugin"))
+  VideoPlayerPlugin.register(with: registry.registrar(forPlugin: "VideoPlayerPlugin"))
 }
diff --git a/packages/genui/lib/src/facade/prompt_builder.dart b/packages/genui/lib/src/facade/prompt_builder.dart
index 77ecada7c..9abb5211d 100644
--- a/packages/genui/lib/src/facade/prompt_builder.dart
+++ b/packages/genui/lib/src/facade/prompt_builder.dart
@@ -131,7 +131,7 @@ enum ProtocolMessages {
     explanation: 'Creates a new surface.',
     properties: '''
 Requires `surfaceId` (you must always use a unique ID for each created surface),
-`catalogId` (use the catalog ID provided in system instructions),
+`catalogId` (use the active catalog ID if provided in system instructions),
 and `sendDataModel: true`.
 ''',
     // TODO: figure out why we instruct AI to always set sendDataModel: true,
@@ -284,7 +284,7 @@ You can control the UI by outputting valid A2UI JSON messages wrapped in markdow
     if (create)
       '''
 To create a new UI:
-1. Output a ${ProtocolMessages.createSurface.tickedName} message with a unique `surfaceId` and `catalogId` (use the catalog ID provided in system instructions).
+1. Output a ${ProtocolMessages.createSurface.tickedName} message with a unique `surfaceId` and `catalogId` (use the active catalog ID if provided in system instructions).
 2. Output an ${ProtocolMessages.updateComponents.tickedName} message with the `surfaceId` and the component definitions.
 ''',
     if (!update)
@@ -363,9 +363,14 @@ final class _BasicPromptBuilder extends PromptBuilder {
       catalog,
     ).toJson(indent: '  ');
 
+    final String? activeCatalogId = catalog.catalogId;
+
     final fragments = <String>[
       ...systemPromptFragments,
       'Use the provided tools to respond to user using rich UI elements.',
+      if (activeCatalogId != null)
+        'The active catalog ID is: "$activeCatalogId". '
+            'You must use this catalog ID when creating surfaces.',
       ...technicalPossibilities.systemPromptFragment(),
       ...catalog.systemPromptFragments,
       ...allowedOperations.systemPromptFragments,
diff --git a/packages/genui/lib/src/model/a2ui_schemas.dart b/packages/genui/lib/src/model/a2ui_schemas.dart
index 29ba6feca..dbfc4835b 100644
--- a/packages/genui/lib/src/model/a2ui_schemas.dart
+++ b/packages/genui/lib/src/model/a2ui_schemas.dart
@@ -436,7 +436,12 @@ abstract final class A2uiSchemas {
         'the component tree.',
     properties: {
       surfaceIdKey: S.string(description: 'The unique ID for the surface.'),
-      'catalogId': S.string(description: 'The URI of the component catalog.'),
+      'catalogId': S.string(
+        description:
+            'A string that uniquely identifies this catalog. This is typically '
+            'a URI, but the URI is never accessed, only used as a unique '
+            'identifier.',
+      ),
       'theme': S.object(
         description: 'Theme parameters for the surface.',
         additionalProperties: true,
diff --git a/packages/genui/test/facade/prompt_builder_test.dart b/packages/genui/test/facade/prompt_builder_test.dart
index dc573fdc5..cbb04f1ef 100644
--- a/packages/genui/test/facade/prompt_builder_test.dart
+++ b/packages/genui/test/facade/prompt_builder_test.dart
@@ -123,4 +123,22 @@ void main() {
       });
     }
   });
+
+  group('Catalog ID', () {
+    test('is surfaced in system prompt when provided', () {
+      final catalog = Catalog([
+        BasicCatalogItems.text,
+      ], catalogId: 'my_custom_catalog');
+      final builder = PromptBuilder.chat(catalog: catalog);
+      final String prompt = builder.systemPromptJoined();
+      expect(prompt, contains('The active catalog ID is: "my_custom_catalog"'));
+    });
+
+    test('is not surfaced in system prompt when not provided', () {
+      final catalog = Catalog([BasicCatalogItems.text]);
+      final builder = PromptBuilder.chat(catalog: catalog);
+      final String prompt = builder.systemPromptJoined();
+      expect(prompt, isNot(contains('The active catalog ID is:')));
+    });
+  });
 }
diff --git a/packages/genui/test/facade/prompt_builder_test.golden/all_operations_with_dataModel_false.txt b/packages/genui/test/facade/prompt_builder_test.golden/all_operations_with_dataModel_false.txt
index 55f3a5978..3d27339c3 100644
--- a/packages/genui/test/facade/prompt_builder_test.golden/all_operations_with_dataModel_false.txt
+++ b/packages/genui/test/facade/prompt_builder_test.golden/all_operations_with_dataModel_false.txt
@@ -16,6 +16,10 @@ Use the provided tools to respond to user using rich UI elements.
 
 -------------------------------------
 
+The active catalog ID is: "test_catalog". You must use this catalog ID when creating surfaces.
+
+-------------------------------------
+
 IMPORTANT: You do not have the ability to execute code. If you need to perform calculations, do them yourself.
 
 -------------------------------------
@@ -100,14 +104,14 @@ Supported messages are: `createSurface`, `updateComponents`, `deleteSurface`.
 Properties:
 
 - `createSurface`: Requires `surfaceId` (you must always use a unique ID for each created surface),
-`catalogId` (use the catalog ID provided in system instructions),
+`catalogId` (use the active catalog ID if provided in system instructions),
 and `sendDataModel: true`.
 - `updateComponents`: Requires `surfaceId` and a list of `components`.
 One component MUST have `id: "root"`.
 - `deleteSurface`: Requires `surfaceId`.
 
 To create a new UI:
-1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the catalog ID provided in system instructions).
+1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the active catalog ID if provided in system instructions).
 2. Output an `updateComponents` message with the `surfaceId` and the component definitions.
 
 To update an existing UI:
@@ -147,7 +151,7 @@ When constructing UI, you must output a VALID A2UI JSON object representing one
             },
             "catalogId": {
               "type": "string",
-              "description": "The URI of the component catalog."
+              "description": "A string that uniquely identifies this catalog. It is recommended to prefix this with an internet domain that you own, to avoid conflicts e.g. 'mycompany.com:somecatalog'."
             },
             "theme": {
               "type": "object",
diff --git a/packages/genui/test/facade/prompt_builder_test.golden/all_operations_with_dataModel_true.txt b/packages/genui/test/facade/prompt_builder_test.golden/all_operations_with_dataModel_true.txt
index 37e522f94..7661b3a97 100644
--- a/packages/genui/test/facade/prompt_builder_test.golden/all_operations_with_dataModel_true.txt
+++ b/packages/genui/test/facade/prompt_builder_test.golden/all_operations_with_dataModel_true.txt
@@ -16,6 +16,10 @@ Use the provided tools to respond to user using rich UI elements.
 
 -------------------------------------
 
+The active catalog ID is: "test_catalog". You must use this catalog ID when creating surfaces.
+
+-------------------------------------
+
 IMPORTANT: You do not have the ability to execute code. If you need to perform calculations, do them yourself.
 
 -------------------------------------
@@ -101,7 +105,7 @@ Supported messages are: `createSurface`, `updateComponents`, `deleteSurface`, `u
 Properties:
 
 - `createSurface`: Requires `surfaceId` (you must always use a unique ID for each created surface),
-`catalogId` (use the catalog ID provided in system instructions),
+`catalogId` (use the active catalog ID if provided in system instructions),
 and `sendDataModel: true`.
 - `updateComponents`: Requires `surfaceId` and a list of `components`.
 One component MUST have `id: "root"`.
@@ -109,7 +113,7 @@ One component MUST have `id: "root"`.
 - `updateDataModel`: Requires `surfaceId`, `path` and `value`.
 
 To create a new UI:
-1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the catalog ID provided in system instructions).
+1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the active catalog ID if provided in system instructions).
 2. Output an `updateComponents` message with the `surfaceId` and the component definitions.
 
 To update an existing UI:
@@ -149,7 +153,7 @@ When constructing UI, you must output a VALID A2UI JSON object representing one
             },
             "catalogId": {
               "type": "string",
-              "description": "The URI of the component catalog."
+              "description": "A string that uniquely identifies this catalog. It is recommended to prefix this with an internet domain that you own, to avoid conflicts e.g. 'mycompany.com:somecatalog'."
             },
             "theme": {
               "type": "object",
diff --git a/packages/genui/test/facade/prompt_builder_test.golden/create_and_update_with_dataModel_false.txt b/packages/genui/test/facade/prompt_builder_test.golden/create_and_update_with_dataModel_false.txt
index 6dd36efd5..dd3adc395 100644
--- a/packages/genui/test/facade/prompt_builder_test.golden/create_and_update_with_dataModel_false.txt
+++ b/packages/genui/test/facade/prompt_builder_test.golden/create_and_update_with_dataModel_false.txt
@@ -16,6 +16,10 @@ Use the provided tools to respond to user using rich UI elements.
 
 -------------------------------------
 
+The active catalog ID is: "test_catalog". You must use this catalog ID when creating surfaces.
+
+-------------------------------------
+
 IMPORTANT: You do not have the ability to execute code. If you need to perform calculations, do them yourself.
 
 -------------------------------------
@@ -99,13 +103,13 @@ Supported messages are: `createSurface`, `updateComponents`.
 Properties:
 
 - `createSurface`: Requires `surfaceId` (you must always use a unique ID for each created surface),
-`catalogId` (use the catalog ID provided in system instructions),
+`catalogId` (use the active catalog ID if provided in system instructions),
 and `sendDataModel: true`.
 - `updateComponents`: Requires `surfaceId` and a list of `components`.
 One component MUST have `id: "root"`.
 
 To create a new UI:
-1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the catalog ID provided in system instructions).
+1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the active catalog ID if provided in system instructions).
 2. Output an `updateComponents` message with the `surfaceId` and the component definitions.
 
 To update an existing UI:
@@ -145,7 +149,7 @@ When constructing UI, you must output a VALID A2UI JSON object representing one
             },
             "catalogId": {
               "type": "string",
-              "description": "The URI of the component catalog."
+              "description": "A string that uniquely identifies this catalog. It is recommended to prefix this with an internet domain that you own, to avoid conflicts e.g. 'mycompany.com:somecatalog'."
             },
             "theme": {
               "type": "object",
diff --git a/packages/genui/test/facade/prompt_builder_test.golden/create_and_update_with_dataModel_true.txt b/packages/genui/test/facade/prompt_builder_test.golden/create_and_update_with_dataModel_true.txt
index cdc0a60ad..c23b0e23b 100644
--- a/packages/genui/test/facade/prompt_builder_test.golden/create_and_update_with_dataModel_true.txt
+++ b/packages/genui/test/facade/prompt_builder_test.golden/create_and_update_with_dataModel_true.txt
@@ -16,6 +16,10 @@ Use the provided tools to respond to user using rich UI elements.
 
 -------------------------------------
 
+The active catalog ID is: "test_catalog". You must use this catalog ID when creating surfaces.
+
+-------------------------------------
+
 IMPORTANT: You do not have the ability to execute code. If you need to perform calculations, do them yourself.
 
 -------------------------------------
@@ -100,14 +104,14 @@ Supported messages are: `createSurface`, `updateComponents`, `updateDataModel`.
 Properties:
 
 - `createSurface`: Requires `surfaceId` (you must always use a unique ID for each created surface),
-`catalogId` (use the catalog ID provided in system instructions),
+`catalogId` (use the active catalog ID if provided in system instructions),
 and `sendDataModel: true`.
 - `updateComponents`: Requires `surfaceId` and a list of `components`.
 One component MUST have `id: "root"`.
 - `updateDataModel`: Requires `surfaceId`, `path` and `value`.
 
 To create a new UI:
-1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the catalog ID provided in system instructions).
+1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the active catalog ID if provided in system instructions).
 2. Output an `updateComponents` message with the `surfaceId` and the component definitions.
 
 To update an existing UI:
@@ -147,7 +151,7 @@ When constructing UI, you must output a VALID A2UI JSON object representing one
             },
             "catalogId": {
               "type": "string",
-              "description": "The URI of the component catalog."
+              "description": "A string that uniquely identifies this catalog. It is recommended to prefix this with an internet domain that you own, to avoid conflicts e.g. 'mycompany.com:somecatalog'."
             },
             "theme": {
               "type": "object",
diff --git a/packages/genui/test/facade/prompt_builder_test.golden/create_only_with_dataModel_false.txt b/packages/genui/test/facade/prompt_builder_test.golden/create_only_with_dataModel_false.txt
index fda9dd04c..d35089698 100644
--- a/packages/genui/test/facade/prompt_builder_test.golden/create_only_with_dataModel_false.txt
+++ b/packages/genui/test/facade/prompt_builder_test.golden/create_only_with_dataModel_false.txt
@@ -16,6 +16,10 @@ Use the provided tools to respond to user using rich UI elements.
 
 -------------------------------------
 
+The active catalog ID is: "test_catalog". You must use this catalog ID when creating surfaces.
+
+-------------------------------------
+
 IMPORTANT: You do not have the ability to execute code. If you need to perform calculations, do them yourself.
 
 -------------------------------------
@@ -99,13 +103,13 @@ Supported messages are: `createSurface`, `updateComponents`.
 Properties:
 
 - `createSurface`: Requires `surfaceId` (you must always use a unique ID for each created surface),
-`catalogId` (use the catalog ID provided in system instructions),
+`catalogId` (use the active catalog ID if provided in system instructions),
 and `sendDataModel: true`.
 - `updateComponents`: Requires `surfaceId` and a list of `components`.
 One component MUST have `id: "root"`.
 
 To create a new UI:
-1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the catalog ID provided in system instructions).
+1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the active catalog ID if provided in system instructions).
 2. Output an `updateComponents` message with the `surfaceId` and the component definitions.
 
 IMPORTANT: DO NOT update or modify surfaces created in previous turns. If the UI needs to change, you MUST create a NEW surface with a new unique `surfaceId`. You may only use `updateComponents` to populate the components of a freshly created surface.
@@ -144,7 +148,7 @@ When constructing UI, you must output a VALID A2UI JSON object representing one
             },
             "catalogId": {
               "type": "string",
-              "description": "The URI of the component catalog."
+              "description": "A string that uniquely identifies this catalog. It is recommended to prefix this with an internet domain that you own, to avoid conflicts e.g. 'mycompany.com:somecatalog'."
             },
             "theme": {
               "type": "object",
diff --git a/packages/genui/test/facade/prompt_builder_test.golden/create_only_with_dataModel_true.txt b/packages/genui/test/facade/prompt_builder_test.golden/create_only_with_dataModel_true.txt
index 75f6319ff..0ae7dfeed 100644
--- a/packages/genui/test/facade/prompt_builder_test.golden/create_only_with_dataModel_true.txt
+++ b/packages/genui/test/facade/prompt_builder_test.golden/create_only_with_dataModel_true.txt
@@ -16,6 +16,10 @@ Use the provided tools to respond to user using rich UI elements.
 
 -------------------------------------
 
+The active catalog ID is: "test_catalog". You must use this catalog ID when creating surfaces.
+
+-------------------------------------
+
 IMPORTANT: You do not have the ability to execute code. If you need to perform calculations, do them yourself.
 
 -------------------------------------
@@ -100,14 +104,14 @@ Supported messages are: `createSurface`, `updateComponents`, `updateDataModel`.
 Properties:
 
 - `createSurface`: Requires `surfaceId` (you must always use a unique ID for each created surface),
-`catalogId` (use the catalog ID provided in system instructions),
+`catalogId` (use the active catalog ID if provided in system instructions),
 and `sendDataModel: true`.
 - `updateComponents`: Requires `surfaceId` and a list of `components`.
 One component MUST have `id: "root"`.
 - `updateDataModel`: Requires `surfaceId`, `path` and `value`.
 
 To create a new UI:
-1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the catalog ID provided in system instructions).
+1. Output a `createSurface` message with a unique `surfaceId` and `catalogId` (use the active catalog ID if provided in system instructions).
 2. Output an `updateComponents` message with the `surfaceId` and the component definitions.
 
 IMPORTANT: DO NOT update or modify surfaces created in previous turns. If the UI needs to change, you MUST create a NEW surface with a new unique `surfaceId`. You may only use `updateComponents` to populate the components of a freshly created surface.
@@ -146,7 +150,7 @@ When constructing UI, you must output a VALID A2UI JSON object representing one
             },
             "catalogId": {
               "type": "string",
-              "description": "The URI of the component catalog."
+              "description": "A string that uniquely identifies this catalog. It is recommended to prefix this with an internet domain that you own, to avoid conflicts e.g. 'mycompany.com:somecatalog'."
             },
             "theme": {
               "type": "object",
diff --git a/packages/genui/test/facade/prompt_builder_test.golden/update_only_with_dataModel_false.txt b/packages/genui/test/facade/prompt_builder_test.golden/update_only_with_dataModel_false.txt
index ca6bf4884..6f63a173a 100644
--- a/packages/genui/test/facade/prompt_builder_test.golden/update_only_with_dataModel_false.txt
+++ b/packages/genui/test/facade/prompt_builder_test.golden/update_only_with_dataModel_false.txt
@@ -16,6 +16,10 @@ Use the provided tools to respond to user using rich UI elements.
 
 -------------------------------------
 
+The active catalog ID is: "test_catalog". You must use this catalog ID when creating surfaces.
+
+-------------------------------------
+
 IMPORTANT: You do not have the ability to execute code. If you need to perform calculations, do them yourself.
 
 -------------------------------------
@@ -137,7 +141,7 @@ When constructing UI, you must output a VALID A2UI JSON object representing one
             },
             "catalogId": {
               "type": "string",
-              "description": "The URI of the component catalog."
+              "description": "A string that uniquely identifies this catalog. It is recommended to prefix this with an internet domain that you own, to avoid conflicts e.g. 'mycompany.com:somecatalog'."
             },
             "theme": {
               "type": "object",
diff --git a/packages/genui/test/facade/prompt_builder_test.golden/update_only_with_dataModel_true.txt b/packages/genui/test/facade/prompt_builder_test.golden/update_only_with_dataModel_true.txt
index e04604e4f..d85d3f55f 100644
--- a/packages/genui/test/facade/prompt_builder_test.golden/update_only_with_dataModel_true.txt
+++ b/packages/genui/test/facade/prompt_builder_test.golden/update_only_with_dataModel_true.txt
@@ -16,6 +16,10 @@ Use the provided tools to respond to user using rich UI elements.
 
 -------------------------------------
 
+The active catalog ID is: "test_catalog". You must use this catalog ID when creating surfaces.
+
+-------------------------------------
+
 IMPORTANT: You do not have the ability to execute code. If you need to perform calculations, do them yourself.
 
 -------------------------------------
@@ -139,7 +143,7 @@ When constructing UI, you must output a VALID A2UI JSON object representing one
             },
             "catalogId": {
               "type": "string",
-              "description": "The URI of the component catalog."
+              "description": "A string that uniquely identifies this catalog. It is recommended to prefix this with an internet domain that you own, to avoid conflicts e.g. 'mycompany.com:somecatalog'."
             },
             "theme": {
               "type": "object",