diff --git a/js/genkit/src/genkit.ts b/js/genkit/src/genkit.ts
index f2892a4fa6..0f40fab8d0 100644
--- a/js/genkit/src/genkit.ts
+++ b/js/genkit/src/genkit.ts
@@ -945,11 +945,16 @@ export class Genkit implements HasRegistry {
           },
           async listActions() {
             if (typeof plugin.list === 'function') {
-              return (await plugin.list()).map((a) => ({
-                ...a,
-                // Apply namespace for v2 plugins.
-                name: `${plugin.name}/${a.name}`,
-              }));
+              return (await plugin.list()).map((a) => {
+                if (a.name.startsWith(`${plugin.name}/`)) {
+                  return a;
+                }
+                return {
+                  ...a,
+                  // Apply namespace for v2 plugins.
+                  name: `${plugin.name}/${a.name}`,
+                };
+              });
             }
             return [];
           },
diff --git a/js/plugins/compat-oai/src/audio.ts b/js/plugins/compat-oai/src/audio.ts
index 041491b793..149054242d 100644
--- a/js/plugins/compat-oai/src/audio.ts
+++ b/js/plugins/compat-oai/src/audio.ts
@@ -17,11 +17,11 @@
 import type {
   GenerateRequest,
   GenerateResponseData,
-  Genkit,
   ModelReference,
 } from 'genkit';
 import { GenerationCommonConfigSchema, Message, modelRef, z } from 'genkit';
 import type { ModelAction, ModelInfo } from 'genkit/model';
+import { model } from 'genkit/plugin';
 import type OpenAI from 'openai';
 import { Response } from 'openai/core.mjs';
 import type {
@@ -181,19 +181,17 @@ async function toGenerateResponse(
 export function defineCompatOpenAISpeechModel<
   CustomOptions extends z.ZodTypeAny = z.ZodTypeAny,
 >(params: {
-  ai: Genkit;
   name: string;
   client: OpenAI;
   modelRef?: ModelReference<CustomOptions>;
   requestBuilder?: SpeechRequestBuilder;
 }): ModelAction {
-  const { ai, name, client, modelRef, requestBuilder } = params;
+  const { name, client, modelRef, requestBuilder } = params;
   const modelName = name.substring(name.indexOf('/') + 1);
 
-  return ai.defineModel(
+  return model(
     {
       name,
-      apiVersion: 'v2',
       ...modelRef?.info,
       configSchema: modelRef?.configSchema,
     },
@@ -335,18 +333,16 @@ function transcriptionToGenerateResponse(
 export function defineCompatOpenAITranscriptionModel<
   CustomOptions extends z.ZodTypeAny = z.ZodTypeAny,
 >(params: {
-  ai: Genkit;
   name: string;
   client: OpenAI;
   modelRef?: ModelReference<CustomOptions>;
   requestBuilder?: TranscriptionRequestBuilder;
 }): ModelAction {
-  const { ai, name, client, modelRef, requestBuilder } = params;
+  const { name, client, modelRef, requestBuilder } = params;
 
-  return ai.defineModel(
+  return model(
     {
       name,
-      apiVersion: 'v2',
       ...modelRef?.info,
       configSchema: modelRef?.configSchema,
     },
diff --git a/js/plugins/compat-oai/src/deepseek/index.ts b/js/plugins/compat-oai/src/deepseek/index.ts
index ae68f90887..126af7a58e 100644
--- a/js/plugins/compat-oai/src/deepseek/index.ts
+++ b/js/plugins/compat-oai/src/deepseek/index.ts
@@ -16,14 +16,13 @@
 
 import {
   ActionMetadata,
-  Genkit,
   GenkitError,
   modelActionMetadata,
   ModelReference,
   z,
 } from 'genkit';
 import { logger } from 'genkit/logging';
-import { GenkitPlugin } from 'genkit/plugin';
+import { GenkitPluginV2 } from 'genkit/plugin';
 import { ActionType } from 'genkit/registry';
 import OpenAI from 'openai';
 import { openAICompatible, PluginOptions } from '../index.js';
@@ -38,17 +37,15 @@ import {
 export type DeepSeekPluginOptions = Omit<PluginOptions, 'name' | 'baseURL'>;
 
 const resolver = async (
-  ai: Genkit,
   client: OpenAI,
   actionType: ActionType,
   actionName: string
 ) => {
   if (actionType === 'model') {
     const modelRef = deepSeekModelRef({
-      name: `deepseek/${actionName}`,
+      name: actionName,
     });
-    defineCompatOpenAIModel({
-      ai,
+    return defineCompatOpenAIModel({
       name: modelRef.name,
       client,
       modelRef,
@@ -56,6 +53,7 @@ const resolver = async (
     });
   } else {
     logger.warn('Only model actions are supported by the DeepSeek plugin');
+    return undefined;
   }
 };
 
@@ -67,7 +65,7 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
         const modelRef =
           SUPPORTED_DEEPSEEK_MODELS[model.id] ??
           deepSeekModelRef({
-            name: `deepseek/${model.id}`,
+            name: model.id,
           });
         return modelActionMetadata({
           name: modelRef.name,
@@ -78,7 +76,9 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
   );
 };
 
-export function deepSeekPlugin(options?: DeepSeekPluginOptions): GenkitPlugin {
+export function deepSeekPlugin(
+  options?: DeepSeekPluginOptions
+): GenkitPluginV2 {
   const apiKey = options?.apiKey ?? process.env.DEEPSEEK_API_KEY;
   if (!apiKey) {
     throw new GenkitError({
@@ -92,10 +92,9 @@ export function deepSeekPlugin(options?: DeepSeekPluginOptions): GenkitPlugin {
     baseURL: 'https://api.deepseek.com',
     apiKey,
     ...options,
-    initializer: async (ai, client) => {
-      Object.values(SUPPORTED_DEEPSEEK_MODELS).forEach((modelRef) =>
+    initializer: async (client) => {
+      return Object.values(SUPPORTED_DEEPSEEK_MODELS).map((modelRef) =>
         defineCompatOpenAIModel({
-          ai,
           name: modelRef.name,
           client,
           modelRef,
@@ -109,7 +108,7 @@ export function deepSeekPlugin(options?: DeepSeekPluginOptions): GenkitPlugin {
 }
 
 export type DeepSeekPlugin = {
-  (params?: DeepSeekPluginOptions): GenkitPlugin;
+  (params?: DeepSeekPluginOptions): GenkitPluginV2;
   model(
     name: keyof typeof SUPPORTED_DEEPSEEK_MODELS,
     config?: z.infer<typeof DeepSeekChatCompletionConfigSchema>
@@ -119,7 +118,7 @@ export type DeepSeekPlugin = {
 
 const model = ((name: string, config?: any): ModelReference<z.ZodTypeAny> => {
   return deepSeekModelRef({
-    name: `deepseek/${name}`,
+    name,
     config,
   });
 }) as DeepSeekPlugin['model'];
diff --git a/js/plugins/compat-oai/src/embedder.ts b/js/plugins/compat-oai/src/embedder.ts
index 2fab7e86fe..f4499eccad 100644
--- a/js/plugins/compat-oai/src/embedder.ts
+++ b/js/plugins/compat-oai/src/embedder.ts
@@ -17,7 +17,8 @@
 
 // import { defineEmbedder, embedderRef } from '@genkit-ai/ai/embedder';
 
-import type { EmbedderAction, EmbedderReference, Genkit } from 'genkit';
+import type { EmbedderAction, EmbedderReference } from 'genkit';
+import { embedder } from 'genkit/plugin';
 import OpenAI from 'openai';
 
 /**
@@ -34,25 +35,24 @@ import OpenAI from 'openai';
  * @returns the created {@link EmbedderAction}
  */
 export function defineCompatOpenAIEmbedder(params: {
-  ai: Genkit;
   name: string;
   client: OpenAI;
   embedderRef?: EmbedderReference;
 }): EmbedderAction {
-  const { ai, name, client, embedderRef } = params;
+  const { name, client, embedderRef } = params;
   const modelName = name.substring(name.indexOf('/') + 1);
 
-  return ai.defineEmbedder(
+  return embedder(
     {
       name,
       configSchema: embedderRef?.configSchema,
       ...embedderRef?.info,
     },
-    async (input, options) => {
-      const { encodingFormat: encoding_format, ...restOfConfig } = options;
+    async (req) => {
+      const { encodingFormat: encoding_format, ...restOfConfig } = req.options;
       const embeddings = await client.embeddings.create({
         model: modelName!,
-        input: input.map((d) => d.text),
+        input: req.input.map((d) => d.text),
         encoding_format,
         ...restOfConfig,
       });
diff --git a/js/plugins/compat-oai/src/image.ts b/js/plugins/compat-oai/src/image.ts
index ee195eac45..1754e5e0b0 100644
--- a/js/plugins/compat-oai/src/image.ts
+++ b/js/plugins/compat-oai/src/image.ts
@@ -17,11 +17,11 @@
 import type {
   GenerateRequest,
   GenerateResponseData,
-  Genkit,
   ModelReference,
 } from 'genkit';
 import { Message, modelRef, z } from 'genkit';
 import { ModelAction, ModelInfo } from 'genkit/model';
+import { model } from 'genkit/plugin';
 import OpenAI from 'openai';
 import type {
   ImageGenerateParams,
@@ -120,20 +120,18 @@ function toGenerateResponse(result: ImagesResponse): GenerateResponseData {
 export function defineCompatOpenAIImageModel<
   CustomOptions extends z.ZodTypeAny = z.ZodTypeAny,
 >(params: {
-  ai: Genkit;
   name: string;
   client: OpenAI;
   modelRef?: ModelReference<CustomOptions>;
   requestBuilder?: ImageRequestBuilder;
 }): ModelAction<CustomOptions> {
-  const { ai, name, client, modelRef, requestBuilder } = params;
+  const { name, client, modelRef, requestBuilder } = params;
   const modelName = name.substring(name.indexOf('/') + 1);
 
-  return ai.defineModel(
+  return model(
     {
       name,
       ...modelRef?.info,
-      apiVersion: 'v2',
       configSchema: modelRef?.configSchema,
     },
     async (request, { abortSignal }) => {
diff --git a/js/plugins/compat-oai/src/index.ts b/js/plugins/compat-oai/src/index.ts
index e5a40023f2..1c5a5d5ec1 100644
--- a/js/plugins/compat-oai/src/index.ts
+++ b/js/plugins/compat-oai/src/index.ts
@@ -14,10 +14,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { ActionMetadata, type Genkit } from 'genkit';
-import { genkitPlugin } from 'genkit/plugin';
+import { ActionMetadata } from 'genkit';
+import { ResolvableAction, genkitPluginV2 } from 'genkit/plugin';
 import { ActionType } from 'genkit/registry';
 import { OpenAI, type ClientOptions } from 'openai';
+import { compatOaiModelRef, defineCompatOpenAIModel } from './model.js';
 
 export {
   SpeechConfigSchema,
@@ -46,13 +47,12 @@ export {
 
 export interface PluginOptions extends Partial<ClientOptions> {
   name: string;
-  initializer?: (ai: Genkit, client: OpenAI) => Promise<void>;
+  initializer?: (client: OpenAI) => Promise<ResolvableAction[]>;
   resolver?: (
-    ai: Genkit,
     client: OpenAI,
     actionType: ActionType,
     actionName: string
-  ) => Promise<void>;
+  ) => Promise<ResolvableAction | undefined> | ResolvableAction | undefined;
   listActions?: (client: OpenAI) => Promise<ActionMetadata[]>;
 }
 
@@ -110,29 +110,41 @@ export interface PluginOptions extends Partial<ClientOptions> {
  */
 export const openAICompatible = (options: PluginOptions) => {
   let listActionsCache;
-  return genkitPlugin(
-    options.name,
-    async (ai: Genkit) => {
-      if (options.initializer) {
-        const client = new OpenAI(options);
-        await options.initializer(ai, client);
+  return genkitPluginV2({
+    name: options.name,
+    async init() {
+      if (!options.initializer) {
+        return [];
       }
+      const client = new OpenAI(options);
+      return await options.initializer(client);
     },
-    async (ai: Genkit, actionType: ActionType, actionName: string) => {
+    async resolve(actionType: ActionType, actionName: string) {
+      const client = new OpenAI(options);
       if (options.resolver) {
-        const client = new OpenAI(options);
-        await options.resolver(ai, client, actionType, actionName);
+        return await options.resolver(client, actionType, actionName);
+      } else {
+        if (actionType === 'model') {
+          return defineCompatOpenAIModel({
+            name: actionName,
+            client,
+            modelRef: compatOaiModelRef({
+              name: actionName,
+            }),
+          });
+        }
+        return undefined;
       }
     },
-    options.listActions
+    list: options.listActions
       ? async () => {
           if (listActionsCache) return listActionsCache;
           const client = new OpenAI(options);
           listActionsCache = await options.listActions!(client);
           return listActionsCache;
         }
-      : undefined
-  );
+      : undefined,
+  });
 };
 
 export default openAICompatible;
diff --git a/js/plugins/compat-oai/src/model.ts b/js/plugins/compat-oai/src/model.ts
index 4300e630ca..09fde93026 100644
--- a/js/plugins/compat-oai/src/model.ts
+++ b/js/plugins/compat-oai/src/model.ts
@@ -19,7 +19,6 @@ import type {
   GenerateRequest,
   GenerateResponseChunkData,
   GenerateResponseData,
-  Genkit,
   MessageData,
   ModelReference,
   Part,
@@ -29,6 +28,7 @@ import type {
 } from 'genkit';
 import { GenerationCommonConfigSchema, Message, modelRef, z } from 'genkit';
 import type { ModelAction, ModelInfo, ToolDefinition } from 'genkit/model';
+import { model } from 'genkit/plugin';
 import type OpenAI from 'openai';
 import type {
   ChatCompletion,
@@ -485,19 +485,17 @@ export function openAIModelRunner(
 export function defineCompatOpenAIModel<
   CustomOptions extends z.ZodTypeAny = z.ZodTypeAny,
 >(params: {
-  ai: Genkit;
   name: string;
   client: OpenAI;
   modelRef?: ModelReference<CustomOptions>;
   requestBuilder?: ModelRequestBuilder;
 }): ModelAction {
-  const { ai, name, client, modelRef, requestBuilder } = params;
+  const { name, client, modelRef, requestBuilder } = params;
   const modelName = name.substring(name.indexOf('/') + 1);
 
-  return ai.defineModel(
+  return model(
     {
       name,
-      apiVersion: 'v2',
       ...modelRef?.info,
       configSchema: modelRef?.configSchema,
     },
diff --git a/js/plugins/compat-oai/src/openai/index.ts b/js/plugins/compat-oai/src/openai/index.ts
index 7709fd6f9a..a9358602ee 100644
--- a/js/plugins/compat-oai/src/openai/index.ts
+++ b/js/plugins/compat-oai/src/openai/index.ts
@@ -20,12 +20,11 @@ import {
   embedderActionMetadata,
   embedderRef,
   EmbedderReference,
-  Genkit,
   modelActionMetadata,
   ModelReference,
   z,
 } from 'genkit';
-import { GenkitPlugin } from 'genkit/plugin';
+import { GenkitPluginV2, ResolvableAction } from 'genkit/plugin';
 import { ActionType } from 'genkit/registry';
 import OpenAI from 'openai';
 import {
@@ -66,23 +65,25 @@ export type OpenAIPluginOptions = Omit<PluginOptions, 'name' | 'baseURL'>;
 const UNSUPPORTED_MODEL_MATCHERS = ['babbage', 'davinci', 'codex'];
 
 const resolver = async (
-  ai: Genkit,
   client: OpenAI,
   actionType: ActionType,
   actionName: string
 ) => {
   if (actionType === 'embedder') {
-    defineCompatOpenAIEmbedder({ ai, name: `openai/${actionName}`, client });
+    return defineCompatOpenAIEmbedder({ name: actionName, client });
   } else if (
     actionName.includes('gpt-image-1') ||
     actionName.includes('dall-e')
   ) {
-    const modelRef = openAIImageModelRef({ name: `openai/${actionName}` });
-    defineCompatOpenAIImageModel({ ai, name: modelRef.name, client, modelRef });
+    const modelRef = openAIImageModelRef({ name: actionName });
+    return defineCompatOpenAIImageModel({
+      name: modelRef.name,
+      client,
+      modelRef,
+    });
   } else if (actionName.includes('tts')) {
-    const modelRef = openAISpeechModelRef({ name: `openai/${actionName}` });
-    defineCompatOpenAISpeechModel({
-      ai,
+    const modelRef = openAISpeechModelRef({ name: actionName });
+    return defineCompatOpenAISpeechModel({
       name: modelRef.name,
       client,
       modelRef,
@@ -92,18 +93,16 @@ const resolver = async (
     actionName.includes('transcribe')
   ) {
     const modelRef = openAITranscriptionModelRef({
-      name: `openai/${actionName}`,
+      name: actionName,
     });
-    defineCompatOpenAITranscriptionModel({
-      ai,
+    return defineCompatOpenAITranscriptionModel({
       name: modelRef.name,
       client,
       modelRef,
     });
   } else {
-    const modelRef = openAIModelRef({ name: `openai/${actionName}` });
-    defineCompatOpenAIModel({
-      ai,
+    const modelRef = openAIModelRef({ name: actionName });
+    return defineCompatOpenAIModel({
       name: modelRef.name,
       client,
       modelRef,
@@ -120,7 +119,7 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
     response.data.filter(filterOpenAiModels).map((model: OpenAI.Model) => {
       if (model.id.includes('embedding')) {
         return embedderActionMetadata({
-          name: `openai/${model.id}`,
+          name: model.id,
           configSchema: TextEmbeddingConfigSchema,
           info: SUPPORTED_EMBEDDING_MODELS[model.id]?.info,
         });
@@ -130,7 +129,7 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
       ) {
         const modelRef =
           SUPPORTED_IMAGE_MODELS[model.id] ??
-          openAIImageModelRef({ name: `openai/${model.id}` });
+          openAIImageModelRef({ name: model.id });
         return modelActionMetadata({
           name: modelRef.name,
           info: modelRef.info,
@@ -139,7 +138,7 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
       } else if (model.id.includes('tts')) {
         const modelRef =
           SUPPORTED_TTS_MODELS[model.id] ??
-          openAISpeechModelRef({ name: `openai/${model.id}` });
+          openAISpeechModelRef({ name: model.id });
         return modelActionMetadata({
           name: modelRef.name,
           info: modelRef.info,
@@ -151,7 +150,7 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
       ) {
         const modelRef =
           SUPPORTED_STT_MODELS[model.id] ??
-          openAITranscriptionModelRef({ name: `openai/${model.id}` });
+          openAITranscriptionModelRef({ name: model.id });
         return modelActionMetadata({
           name: modelRef.name,
           info: modelRef.info,
@@ -159,8 +158,7 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
         });
       } else {
         const modelRef =
-          SUPPORTED_GPT_MODELS[model.id] ??
-          openAIModelRef({ name: `openai/${model.id}` });
+          SUPPORTED_GPT_MODELS[model.id] ?? openAIModelRef({ name: model.id });
         return modelActionMetadata({
           name: modelRef.name,
           info: modelRef.info,
@@ -171,49 +169,57 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
   );
 };
 
-export function openAIPlugin(options?: OpenAIPluginOptions): GenkitPlugin {
+export function openAIPlugin(options?: OpenAIPluginOptions): GenkitPluginV2 {
   return openAICompatible({
     name: 'openai',
     ...options,
-    initializer: async (ai, client) => {
-      Object.values(SUPPORTED_GPT_MODELS).forEach((modelRef) =>
-        defineCompatOpenAIModel({ ai, name: modelRef.name, client, modelRef })
+    initializer: async (client) => {
+      const models = [] as ResolvableAction[];
+      models.push(
+        ...Object.values(SUPPORTED_GPT_MODELS).map((modelRef) =>
+          defineCompatOpenAIModel({ name: modelRef.name, client, modelRef })
+        )
       );
-      Object.values(SUPPORTED_EMBEDDING_MODELS).forEach((embedderRef) =>
-        defineCompatOpenAIEmbedder({
-          ai,
-          name: embedderRef.name,
-          client,
-          embedderRef,
-        })
+      models.push(
+        ...Object.values(SUPPORTED_EMBEDDING_MODELS).map((embedderRef) =>
+          defineCompatOpenAIEmbedder({
+            name: embedderRef.name,
+            client,
+            embedderRef,
+          })
+        )
       );
-      Object.values(SUPPORTED_TTS_MODELS).forEach((modelRef) =>
-        defineCompatOpenAISpeechModel({
-          ai,
-          name: modelRef.name,
-          client,
-          modelRef,
-        })
+      models.push(
+        ...Object.values(SUPPORTED_TTS_MODELS).map((modelRef) =>
+          defineCompatOpenAISpeechModel({
+            name: modelRef.name,
+            client,
+            modelRef,
+          })
+        )
       );
-      Object.values(SUPPORTED_STT_MODELS).forEach((modelRef) =>
-        defineCompatOpenAITranscriptionModel({
-          ai,
-          name: modelRef.name,
-          client,
-          modelRef,
-        })
+      models.push(
+        ...Object.values(SUPPORTED_STT_MODELS).map((modelRef) =>
+          defineCompatOpenAITranscriptionModel({
+            name: modelRef.name,
+            client,
+            modelRef,
+          })
+        )
       );
-      Object.values(SUPPORTED_IMAGE_MODELS).forEach((modelRef) =>
-        defineCompatOpenAIImageModel({
-          ai,
-          name: modelRef.name,
-          client,
-          modelRef,
-          requestBuilder: modelRef.name.includes('gpt-image-1')
-            ? gptImage1RequestBuilder
-            : undefined,
-        })
+      models.push(
+        ...Object.values(SUPPORTED_IMAGE_MODELS).map((modelRef) =>
+          defineCompatOpenAIImageModel({
+            name: modelRef.name,
+            client,
+            modelRef,
+            requestBuilder: modelRef.name.includes('gpt-image-1')
+              ? gptImage1RequestBuilder
+              : undefined,
+          })
+        )
       );
+      return models;
     },
     resolver,
     listActions,
@@ -221,7 +227,7 @@ export function openAIPlugin(options?: OpenAIPluginOptions): GenkitPlugin {
 }
 
 export type OpenAIPlugin = {
-  (params?: OpenAIPluginOptions): GenkitPlugin;
+  (params?: OpenAIPluginOptions): GenkitPluginV2;
   model(
     name:
       | keyof typeof SUPPORTED_GPT_MODELS
@@ -263,24 +269,24 @@ export type OpenAIPlugin = {
 const model = ((name: string, config?: any): ModelReference<z.ZodTypeAny> => {
   if (name.includes('gpt-image-1') || name.includes('dall-e')) {
     return openAIImageModelRef({
-      name: `openai/${name}`,
+      name,
       config,
     });
   }
   if (name.includes('tts')) {
     return openAISpeechModelRef({
-      name: `openai/${name}`,
+      name,
       config,
     });
   }
   if (name.includes('whisper') || name.includes('transcribe')) {
     return openAITranscriptionModelRef({
-      name: `openai/${name}`,
+      name,
       config,
     });
   }
   return openAIModelRef({
-    name: `openai/${name}`,
+    name,
     config,
   });
 }) as OpenAIPlugin['model'];
@@ -290,7 +296,7 @@ const embedder = ((
   config?: any
 ): EmbedderReference<z.ZodTypeAny> => {
   return embedderRef({
-    name: `openai/${name}`,
+    name,
     config,
     configSchema: TextEmbeddingConfigSchema,
   });
diff --git a/js/plugins/compat-oai/src/xai/index.ts b/js/plugins/compat-oai/src/xai/index.ts
index 3bd72534c4..8a4bf6a4b3 100644
--- a/js/plugins/compat-oai/src/xai/index.ts
+++ b/js/plugins/compat-oai/src/xai/index.ts
@@ -16,14 +16,13 @@
 
 import {
   ActionMetadata,
-  Genkit,
   GenkitError,
   modelActionMetadata,
   ModelReference,
   z,
 } from 'genkit';
 import { logger } from 'genkit/logging';
-import { GenkitPlugin } from 'genkit/plugin';
+import { GenkitPluginV2, ResolvableAction } from 'genkit/plugin';
 import { ActionType } from 'genkit/registry';
 import OpenAI from 'openai';
 import {
@@ -43,15 +42,13 @@ import {
 export type XAIPluginOptions = Omit<PluginOptions, 'name' | 'baseURL'>;
 
 const resolver = async (
-  ai: Genkit,
   client: OpenAI,
   actionType: ActionType,
   actionName: string
 ) => {
   if (actionType === 'model') {
-    const modelRef = xaiModelRef({ name: `xai/${actionName}` });
-    defineCompatOpenAIModel({
-      ai,
+    const modelRef = xaiModelRef({ name: actionName });
+    return defineCompatOpenAIModel({
       name: modelRef.name,
       client,
       modelRef,
@@ -60,6 +57,7 @@ const resolver = async (
   } else {
     logger.warn('Only model actions are supported by the XAI plugin');
   }
+  return undefined;
 };
 
 const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
@@ -70,7 +68,7 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
         if (model.id.includes('image')) {
           const modelRef =
             SUPPORTED_IMAGE_MODELS[model.id] ??
-            xaiImageModelRef({ name: `xai/${model.id}` });
+            xaiImageModelRef({ name: model.id });
           return modelActionMetadata({
             name: modelRef.name,
             info: modelRef.info,
@@ -79,7 +77,7 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
         } else {
           const modelRef =
             SUPPORTED_LANGUAGE_MODELS[model.id] ??
-            xaiModelRef({ name: `xai/${model.id}` });
+            xaiModelRef({ name: model.id });
           return modelActionMetadata({
             name: modelRef.name,
             info: modelRef.info,
@@ -90,7 +88,7 @@ const listActions = async (client: OpenAI): Promise<ActionMetadata[]> => {
   );
 };
 
-export function xAIPlugin(options?: XAIPluginOptions): GenkitPlugin {
+export function xAIPlugin(options?: XAIPluginOptions): GenkitPluginV2 {
   const apiKey = options?.apiKey ?? process.env.XAI_API_KEY;
   if (!apiKey) {
     throw new GenkitError({
@@ -104,24 +102,28 @@ export function xAIPlugin(options?: XAIPluginOptions): GenkitPlugin {
     baseURL: 'https://api.x.ai/v1',
     apiKey,
     ...options,
-    initializer: async (ai, client) => {
-      Object.values(SUPPORTED_LANGUAGE_MODELS).forEach((modelRef) =>
-        defineCompatOpenAIModel({
-          ai,
-          name: modelRef.name,
-          client,
-          modelRef,
-          requestBuilder: grokRequestBuilder,
-        })
+    initializer: async (client) => {
+      const models = [] as ResolvableAction[];
+      models.push(
+        ...Object.values(SUPPORTED_LANGUAGE_MODELS).map((modelRef) =>
+          defineCompatOpenAIModel({
+            name: modelRef.name,
+            client,
+            modelRef,
+            requestBuilder: grokRequestBuilder,
+          })
+        )
       );
-      Object.values(SUPPORTED_IMAGE_MODELS).forEach((modelRef) =>
-        defineCompatOpenAIImageModel({
-          ai,
-          name: modelRef.name,
-          client,
-          modelRef,
-        })
+      models.push(
+        ...Object.values(SUPPORTED_IMAGE_MODELS).map((modelRef) =>
+          defineCompatOpenAIImageModel({
+            name: modelRef.name,
+            client,
+            modelRef,
+          })
+        )
       );
+      return models;
     },
     resolver,
     listActions,
@@ -129,7 +131,7 @@ export function xAIPlugin(options?: XAIPluginOptions): GenkitPlugin {
 }
 
 export type XAIPlugin = {
-  (params?: XAIPluginOptions): GenkitPlugin;
+  (params?: XAIPluginOptions): GenkitPluginV2;
   model(
     name: keyof typeof SUPPORTED_LANGUAGE_MODELS,
     config?: z.infer<typeof XaiChatCompletionConfigSchema>
@@ -144,12 +146,12 @@ export type XAIPlugin = {
 const model = ((name: string, config?: any): ModelReference<z.ZodTypeAny> => {
   if (name.includes('image')) {
     return xaiImageModelRef({
-      name: `xai/${name}`,
+      name,
       config,
     });
   }
   return xaiModelRef({
-    name: `xai/${name}`,
+    name,
     config,
   });
 }) as XAIPlugin['model'];
diff --git a/js/plugins/compat-oai/tests/openai_test.ts b/js/plugins/compat-oai/tests/openai_test.ts
index 1653a07ea3..a5ee506fec 100644
--- a/js/plugins/compat-oai/tests/openai_test.ts
+++ b/js/plugins/compat-oai/tests/openai_test.ts
@@ -15,15 +15,8 @@
  * limitations under the License.
  */
 
-import {
-  afterEach,
-  beforeEach,
-  describe,
-  expect,
-  it,
-  jest,
-} from '@jest/globals';
-import { modelRef, type GenerateRequest, type Genkit } from 'genkit';
+import { afterEach, describe, expect, it, jest } from '@jest/globals';
+import { modelRef, type GenerateRequest } from 'genkit/model';
 import type OpenAI from 'openai';
 
 import {
@@ -32,116 +25,89 @@ import {
   toOpenAIRequestBody,
 } from '../src/model';
 
-jest.mock('@genkit-ai/ai/model', () => ({
-  ...(jest.requireActual('@genkit-ai/ai/model') as Record<string, unknown>),
-  defineModel: jest.fn(),
-}));
-
 describe('gptModel', () => {
-  let ai: Genkit;
-
-  beforeEach(() => {
-    ai = {
-      defineModel: jest.fn(),
-    } as unknown as Genkit;
-  });
-
   afterEach(() => {
     jest.clearAllMocks();
   });
 
   it('should correctly define supported GPT models', () => {
-    jest.spyOn(ai, 'defineModel').mockImplementation((() => ({})) as any);
-    defineCompatOpenAIModel({
-      ai,
+    const model = defineCompatOpenAIModel({
       name: 'openai/gpt-4o',
       client: {} as OpenAI,
       modelRef: testModelRef('openai/gpt-4o'),
     });
-    expect(ai.defineModel).toHaveBeenCalledWith(
-      {
-        name: 'openai/gpt-4o',
-        supports: {
-          multiturn: true,
-          tools: true,
-          media: true,
-          systemRole: true,
-          output: ['text', 'json'],
-        },
-        configSchema: ChatCompletionCommonConfigSchema,
-        apiVersion: 'v2',
+    expect({
+      name: model.__action.name,
+      supports: model.__action.metadata?.model.supports,
+    }).toStrictEqual({
+      name: 'openai/gpt-4o',
+      supports: {
+        multiturn: true,
+        tools: true,
+        media: true,
+        systemRole: true,
+        output: ['text', 'json'],
       },
-      expect.any(Function)
-    );
+    });
   });
 
   it('should correctly define gpt-4.1, gpt-4.1-mini, and gpt-4.1-nano', () => {
-    jest.spyOn(ai, 'defineModel').mockImplementation((() => ({})) as any);
-    defineCompatOpenAIModel({
-      ai,
+    const gpt41 = defineCompatOpenAIModel({
       name: 'openai/gpt-4.1',
       client: {} as OpenAI,
       modelRef: testModelRef('openai/gpt-4.1'),
     });
-    expect(ai.defineModel).toHaveBeenCalledWith(
-      {
-        name: 'openai/gpt-4.1',
-        supports: {
-          multiturn: true,
-          tools: true,
-          media: true,
-          systemRole: true,
-          output: ['text', 'json'],
-        },
-        configSchema: ChatCompletionCommonConfigSchema,
-        apiVersion: 'v2',
+    expect({
+      name: gpt41.__action.name,
+      supports: gpt41.__action.metadata?.model.supports,
+    }).toStrictEqual({
+      name: 'openai/gpt-4.1',
+      supports: {
+        multiturn: true,
+        tools: true,
+        media: true,
+        systemRole: true,
+        output: ['text', 'json'],
       },
-      expect.any(Function)
-    );
+    });
 
-    defineCompatOpenAIModel({
-      ai,
+    const gpt41mini = defineCompatOpenAIModel({
       name: 'openai/gpt-4.1-mini',
       client: {} as OpenAI,
       modelRef: testModelRef('openai/gpt-4.1-mini'),
     });
-    expect(ai.defineModel).toHaveBeenCalledWith(
-      {
-        name: 'openai/gpt-4.1-mini',
-        supports: {
-          multiturn: true,
-          tools: true,
-          media: true,
-          systemRole: true,
-          output: ['text', 'json'],
-        },
-        configSchema: ChatCompletionCommonConfigSchema,
-        apiVersion: 'v2',
+    expect({
+      name: gpt41mini.__action.name,
+      supports: gpt41mini.__action.metadata?.model.supports,
+    }).toStrictEqual({
+      name: 'openai/gpt-4.1-mini',
+      supports: {
+        multiturn: true,
+        tools: true,
+        media: true,
+        systemRole: true,
+        output: ['text', 'json'],
       },
-      expect.any(Function)
-    );
+    });
 
-    defineCompatOpenAIModel({
-      ai,
+    const gpt41nano = defineCompatOpenAIModel({
       name: 'openai/gpt-4.1-nano',
       client: {} as OpenAI,
       modelRef: testModelRef('openai/gpt-4.1-nano'),
     });
-    expect(ai.defineModel).toHaveBeenCalledWith(
-      {
-        name: 'openai/gpt-4.1-nano',
-        supports: {
-          multiturn: true,
-          tools: true,
-          media: true,
-          systemRole: true,
-          output: ['text', 'json'],
-        },
-        configSchema: ChatCompletionCommonConfigSchema,
-        apiVersion: 'v2',
+    expect({
+      name: gpt41nano.__action.name,
+      supports: gpt41nano.__action.metadata?.model.supports,
+    }).toStrictEqual({
+      name: 'openai/gpt-4.1-nano',
+      supports: {
+        multiturn: true,
+        tools: true,
+        media: true,
+        systemRole: true,
+        output: ['text', 'json'],
       },
-      expect.any(Function)
-    );
+    });
   });
 });
 
diff --git a/js/testapps/compat-oai/src/index.ts b/js/testapps/compat-oai/src/index.ts
index 00f65290e5..10fde22780 100644
--- a/js/testapps/compat-oai/src/index.ts
+++ b/js/testapps/compat-oai/src/index.ts
@@ -40,17 +40,16 @@ const ai = genkit({
       name: 'openrouter',
       baseURL: 'https://openrouter.ai/api/v1',
       apiKey: process.env['OPENROUTER_API_KEY'],
-      initializer: async (ai, client) => {
-        for (const model of DECLARED_MODELS) {
+      async initializer(client) {
+        return DECLARED_MODELS.map((model) =>
           defineCompatOpenAIModel({
-            ai,
             name: `openrouter/${model}`,
             client,
             modelRef: compatOaiModelRef({
               name: `openrouter/${model}`,
             }),
-          });
-        }
+          })
+        );
       },
     }),
   ],