feat(server): gemini embedding 2 support (#14956)

#### PR Dependency Tree


* **PR #14956** 👈

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## Summary by CodeRabbit

## Release Notes

* **Bug Fixes**
* Improved Gemini Vertex provider configuration validation logic for
enhanced reliability.
  * Refined Google Vertex publisher base URL construction handling.

* **Tests**
  * Added test coverage for Gemini Embedding 2 model resolution.
* Added test coverage for Gemini Vertex provider Google Cloud
integration.

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Cargo.lock

@@ -3625,9 +3625,9 @@ dependencies = [
 
 [[package]]
 name = "llm_adapter"
-version = "0.2.5"
+version = "0.2.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c6e139f0a1609d6078293140fb7e281cf2bd5a45a7a29ef39f8606c803be7822"
+checksum = "8ca30267ba36e247d1ff7a916a03db2ceb1de7f0bfcab7250cde006cdda68c19"
 dependencies = [
  "base64",
  "jsonschema",

packages/backend/native/src/llm/core/model_registry.rs

@@ -111,6 +111,21 @@ mod tests {
     assert_eq!(response.variant.unwrap().raw_model_id, "gemini-embedding-001");
   }
 
+  #[test]
+  fn should_resolve_gemini_embedding_2() {
+    let response = llm_resolve_model_registry_variant(ModelRegistryResolveRequest {
+      backend_kind: Some("gemini_api".to_string()),
+      model_id: "gemini-embedding-2".to_string(),
+    })
+    .unwrap();
+    let variant = response.variant.unwrap();
+
+    assert_eq!(variant.raw_model_id, "gemini-embedding-2");
+    assert_eq!(variant.protocol.as_deref(), Some("gemini"));
+    assert_eq!(variant.request_layer.as_deref(), Some("gemini_api"));
+    assert_eq!(variant.display_name.as_deref(), Some("Gemini Embedding 2"));
+  }
+
   #[test]
   fn should_keep_same_raw_id_as_two_backend_variants() {
     let api_variant = llm_resolve_model_registry_variant(ModelRegistryResolveRequest {

packages/backend/server/src/__tests__/copilot/native-provider.spec.ts

@@ -25,6 +25,7 @@ import {
   type PromptMessage,
   type StreamObject,
 } from '../../plugins/copilot/providers/types';
+import { getVertexGoogleBaseUrl } from '../../plugins/copilot/providers/utils';
 import {
   buildPromptStructuredResponseFromFields,
   buildStructuredResponseContract,
@@ -1823,6 +1824,17 @@ test('GeminiVertexProvider should prefetch bearer token for native config', asyn
   t.snapshot(config);
 });
 
+test('GeminiVertexProvider should build project scoped Vertex base URL', t => {
+  t.is(
+    getVertexGoogleBaseUrl({
+      project: 'p1',
+      location: 'us-central1',
+      googleAuthOptions: {},
+    }),
+    'https://us-central1-aiplatform.googleapis.com/v1/projects/p1/locations/us-central1/publishers/google'
+  );
+});
+
 test('GeminiVertexProvider should materialize remote attachments before native text path', async t => {
   const cases = [
     {

packages/backend/server/src/plugins/copilot/providers/gemini/vertex.ts

@@ -1,7 +1,11 @@
 import type { LlmBackendConfig } from '../../../../native';
 import type { CopilotProviderExecution } from '../provider-runtime-contract';
 import { CopilotProviderType } from '../types';
-import { getGoogleAuth, type VertexProviderConfig } from '../utils';
+import {
+  getGoogleAuth,
+  getVertexGoogleBaseUrl,
+  type VertexProviderConfig,
+} from '../utils';
 import { GeminiProvider } from './gemini';
 
 export type GeminiVertexConfig = VertexProviderConfig;
@@ -10,7 +14,7 @@ export class GeminiVertexProvider extends GeminiProvider<GeminiVertexConfig> {
   override readonly type = CopilotProviderType.GeminiVertex;
   override configured(execution?: CopilotProviderExecution): boolean {
     const config = this.getConfig(execution);
-    return !!config.location && !!config.googleAuthOptions;
+    return !!getVertexGoogleBaseUrl(config) && !!config.googleAuthOptions;
   }
   protected async resolveVertexAuth(execution?: CopilotProviderExecution) {
     return await getGoogleAuth(this.getConfig(execution), 'google');

packages/backend/server/src/plugins/copilot/providers/utils.ts

@@ -403,18 +403,22 @@ export function getVertexAnthropicBaseUrl(options: VertexProviderConfig) {
   return `https://${location}-aiplatform.googleapis.com/v1/projects/${project}/locations/${location}/publishers/anthropic`;
 }
 
+export function getVertexGoogleBaseUrl(options: VertexProviderConfig) {
+  const normalizedBaseUrl = normalizeUrl(options.baseURL);
+  if (normalizedBaseUrl) return normalizedBaseUrl;
+  const { location, project } = options;
+  if (!location || !project) return undefined;
+  return `https://${location}-aiplatform.googleapis.com/v1/projects/${project}/locations/${location}/publishers/google`;
+}
+
 export async function getGoogleAuth(
   options: VertexProviderConfig,
   publisher: 'anthropic' | 'google'
 ) {
   function getBaseUrl() {
-    const normalizedBaseUrl = normalizeUrl(options.baseURL);
-    if (normalizedBaseUrl) return normalizedBaseUrl;
-    const { location } = options;
-    if (location) {
-      return `https://${location}-aiplatform.googleapis.com/v1beta1/publishers/${publisher}`;
-    }
-    return undefined;
+    return publisher === 'google'
+      ? getVertexGoogleBaseUrl(options)
+      : getVertexAnthropicBaseUrl(options);
   }
 
   async function generateAuthToken() {