fix: improve Gemini model configuration consistency

- Fix inconsistent logic in CodeIndexSettings where Gemini was incorrectly included in OpenAI model fallback
- Add clarifying comment for hardcoded Gemini embedding dimension (768) in service-factory

Author: SannidhyaSah

src/services/code-index/service-factory.ts

@@ -85,7 +85,7 @@ export class CodeIndexServiceFactory {
 				vectorSize = getModelDimension(provider, modelId)
 			}
 		} else if (provider === "gemini") {
-			// Gemini has a fixed dimension of 768
+			// Gemini's text-embedding-004 has a fixed dimension of 768
 			vectorSize = 768
 		} else {
 			vectorSize = getModelDimension(provider, modelId)

webview-ui/src/components/settings/CodeIndexSettings.tsx

@@ -63,12 +63,11 @@ export const CodeIndexSettings: React.FC<CodeIndexSettingsProps> = ({
 	// Safely calculate available models for current provider
 	const currentProvider = codebaseIndexConfig?.codebaseIndexEmbedderProvider
 	const modelsForProvider =
-		currentProvider === "openai" ||
-		currentProvider === "ollama" ||
-		currentProvider === "openai-compatible" ||
 		currentProvider === "gemini"
-			? codebaseIndexModels?.[currentProvider] || codebaseIndexModels?.openai
-			: codebaseIndexModels?.openai
+			? undefined // or an empty array, since Gemini has a fixed model
+			: currentProvider === "openai" || currentProvider === "openai-compatible"
+				? (codebaseIndexModels?.openai ?? codebaseIndexModels?.["openai-compatible"])
+				: codebaseIndexModels?.[currentProvider as keyof typeof codebaseIndexModels]
 	const availableModelIds = Object.keys(modelsForProvider || {})
 
 	useEffect(() => {