fix: add frontend model discovery pipeline for litellm provider

Add API route, contract, query hook case, and ProviderModelsLoader
entry so litellm models are fetched and synced to the store on
workspace load, matching the vllm/ollama/openrouter/fireworks pattern.

Also fixes defaultModel to empty string and adds litellm/ prefix
early-return in blocks/utils.ts (reviewer feedback).

Author: RheagalFire

apps/sim/app/api/providers/litellm/models/route.ts

@@ -0,0 +1,70 @@
+import { createLogger } from '@sim/logger'
+import { getErrorMessage } from '@sim/utils/errors'
+import { type NextRequest, NextResponse } from 'next/server'
+import {
+  providerModelsResponseSchema,
+  vllmUpstreamResponseSchema,
+} from '@/lib/api/contracts/providers'
+import { env } from '@/lib/core/config/env'
+import { withRouteHandler } from '@/lib/core/utils/with-route-handler'
+import { filterBlacklistedModels, isProviderBlacklisted } from '@/providers/utils'
+
+const logger = createLogger('LiteLLMModelsAPI')
+
+export const GET = withRouteHandler(async (_request: NextRequest) => {
+  if (isProviderBlacklisted('litellm')) {
+    logger.info('LiteLLM provider is blacklisted, returning empty models')
+    return NextResponse.json({ models: [] })
+  }
+
+  const baseUrl = (env.LITELLM_BASE_URL || '').replace(/\/$/, '')
+
+  if (!baseUrl) {
+    logger.info('LITELLM_BASE_URL not configured')
+    return NextResponse.json({ models: [] })
+  }
+
+  try {
+    logger.info('Fetching LiteLLM models', { baseUrl })
+
+    const headers: Record<string, string> = {
+      'Content-Type': 'application/json',
+    }
+
+    if (env.LITELLM_API_KEY) {
+      headers.Authorization = `Bearer ${env.LITELLM_API_KEY}`
+    }
+
+    const response = await fetch(`${baseUrl}/v1/models`, {
+      headers,
+      next: { revalidate: 60 },
+    })
+
+    if (!response.ok) {
+      logger.warn('LiteLLM service is not available', {
+        status: response.status,
+        statusText: response.statusText,
+      })
+      return NextResponse.json({ models: [] })
+    }
+
+    const data = vllmUpstreamResponseSchema.parse(await response.json())
+    const allModels = data.data.map((model) => `litellm/${model.id}`)
+    const models = filterBlacklistedModels(allModels)
+
+    logger.info('Successfully fetched LiteLLM models', {
+      count: models.length,
+      filtered: allModels.length - models.length,
+      models,
+    })
+
+    return NextResponse.json(providerModelsResponseSchema.parse({ models }))
+  } catch (error) {
+    logger.error('Failed to fetch LiteLLM models', {
+      error: getErrorMessage(error, 'Unknown error'),
+      baseUrl,
+    })
+
+    return NextResponse.json({ models: [] })
+  }
+})

apps/sim/app/workspace/[workspaceId]/providers/provider-models-loader.tsx

@@ -6,6 +6,7 @@ import { useParams } from 'next/navigation'
 import { useProviderModels } from '@/hooks/queries/providers'
 import {
   updateFireworksProviderModels,
+  updateLiteLLMProviderModels,
   updateOllamaProviderModels,
   updateOpenRouterProviderModels,
   updateVLLMProviderModels,
@@ -32,6 +33,8 @@ function useSyncProvider(provider: ProviderName, workspaceId?: string) {
         updateOllamaProviderModels(data.models)
       } else if (provider === 'vllm') {
         updateVLLMProviderModels(data.models)
+      } else if (provider === 'litellm') {
+        updateLiteLLMProviderModels(data.models)
       } else if (provider === 'openrouter') {
         void updateOpenRouterProviderModels(data.models)
         if (data.modelInfo) {
@@ -61,6 +64,7 @@ export function ProviderModelsLoader() {
   useSyncProvider('base')
   useSyncProvider('ollama')
   useSyncProvider('vllm')
+  useSyncProvider('litellm')
   useSyncProvider('openrouter')
   useSyncProvider('fireworks', workspaceId)
   return null

apps/sim/blocks/utils.ts

@@ -160,7 +160,7 @@ function shouldRequireApiKeyForModel(model: string): boolean {
   ) {
     return false
   }
-  if (normalizedModel.startsWith('vllm/')) {
+  if (normalizedModel.startsWith('vllm/') || normalizedModel.startsWith('litellm/')) {
     return false
   }
 

apps/sim/hooks/queries/providers.ts

@@ -5,6 +5,7 @@ import { requestJson } from '@/lib/api/client/request'
 import {
   getBaseProviderModelsContract,
   getFireworksProviderModelsContract,
+  getLitellmProviderModelsContract,
   getOllamaProviderModelsContract,
   getOpenRouterProviderModelsContract,
   getVllmProviderModelsContract,
@@ -54,6 +55,8 @@ async function requestProviderModels(
       return requestJson(getOllamaProviderModelsContract, { signal })
     case 'vllm':
       return requestJson(getVllmProviderModelsContract, { signal })
+    case 'litellm':
+      return requestJson(getLitellmProviderModelsContract, { signal })
     case 'openrouter':
       return requestJson(getOpenRouterProviderModelsContract, { signal })
     case 'fireworks':

apps/sim/lib/api/contracts/providers.ts

@@ -207,6 +207,15 @@ export const getOpenRouterProviderModelsContract = defineRouteContract({
   },
 })
 
+export const getLitellmProviderModelsContract = defineRouteContract({
+  method: 'GET',
+  path: '/api/providers/litellm/models',
+  response: {
+    mode: 'json',
+    schema: providerModelsResponseSchema,
+  },
+})
+
 export const getFireworksProviderModelsContract = defineRouteContract({
   method: 'GET',
   path: '/api/providers/fireworks/models',

apps/sim/providers/models.ts

@@ -131,7 +131,7 @@ export const PROVIDER_DEFINITIONS: Record<string, ProviderDefinition> = {
     name: 'LiteLLM',
     icon: LitellmIcon,
     description: 'LiteLLM proxy with an OpenAI-compatible API',
-    defaultModel: 'litellm/generic',
+    defaultModel: '',
     modelPatterns: [/^litellm\//],
     capabilities: {
       temperature: { min: 0, max: 2 },