feat: add Azure Foundry and Azure OpenAI provider support

docs/config/providers.mdx

@@ -16,32 +16,34 @@ Most providers only need an API key. The UI handles validation and shows which p
 
 ## Supported Providers
 
-| Provider       | Models                     | Get API Key                                             |
-| -------------- | -------------------------- | ------------------------------------------------------- |
-| **Anthropic**  | Claude Opus, Sonnet, Haiku | [console.anthropic.com](https://console.anthropic.com/) |
-| **OpenAI**     | GPT-5, Codex               | [platform.openai.com](https://platform.openai.com/)     |
-| **Google**     | Gemini Pro, Flash          | [aistudio.google.com](https://aistudio.google.com/)     |
-| **xAI**        | Grok                       | [console.x.ai](https://console.x.ai/)                   |
-| **DeepSeek**   | DeepSeek Chat, Reasoner    | [platform.deepseek.com](https://platform.deepseek.com/) |
-| **OpenRouter** | 300+ models                | [openrouter.ai](https://openrouter.ai/)                 |
-| **Ollama**     | Local models               | [ollama.com](https://ollama.com/) (no key needed)       |
-| **Bedrock**    | Claude via AWS             | AWS Console                                             |
+| Provider          | Models                     | Get API Key                                             |
+| ----------------- | -------------------------- | ------------------------------------------------------- |
+| **Anthropic**     | Claude Opus, Sonnet, Haiku | [console.anthropic.com](https://console.anthropic.com/) |
+| **Azure Foundry** | Claude via Azure Foundry   | [ai.azure.com](https://ai.azure.com/)                   |
+| **OpenAI**        | GPT-5, Codex               | [platform.openai.com](https://platform.openai.com/)     |
+| **Google**        | Gemini Pro, Flash          | [aistudio.google.com](https://aistudio.google.com/)     |
+| **xAI**           | Grok                       | [console.x.ai](https://console.x.ai/)                   |
+| **DeepSeek**      | DeepSeek Chat, Reasoner    | [platform.deepseek.com](https://platform.deepseek.com/) |
+| **OpenRouter**    | 300+ models                | [openrouter.ai](https://openrouter.ai/)                 |
+| **Ollama**        | Local models               | [ollama.com](https://ollama.com/) (no key needed)       |
+| **Bedrock**       | Claude via AWS             | AWS Console                                             |
 
 ## Environment Variables
 
 Providers also read from environment variables as fallback:
 
 {/* BEGIN PROVIDER_ENV_VARS */}
 
-| Provider   | Environment Variable                               |
-| ---------- | -------------------------------------------------- |
-| Anthropic  | `ANTHROPIC_API_KEY` or `ANTHROPIC_AUTH_TOKEN`      |
-| OpenAI     | `OPENAI_API_KEY`                                   |
-| Google     | `GOOGLE_GENERATIVE_AI_API_KEY` or `GOOGLE_API_KEY` |
-| xAI        | `XAI_API_KEY`                                      |
-| OpenRouter | `OPENROUTER_API_KEY`                               |
-| DeepSeek   | `DEEPSEEK_API_KEY`                                 |
-| Bedrock    | `AWS_REGION` (credentials via AWS SDK chain)       |
+| Provider      | Environment Variable                                  |
+| ------------- | ----------------------------------------------------- |
+| Anthropic     | `ANTHROPIC_API_KEY` or `ANTHROPIC_AUTH_TOKEN`         |
+| Azure Foundry | `AZURE_FOUNDRY_API_KEY` and `AZURE_FOUNDRY_RESOURCE` |
+| OpenAI        | `OPENAI_API_KEY`                                      |
+| Google        | `GOOGLE_GENERATIVE_AI_API_KEY` or `GOOGLE_API_KEY`   |
+| xAI           | `XAI_API_KEY`                                         |
+| OpenRouter    | `OPENROUTER_API_KEY`                                  |
+| DeepSeek      | `DEEPSEEK_API_KEY`                                    |
+| Bedrock       | `AWS_REGION` (credentials via AWS SDK chain)          |
 
 <details>
 <summary>Additional environment variables</summary>
@@ -95,6 +97,33 @@ For advanced options not exposed in the UI, edit `~/.mux/providers.jsonc` direct
 }
 ```
 
+### Azure Foundry
+
+Azure Foundry provides access to Claude models through Microsoft's AI marketplace. It uses Anthropic's native API format.
+
+```jsonc
+{
+  "azure-foundry": {
+    "apiKey": "your-azure-api-key",
+    "resource": "your-resource-name"  // Just the resource name, not full URL
+  }
+}
+```
+
+**Getting your credentials:**
+1. Go to [Azure AI Foundry](https://ai.azure.com/)
+2. Create a project and deploy a Claude model
+3. Find your resource name (e.g., `my-resource` from `https://my-resource.services.ai.azure.com/`)
+4. Copy your API key from the Keys section
+
+**Environment variables:**
+```bash
+export AZURE_FOUNDRY_RESOURCE=your-resource-name  # Just the name, not full URL
+export AZURE_FOUNDRY_API_KEY=your-azure-api-key
+```
+
+**Note:** Azure Foundry is separate from Azure OpenAI. All Claude features work identically: streaming, tool calling, thinking, and prompt caching.
+
 ### Bedrock Authentication
 
 Bedrock supports multiple authentication methods (tried in order):

src/browser/components/ProviderIcon.tsx

@@ -19,6 +19,7 @@ import { cn } from "@/common/lib/utils";
  */
 const PROVIDER_ICONS: Partial<Record<ProviderName, React.FC>> = {
   anthropic: AnthropicIcon,
+  "azure-foundry": AnthropicIcon, // Same icon as Anthropic (Claude branding)
   openai: OpenAIIcon,
   google: GoogleIcon,
   xai: XAIIcon,

src/browser/components/Settings/sections/ProvidersSection.tsx

@@ -116,6 +116,18 @@ function getProviderFields(provider: ProviderName): FieldConfig[] {
     return [];
   }
 
+  if (provider === "azure-foundry") {
+    return [
+      { key: "apiKey", label: "API Key", placeholder: "Enter API key", type: "secret" },
+      {
+        key: "resource",
+        label: "Resource",
+        placeholder: "your-resource-name",
+        type: "text",
+      },
+    ];
+  }
+
   // Default for most providers
   return [
     { key: "apiKey", label: "API Key", placeholder: "Enter API key", type: "secret" },
@@ -134,6 +146,7 @@ function getProviderFields(provider: ProviderName): FieldConfig[] {
  */
 const PROVIDER_KEY_URLS: Partial<Record<ProviderName, string>> = {
   anthropic: "https://console.anthropic.com/settings/keys",
+  "azure-foundry": "https://ai.azure.com/",
   openai: "https://platform.openai.com/api-keys",
   google: "https://aistudio.google.com/app/apikey",
   xai: "https://console.x.ai/team/default/api-keys",
@@ -430,6 +443,8 @@ export function ProvidersSection() {
       updateOptimistically(provider, { apiKeySet: editValue !== "" });
     } else if (field === "baseUrl") {
       updateOptimistically(provider, { baseUrl: editValue || undefined });
+    } else if (field === "resource") {
+      updateOptimistically(provider, { resource: editValue || undefined });
     }
 
     setEditingField(null);
@@ -449,6 +464,8 @@ export function ProvidersSection() {
         updateOptimistically(provider, { apiKeySet: false });
       } else if (field === "baseUrl") {
         updateOptimistically(provider, { baseUrl: undefined });
+      } else if (field === "resource") {
+        updateOptimistically(provider, { resource: undefined });
       }
 
       // Save in background

src/common/constants/knownModels.ts

@@ -4,7 +4,7 @@
 
 import { formatModelDisplayName } from "../utils/ai/modelDisplay";
 
-type ModelProvider = "anthropic" | "openai" | "google" | "xai";
+type ModelProvider = "anthropic" | "openai" | "google" | "xai" | "azure-foundry";
 
 interface KnownModelDefinition {
   /** Provider identifier used by SDK factories */
@@ -46,6 +46,23 @@ const MODEL_DEFINITIONS = {
     aliases: ["haiku"],
     tokenizerOverride: "anthropic/claude-3.5-haiku",
   },
+  AZURE_FOUNDRY_OPUS: {
+    provider: "azure-foundry",
+    providerModelId: "claude-opus-4-5",
+    aliases: ["azure-opus", "foundry-opus"],
+  },
+  AZURE_FOUNDRY_SONNET: {
+    provider: "azure-foundry",
+    providerModelId: "claude-sonnet-4-5",
+    aliases: ["azure-sonnet", "foundry-sonnet"],
+    tokenizerOverride: "anthropic/claude-sonnet-4.5",
+  },
+  AZURE_FOUNDRY_HAIKU: {
+    provider: "azure-foundry",
+    providerModelId: "claude-haiku-4-5",
+    aliases: ["azure-haiku", "foundry-haiku"],
+    tokenizerOverride: "anthropic/claude-3.5-haiku",
+  },
   GPT: {
     provider: "openai",
     providerModelId: "gpt-5.2",

src/common/constants/providers.ts

@@ -38,6 +38,12 @@ export const PROVIDER_DEFINITIONS = {
     factoryName: "createAnthropic",
     requiresApiKey: true,
   },
+  "azure-foundry": {
+    displayName: "Azure Foundry",
+    import: () => import("@ai-sdk/anthropic"), // Uses Anthropic SDK with Azure baseURL
+    factoryName: "createAnthropic",
+    requiresApiKey: true,
+  },
   openai: {
     displayName: "OpenAI",
     import: () => import("@ai-sdk/openai"),

src/common/orpc/schemas/api.ts

@@ -100,6 +100,8 @@ export const ProviderConfigInfoSchema = z.object({
   /** Whether this provider is configured and ready to use */
   isConfigured: z.boolean(),
   baseUrl: z.string().optional(),
+  /** Azure Foundry resource name */
+  resource: z.string().optional(),
   models: z.array(z.string()).optional(),
   /** OpenAI-specific fields */
   serviceTier: z.enum(["auto", "default", "flex", "priority"]).optional(),

src/node/services/aiService.ts

@@ -632,6 +632,31 @@ export class AIService extends EventEmitter {
         return Ok(provider(modelId));
       }
 
+      // Handle Azure Foundry provider (uses @ai-sdk/anthropic with Azure baseURL)
+      if (providerName === "azure-foundry") {
+        // Resolve credentials from config + env
+        const creds = resolveProviderCredentials("azure-foundry", providerConfig);
+        if (!creds.isConfigured || !creds.apiKey || !creds.resource) {
+          return Err({ type: "api_key_not_found", provider: providerName });
+        }
+
+        // Build Azure Foundry baseURL from resource name
+        const baseURL = `https://${creds.resource}.services.ai.azure.com/anthropic/v1/`;
+        log.debug(`Azure Foundry baseURL: ${baseURL}`);
+
+        // Use @ai-sdk/anthropic with Azure baseURL - no special adapter needed
+        const { createAnthropic } = await import("@ai-sdk/anthropic");
+
+        const provider = createAnthropic({
+          apiKey: creds.apiKey,
+          baseURL,
+          headers: providerConfig.headers,
+          fetch: getProviderFetch(providerConfig),
+        });
+
+        return Ok(provider(modelId));
+      }
+
       // Handle OpenAI provider (using Responses API)
       if (providerName === "openai") {
         // Resolve credentials from config + env (single source of truth)

src/node/services/providerService.ts

@@ -55,6 +55,7 @@ export class ProviderService {
       const config = (providersConfig[provider] ?? {}) as {
         apiKey?: string;
         baseUrl?: string;
+        resource?: string;
         models?: string[];
         serviceTier?: unknown;
         region?: string;
@@ -67,6 +68,7 @@ export class ProviderService {
         apiKeySet: !!config.apiKey,
         isConfigured: false, // computed below
         baseUrl: config.baseUrl,
+        resource: config.resource,
         models: config.models,
       };
 

src/node/utils/providerRequirements.ts

@@ -23,13 +23,18 @@ export const PROVIDER_ENV_VARS: Partial<
       baseUrl?: string[];
       organization?: string[];
       region?: string[];
+      resource?: string[];
     }
   >
 > = {
   anthropic: {
     apiKey: ["ANTHROPIC_API_KEY", "ANTHROPIC_AUTH_TOKEN"],
     baseUrl: ["ANTHROPIC_BASE_URL"],
   },
+  "azure-foundry": {
+    apiKey: ["AZURE_FOUNDRY_API_KEY", "AZURE_API_KEY"],
+    resource: ["AZURE_FOUNDRY_RESOURCE"],
+  },
   openai: {
     apiKey: ["OPENAI_API_KEY"],
     baseUrl: ["OPENAI_BASE_URL", "OPENAI_API_BASE"],
@@ -91,6 +96,7 @@ export interface ProviderConfigRaw {
   couponCode?: string;
   voucher?: string; // legacy mux-gateway field
   organization?: string; // OpenAI org ID
+  resource?: string; // Azure Foundry resource name
 }
 
 /** Result of resolving provider credentials */
@@ -105,6 +111,7 @@ export interface ResolvedCredentials {
   couponCode?: string; // mux-gateway
   baseUrl?: string; // from config or env
   organization?: string; // openai
+  resource?: string; // azure-foundry
 }
 
 /** Legacy alias for backward compatibility */
@@ -144,6 +151,20 @@ export function resolveProviderCredentials(
       : { isConfigured: false, missingRequirement: "coupon_code" };
   }
 
+  // Azure Foundry: requires both API key and resource name
+  if (provider === "azure-foundry") {
+    const envMapping = PROVIDER_ENV_VARS[provider];
+    // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing -- empty string should be treated as unset
+    const configKey = config.apiKey || null;
+    const apiKey = configKey ?? resolveEnv(envMapping?.apiKey, env);
+    const resource = config.resource ?? resolveEnv(envMapping?.resource, env);
+
+    if (apiKey && resource) {
+      return { isConfigured: true, apiKey, resource };
+    }
+    return { isConfigured: false, missingRequirement: "api_key" };
+  }
+
   // Keyless providers (e.g., ollama): require explicit opt-in via baseUrl or models
   const def = PROVIDER_DEFINITIONS[provider];
   if (!def.requiresApiKey) {