Add Azure Anthropic support

config.example.yaml

@@ -14,3 +14,8 @@ providers:
     api_key: "YOUR_OPENAI_API_KEY"
     model: "gpt-4o-mini"
     endpoint: "https://api.openai.com"
+  # Azure-hosted Anthropic (Microsoft Foundry) - optional, overrides anthropic if set
+  # azureanthropic:
+  #   api_key: "YOUR_AZURE_ANTHROPIC_API_KEY"
+  #   endpoint: "https://your-resource.services.ai.azure.com/anthropic"
+  #   model: "claude-sonnet-4-5-20250514"

internal/config/config.go

@@ -32,6 +32,14 @@ type ProvidersConfig struct {
 	Anthropic      ProviderConfig       `yaml:"anthropic"`
 	OpenAI         ProviderConfig       `yaml:"openai"`
 	AzureOpenAI    AzureOpenAIConfig    `yaml:"azureopenai"`
+	AzureAnthropic AzureAnthropicConfig `yaml:"azureanthropic"`
+}
+
+// AzureAnthropicConfig contains Azure-specific settings for Anthropic (Microsoft Foundry).
+type AzureAnthropicConfig struct {
+	APIKey   string `yaml:"api_key"`
+	Endpoint string `yaml:"endpoint"`
+	Model    string `yaml:"model"`
 }
 
 // ProviderConfig contains shared provider configuration fields.
@@ -83,6 +91,17 @@ func (cfg *Config) applyEnvOverrides() {
 	if v := os.Getenv("AZURE_OPENAI_API_VERSION"); v != "" {
 		cfg.Providers.AzureOpenAI.APIVersion = v
 	}
+
+	// Azure Anthropic (Microsoft Foundry) overrides
+	if v := os.Getenv("AZURE_ANTHROPIC_API_KEY"); v != "" {
+		cfg.Providers.AzureAnthropic.APIKey = v
+	}
+	if v := os.Getenv("AZURE_ANTHROPIC_ENDPOINT"); v != "" {
+		cfg.Providers.AzureAnthropic.Endpoint = v
+	}
+	if v := os.Getenv("AZURE_ANTHROPIC_MODEL"); v != "" {
+		cfg.Providers.AzureAnthropic.Model = v
+	}
 }
 
 func overrideAPIKey(cfg *ProviderConfig, envKey string) {

internal/providers/anthropic/anthropic.go

@@ -15,12 +15,14 @@ import (
 const Name = "anthropic"
 
 // Provider implements the Anthropic SDK integration.
+// It supports both direct Anthropic API and Azure-hosted (Microsoft Foundry) endpoints.
 type Provider struct {
 	cfg    config.ProviderConfig
 	client *anthropic.Client
+	azure  bool
 }
 
-// New constructs a Provider from configuration.
+// New constructs a Provider for the direct Anthropic API.
 func New(cfg config.ProviderConfig) *Provider {
 	var client *anthropic.Client
 	if cfg.APIKey != "" {
@@ -33,6 +35,29 @@ func New(cfg config.ProviderConfig) *Provider {
 	}
 }
 
+// NewAzure constructs a Provider targeting Azure-hosted Anthropic (Microsoft Foundry).
+// The Azure endpoint uses api-key header auth and a base URL like
+// https://<resource>.services.ai.azure.com/anthropic.
+func NewAzure(azureCfg config.AzureAnthropicConfig) *Provider {
+	var client *anthropic.Client
+	if azureCfg.APIKey != "" && azureCfg.Endpoint != "" {
+		c := anthropic.NewClient(
+			option.WithBaseURL(azureCfg.Endpoint),
+			option.WithAPIKey("unused"),
+			option.WithAuthToken(azureCfg.APIKey),
+		)
+		client = &c
+	}
+	return &Provider{
+		cfg: config.ProviderConfig{
+			APIKey: azureCfg.APIKey,
+			Model:  azureCfg.Model,
+		},
+		client: client,
+		azure:  true,
+	}
+}
+
 func (p *Provider) Name() string { return Name }
 
 // Generate routes the Open Responses request to Anthropic's API.

internal/providers/providers.go

@@ -31,7 +31,9 @@ func NewRegistry(cfg config.ProvidersConfig) (*Registry, error) {
 	if cfg.Google.APIKey != "" {
 		reg.providers[googleprovider.Name] = googleprovider.New(cfg.Google)
 	}
-	if cfg.Anthropic.APIKey != "" {
+	if cfg.AzureAnthropic.APIKey != "" && cfg.AzureAnthropic.Endpoint != "" {
+		reg.providers[anthropicprovider.Name] = anthropicprovider.NewAzure(cfg.AzureAnthropic)
+	} else if cfg.Anthropic.APIKey != "" {
 		reg.providers[anthropicprovider.Name] = anthropicprovider.New(cfg.Anthropic)
 	}
 	if cfg.AzureOpenAI.APIKey != "" && cfg.AzureOpenAI.Endpoint != "" {