feat: add Azure AI Foundry support to Anthropic provider

- Add anthropicUseAzureFoundry and anthropicAzureDeploymentName settings
- Allow overriding model ID with Azure deployment name
- Maintain model capabilities while using custom deployment names
- Add comprehensive tests for Azure Foundry functionality

Fixes #9940

packages/types/src/provider-settings.ts

@@ -199,6 +199,8 @@ const anthropicSchema = apiModelIdProviderModelSchema.extend({
 	anthropicBaseUrl: z.string().optional(),
 	anthropicUseAuthToken: z.boolean().optional(),
 	anthropicBeta1MContext: z.boolean().optional(), // Enable 'context-1m-2025-08-07' beta for 1M context window.
+	anthropicUseAzureFoundry: z.boolean().optional(), // Enable Azure AI Foundry mode for Anthropic-compatible endpoints.
+	anthropicAzureDeploymentName: z.string().optional(), // Override model ID with Azure deployment name.
 })
 
 const claudeCodeSchema = apiModelIdProviderModelSchema.extend({

src/api/providers/__tests__/anthropic-azure-foundry.spec.ts

@@ -0,0 +1,257 @@
+// npx vitest run src/api/providers/__tests__/anthropic-azure-foundry.spec.ts
+
+import { AnthropicHandler } from "../anthropic"
+import { ApiHandlerOptions } from "../../../shared/api"
+
+const mockCreate = vitest.fn()
+
+vitest.mock("@anthropic-ai/sdk", () => {
+	const mockAnthropicConstructor = vitest.fn().mockImplementation(() => ({
+		messages: {
+			create: mockCreate.mockImplementation(async (options) => {
+				if (!options.stream) {
+					return {
+						id: "test-completion",
+						content: [{ type: "text", text: "Test response" }],
+						role: "assistant",
+						model: options.model,
+						usage: {
+							input_tokens: 10,
+							output_tokens: 5,
+						},
+					}
+				}
+				return {
+					async *[Symbol.asyncIterator]() {
+						yield {
+							type: "message_start",
+							message: {
+								usage: {
+									input_tokens: 100,
+									output_tokens: 50,
+								},
+							},
+						}
+						yield {
+							type: "content_block_start",
+							index: 0,
+							content_block: {
+								type: "text",
+								text: "Hello from Azure",
+							},
+						}
+						yield {
+							type: "content_block_delta",
+							delta: {
+								type: "text_delta",
+								text: " Foundry",
+							},
+						}
+					},
+				}
+			}),
+		},
+	}))
+
+	return {
+		Anthropic: mockAnthropicConstructor,
+	}
+})
+
+// Import after mock
+import { Anthropic } from "@anthropic-ai/sdk"
+
+const mockAnthropicConstructor = vitest.mocked(Anthropic)
+
+describe("AnthropicHandler - Azure Foundry Support", () => {
+	let handler: AnthropicHandler
+	let mockOptions: ApiHandlerOptions
+
+	beforeEach(() => {
+		vitest.clearAllMocks()
+	})
+
+	describe("Azure Foundry mode", () => {
+		it("should use deployment name as model ID when Azure Foundry mode is enabled", () => {
+			mockOptions = {
+				apiKey: "test-api-key",
+				apiModelId: "claude-opus-4-5-20251101",
+				anthropicBaseUrl: "https://my-resource.services.ai.azure.com/anthropic",
+				anthropicUseAzureFoundry: true,
+				anthropicAzureDeploymentName: "claude-opus-4-5",
+				anthropicUseAuthToken: true,
+			}
+			handler = new AnthropicHandler(mockOptions)
+
+			const model = handler.getModel()
+			expect(model.id).toBe("claude-opus-4-5")
+			// Should still have the correct model info for capabilities
+			expect(model.info).toBeDefined()
+			expect(model.info.maxTokens).toBe(32000) // Raw model info value
+			expect(model.info.contextWindow).toBe(200000)
+		})
+
+		it("should use authToken when Azure Foundry mode is enabled with custom base URL", () => {
+			mockOptions = {
+				apiKey: "test-azure-key",
+				apiModelId: "claude-sonnet-4-5",
+				anthropicBaseUrl: "https://my-resource.services.ai.azure.com/anthropic",
+				anthropicUseAzureFoundry: true,
+				anthropicAzureDeploymentName: "my-sonnet-deployment",
+				anthropicUseAuthToken: true,
+			}
+			handler = new AnthropicHandler(mockOptions)
+
+			expect(mockAnthropicConstructor).toHaveBeenCalledWith({
+				baseURL: "https://my-resource.services.ai.azure.com/anthropic",
+				authToken: "test-azure-key",
+			})
+		})
+
+		it("should fall back to selected model when no deployment name is provided", () => {
+			mockOptions = {
+				apiKey: "test-api-key",
+				apiModelId: "claude-opus-4-5-20251101",
+				anthropicBaseUrl: "https://my-resource.services.ai.azure.com/anthropic",
+				anthropicUseAzureFoundry: true,
+				// No deployment name provided
+				anthropicUseAuthToken: true,
+			}
+			handler = new AnthropicHandler(mockOptions)
+
+			const model = handler.getModel()
+			// Should use the original model ID
+			expect(model.id).toBe("claude-opus-4-5-20251101")
+		})
+
+		it("should not use deployment name when Azure Foundry mode is disabled", () => {
+			mockOptions = {
+				apiKey: "test-api-key",
+				apiModelId: "claude-opus-4-5-20251101",
+				anthropicBaseUrl: "https://my-resource.services.ai.azure.com/anthropic",
+				anthropicUseAzureFoundry: false,
+				anthropicAzureDeploymentName: "claude-opus-4-5",
+				anthropicUseAuthToken: true,
+			}
+			handler = new AnthropicHandler(mockOptions)
+
+			const model = handler.getModel()
+			// Should use the original model ID, not the deployment name
+			expect(model.id).toBe("claude-opus-4-5-20251101")
+		})
+
+		it("should send correct model name in API requests with Azure Foundry", async () => {
+			mockOptions = {
+				apiKey: "test-azure-key",
+				apiModelId: "claude-opus-4-5-20251101",
+				anthropicBaseUrl: "https://my-resource.services.ai.azure.com/anthropic",
+				anthropicUseAzureFoundry: true,
+				anthropicAzureDeploymentName: "my-custom-deployment",
+				anthropicUseAuthToken: true,
+			}
+			handler = new AnthropicHandler(mockOptions)
+
+			const systemPrompt = "You are a helpful assistant."
+			const messages: Anthropic.Messages.MessageParam[] = [
+				{
+					role: "user",
+					content: "Hello",
+				},
+			]
+
+			const stream = handler.createMessage(systemPrompt, messages)
+			const chunks: any[] = []
+			for await (const chunk of stream) {
+				chunks.push(chunk)
+			}
+
+			// Verify the API was called with the deployment name as the model
+			const callArgs = mockCreate.mock.calls[0][0]
+			expect(callArgs.model).toBe("my-custom-deployment")
+
+			// Verify we got the expected response
+			const textChunks = chunks.filter((chunk) => chunk.type === "text")
+			expect(textChunks).toHaveLength(2)
+			expect(textChunks[0].text).toBe("Hello from Azure")
+			expect(textChunks[1].text).toBe(" Foundry")
+		})
+
+		it("should work with different Claude models in Azure Foundry", () => {
+			// Test with Claude Sonnet 4.5
+			mockOptions = {
+				apiKey: "test-api-key",
+				apiModelId: "claude-sonnet-4-5",
+				anthropicBaseUrl: "https://my-resource.services.ai.azure.com/anthropic",
+				anthropicUseAzureFoundry: true,
+				anthropicAzureDeploymentName: "sonnet-deployment",
+				anthropicUseAuthToken: true,
+			}
+			handler = new AnthropicHandler(mockOptions)
+
+			let model = handler.getModel()
+			expect(model.id).toBe("sonnet-deployment")
+			expect(model.info.maxTokens).toBe(64000) // Raw model info value for Sonnet 4.5
+
+			// Test with Claude Haiku 4.5
+			mockOptions = {
+				apiKey: "test-api-key",
+				apiModelId: "claude-haiku-4-5-20251001",
+				anthropicBaseUrl: "https://my-resource.services.ai.azure.com/anthropic",
+				anthropicUseAzureFoundry: true,
+				anthropicAzureDeploymentName: "haiku-deployment",
+				anthropicUseAuthToken: true,
+			}
+			handler = new AnthropicHandler(mockOptions)
+
+			model = handler.getModel()
+			expect(model.id).toBe("haiku-deployment")
+			expect(model.info.maxTokens).toBe(64000) // Raw model info value for Haiku 4.5
+		})
+
+		it("should handle completePrompt with Azure Foundry deployment name", async () => {
+			mockOptions = {
+				apiKey: "test-azure-key",
+				apiModelId: "claude-opus-4-5-20251101",
+				anthropicBaseUrl: "https://my-resource.services.ai.azure.com/anthropic",
+				anthropicUseAzureFoundry: true,
+				anthropicAzureDeploymentName: "my-opus-deployment",
+				anthropicUseAuthToken: true,
+			}
+			handler = new AnthropicHandler(mockOptions)
+
+			const result = await handler.completePrompt("Test prompt")
+
+			expect(result).toBe("Test response")
+			expect(mockCreate).toHaveBeenCalledWith({
+				model: "my-opus-deployment",
+				messages: [{ role: "user", content: "Test prompt" }],
+				max_tokens: 8192,
+				temperature: 0,
+				thinking: undefined,
+				stream: false,
+			})
+		})
+	})
+
+	describe("Azure Foundry with 1M context", () => {
+		it("should support 1M context beta with Azure Foundry for Claude Sonnet 4.5", () => {
+			mockOptions = {
+				apiKey: "test-api-key",
+				apiModelId: "claude-sonnet-4-5",
+				anthropicBaseUrl: "https://my-resource.services.ai.azure.com/anthropic",
+				anthropicUseAzureFoundry: true,
+				anthropicAzureDeploymentName: "sonnet-1m-deployment",
+				anthropicBeta1MContext: true,
+				anthropicUseAuthToken: true,
+			}
+			handler = new AnthropicHandler(mockOptions)
+
+			const model = handler.getModel()
+			expect(model.id).toBe("sonnet-1m-deployment")
+			// Should have 1M context window
+			expect(model.info.contextWindow).toBe(1000000)
+			expect(model.info.inputPrice).toBe(6.0)
+			expect(model.info.outputPrice).toBe(22.5)
+		})
+	})
+})

src/api/providers/anthropic.ts

@@ -336,10 +336,27 @@ export class AnthropicHandler extends BaseProvider implements SingleCompletionHa
 		// reasoning model and that reasoning is required to be enabled.
 		// The actual model ID honored by Anthropic's API does not have this
 		// suffix.
+		const baseId = id === "claude-3-7-sonnet-20250219:thinking" ? "claude-3-7-sonnet-20250219" : id
+		const betas = id === "claude-3-7-sonnet-20250219:thinking" ? ["output-128k-2025-02-19"] : undefined
+
+		// If Azure Foundry mode is enabled and a deployment name is provided, use it as the model ID
+		if (this.options.anthropicUseAzureFoundry && this.options.anthropicAzureDeploymentName) {
+			// Override the model ID with the Azure deployment name
+			// Keep the model info from the selected model for pricing/capabilities
+			const deploymentName = this.options.anthropicAzureDeploymentName
+
+			return {
+				id: deploymentName,
+				info,
+				betas,
+				...params,
+			}
+		}
+
 		return {
-			id: id === "claude-3-7-sonnet-20250219:thinking" ? "claude-3-7-sonnet-20250219" : id,
+			id: baseId,
 			info,
-			betas: id === "claude-3-7-sonnet-20250219:thinking" ? ["output-128k-2025-02-19"] : undefined,
+			betas,
 			...params,
 		}
 	}