feat: add OpenRouter multi-provider failover support

- Add support for up to 4 OpenRouter providers with automatic failover
- Implement priority-based provider selection in UI with dynamic dropdowns
- Add comprehensive test coverage for multi-provider functionality
- Enable seamless switching between single and multi-provider modes
- Ensure primary provider's context window and pricing is used for model info

Author: shariqriazz

packages/types/src/provider-settings.ts

@@ -136,7 +136,9 @@ const openRouterSchema = baseProviderSettingsSchema.extend({
 	openRouterApiKey: z.string().optional(),
 	openRouterModelId: z.string().optional(),
 	openRouterBaseUrl: z.string().optional(),
-	openRouterSpecificProvider: z.string().optional(),
+	openRouterSpecificProvider: z.string().optional(), // Keep for backward compatibility
+	openRouterProviders: z.array(z.string()).max(4).optional(), // New multi-provider support
+	openRouterFailoverEnabled: z.boolean().optional(), // Enable automatic failover
 	openRouterUseMiddleOutTransform: z.boolean().optional(),
 })
 

src/api/providers/__tests__/openrouter-multi-provider.spec.ts

@@ -0,0 +1,236 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest"
+import { OpenRouterHandler } from "../openrouter"
+import type { ApiHandlerOptions } from "../../../shared/api"
+
+// Mock OpenAI
+vi.mock("openai")
+
+describe("OpenRouterHandler Multi-Provider Support", () => {
+	let mockOptions: ApiHandlerOptions
+	let handler: OpenRouterHandler
+
+	beforeEach(() => {
+		mockOptions = {
+			openRouterApiKey: "test-api-key",
+			openRouterModelId: "anthropic/claude-sonnet-4",
+			openRouterFailoverEnabled: true,
+		}
+	})
+
+	afterEach(() => {
+		vi.restoreAllMocks()
+	})
+
+	describe("getProvidersToUse", () => {
+		it("should return multi-provider configuration when available", () => {
+			const optionsWithMultiProvider: ApiHandlerOptions = {
+				...mockOptions,
+				openRouterProviders: ["provider1", "provider2", "provider3"],
+			}
+			handler = new OpenRouterHandler(optionsWithMultiProvider)
+
+			// Access private method for testing
+			const providers = (handler as any).getProvidersToUse()
+			expect(providers).toEqual(["provider1", "provider2", "provider3"])
+		})
+
+		it("should fallback to single provider configuration", () => {
+			const optionsWithSingleProvider: ApiHandlerOptions = {
+				...mockOptions,
+				openRouterSpecificProvider: "single-provider",
+			}
+			handler = new OpenRouterHandler(optionsWithSingleProvider)
+
+			const providers = (handler as any).getProvidersToUse()
+			expect(providers).toEqual(["single-provider"])
+		})
+
+		it("should return empty array when no providers configured", () => {
+			handler = new OpenRouterHandler(mockOptions)
+
+			const providers = (handler as any).getProvidersToUse()
+			expect(providers).toEqual([])
+		})
+
+		it("should filter out default provider from multi-provider list", () => {
+			const optionsWithDefault: ApiHandlerOptions = {
+				...mockOptions,
+				openRouterProviders: ["provider1", "[default]", "provider2"],
+			}
+			handler = new OpenRouterHandler(optionsWithDefault)
+
+			const providers = (handler as any).getProvidersToUse()
+			expect(providers).toEqual(["provider1", "provider2"])
+		})
+	})
+
+	describe("shouldFailover", () => {
+		beforeEach(() => {
+			handler = new OpenRouterHandler(mockOptions)
+		})
+
+		it("should failover on rate limit errors (429)", () => {
+			const error = { status: 429, message: "Rate limit exceeded" }
+			expect((handler as any).shouldFailover(error)).toBe(true)
+		})
+
+		it("should failover on service unavailable errors", () => {
+			const error503 = { status: 503, message: "Service unavailable" }
+			const error502 = { status: 502, message: "Bad gateway" }
+
+			expect((handler as any).shouldFailover(error503)).toBe(true)
+			expect((handler as any).shouldFailover(error502)).toBe(true)
+		})
+
+		it("should failover on context window errors", () => {
+			const contextErrors = [
+				{ status: 400, message: "context length exceeded" },
+				{ status: 400, message: "maximum context window reached" },
+				{ status: 400, message: "too many tokens in request" },
+				{ status: 400, message: "input tokens exceed limit" },
+			]
+
+			contextErrors.forEach((error) => {
+				expect((handler as any).shouldFailover(error)).toBe(true)
+			})
+		})
+
+		it("should failover on timeout errors", () => {
+			const timeoutErrors = [{ code: "ECONNABORTED", message: "timeout" }, { message: "timeout error occurred" }]
+
+			timeoutErrors.forEach((error) => {
+				expect((handler as any).shouldFailover(error)).toBe(true)
+			})
+		})
+
+		it("should not failover on non-failover errors", () => {
+			const nonFailoverErrors = [
+				{ status: 401, message: "Unauthorized" },
+				{ status: 400, message: "Invalid request format" },
+				{ status: 500, message: "Internal server error" },
+				null,
+				undefined,
+			]
+
+			nonFailoverErrors.forEach((error) => {
+				expect((handler as any).shouldFailover(error)).toBe(false)
+			})
+		})
+	})
+
+	describe("createCompletionParams", () => {
+		beforeEach(() => {
+			handler = new OpenRouterHandler(mockOptions)
+		})
+
+		it("should create params with single provider routing", () => {
+			const providers = ["provider1"]
+			const params = (handler as any).createCompletionParams(
+				"test-model",
+				4096,
+				0.7,
+				0.9,
+				[{ role: "user", content: "test" }],
+				["middle-out"],
+				undefined,
+				providers,
+				0,
+			)
+
+			expect(params.provider).toEqual({
+				order: ["provider1"],
+				only: ["provider1"],
+				allow_fallbacks: false,
+			})
+		})
+
+		it("should create params with multi-provider routing for first attempt", () => {
+			const providers = ["provider1", "provider2", "provider3"]
+			const params = (handler as any).createCompletionParams(
+				"test-model",
+				4096,
+				0.7,
+				0.9,
+				[{ role: "user", content: "test" }],
+				["middle-out"],
+				undefined,
+				providers,
+				0,
+			)
+
+			expect(params.provider).toEqual({
+				order: ["provider1", "provider2", "provider3"],
+				only: ["provider1", "provider2", "provider3"],
+				allow_fallbacks: true,
+			})
+		})
+
+		it("should create params with remaining providers for retry attempt", () => {
+			const providers = ["provider1", "provider2", "provider3"]
+			const params = (handler as any).createCompletionParams(
+				"test-model",
+				4096,
+				0.7,
+				0.9,
+				[{ role: "user", content: "test" }],
+				["middle-out"],
+				undefined,
+				providers,
+				1,
+			)
+
+			expect(params.provider).toEqual({
+				order: ["provider2", "provider3"],
+				only: ["provider2", "provider3"],
+				allow_fallbacks: true,
+			})
+		})
+
+		it("should create params with last provider only for final attempt", () => {
+			const providers = ["provider1", "provider2", "provider3"]
+			const params = (handler as any).createCompletionParams(
+				"test-model",
+				4096,
+				0.7,
+				0.9,
+				[{ role: "user", content: "test" }],
+				["middle-out"],
+				undefined,
+				providers,
+				2,
+			)
+
+			expect(params.provider).toEqual({
+				order: ["provider3"],
+				only: ["provider3"],
+				allow_fallbacks: false,
+			})
+		})
+	})
+
+	describe("backward compatibility", () => {
+		it("should support legacy single provider configuration", () => {
+			const legacyOptions: ApiHandlerOptions = {
+				...mockOptions,
+				openRouterSpecificProvider: "legacy-provider",
+				openRouterFailoverEnabled: false,
+			}
+			handler = new OpenRouterHandler(legacyOptions)
+
+			const providers = (handler as any).getProvidersToUse()
+			expect(providers).toEqual(["legacy-provider"])
+		})
+
+		it("should prefer multi-provider over single provider when both are set", () => {
+			const mixedOptions: ApiHandlerOptions = {
+				...mockOptions,
+				openRouterProviders: ["multi1", "multi2"],
+				openRouterSpecificProvider: "single-provider",
+			}
+			handler = new OpenRouterHandler(mixedOptions)
+
+			const providers = (handler as any).getProvidersToUse()
+			expect(providers).toEqual(["multi1", "multi2"])
+		})
+	})
+})