fix: address PR review comments for Nebius provider

- Fix typo in Nebius component (was using litellmApiKey)
- Fix inconsistent default base URL between UI and API handler
- Add Zod validation for Nebius API responses
- Add comprehensive unit tests for Nebius provider and fetcher
- Improve error handling with schema validation

Author: daniel-lxs

src/api/providers/__tests__/nebius.test.ts

@@ -0,0 +1,221 @@
+// npx jest src/api/providers/__tests__/nebius.test.ts
+
+import { Anthropic } from "@anthropic-ai/sdk"
+import OpenAI from "openai"
+
+import { NebiusHandler } from "../nebius"
+import { ApiHandlerOptions } from "../../../shared/api"
+
+// Mock dependencies
+jest.mock("openai")
+jest.mock("delay", () => jest.fn(() => Promise.resolve()))
+jest.mock("../fetchers/modelCache", () => ({
+	getModels: jest.fn().mockImplementation(() => {
+		return Promise.resolve({
+			"Qwen/Qwen2.5-32B-Instruct-fast": {
+				maxTokens: 8192,
+				contextWindow: 32768,
+				supportsImages: false,
+				supportsPromptCache: false,
+				inputPrice: 0.13,
+				outputPrice: 0.4,
+				description: "Qwen 2.5 32B Instruct Fast",
+			},
+			"deepseek-ai/DeepSeek-R1": {
+				maxTokens: 32000,
+				contextWindow: 96000,
+				supportsImages: false,
+				supportsPromptCache: false,
+				inputPrice: 0.8,
+				outputPrice: 2.4,
+				description: "DeepSeek R1",
+			},
+		})
+	}),
+}))
+
+describe("NebiusHandler", () => {
+	const mockOptions: ApiHandlerOptions = {
+		nebiusApiKey: "test-key",
+		nebiusModelId: "Qwen/Qwen2.5-32B-Instruct-fast",
+		nebiusBaseUrl: "https://api.studio.nebius.ai/v1",
+	}
+
+	beforeEach(() => jest.clearAllMocks())
+
+	it("initializes with correct options", () => {
+		const handler = new NebiusHandler(mockOptions)
+		expect(handler).toBeInstanceOf(NebiusHandler)
+
+		expect(OpenAI).toHaveBeenCalledWith({
+			baseURL: "https://api.studio.nebius.ai/v1",
+			apiKey: mockOptions.nebiusApiKey,
+		})
+	})
+
+	it("uses default base URL when not provided", () => {
+		const handler = new NebiusHandler({
+			nebiusApiKey: "test-key",
+			nebiusModelId: "Qwen/Qwen2.5-32B-Instruct-fast",
+		})
+		expect(handler).toBeInstanceOf(NebiusHandler)
+
+		expect(OpenAI).toHaveBeenCalledWith({
+			baseURL: "https://api.studio.nebius.ai/v1",
+			apiKey: "test-key",
+		})
+	})
+
+	describe("fetchModel", () => {
+		it("returns correct model info when options are provided", async () => {
+			const handler = new NebiusHandler(mockOptions)
+			const result = await handler.fetchModel()
+
+			expect(result).toMatchObject({
+				id: mockOptions.nebiusModelId,
+				info: {
+					maxTokens: 8192,
+					contextWindow: 32768,
+					supportsImages: false,
+					supportsPromptCache: false,
+					inputPrice: 0.13,
+					outputPrice: 0.4,
+					description: "Qwen 2.5 32B Instruct Fast",
+				},
+			})
+		})
+
+		it("returns default model info when options are not provided", async () => {
+			const handler = new NebiusHandler({})
+			const result = await handler.fetchModel()
+			expect(result.id).toBe("Qwen/Qwen2.5-32B-Instruct-fast")
+		})
+	})
+
+	describe("createMessage", () => {
+		it("generates correct stream chunks", async () => {
+			const handler = new NebiusHandler(mockOptions)
+
+			const mockStream = {
+				async *[Symbol.asyncIterator]() {
+					yield {
+						choices: [{ delta: { content: "test response" } }],
+					}
+					yield {
+						choices: [{ delta: {} }],
+						usage: { prompt_tokens: 10, completion_tokens: 20 },
+					}
+				},
+			}
+
+			// Mock OpenAI chat.completions.create
+			const mockCreate = jest.fn().mockResolvedValue(mockStream)
+
+			;(OpenAI as jest.MockedClass<typeof OpenAI>).prototype.chat = {
+				completions: { create: mockCreate },
+			} as any
+
+			const systemPrompt = "test system prompt"
+			const messages: Anthropic.Messages.MessageParam[] = [{ role: "user" as const, content: "test message" }]
+
+			const generator = handler.createMessage(systemPrompt, messages)
+			const chunks = []
+
+			for await (const chunk of generator) {
+				chunks.push(chunk)
+			}
+
+			// Verify stream chunks
+			expect(chunks).toHaveLength(2) // One text chunk and one usage chunk
+			expect(chunks[0]).toEqual({ type: "text", text: "test response" })
+			expect(chunks[1]).toEqual({ type: "usage", inputTokens: 10, outputTokens: 20 })
+
+			// Verify OpenAI client was called with correct parameters
+			expect(mockCreate).toHaveBeenCalledWith(
+				expect.objectContaining({
+					model: "Qwen/Qwen2.5-32B-Instruct-fast",
+					messages: [
+						{ role: "system", content: "test system prompt" },
+						{ role: "user", content: "test message" },
+					],
+					temperature: 0,
+					stream: true,
+					stream_options: { include_usage: true },
+				}),
+			)
+		})
+
+		it("handles R1 format for DeepSeek-R1 models", async () => {
+			const handler = new NebiusHandler({
+				...mockOptions,
+				nebiusModelId: "deepseek-ai/DeepSeek-R1",
+			})
+
+			const mockStream = {
+				async *[Symbol.asyncIterator]() {
+					yield {
+						choices: [{ delta: { content: "test response" } }],
+					}
+				},
+			}
+
+			const mockCreate = jest.fn().mockResolvedValue(mockStream)
+			;(OpenAI as jest.MockedClass<typeof OpenAI>).prototype.chat = {
+				completions: { create: mockCreate },
+			} as any
+
+			const systemPrompt = "test system prompt"
+			const messages: Anthropic.Messages.MessageParam[] = [{ role: "user" as const, content: "test message" }]
+
+			await handler.createMessage(systemPrompt, messages).next()
+
+			// Verify R1 format is used - the first message should combine system and user content
+			expect(mockCreate).toHaveBeenCalledWith(
+				expect.objectContaining({
+					model: "deepseek-ai/DeepSeek-R1",
+					messages: expect.arrayContaining([
+						expect.objectContaining({
+							role: "user",
+							content: expect.stringContaining("test system prompt"),
+						}),
+					]),
+				}),
+			)
+		})
+	})
+
+	describe("completePrompt", () => {
+		it("returns correct response", async () => {
+			const handler = new NebiusHandler(mockOptions)
+			const mockResponse = { choices: [{ message: { content: "test completion" } }] }
+
+			const mockCreate = jest.fn().mockResolvedValue(mockResponse)
+			;(OpenAI as jest.MockedClass<typeof OpenAI>).prototype.chat = {
+				completions: { create: mockCreate },
+			} as any
+
+			const result = await handler.completePrompt("test prompt")
+
+			expect(result).toBe("test completion")
+
+			expect(mockCreate).toHaveBeenCalledWith({
+				model: mockOptions.nebiusModelId,
+				max_tokens: 8192,
+				temperature: 0,
+				messages: [{ role: "user", content: "test prompt" }],
+			})
+		})
+
+		it("handles errors", async () => {
+			const handler = new NebiusHandler(mockOptions)
+			const mockError = new Error("API Error")
+
+			const mockCreate = jest.fn().mockRejectedValue(mockError)
+			;(OpenAI as jest.MockedClass<typeof OpenAI>).prototype.chat = {
+				completions: { create: mockCreate },
+			} as any
+
+			await expect(handler.completePrompt("test prompt")).rejects.toThrow("nebius completion error: API Error")
+		})
+	})
+})