Add DeepSeek Provider

src/api/providers/deepseek.ts

@@ -0,0 +1,85 @@
+import OpenAI from "openai"
+import { Anthropic } from "@anthropic-ai/sdk"
+import {
+	ApiHandlerOptions,
+	DeepSeekModelId,
+	deepSeekModels,
+	deepSeekDefaultModelId,
+	ModelInfo,
+} from "../../shared/api"
+import { ApiHandler } from "../index"
+import { convertToOpenAiMessages } from "../transform/openai-format"
+import { ApiStream } from "../transform/stream"
+
+// Extend OpenAI's CompletionUsage type to include DeepSeek's cache fields
+interface DeepSeekCompletionUsage extends OpenAI.CompletionUsage {
+	prompt_cache_hit_tokens?: number
+	prompt_cache_miss_tokens?: number
+}
+
+export class DeepSeekHandler implements ApiHandler {
+	private options: ApiHandlerOptions
+	private client: OpenAI
+	private isBeta: boolean
+
+	constructor(options: ApiHandlerOptions) {
+		if (!options.deepSeekApiKey) {
+			throw new Error("API key is required for DeepSeek")
+		}
+		this.options = options
+
+		const baseUrl = this.options.deepSeekBaseUrl || "https://api.deepseek.com"
+		this.isBeta = baseUrl.includes("/beta")
+
+		this.client = new OpenAI({
+			baseURL: baseUrl + "/v1",
+			apiKey: this.options.deepSeekApiKey,
+		})
+	}
+
+	async *createMessage(systemPrompt: string, messages: Anthropic.Messages.MessageParam[]): ApiStream {
+		const openAiMessages: OpenAI.Chat.ChatCompletionMessageParam[] = [
+			{ role: "system", content: systemPrompt },
+			...convertToOpenAiMessages(messages),
+		]
+
+		const stream = await this.client.chat.completions.create({
+			model: "deepseek-chat", // Always use deepseek-chat as the model ID
+			messages: openAiMessages,
+			max_tokens: this.isBeta ? 8192 : 4096, // Set max tokens based on endpoint
+			temperature: 0,
+			stream: true,
+		})
+
+		for await (const chunk of stream) {
+			const delta = chunk.choices[0]?.delta
+			if (delta?.content) {
+				yield {
+					type: "text",
+					text: delta.content,
+				}
+			}
+
+			// DeepSeek provides cache hit status in usage
+			if (chunk.usage) {
+				const usage = chunk.usage as DeepSeekCompletionUsage
+				yield {
+					type: "usage",
+					inputTokens: usage.prompt_tokens || 0,
+					outputTokens: usage.completion_tokens || 0,
+					cacheReadTokens: usage.prompt_cache_hit_tokens || 0,
+					cacheWriteTokens: usage.prompt_cache_miss_tokens || 0,
+				}
+			}
+		}
+	}
+
+	getModel(): { id: DeepSeekModelId; info: ModelInfo } {
+		const modelId = this.options.apiModelId
+		if (modelId && modelId in deepSeekModels) {
+			const id = modelId as DeepSeekModelId
+			return { id, info: deepSeekModels[id] }
+		}
+		return { id: deepSeekDefaultModelId, info: deepSeekModels[deepSeekDefaultModelId] }
+	}
+}