import Anthropic from '@anthropic-ai/sdk';
import type { LLMProvider, LLMMessage, LLMResponse } from './types.js';
export class AnthropicProvider implements LLMProvider {
private client: Anthropic;
constructor(apiKey: string) {
this.client = new Anthropic({ apiKey });
}
validateApiKey(): boolean {
return !!this.client.apiKey;
}
async generateMessage(
messages: LLMMessage[],
systemPrompt: string | undefined,
model: string,
maxTokens: number
): Promise<LLMResponse> {
const anthropicMessages = this.convertMessages(messages);
const response = await this.client.messages.create({
model,
max_tokens: maxTokens,
messages: anthropicMessages,
system: systemPrompt,
});
return {
content: response.content.map(block => {
if (block.type === 'text') {
return { type: 'text', text: block.text };
}
return { type: 'text', text: JSON.stringify(block) }; // Fallback for non-text blocks
}),
stopReason: response.stop_reason || undefined,
model: response.model,
usage: {
inputTokens: response.usage.input_tokens,
outputTokens: response.usage.output_tokens,
},
};
}
async *streamMessage(
messages: LLMMessage[],
systemPrompt: string | undefined,
model: string,
maxTokens: number
): AsyncGenerator<{ type: 'chunk'; content: string } | { type: 'usage'; inputTokens: number; outputTokens: number }, void, unknown> {
const anthropicMessages = this.convertMessages(messages);
const stream = this.client.messages.stream({
model,
max_tokens: maxTokens,
messages: anthropicMessages,
system: systemPrompt,
});
for await (const event of stream) {
if (event.type === 'content_block_delta' && event.delta.type === 'text_delta') {
yield { type: 'chunk', content: event.delta.text };
} else if (event.type === 'message_delta' && event.usage) {
yield {
type: 'usage',
inputTokens: 0, // Anthropic stream doesn't send input tokens in message_delta? Need to check.
// Actually, message_start has input tokens, message_delta has output tokens.
// The stream helper might abstract this.
// Let's look at the raw events or the stream helper.
// The stream helper emits events.
outputTokens: event.usage.output_tokens,
};
} else if (event.type === 'message_start' && event.message.usage) {
yield {
type: 'usage',
inputTokens: event.message.usage.input_tokens,
outputTokens: 0
}
}
}
}
private convertMessages(messages: LLMMessage[]): Anthropic.MessageParam[] {
return messages.map(msg => {
// Anthropic expects content to be string or array of blocks
let content: string | Anthropic.ContentBlockParam[];
if (typeof msg.content === 'string') {
content = msg.content;
} else {
content = msg.content.map(c => {
if (c.type === 'text') {
return { type: 'text', text: c.text };
}
// Image support not implemented yet
// Throw error for unsupported content types instead of unsafe casting
throw new Error(`Unsupported content type '${c.type}' for Anthropic provider. Only 'text' is supported.`);
});
}
return {
role: msg.role === 'system' ? 'user' : msg.role, // Anthropic uses top-level system param, not role
content,
};
});
}
}
