MCP AI Bug Helper

import { RateLimitError, OpenRouterError } from './errors.js'; export interface ChatOptions { question: string; context?: string; temperature?: number; maxTokens?: number; } export interface ChatResult { text: string; usage?: { promptTokens?: number; completionTokens?: number; totalTokens?: number; }; raw?: unknown; } export class OpenRouterClient { private readonly baseUrl = 'https://openrouter.ai/api/v1'; private modelCache?: { ids: Set<string>; fetchedAt: number }; private readonly modelCacheTtlMs = 5 * 60 * 1000; constructor( private readonly apiKey: string, private readonly metadata: { referer: string; appName: string } ) { if (!apiKey) { throw new Error('Missing OpenRouter API key.'); } } async chat(model: string, opts: ChatOptions): Promise<ChatResult> { const systemPrompt = [ 'You are a veteran debugging partner for complex production systems.', 'Goals:', '1. Identify the most probable root cause using the provided details.', '2. Propose concrete code-level fixes or experiments (assume editor + shell access).', '3. Explain trade-offs, risks, and validation steps.', '4. Suggest log/telemetry probes when evidence is missing.', 'Return Markdown with sections: Summary, Root Cause, Fix Plan, Validation, Follow-ups.', 'Use concise bullets, but include code snippets or shell commands where they unblock the investigation.', ].join(' '); const userLines = [`### Primary bug\n${opts.question.trim()}`]; if (opts.context) { userLines.push('\n### Additional context\n' + opts.context.trim()); } userLines.push( '\n### Output expectations\n- Emphasise reproducible steps and failing assumptions.\n- Include at least one validation or logging idea.\n- Mention relevant docs/packages if they help.' ); const payload = { model, temperature: opts.temperature ?? 0.15, max_output_tokens: opts.maxTokens ?? 900, messages: [ { role: 'system', content: systemPrompt }, { role: 'user', content: userLines.join('\n') }, ], }; const response = await fetch(`${this.baseUrl}/chat/completions`, { method: 'POST', headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${this.apiKey}`, 'HTTP-Referer': this.metadata.referer, 'X-Title': this.metadata.appName, }, body: JSON.stringify(payload), }); if (response.status === 429) { const retryAfter = Number(response.headers.get('retry-after')); const errorPayload = await safeJson(response); throw new RateLimitError( formatErrorMessage(errorPayload) ?? 'OpenRouter rate limit reached.', Number.isFinite(retryAfter) ? retryAfter : undefined ); } if (!response.ok) { const errorPayload = await safeJson(response); throw new OpenRouterError( formatErrorMessage(errorPayload) ?? `OpenRouter error ${response.status}`, response.status ); } const data = (await response.json()) as any; const content = data?.choices?.[0]?.message?.content; const text = extractText(content); return { text, usage: { promptTokens: data?.usage?.prompt_tokens, completionTokens: data?.usage?.completion_tokens, totalTokens: data?.usage?.total_tokens, }, raw: data, }; } async ensureModelAvailable(modelId: string): Promise<boolean> { const cache = await this.getModelList(); return cache.has(modelId); } private async getModelList(): Promise<Set<string>> { const now = Date.now(); if (this.modelCache && now - this.modelCache.fetchedAt < this.modelCacheTtlMs) { return this.modelCache.ids; } const response = await fetch(`${this.baseUrl}/models`, { headers: { Authorization: `Bearer ${this.apiKey}`, 'HTTP-Referer': this.metadata.referer, 'X-Title': this.metadata.appName, }, }); if (!response.ok) { throw new OpenRouterError(`Failed to list OpenRouter models (${response.status})`, response.status); } const payload = (await response.json()) as { data?: { id: string }[] }; const ids = new Set<string>((payload.data ?? []).map((entry) => entry.id)); this.modelCache = { ids, fetchedAt: now }; return ids; } } async function safeJson(response: Response): Promise<unknown> { try { return await response.clone().json(); } catch { try { return await response.clone().text(); } catch { return undefined; } } } function formatErrorMessage(payload: unknown): string | undefined { if (!payload) return undefined; if (typeof payload === 'string') { return payload; } if (typeof payload === 'object' && 'error' in payload) { const errorValue = (payload as any).error; if (typeof errorValue === 'string') { return errorValue; } if (errorValue && typeof errorValue === 'object') { return errorValue.message ?? JSON.stringify(errorValue); } } return undefined; } function extractText( content: unknown ): string { if (!content) { return ''; } if (typeof content === 'string') { return content; } if (Array.isArray(content)) { return content .map((chunk) => { if (!chunk || typeof chunk !== 'object') return ''; if ('text' in chunk && typeof (chunk as any).text === 'string') { return (chunk as any).text; } if ('content' in chunk && typeof (chunk as any).content === 'string') { return (chunk as any).content; } return ''; }) .filter(Boolean) .join('\n'); } if (typeof content === 'object' && 'text' in (content as any)) { return String((content as any).text ?? ''); } return ''; }