tokenvault/packages/core/src/routes/anthropic-proxy.ts

import type { FastifyInstance } from 'fastify';
import { createTicket, hashContent } from '../tickets/ticket-service.js';
import { logger } from '../observability/logger.js';
import { config } from '../config.js';

// Anthropic pricing per 1M tokens (USD)
const ANTHROPIC_PRICING: Record<string, { input: number; output: number; cached?: number }> = {
  'claude-opus-4-20250514':    { input: 15.0,  output: 75.0,  cached: 1.50  },
  'claude-opus-4-5':           { input: 15.0,  output: 75.0,  cached: 1.50  },
  'claude-sonnet-4-20250514':  { input: 3.0,   output: 15.0,  cached: 0.30  },
  'claude-sonnet-4-5-20251001':{ input: 3.0,   output: 15.0,  cached: 0.30  },
  'claude-haiku-3-5-20251022': { input: 0.80,  output: 4.0,   cached: 0.08  },
  'claude-haiku-3-20250307':   { input: 0.25,  output: 1.25,  cached: 0.025 },
};

function calcCost(model: string, inputTokens: number, outputTokens: number, cachedTokens: number): number {
  const pricing = ANTHROPIC_PRICING[model] ?? ANTHROPIC_PRICING['claude-sonnet-4-20250514']!;
  const inputCost  = ((inputTokens - cachedTokens) / 1_000_000) * pricing.input;
  const outputCost = (outputTokens / 1_000_000) * pricing.output;
  const cacheCost  = pricing.cached ? (cachedTokens / 1_000_000) * pricing.cached : 0;
  return Math.max(0, inputCost + outputCost + cacheCost);
}

/**
 * Anthropic API passthrough — enables ANTHROPIC_BASE_URL routing.
 *
 * Claude Code (and any Anthropic SDK client) sends requests here when
 * ANTHROPIC_BASE_URL=https://tokenvault.fichtmueller.org is set.
 * We forward the request to Anthropic using the client's own API key,
 * then create a TokenVault ticket to track usage and cost.
 */
export async function anthropicProxyRoutes(app: FastifyInstance): Promise<void> {

  // ─── POST /v1/messages — Anthropic Messages API passthrough ──────────────
  app.post('/v1/messages', async (req, reply) => {
    const body = req.body as Record<string, unknown>;
    const model = (body['model'] as string) ?? 'claude-sonnet-4-20250514';

    // Use the client's API key if provided, fall back to configured key
    const apiKey = (req.headers['x-api-key'] as string)
      || (req.headers['authorization'] as string)?.replace(/^Bearer /, '')
      || config.providers.anthropic.apiKey;

    const anthropicVersion = (req.headers['anthropic-version'] as string) ?? '2023-06-01';
    const anthropicBeta    = req.headers['anthropic-beta'] as string | undefined;

    const caller  = req.headers['x-tokenvault-caller'] as string | undefined;
    const project = req.headers['x-tokenvault-project'] as string | undefined;
    const team    = req.headers['x-tokenvault-team'] as string | undefined;

    const start = Date.now();

    // ── Forward to Anthropic ────────────────────────────────────────────────
    const forwardHeaders: Record<string, string> = {
      'Content-Type':       'application/json',
      'x-api-key':          apiKey,
      'anthropic-version':  anthropicVersion,
    };
    if (anthropicBeta) forwardHeaders['anthropic-beta'] = anthropicBeta;

    const upstream = await fetch('https://api.anthropic.com/v1/messages', {
      method:  'POST',
      headers: forwardHeaders,
      body:    JSON.stringify(body),
    });

    const latency = Date.now() - start;
    const responseBody = await upstream.json() as Record<string, unknown>;

    // ── Track as TokenVault ticket (best-effort, non-blocking) ─────────────
    if (upstream.ok) {
      const usage = responseBody['usage'] as {
        input_tokens?: number;
        output_tokens?: number;
        cache_read_input_tokens?: number;
        cache_creation_input_tokens?: number;
      } | undefined;

      if (usage) {
        const inputTokens  = usage.input_tokens  ?? 0;
        const outputTokens = usage.output_tokens ?? 0;
        const cachedTokens = usage.cache_read_input_tokens ?? 0;
        const cost = calcCost(model, inputTokens, outputTokens, cachedTokens);

        const messages = (body['messages'] as Array<{ role: string; content: unknown }>) ?? [];
        const inputText = messages.map(m => {
          if (typeof m.content === 'string') return m.content;
          if (Array.isArray(m.content)) return m.content.map((c: Record<string, unknown>) => c['text'] ?? '').join('');
          return '';
        }).join('\n');
        const outputContent = (responseBody['content'] as Array<{ text?: string }> | undefined) ?? [];
        const outputText = outputContent.map(c => c.text ?? '').join('');

        createTicket({
          provider:   'anthropic',
          model,
          status:     'completed',
          tokens_in:  inputTokens,
          tokens_out: outputTokens,
          tokens_cached: cachedTokens,
          tokens_saved:  0,
          cost_usd:   cost,
          latency_ms: latency,
          cache_hit:  cachedTokens > 0,
          caller:     caller ?? 'claude-code',
          project,
          team,
          input_hash:  hashContent(inputText),
          output_hash: hashContent(outputText),
        }).catch(err => logger.warn({ err }, 'Failed to create ticket for Anthropic passthrough'));
      }
    } else {
      // Track failed requests too
      createTicket({
        provider:   'anthropic',
        model,
        status:     'failed',
        tokens_in:  0,
        tokens_out: 0,
        cost_usd:   0,
        latency_ms: latency,
        caller:     caller ?? 'claude-code',
        project,
        team,
        input_hash: hashContent(model),
        output_hash: '',
      }).catch(() => { /* best effort */ });

      logger.warn({ model, status: upstream.status }, 'Anthropic upstream error');
    }

    // ── Return Anthropic response as-is ────────────────────────────────────
    reply.code(upstream.status);
    reply.header('Content-Type', 'application/json');

    // Pass through useful Anthropic response headers
    const anthropicReqId = upstream.headers.get('request-id');
    if (anthropicReqId) reply.header('request-id', anthropicReqId);

    return responseBody;
  });

}