open-sse/services/compression/eval/executorModelClient.ts

import { getExecutor } from "../../../executors/index.ts";
import type { ExecuteInput, ProviderCredentials } from "../../../executors/base.ts";
import type { ChatTurn, ModelCallResult, ModelClient } from "./types.ts";

/**
 * Production ModelClient adapter (Hard Rule #18 — NOT unit-tested; validated on a real
 * VPS/account). Wraps the server executor: builds a minimal non-stream chat body, calls
 * `getExecutor(provider).execute(...)`, reads the response text + (best-effort) usage cost.
 *
 * The pure runner depends only on the `ModelClient` interface; this adapter is the single
 * place that touches credentials, the executor, and Response parsing — so the eval stays
 * faithful to production while the runner/scorers remain fully testable with a stub.
 */
export function createExecutorModelClient(
  provider: string,
  credentials: ProviderCredentials,
  costPerKTokenOut?: number
): ModelClient {
  const executor = getExecutor(provider);
  return {
    async complete(model: string, messages: ChatTurn[]): Promise<ModelCallResult> {
      const body = { model, messages, stream: false };
      const input: ExecuteInput = {
        model,
        body,
        stream: false,
        credentials,
      };
      // BaseExecutor.execute resolves to { response, url, headers, transformedBody } — the
      // upstream Response lives on `.response` (never a bare Response). Validated live on VPS.
      const raw = (await executor.execute(input)) as { response: Response };
      const response = raw.response;
      const json = (await response.json()) as {
        choices?: Array<{ message?: { content?: string } }>;
        usage?: { completion_tokens?: number };
      };
      const text = json.choices?.[0]?.message?.content ?? "";
      const outTokens = json.usage?.completion_tokens ?? 0;
      const usdCost =
        typeof costPerKTokenOut === "number" ? (outTokens / 1000) * costPerKTokenOut : undefined;
      return usdCost === undefined ? { text } : { text, usdCost };
    },
  };
}