chore: import upstream snapshot with attribution

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

@@ -0,0 +1,44 @@
+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 };
+    },
+  };
+}