import { describe, expect, it } from "vitest";
import { getModel } from "../src/models.js";
import { completeSimple } from "../src/stream.js";
function createLongSystemPrompt(): string {
const nonce = `${Date.now()}-${Math.random()}`;
return `You are a concise assistant.\nCache nonce: ${nonce}\n\n${Array(80)
.fill(
"Prompt-caching probe content. Keep this exact text stable across requests so the provider can reuse prefix tokens and report cache read and cache write usage.",
)
.join("\n\n")}`;
}
describe.skipIf(!process.env.OPENROUTER_API_KEY)("OpenRouter cache_write repro E2E", () => {
it("regression: preserves cache_write_tokens on openai-completions stream path", {
retry: 2,
timeout: 90000,
}, async () => {
const model = getModel("openrouter", "google/gemini-2.5-flash");
const context = {
systemPrompt: createLongSystemPrompt(),
messages: [
{
role: "user" as const,
content: "Reply with exactly: OK",
timestamp: Date.now(),
},
],
};
const options = {
apiKey: process.env.OPENROUTER_API_KEY!,
maxTokens: 32,
temperature: 0,
onPayload: (payload: unknown) => {
const params = payload as {
messages?: Array<{
role?: string;
content?: string | Array<{ type?: string; text?: string; cache_control?: { type: string } }>;
}>;
};
const messages = params.messages;
if (!Array.isArray(messages)) return payload;
for (let i = messages.length - 1; i >= 0; i--) {
const msg = messages[i];
if (msg.role !== "user") continue;
if (typeof msg.content === "string") {
msg.content = [{ type: "text", text: msg.content, cache_control: { type: "ephemeral" } }];
break;
}
if (!Array.isArray(msg.content)) continue;
for (let j = msg.content.length - 1; j >= 0; j--) {
const part = msg.content[j];
if (part.type === "text") {
part.cache_control = { type: "ephemeral" };
break;
}
}
break;
}
return payload;
},
};
const first = await completeSimple(model, context, options);
expect(first.stopReason, first.errorMessage).toBe("stop");
const second = await completeSimple(model, context, options);
expect(second.stopReason, second.errorMessage).toBe("stop");
const hasCacheWrite = first.usage.cacheWrite > 0 || second.usage.cacheWrite > 0;
expect(hasCacheWrite).toBe(true);
});
});