expect(body.error.message).toContain("Malformed JSON body");

});

it("rejects malformed OpenAI-compatible JSON without crashing the mock server", async () => {

const server = await startQaMockOpenAiServer({

host: "127.0.0.1",

port: 0,

});

cleanups.push(async () => {

await server.stop();

});

for (const path of ["/v1/responses", "/v1/embeddings", "/v1/images/generations"]) {

const response = await fetch(`${server.baseUrl}${path}`, {

method: "POST",

headers: { "content-type": "application/json" },

body: "{bad",

});

expect(response.status).toBe(400);

const body = (await response.json()) as {

error: { type: string; message: string };

};

expect(body.error.type).toBe("invalid_request_error");

expect(body.error.message).toContain("Malformed JSON body");

}

const health = await fetch(`${server.baseUrl}/healthz`);

expect(health.status).toBe(200);

});

it("defaults empty-string Anthropic /v1/messages model to claude-opus-4-8", async () => {

// Regression for the loop-7 Copilot finding: a bare `typeof

// body.model === "string"` check lets an empty-string model leak

});

}

function parseOpenAiJsonBody(raw: string): Record<string, unknown> | null {

try {

return raw ? (JSON.parse(raw) as Record<string, unknown>) : {};

} catch {

return null;

}

}

function writeOpenAiMalformedJsonError(res: ServerResponse, label: string) {

writeJson(res, 400, {

error: {

type: "invalid_request_error",

message: `Malformed JSON body for ${label} request.`,

},

});

}

function transcriptionTextForAudioRequest(rawBody: string) {

if (rawBody.length >= QA_GROUP_AUDIO_MIN_MULTIPART_BODY_CHARS) {

return QA_GROUP_AUDIO_TRANSCRIPTION_TEXT;

}

if (req.method === "POST" && url.pathname === "/v1/images/generations") {

const raw = await readBody(req);

const body = raw ? (JSON.parse(raw) as Record<string, unknown>) : {};

const body = parseOpenAiJsonBody(raw);

if (!body) {

writeOpenAiMalformedJsonError(res, "OpenAI Images");

return;

}

imageGenerationRequests.push(body);

if (imageGenerationRequests.length > 20) {

imageGenerationRequests.splice(0, imageGenerationRequests.length - 20);

}

if (req.method === "POST" && url.pathname === "/v1/embeddings") {

const raw = await readBody(req);

const body = raw ? (JSON.parse(raw) as Record<string, unknown>) : {};

const body = parseOpenAiJsonBody(raw);

if (!body) {

writeOpenAiMalformedJsonError(res, "OpenAI Embeddings");

return;

}

const inputs = extractEmbeddingInputTexts(body.input);

writeJson(res, 200, {

object: "list",

}

if (req.method === "POST" && url.pathname === "/v1/responses") {

const raw = await readBody(req);

const body = raw ? (JSON.parse(raw) as Record<string, unknown>) : {};

const body = parseOpenAiJsonBody(raw);

if (!body) {

writeOpenAiMalformedJsonError(res, "OpenAI Responses");

return;

}

const input = Array.isArray(body.input) ? (body.input as ResponsesInputItem[]) : [];

const events = await buildResponsesPayload(body, scenarioState);

const resolvedModel = typeof body.model === "string" ? body.model : "";