Function streamRequest

src/app/apiClient.ts:242–316

(
    url: string,
    options: RequestInit,
    signal?: AbortSignal,
)

 *   backend rejected the request but responded with a structured body
 */
export async function* streamRequest<T = any>(
    url: string,
    options: RequestInit,
    signal?: AbortSignal,
): AsyncGenerator<StreamEvent<T>> {
    const response = await fetchWithIdentity(url, { ...options, signal });

    // Defensive: true transport-level errors (500 crash, 413 WSGI reject, etc.)
    if (!response.ok) {
        let apiError: ApiError;
        try {
            const body = await response.json();
            apiError = body.error ?? {
                code: 'HTTP_ERROR',
                message: `HTTP ${response.status}`,
                retry: false,
            };
        } catch {
            apiError = { code: 'HTTP_ERROR', message: `HTTP ${response.status}`, retry: false };
        }
        throw new ApiRequestError(apiError, response.status);
    }

    // Validation errors: backend returns 200 + application/json instead of NDJSON
    const contentType = response.headers.get('content-type') ?? '';
    if (contentType.includes('application/json')) {
        const body = await response.json();
        if (body.status === 'error') {
            const apiError: ApiError = body.error ?? {
                code: 'MALFORMED_ERROR',
                message: 'Malformed error response',
                retry: false,
            };
            throw new ApiRequestError(apiError, response.status);
        }
        throw new ApiRequestError(
            { code: 'MALFORMED_STREAM_RESPONSE', message: 'Expected NDJSON stream response', retry: false },
            response.status,
        );
    }

    const reader = response.body?.getReader();
    if (!reader) {
        throw new ApiRequestError(
            { code: 'MALFORMED_STREAM_RESPONSE', message: 'Missing stream body', retry: false },
            response.status,
        );
    }
    const decoder = new TextDecoder();
    let buffer = '';

    try {
        while (true) {
            const { done, value } = await reader.read();
            if (done) break;

            buffer += decoder.decode(value, { stream: true });
            const lines = buffer.split('\n');