Class CurlWriteCtx

server/src/server/http_server.cpp:131–139

#ifdef DFLASH_HAS_CURL

struct CurlWriteCtx {
    int client_fd;
    bool streaming;
    bool first_chunk;
    bool chat_rewrite;   // rewrite completions → chat format
    std::string buffer;  // accumulates non-streaming response
    std::string response_id;
    std::string model;
};

static size_t curl_write_passthrough(char * ptr, size_t size, size_t nmemb, void * userdata) {
    size_t total = size * nmemb;