diff --git a/tests/test_dm_media.c b/tests/test_dm_media.c
index fe16bcdb..1396619e 100644
--- a/tests/test_dm_media.c
+++ b/tests/test_dm_media.c
@@ -24,6 +24,7 @@
 #include "../src/routing_layer/etcp_router.h"
 #include "../src/transport_layer/secure_channel.h"
 #include "../src/transport_layer/etcp.h"
+#include "../src/media_delivery/file_transfer.h"
 #include "test_utils.h"
 
 #define GROUP 4242424242424243ULL
@@ -166,6 +167,48 @@ static void control(struct media_test* t, int dst, uint64_t source, uint8_t cmd,
     inst->router_bindings.callbacks[ETCP_RT_ID_DM_MEDIA](conn, e);
 }
 
+static void cancelled(void* arg, int error) {
+    int* calls = arg;
+    *calls += error == -2 ? 1 : 100;
+}
+
+/* Ошибки регистрации не расходуют seq; квота проверяется до получения байтов. */
+static int protocol_checks(struct media_test* t) {
+    struct UTUN_INSTANCE* a = t->nodes[A];
+    struct UTUN_INSTANCE* m = t->nodes[M];
+    const uint8_t* desc = dm_message_media(t->body, t->body_len);
+    uint8_t input[DM_MEDIA_DESC_SIZE + 1];
+    memcpy(input, desc, DM_MEDIA_DESC_SIZE); input[DM_MEDIA_DESC_SIZE] = 'x';
+    if (sqlite3_exec(a->topo_sqlite_db, "CREATE TEMP TRIGGER reject_dm_file BEFORE INSERT ON dm_files"
+        " BEGIN SELECT RAISE(ABORT,'injected media registration failure'); END", NULL, NULL, NULL)) return -1;
+    int rejected = dm_send(a, t->conv, "file", input, sizeof(input)) < 0;
+    if (sqlite3_exec(a->topo_sqlite_db, "DROP TRIGGER reject_dm_file", NULL, NULL, NULL)) return -1;
+    if (!rejected || value(a, "SELECT last_out_seq FROM dm_conversations") != 1 ||
+        value(a, "SELECT count(*) FROM dm_messages") != 1 || value(a, "SELECT count(*) FROM dm_outbox") != 0) return -1;
+    char json[8192]; size_t len;
+    if (dm_list_messages_json(a, t->conv, 200, 0, json, sizeof(json), &len) ||
+        !strstr(json, "\"media_status\":\"delivered\"") || !strstr(json, "\"media_path\":")) return -1;
+    uint8_t request[8 + sizeof(t->body)];
+    memcpy(request, &t->ids[B], 8); memcpy(request + 8, t->body, t->body_len);
+    uint8_t* metadata = (uint8_t*)dm_message_media(request + 8, t->body_len);
+    metadata[0] ^= 0x80;
+    uint64_t size = 2 * 1024 * 1024;
+    memcpy(metadata + 16, &size, 8);
+    if (sc_ed25519_sign(a->my_ed25519_privkey, request + 8, t->body_len - DM_MSG_SIG_SIZE,
+                       request + 8 + t->body_len - DM_MSG_SIG_SIZE) || chat_setting_set(m, "dm_media_storage_mb", "1")) return -1;
+    control(t, M, t->ids[S], DM_MEDIA_STORE, request, 8 + t->body_len);
+    if (value(m, "SELECT count(*) FROM dm_custody") != 0 || chat_setting_set(m, "dm_media_storage_mb", "1024")) return -1;
+    char path[768]; snprintf(path, sizeof(path), "%s/cancelled.download", t->dir);
+    int calls = 0;
+    struct file_transfer_op* op = file_transfer_pull(t->nodes[B]->file_transfer, GROUP, t->ids[A], t->id,
+        dm_media_cipher_size(FILE_BYTES), path, cancelled, &calls);
+    if (!op) return -1;
+    file_transfer_cancel_object(t->nodes[B]->file_transfer, t->id);
+    if (calls != 1) return -1;
+    DEBUG_INFO(DEBUG_CATEGORY_DM, "media protocol checks passed: SQL rollback, quota, JSON state, CM operation cancellation");
+    return 0;
+}
+
 /* Таймер служит heartbeat: большие криптозадачи не должны останавливать сценарий. */
 static void tick(void* arg) {
     struct media_test* t = arg;
@@ -193,6 +236,7 @@ static void tick(void* arg) {
                 value(m, "SELECT count(*) FROM dm_custody") != 0) { failure(t, "direct transfer/custody isolation"); return; }
             uint8_t bad[DM_MEDIA_RECEIPT_SIZE]; memcpy(bad, t->receipt, sizeof(bad)); bad[56] ^= 1;
             if (!dm_media_verify_receipt(a, bad, t->body, t->body_len)) { failure(t, "forged media receipt accepted"); return; }
+            if (protocol_checks(t)) { failure(t, "media protocol invariants"); return; }
             utun_instance_destroy(b); t->nodes[B] = NULL; t->phase++;
         }
         break;