diff --git a/tests/test_attachment.c b/tests/test_attachment.c
new file mode 100644
index 00000000..b9943dc6
--- /dev/null
+++ b/tests/test_attachment.c
@@ -0,0 +1,51 @@
+/* Строгие метаданные и реальный Opus-файл: границы, повреждения, длительность. */
+#include <stdio.h>
+#include <string.h>
+#include "../lib/mem.h"
+#include "../lib/debug_config.h"
+#include "../lib/opus_codec.h"
+#include "../src/media_async/attachment.h"
+#include "../src/media_async/voice_file.h"
+#define REQUIRE(value) do { if (!(value)) { fprintf(stderr, "attachment check failed line=%d\n", __LINE__); return 1; } } while (0)
+
+int main(void) {
+    debug_config_init(); debug_set_level(DEBUG_LEVEL_ERROR);
+    struct attachment_info in = { .kind = ATTACHMENT_VOICE, .name = "голос.opus", .duration_ms = 1200 }, out;
+    memset(in.waveform, 'A', 100);
+    uint8_t wire[ATTACHMENT_WIRE_MAX + 1];
+    int length = attachment_encode(&in, wire, sizeof(wire));
+    REQUIRE(length > 0 && !attachment_decode(wire, length, &out));
+    REQUIRE(out.kind == in.kind && out.duration_ms == 1200 && !strcmp(in.name, out.name) && !strcmp(in.waveform, out.waveform));
+    for (int i = 0; i < length; i++) REQUIRE(attachment_decode(wire, i, &out) < 0);
+    REQUIRE(attachment_decode(wire, length + 1, &out) < 0);
+    wire[0] = 99; REQUIRE(attachment_decode(wire, length, &out) < 0);
+    wire[0] = ATTACHMENT_VOICE; wire[length - 1] = '?'; REQUIRE(attachment_decode(wire, length, &out) < 0);
+    in.kind = ATTACHMENT_VIDEO; in.waveform[0] = 0; in.width = 640; in.height = 480;
+    length = attachment_encode(&in, wire, sizeof(wire)); REQUIRE(length > 0 && !attachment_decode(wire, length, &out));
+    REQUIRE(out.width == 640 && out.height == 480);
+    in.width = 0; REQUIRE(attachment_validate(&in) < 0);
+    in = (struct attachment_info){ .kind = ATTACHMENT_FILE, .name = "../unsafe" }; REQUIRE(attachment_validate(&in) < 0);
+    strcpy(in.name, "\xc0\xaf"); REQUIRE(attachment_validate(&in) < 0);
+    memset(in.name, 'n', 255); in.name[255] = 0;
+    REQUIRE(attachment_encode(&in, wire, 265) < 0); REQUIRE(attachment_encode(&in, wire, 266) == 266);
+    int16_t* pcm = u_calloc(48001, sizeof(*pcm)); REQUIRE(pcm != NULL);
+    for (unsigned i = 0; i < 48001; i++) pcm[i] = (int16_t)((i % 200) * 100 - 10000);
+    in = (struct attachment_info){ .name = "voice.opus" };
+    const char* path = "test_attachment_voice.opus";
+    REQUIRE(!voice_file_encode(pcm, 48001, 48000, 1, 1, path, &in));
+    REQUIRE(in.duration_ms == 1000 && strlen(in.waveform) == 100 && !attachment_validate(&in));
+    FILE* file = fopen(path, "rb"); REQUIRE(file != NULL);
+    uint8_t header[12]; REQUIRE(fread(header, 1, 12, file) == 12);
+    opus_codec_decoder_t* decoder = opus_codec_decoder_create(48000, 1); REQUIRE(decoder != NULL);
+    uint8_t packet[4000]; int16_t decoded[960]; unsigned frames = 0;
+    for (;;) {
+        uint16_t n; REQUIRE(fread(&n, 2, 1, file) == 1);
+        if (!n) break;
+        REQUIRE(n <= sizeof(packet) && fread(packet, 1, n, file) == n);
+        REQUIRE(opus_codec_decode(decoder, packet, n, decoded, 960) == 960); frames++;
+    }
+    REQUIRE(frames == 50 && fgetc(file) == EOF);
+    fclose(file); remove(path); opus_codec_decoder_destroy(decoder); u_free(pcm);
+    printf("test_attachment: strict metadata and shared Opus encode/decode PASS\n");
+    return 0;
+}
diff --git a/tests/test_dm_media.c b/tests/test_dm_media.c
index aad3bdb6..ab11ca5e 100644
--- a/tests/test_dm_media.c
+++ b/tests/test_dm_media.c
@@ -178,17 +178,21 @@ 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';
+    uint8_t input[DM_MEDIA_DESC_SIZE + ATTACHMENT_WIRE_MAX];
+    struct attachment_info info = { .kind = ATTACHMENT_FILE, .name = "rollback.bin" };
+    int metadata_len = attachment_encode(&info, input + DM_MEDIA_DESC_SIZE, ATTACHMENT_WIRE_MAX);
+    if (metadata_len < 0) return -1;
+    memcpy(input, desc, DM_MEDIA_DESC_SIZE);
     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;
+    int rejected = dm_send(a, t->conv, "file", input, DM_MEDIA_DESC_SIZE + metadata_len) < 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;
+        !strstr(json, "\"media_status\":\"delivered\"") || !strstr(json, "\"media_path\":") ||
+        !strstr(json, "\"content_type\":\"audio/opus\"") || !strstr(json, "\"duration_ms\":3000")) 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);
@@ -212,6 +216,15 @@ static int protocol_checks(struct media_test* t) {
 }
 
 /* Таймер служит heartbeat: большие криптозадачи не должны останавливать сценарий. */
+/* Одни и те же transfer/custody гарантии для разных типов вложений. */
+static int send_fixture(struct media_test* t, enum attachment_kind kind, const char* name) {
+    struct attachment_info info = { .kind = kind };
+    snprintf(info.name, sizeof(info.name), "%s", name);
+    if (kind == ATTACHMENT_VOICE) { info.duration_ms = 3000; memset(info.waveform, 'A', 100); }
+    if (kind == ATTACHMENT_VIDEO) { info.duration_ms = 3000; info.width = 640; info.height = 480; }
+    return dm_send_file(t->nodes[A], t->conv, t->file, &info, 0);
+}
+
 static void tick(void* arg) {
     struct media_test* t = arg;
     t->timer = NULL; t->ticks++; t->heartbeats++;
@@ -228,7 +241,7 @@ static void tick(void* arg) {
         break;
     case 1:
         if (live(a, t->ids[B]) && live(m, t->ids[A])) {
-            if (dm_send_file(a, t->conv, t->file, "direct.bin")) { failure(t, "direct file enqueue"); return; }
+            if (send_fixture(t, ATTACHMENT_VOICE, "direct.opus")) { failure(t, "direct voice enqueue"); return; }
             t->phase++;
         }
         break;
@@ -244,7 +257,7 @@ static void tick(void* arg) {
         break;
     case 3:
         if (!live(a, t->ids[B])) {
-            if (dm_send_file(a, t->conv, t->file, "offline.bin")) { failure(t, "offline file enqueue"); return; }
+            if (send_fixture(t, ATTACHMENT_VIDEO, "offline.mp4")) { failure(t, "offline video enqueue"); return; }
             t->phase++;
         }
         break;
@@ -282,7 +295,7 @@ static void tick(void* arg) {
         break;
     case 7:
         if (!live(a, t->ids[B])) {
-            if (dm_send_file(a, t->conv, t->file, "expires.bin")) { failure(t, "TTL file enqueue"); return; }
+            if (send_fixture(t, ATTACHMENT_FILE, "expires.bin")) { failure(t, "TTL file enqueue"); return; }
             t->phase++;
         }
         break;