Add one-way OTA target migration aliases

test/test_full_infrastructure_selection.sh

@@ -71,6 +71,15 @@ done
 [ "$(get_exact_identity_full_pio_env heltec_v4_r8_sensor)" \
     = heltec_v4_r8_sensor ] \
   || fail "V4 R8 sensor should retain its own feature base"
+[ "$(get_exact_identity_full_migration_target heltec_v4_r8_repeater_observer_mqtt)" \
+    = heltec_v4_r8_repeater ] \
+  || fail "legacy V4 R8 observer lacks its canonical migration target"
+if get_exact_identity_full_migration_target heltec_v4_r8_repeater >/dev/null; then
+  fail "ordinary V4 R8 target unexpectedly has a migration alias"
+fi
+if get_exact_identity_full_migration_target heltec_v4_r8_repeater_observer_mqtt_sim >/dev/null; then
+  fail "simulated observer target unexpectedly received a migration alias"
+fi
 
 # Portable images and exact reduced OTA identities must not be consolidated.
 for target in heltec_v4_r8_repeater heltec_v4_r8_room_server \

test/test_ota/test_ota_core.cpp

@@ -2443,6 +2443,31 @@ TEST(OtaTransfer, TwoManagersFullTransfer) {
   EXPECT_TRUE(mota_check_image_hash_full(m));
 }
 
+TEST(OtaTransfer, LegacyIdentityAutomaticallyFetchesItsSuccessor) {
+  g_q.clear();
+  OtaManager server, client;
+  OtaStoreRam<4096> store;
+  SendTo to_client{&client}, to_server{&server};
+  const uint32_t legacy_target = SIM_TARGET_ID ^ 0x13579BDFu;
+
+  server.begin(/*server's own target irrelevant for serving*/ 0, sim_send, &to_client);
+  client.begin(legacy_target, sim_send, &to_server);
+  client.set_auto_migration_target(SIM_TARGET_ID);
+  client.set_fetch_store(&store);
+  client.set_autofetch(OtaManager::AUTOFETCH_ANY);
+
+  ASSERT_TRUE(server.serve(SIM_MOTA, SIM_MOTA_LEN));
+  server.announce();
+  pump(client, &server);
+
+  ASSERT_EQ(client.fetchState(), OtaManager::COMPLETE);
+  MotaManifest migrated;
+  ASSERT_TRUE(mota_parse(store.data(), store.staged_size(), migrated));
+  EXPECT_EQ(migrated.target_id, SIM_TARGET_ID);
+  EXPECT_EQ(client.target(), legacy_target);  // identity changes only after reboot/apply
+  EXPECT_EQ(client.auto_migration_target(), SIM_TARGET_ID);
+}
+
 TEST(OtaTransfer, LegacyOneKilobyteV2CodecStillStagesOriginalContainer) {
   g_q.clear();
   MotaManifest manifest;