fix(dns): preserve 127.0.0.42 during restart and add local DNS cache support

- decouple restart() from stop_impl() in lifecycle.uc to avoid premature dnsmasq_restore
- keep dhcp.@dnsmasq[0].server locked to 127.0.0.42 throughout service restarts
- add atomic restart_service hooks in init.d/tachyon and initd.uc
- fix dns_turbo_cache path resolution to promote default cache to /etc/sing-box/cache.db
- add Local DNS Cache support in dnsmasq (dns_local_cache, dns_cache_size)
- add comprehensive behavioral regression test tests/service_restart_lifecycle.sh

fe-app-tachyon/locales/tachyon.ru.po

@@ -7,8 +7,8 @@ msgid ""
 msgstr ""
 "Project-Id-Version: TACHYON\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2026-09-17 08:13+0300\n"
+"POT-Creation-Date: 2026-09-17 08:45+0300\n"
-"PO-Revision-Date: 2026-09-17 08:13+0300\n"
+"PO-Revision-Date: 2026-09-17 08:45+0300\n"
 "Last-Translator: Dushnilin\n"
 "Language-Team: none\n"
 "Language: ru\n"
@@ -1439,6 +1439,9 @@ msgstr "Автоподбор и бенчмарк DNS"
 msgid "DNS Blocking"
 msgstr "Блокировка DNS"
 
+msgid "DNS Cache Size"
+msgstr ""
+
 msgid "DNS Check Interval"
 msgstr "Интервал проверки DNS"
 
@@ -1793,6 +1796,9 @@ msgstr "Включено"
 msgid "Enabled (always prioritize)"
 msgstr "Включено (всегда повышать приоритет)"
 
+msgid "Enables high-capacity local DNS caching in dnsmasq to accelerate DNS queries and absorb transient latency during service restarts."
+msgstr ""
+
 msgid "Enables the background daemon that polls Telegram for commands and sends notifications."
 msgstr "Включает фоновый демон, который опрашивает Telegram на наличие команд и отправляет уведомления."
 
@@ -3095,6 +3101,9 @@ msgstr "Загрузка..."
 msgid "Local Address"
 msgstr "Локальный адрес"
 
+msgid "Local DNS Cache"
+msgstr ""
+
 msgid "Local SOCKS proxy desynchronizer (ciadpi)"
 msgstr "Локальный десинхронизатор SOCKS-прокси (ciadpi)"
 
@@ -3470,6 +3479,9 @@ msgstr "Уведомлять о перезапусках сервиса"
 msgid "Notify on Subscription Updates"
 msgstr "Уведомлять об обновлениях подписок"
 
+msgid "Number of cached DNS domain entries in dnsmasq (default: 10000)."
+msgstr ""
+
 msgid "Number of consecutive failed checks required before switching DNS servers."
 msgstr "Количество последовательных неудачных проверок до переключения DNS-серверов."
 

fe-app-tachyon/src/tachyon/types.ts

@@ -476,6 +476,8 @@ export namespace Tachyon {
     smart_detect_section?: string;
     smart_detect_sections?: string | string[];
     dns_turbo_cache?: '0' | '1';
+    dns_local_cache?: '0' | '1';
+    dns_cache_size?: string;
     // AI Watchdog settings (introduced in AI Watchdog feature)
     ai_proxy_health_enabled?: '0' | '1';
     ai_proxy_health_interval?: string;

luci-app-tachyon/htdocs/luci-static/resources/view/tachyon/settings.js

@@ -1853,6 +1853,30 @@ function createSettingsContent(section, capabilities) {
   o.default = "0";
   o.rmempty = false;
 
+  o = section.taboption(
+    "dns",
+    form.Flag,
+    "dns_local_cache",
+    _("Local DNS Cache"),
+    _(
+      "Enables high-capacity local DNS caching in dnsmasq to accelerate DNS queries and absorb transient latency during service restarts.",
+    ),
+  );
+  o.default = "0";
+  o.rmempty = false;
+
+  o = section.taboption(
+    "dns",
+    form.Value,
+    "dns_cache_size",
+    _("DNS Cache Size"),
+    _("Number of cached DNS domain entries in dnsmasq (default: 10000)."),
+  );
+  o.depends("dns_local_cache", "1");
+  o.default = "10000";
+  o.datatype = "uinteger";
+  o.rmempty = true;
+
   // ─── DNS Strategy ────────────────────────────────────────────────────────
 
   o = section.taboption(

luci-app-tachyon/po/ru/tachyon.po

@@ -7,8 +7,8 @@ msgid ""
 msgstr ""
 "Project-Id-Version: TACHYON\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2026-09-17 08:13+0300\n"
+"POT-Creation-Date: 2026-09-17 08:45+0300\n"
-"PO-Revision-Date: 2026-09-17 08:13+0300\n"
+"PO-Revision-Date: 2026-09-17 08:45+0300\n"
 "Last-Translator: Dushnilin\n"
 "Language-Team: none\n"
 "Language: ru\n"
@@ -1439,6 +1439,9 @@ msgstr "Автоподбор и бенчмарк DNS"
 msgid "DNS Blocking"
 msgstr "Блокировка DNS"
 
+msgid "DNS Cache Size"
+msgstr ""
+
 msgid "DNS Check Interval"
 msgstr "Интервал проверки DNS"
 
@@ -1793,6 +1796,9 @@ msgstr "Включено"
 msgid "Enabled (always prioritize)"
 msgstr "Включено (всегда повышать приоритет)"
 
+msgid "Enables high-capacity local DNS caching in dnsmasq to accelerate DNS queries and absorb transient latency during service restarts."
+msgstr ""
+
 msgid "Enables the background daemon that polls Telegram for commands and sends notifications."
 msgstr "Включает фоновый демон, который опрашивает Telegram на наличие команд и отправляет уведомления."
 
@@ -3095,6 +3101,9 @@ msgstr "Загрузка..."
 msgid "Local Address"
 msgstr "Локальный адрес"
 
+msgid "Local DNS Cache"
+msgstr ""
+
 msgid "Local SOCKS proxy desynchronizer (ciadpi)"
 msgstr "Локальный десинхронизатор SOCKS-прокси (ciadpi)"
 
@@ -3470,6 +3479,9 @@ msgstr "Уведомлять о перезапусках сервиса"
 msgid "Notify on Subscription Updates"
 msgstr "Уведомлять об обновлениях подписок"
 
+msgid "Number of cached DNS domain entries in dnsmasq (default: 10000)."
+msgstr ""
+
 msgid "Number of consecutive failed checks required before switching DNS servers."
 msgstr "Количество последовательных неудачных проверок до переключения DNS-серверов."
 

tachyon/files/etc/config/tachyon

@@ -48,6 +48,8 @@ config settings 'settings'
         #option p2p_ports 'tcp:6881,udp:6881-6889'
         option config_path '/etc/sing-box/config.json'
         option cache_path '/tmp/sing-box/cache.db'
+        option dns_local_cache '0'
+        option dns_cache_size '10000'
         option log_level 'warn'
         option exclude_ntp '0'
         option shutdown_correctly '0'

tachyon/files/etc/init.d/tachyon

@@ -46,6 +46,16 @@ stop_service() {
     trap - INT TERM
 }
 
+restart_service() {
+    trap 'exit 1' INT TERM
+    initd_ucode restart-service "$$"
+    trap - INT TERM
+}
+
+restart() {
+    restart_service "$@"
+}
+
 reload_service() {
     local reason="$1"
     local result status

tachyon/files/usr/lib/dns/apply.uc

@@ -120,10 +120,18 @@ function dnsmasq_management_disabled() {
     return truthy(uci_get(CONFIG_NAME + ".settings.dont_touch_dhcp"));
 }
 
+function dnsmasq_target_cachesize() {
+    if (truthy(uci_get(CONFIG_NAME + ".settings.dns_local_cache"))) {
+        let size = uci_get(CONFIG_NAME + ".settings.dns_cache_size");
+        return (size != null && size != "") ? as_string(size) : "10000";
+    }
+    return "0";
+}
+
 function dnsmasq_default_config_is_complete() {
     return dnsmasq_default_has_tachyon_dns() &&
         uci_get("dhcp.@dnsmasq[0].noresolv") == "1" &&
-        uci_get("dhcp.@dnsmasq[0].cachesize") == "0" &&
+        uci_get("dhcp.@dnsmasq[0].cachesize") == dnsmasq_target_cachesize() &&
         !dnsmasq_legacy_instance_exists();
 }
 
@@ -209,7 +217,7 @@ function dnsmasq_configure_default_instance() {
     uci_delete("dhcp.@dnsmasq[0].server");
     uci_add_list("dhcp.@dnsmasq[0].server", SB_DNS_INBOUND_ADDRESS);
     uci_set("dhcp.@dnsmasq[0].noresolv", "1");
-    uci_set("dhcp.@dnsmasq[0].cachesize", "0");
+    uci_set("dhcp.@dnsmasq[0].cachesize", dnsmasq_target_cachesize());
 }
 
 function dnsmasq_restore_default_instance() {

tachyon/files/usr/lib/service/initd.uc

@@ -647,6 +647,26 @@ function stop_service(owner_pid) {
     return stop_finish(job_id, status);
 }
 
+function restart_service(owner_pid) {
+    clear_start_retry(START_RETRY_FILE);
+    cancel_scheduled_start_retry(START_RETRY_PID_FILE);
+    let job_id = begin_external_service_action("restart", "initd", owner_pid);
+    if (!file_executable(BIN_PATH)) {
+        restore_dnsmasq_failsafe();
+        finish_external_service_action("restart", job_id, 1);
+        return 1;
+    }
+
+    let status = command_status_from_args([ BIN_PATH, "restart" ]);
+    if (status != 0) {
+        mark_start_retry(START_RETRY_FILE, "restart_failed");
+        schedule_start_retry(START_RETRY_PID_FILE, START_RETRY_DELAY_SECONDS);
+        command_success_from_args([ "logger", "-t", SERVICE_NAME, "[warn] Tachyon restart failed; scheduled an automatic retry" ]);
+    }
+    finish_external_service_action("restart", job_id, status);
+    return status;
+}
+
 function reload_begin_value(reason, owner_pid, runtime_running_value, service_enabled_value, active_service_action) {
     reason = as_string(reason);
 
@@ -817,6 +837,8 @@ else if (mode == "stop-finish")
     exit(stop_finish(ARGV[1], ARGV[2]));
 else if (mode == "stop-service")
     exit(stop_service(ARGV[1]));
+else if (mode == "restart-service")
+    exit(restart_service(ARGV[1]));
 else if (mode == "reload-begin")
     exit(reload_begin(ARGV[1], ARGV[2], null, null));
 else if (mode == "reload-begin-fixture") {

tachyon/files/usr/lib/service/lifecycle.uc

@@ -1627,7 +1627,9 @@ function restart() {
     log_message("Restarting Tachyon", "info");
 
     let selector_state = capture_selector_state();
-    let status = stop_impl();
+    invalidate_reload_hash();
+
+    let status = stop_main();
     if (status != 0)
         return status;
 
@@ -1637,6 +1639,17 @@ function restart() {
         return status;
     }
 
+    status = module_status(STATE_UC, [
+        "wait-sing-box-service-stable",
+        as_string(SING_BOX_START_STABLE_MIN_AGE),
+        as_string(SING_BOX_START_VERIFY_TIMEOUT)
+    ]);
+    if (status != 0) {
+        log_message("Restart verification failed after Tachyon was started; rolling back DNS changes", "fatal");
+        cleanup_failed_runtime();
+        return status;
+    }
+
     if (module_success(STATE_UC, [
         "tachyon-stably-running",
         RT_TABLE_NAME,

tachyon/files/usr/lib/singbox/generator.uc

@@ -453,7 +453,9 @@ function base_config(settings, service_address, runtime_context) {
     let log_level = option(settings, "log_level", "warn");
     let rewrite_ttl = int_option(settings, "dns_rewrite_ttl", "60");
     let turbo_cache = bool_option(settings, "dns_turbo_cache", false);
-    let cache_path = option(settings, "cache_path", turbo_cache ? "/etc/sing-box/cache.db" : "/tmp/sing-box/cache.db");
+    let cache_path = option(settings, "cache_path", "/tmp/sing-box/cache.db");
+    if (turbo_cache && (cache_path == "/tmp/sing-box/cache.db" || cache_path == ""))
+        cache_path = "/etc/sing-box/cache.db";
     let cache_dir = replace(cache_path, /\/[^\/]+$/, "");
     if (cache_dir != "" && cache_dir != cache_path) {
         try { fs.mkdir(cache_dir, 0755); } catch(e) {}

tests/service_restart_lifecycle.sh

@@ -0,0 +1,202 @@
+#!/usr/bin/env bash
+set -eo pipefail
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+TACHYON_BIN="$ROOT_DIR/tachyon/files/usr/bin/tachyon"
+TACHYON_INIT="$ROOT_DIR/tachyon/files/etc/init.d/tachyon"
+LIFECYCLE_UC="$ROOT_DIR/tachyon/files/usr/lib/service/lifecycle.uc"
+INITD_UC="$ROOT_DIR/tachyon/files/usr/lib/service/initd.uc"
+APPLY_UC="$ROOT_DIR/tachyon/files/usr/lib/dns/apply.uc"
+GENERATOR_UC="$ROOT_DIR/tachyon/files/usr/lib/singbox/generator.uc"
+
+fail() {
+  printf 'FAIL: %s\n' "$1" >&2
+  exit 1
+}
+
+# --- 1. Static assertions on lifecycle.uc restart() -------------------------
+awk '
+  /function restart\(\)/ { in_restart = 1 }
+  in_restart && /stop_impl\(\)/ { called_stop_impl = 1 }
+  in_restart && /stop_main\(\)/ { called_stop_main = 1 }
+  in_restart && /start_impl\(\)/ { called_start_impl = 1 }
+  in_restart && /capture_selector_state\(\)/ { captured_selector = 1 }
+  in_restart && /restore_selector_state\(selector_state\)/ { restored_selector = 1 }
+  in_restart && /cleanup_failed_runtime\(\)/ { cleaned_on_failure = 1 }
+  in_restart && /^}/ { done = 1; exit }
+  END {
+    if (!done) exit 1
+    if (called_stop_impl) { print "restart() must not call stop_impl()"; exit 2 }
+    if (!called_stop_main) { print "restart() must call stop_main()"; exit 3 }
+    if (!called_start_impl) { print "restart() must call start_impl()"; exit 4 }
+    if (!captured_selector) { print "restart() must capture selector state"; exit 5 }
+    if (!restored_selector) { print "restart() must restore selector state"; exit 6 }
+    if (!cleaned_on_failure) { print "restart() must call cleanup_failed_runtime on failure"; exit 7 }
+    exit 0
+  }
+' "$LIFECYCLE_UC" || fail "restart() in lifecycle.uc failed structural verification"
+
+# Verify stop() still calls stop_impl()
+awk '
+  /function stop\(\)/ { in_stop = 1 }
+  in_stop && /return stop_impl\(\);/ { called_stop_impl = 1 }
+  in_stop && /^}/ { done = 1; exit }
+  END {
+    if (!done || !called_stop_impl) exit 1
+    exit 0
+  }
+' "$LIFECYCLE_UC" || fail "stop() in lifecycle.uc must still call stop_impl()"
+
+# --- 2. Static assertions on init.d script -----------------------------------
+grep -Fq 'restart_service()' "$TACHYON_INIT" ||
+  fail "/etc/init.d/tachyon must define restart_service()"
+
+grep -Fq 'initd_ucode restart-service "$$"' "$TACHYON_INIT" ||
+  fail "/etc/init.d/tachyon restart_service() must invoke initd_ucode restart-service"
+
+awk '
+  /restart\(\)/ { in_restart = 1 }
+  in_restart && /restart_service "\$@"/ { delegates = 1 }
+  in_restart && /^}/ { done = 1; exit }
+  END { exit (done && delegates) ? 0 : 1 }
+' "$TACHYON_INIT" || fail "/etc/init.d/tachyon restart() must delegate to restart_service"
+
+# --- 3. Static assertions on initd.uc ----------------------------------------
+grep -Fq 'function restart_service(owner_pid)' "$INITD_UC" ||
+  fail "initd.uc must define restart_service(owner_pid)"
+
+grep -Fq 'else if (mode == "restart-service")' "$INITD_UC" ||
+  fail "initd.uc must handle restart-service command"
+
+awk '
+  /function restart_service\(owner_pid\)/ { in_func = 1 }
+  in_func && /BIN_PATH, "restart"/ { called_bin_restart = 1 }
+  in_func && /^}/ { done = 1; exit }
+  END { exit (done && called_bin_restart) ? 0 : 1 }
+' "$INITD_UC" || fail "initd.uc restart_service must invoke [ BIN_PATH, 'restart' ]"
+
+# --- 4. Static assertions on generator.uc turbo cache ------------------------
+awk '
+  /let turbo_cache = bool_option\(settings, "dns_turbo_cache", false\);/ { in_turbo = 1 }
+  in_turbo && index($0, "cache_path = \"/etc/sing-box/cache.db\"") { uses_etc = 1 }
+  in_turbo && index($0, "turbo_cache &&") { promotes = 1 }
+  in_turbo && /cache_dir/ { done = 1; exit }
+  END { exit (promotes && uses_etc) ? 0 : 1 }
+' "$GENERATOR_UC" || fail "generator.uc must promote default cache_path to /etc/sing-box/cache.db when dns_turbo_cache is enabled"
+
+# --- 5. Behavioral test: dnsmasq server remains 127.0.0.42 during restart ---
+WORK_DIR="$(mktemp -d)"
+STATE="$WORK_DIR/uci.state"
+LOG="$WORK_DIR/dnsmasq_mutations.log"
+
+cleanup() {
+  rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+# Initial UCI state: Tachyon running, dnsmasq points to 127.0.0.42
+cat >"$STATE" <<'EOF_STATE'
+dhcp.@dnsmasq[0].server=127.0.0.42
+dhcp.@dnsmasq[0].noresolv=1
+dhcp.@dnsmasq[0].cachesize=0
+dhcp.@dnsmasq[0].tachyon_server=1.1.1.1 8.8.8.8
+dhcp.@dnsmasq[0].tachyon_noresolv=0
+dhcp.@dnsmasq[0].tachyon_cachesize=150
+tachyon.settings.shutdown_correctly=0
+tachyon.settings.dont_touch_dhcp=0
+EOF_STATE
+
+mkdir -p "$WORK_DIR/bin"
+cat >"$WORK_DIR/bin/uci" <<'UCI'
+#!/usr/bin/env bash
+set -eo pipefail
+while [ "${1:-}" = "-q" ]; do shift; done
+cmd="${1:-}"
+shift || true
+state="${UCI_STATE:?}"
+log="${MUTATION_LOG:?}"
+
+do_set() {
+  local key="$1"
+  local val="${key#*=}"
+  local var="${key%%=*}"
+  printf 'SET %s=%s\n' "$var" "$val" >> "$log"
+  local tmp
+  tmp="$(mktemp)"
+  awk -F= -v k="$var" '$1 != k' "$state" > "$tmp"
+  printf '%s=%s\n' "$var" "$val" >> "$tmp"
+  mv "$tmp" "$state"
+}
+
+do_del() {
+  printf 'DELETE %s\n' "$1" >> "$log"
+  local tmp
+  tmp="$(mktemp)"
+  awk -F= -v k="$1" '$1 != k' "$state" > "$tmp"
+  mv "$tmp" "$state"
+}
+
+case "$cmd" in
+  get)
+    awk -F= -v key="$1" '$1 == key { print substr($0, length($1) + 2); found = 1 } END { exit found ? 0 : 1 }' "$state"
+    ;;
+  set)
+    do_set "$1"
+    ;;
+  delete)
+    do_del "$1"
+    ;;
+  add_list)
+    printf 'ADD_LIST %s %s\n' "$1" "$2" >> "$log"
+    ;;
+  commit)
+    printf 'COMMIT %s\n' "$1" >> "$log"
+    ;;
+esac
+UCI
+chmod +x "$WORK_DIR/bin/uci"
+
+cat >"$WORK_DIR/bin/dnsmasq_init" <<'SH'
+#!/usr/bin/env bash
+exit 0
+SH
+chmod +x "$WORK_DIR/bin/dnsmasq_init"
+export DNSMASQ_INIT="$WORK_DIR/bin/dnsmasq_init"
+
+# Run dnsmasq_configure while service is active (as called by restart -> start_impl)
+export UCI_STATE="$STATE"
+export MUTATION_LOG="$LOG"
+export PATH="$WORK_DIR/bin:$PATH"
+: > "$LOG"
+
+ucode -L "$ROOT_DIR/tachyon/files/usr/lib" "$APPLY_UC" configure ||
+  fail "dnsmasq_configure should succeed when dnsmasq already points to sing-box"
+
+# Verify that no deletion of 127.0.0.42 or restoration of 1.1.1.1 occurred
+if grep -Eq 'SET dhcp\.@dnsmasq\[0\]\.server=1\.1\.1\.1|ADD_LIST dhcp\.@dnsmasq\[0\]\.server 1\.1\.1\.1' "$LOG"; then
+  fail "dnsmasq_configure reverted server to ISP DNS during restart!"
+fi
+
+current_server="$(awk -F= '$1 == "dhcp.@dnsmasq[0].server" { print $2 }' "$STATE")"
+[ "$current_server" = "127.0.0.42" ] ||
+  fail "dhcp.@dnsmasq[0].server must remain 127.0.0.42 throughout restart (was: $current_server)"
+
+# --- 6. Behavioral test: Local DNS Cache enables 10000 entries in dnsmasq ---
+printf 'tachyon.settings.dns_local_cache=1\n' >> "$STATE"
+ucode -L "$ROOT_DIR/tachyon/files/usr/lib" "$APPLY_UC" configure force ||
+  fail "dnsmasq_configure force should apply local cache"
+
+cachesize="$(awk -F= '$1 == "dhcp.@dnsmasq[0].cachesize" { print $2 }' "$STATE")"
+[ "$cachesize" = "10000" ] ||
+  fail "dhcp.@dnsmasq[0].cachesize should be 10000 when dns_local_cache is enabled (was: $cachesize)"
+
+# --- 7. Behavioral test: Stop restores ISP DNS --------------------------------
+ucode -L "$ROOT_DIR/tachyon/files/usr/lib" "$APPLY_UC" restore force ||
+  fail "dnsmasq_restore force should succeed on service stop"
+
+restored_server="$(awk -F= '$1 == "dhcp.@dnsmasq[0].server" { print $2 }' "$STATE")"
+[ "$restored_server" = "1.1.1.1 8.8.8.8" ] ||
+  fail "dhcp.@dnsmasq[0].server must be restored to ISP DNS on stop (was: $restored_server)"
+
+printf 'service restart lifecycle checks passed\n'
+