feat(notifications): Phase B backend — per-user channel preferences

ordinis-notifications/src/main/java/cloud/nstart/terravault/ordinis/notifications/dispatcher/NotificationsDispatcher.java

@@ -77,6 +77,7 @@ public class NotificationsDispatcher {
   private final MessageRenderer messageRenderer;
   private final List<NotificationChannel> channels;
   private final RecipientResolver recipientResolver;
+  private final UserPreferencesGate preferencesGate;
 
   private final Counter sentCounter;
   private final Counter failedCounter;
@@ -101,6 +102,7 @@ public class NotificationsDispatcher {
       MessageRenderer messageRenderer,
       List<NotificationChannel> channels,
       RecipientResolver recipientResolver,
+      UserPreferencesGate preferencesGate,
       MeterRegistry meterRegistry) {
     this.outboxRepository = outboxRepository;
     this.notificationLogRepository = notificationLogRepository;
@@ -108,6 +110,7 @@ public class NotificationsDispatcher {
     this.messageRenderer = messageRenderer;
     this.channels = channels;
     this.recipientResolver = recipientResolver;
+    this.preferencesGate = preferencesGate;
 
     this.sentCounter = Counter.builder("nsi_notification_sent_total")
         .description("Total notifications successfully sent")
@@ -197,6 +200,16 @@ public class NotificationsDispatcher {
     for (NotificationChannel channel : channels) {
       if (!channel.isEnabled()) continue;
 
+      // Phase B: check user preferences before send. Default policy:
+      // EMAIL = ON, EXPRESS/TELEGRAM = OFF when no row. Reviewer-pool
+      // bypasses gate (shared inbox).
+      if (!preferencesGate.allows(recipient.userId(), channel.kind())) {
+        log.debug("Skip channel={} for user={} — preferences opt-out",
+            channel.kind().wireName(), recipient.userId());
+        skippedCounter.increment();
+        continue;
+      }
+
       String recipientId = recipient.recipientFor(channel.kind());
       if (recipientId == null || recipientId.isBlank()) {
         skippedCounter.increment();

ordinis-notifications/src/main/java/cloud/nstart/terravault/ordinis/notifications/dispatcher/UserPreferencesGate.java

@@ -0,0 +1,74 @@
+package cloud.nstart.terravault.ordinis.notifications.dispatcher;
+
+import cloud.nstart.terravault.ordinis.domain.notification.UserNotificationPref;
+import cloud.nstart.terravault.ordinis.domain.notification.UserNotificationPrefRepository;
+import cloud.nstart.terravault.ordinis.notifications.channel.ChannelKind;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.stereotype.Component;
+
+import java.util.Optional;
+
+/**
+ * Per-recipient channel preferences gate — checks user_notification_prefs row
+ * before dispatcher actually sends. Phase B (`/me/notifications/preferences` UI).
+ *
+ * <p>Default semantics when row is MISSING (user never visited preferences page):
+ * <ul>
+ *   <li>{@link ChannelKind#EMAIL} — ON (matches Phase A default-on behavior).</li>
+ *   <li>{@link ChannelKind#EXPRESS} / {@link ChannelKind#TELEGRAM} — OFF (require
+ *       explicit opt-in; channels also not implemented yet on backend).</li>
+ * </ul>
+ *
+ * <p>Reviewer-pool pseudo-user ({@code userId="reviewer-pool"}) bypasses gate —
+ * pool is a shared inbox, individual prefs don't apply. Always considered ON.
+ *
+ * <p>{@code @ConditionalOnProperty} mirrors {@link NotificationsDispatcher} —
+ * bean не register'ится без {@code ordinis.notifications.enabled=true}.
+ */
+@Component
+@ConditionalOnProperty(name = "ordinis.notifications.enabled", havingValue = "true", matchIfMissing = false)
+public class UserPreferencesGate {
+
+  private static final Logger log = LoggerFactory.getLogger(UserPreferencesGate.class);
+
+  /** Pseudo userId used for the reviewer-pool shared inbox. Never has prefs. */
+  public static final String REVIEWER_POOL_USER_ID = "reviewer-pool";
+
+  private final UserNotificationPrefRepository repo;
+
+  public UserPreferencesGate(UserNotificationPrefRepository repo) {
+    this.repo = repo;
+  }
+
+  /**
+   * @return true если recipient should receive notification on this channel.
+   *         Considers default-on policy (EMAIL) и default-off (EXPRESS/TELEGRAM).
+   */
+  public boolean allows(String userId, ChannelKind channel) {
+    if (userId == null || userId.isBlank()) {
+      return defaultFor(channel);
+    }
+    if (REVIEWER_POOL_USER_ID.equals(userId)) {
+      // Pool is a shared inbox — always ON, prefs don't apply.
+      return true;
+    }
+    Optional<UserNotificationPref> row = repo.findByIdUserIdAndIdChannel(userId, channel.wireName());
+    if (row.isEmpty()) {
+      boolean defaultOn = defaultFor(channel);
+      log.trace("No prefs row for user={} channel={}, defaulting to {}",
+          userId, channel.wireName(), defaultOn);
+      return defaultOn;
+    }
+    return row.get().isEnabled();
+  }
+
+  /**
+   * Default policy when no row exists. EMAIL = ON (preserves Phase A behavior
+   * где users получали emails by default). Others = OFF (require opt-in).
+   */
+  private boolean defaultFor(ChannelKind channel) {
+    return channel == ChannelKind.EMAIL;
+  }
+}

ordinis-notifications/src/test/java/cloud/nstart/terravault/ordinis/notifications/dispatcher/NotificationsDispatcherTest.java

@@ -75,6 +75,14 @@ class NotificationsDispatcherTest {
     notificationLogRepository = new StubNotificationLogRepository();
     idempotencyGuard = new StubIdempotencyGuard(notificationLogRepository);
 
+    // Phase B: UserPreferencesGate — stub all-allow для existing tests (no
+    // prefs row → defaults apply, email ON). Per-channel skip tested separately.
+    UserPreferencesGate allAllowGate = new UserPreferencesGate(null) {
+      @Override
+      public boolean allows(String userId, cloud.nstart.terravault.ordinis.notifications.channel.ChannelKind channel) {
+        return true;
+      }
+    };
     dispatcher = new NotificationsDispatcher(
         outboxRepository,
         notificationLogRepository,
@@ -82,6 +90,7 @@ class NotificationsDispatcherTest {
         messageRenderer,
         List.of(emailChannel),
         recipientResolver,
+        allAllowGate,
         new SimpleMeterRegistry()
     );