diff --git a/crates/buzz-core/src/kind.rs b/crates/buzz-core/src/kind.rs
index 3c6f1d5913..18730c9636 100644
--- a/crates/buzz-core/src/kind.rs
+++ b/crates/buzz-core/src/kind.rs
@@ -811,6 +811,22 @@ pub const fn is_identity_archive_request_kind(kind: u32) -> bool {
     matches!(kind, KIND_IA_ARCHIVE_REQUEST | KIND_IA_UNARCHIVE_REQUEST)
 }
 
+/// Returns `true` if `kind` is a human-visible channel message.
+///
+/// This is the set clients render as timeline content and count toward unreads
+/// (`CHANNEL_MESSAGE_EVENT_KINDS` in Desktop, the equivalent Mobile set). It is
+/// the authoritative trigger for DM resurfacing: a hidden DM must reappear when
+/// any human-visible message arrives, regardless of which supported kind a
+/// client uses. Reactions, edits, diffs, pins, deletions, and system messages
+/// are deliberately excluded — they can land after the last real message and
+/// must not resurface a conversation the recipient hid.
+pub const fn is_human_visible_message_kind(kind: u32) -> bool {
+    matches!(
+        kind,
+        KIND_STREAM_MESSAGE | KIND_STREAM_MESSAGE_V2 | KIND_FORUM_POST | KIND_FORUM_COMMENT
+    )
+}
+
 /// Returns `true` if `kind` is a Buzz command kind that requires transactional execution.
 pub const fn is_command_kind(kind: u32) -> bool {
     matches!(
@@ -913,6 +929,39 @@ mod tests {
         assert!(!is_relay_only_kind(KIND_NIP43_LEAVE_REQUEST));
     }
 
+    #[test]
+    fn human_visible_message_kinds_cover_every_rendered_message() {
+        // Exactly the client `CHANNEL_MESSAGE_EVENT_KINDS` set — the set that
+        // must resurface a hidden DM. Forum posts/comments count: the relay
+        // accepts them as channel writes and both clients render them.
+        for kind in [
+            KIND_STREAM_MESSAGE,
+            KIND_STREAM_MESSAGE_V2,
+            KIND_FORUM_POST,
+            KIND_FORUM_COMMENT,
+        ] {
+            assert!(
+                is_human_visible_message_kind(kind),
+                "kind {kind} must be human-visible"
+            );
+        }
+        // Non-message activity in a channel must not resurface a hidden DM.
+        for kind in [
+            KIND_REACTION,
+            KIND_STREAM_MESSAGE_EDIT,
+            KIND_STREAM_MESSAGE_DIFF,
+            KIND_STREAM_MESSAGE_PINNED,
+            KIND_SYSTEM_MESSAGE,
+            KIND_DELETION,
+            KIND_FORUM_VOTE,
+        ] {
+            assert!(
+                !is_human_visible_message_kind(kind),
+                "kind {kind} must not be human-visible"
+            );
+        }
+    }
+
     #[test]
     fn parameterized_replaceable_range() {
         assert!(!is_parameterized_replaceable(29999));
diff --git a/crates/buzz-relay/src/handlers/ingest.rs b/crates/buzz-relay/src/handlers/ingest.rs
index 352161286f..9fa4c30a02 100644
--- a/crates/buzz-relay/src/handlers/ingest.rs
+++ b/crates/buzz-relay/src/handlers/ingest.rs
@@ -3036,7 +3036,13 @@ async fn ingest_event_inner(
         });
     }
 
-    let dm_message_sender = if matches!(kind_u32, KIND_STREAM_MESSAGE | KIND_STREAM_MESSAGE_V2)
+    // Resurface a hidden DM for every human-visible message kind, not just
+    // kinds 9/40002. The relay also accepts forum posts/comments (45001/45003)
+    // as channel-scoped writes, and both clients render them as timeline
+    // messages, so a custom or stale client posting one into a hidden DM must
+    // reopen it too. Reactions, edits, and system kinds stay excluded via the
+    // shared predicate.
+    let dm_message_sender = if buzz_core::kind::is_human_visible_message_kind(kind_u32)
         && channel_row
             .as_ref()
             .is_some_and(|channel| channel.channel_type == "dm")
diff --git a/crates/buzz-test-client/tests/e2e_nostr_interop.rs b/crates/buzz-test-client/tests/e2e_nostr_interop.rs
index ed342beabf..3e9845f5d8 100644
--- a/crates/buzz-test-client/tests/e2e_nostr_interop.rs
+++ b/crates/buzz-test-client/tests/e2e_nostr_interop.rs
@@ -1331,10 +1331,16 @@ async fn test_nipdv_hide_then_reopen_updates_snapshot() {
 /// the recipient's hidden set. The sender remains hidden if they independently
 /// closed the row: visibility is per viewer and delivery must not rewrite the
 /// author's own preference.
+///
+/// Parameterized over every human-visible message kind the relay accepts as a
+/// channel write (`is_human_visible_message_kind`): kinds 9/40002 plus forum
+/// post/comment 45001/45003. A stale or custom client can post a forum event
+/// into a DM, and both clients render it, so all four must resurface a hidden
+/// DM. Dropping either forum kind from the ingest predicate fails this test.
 #[tokio::test]
 #[ignore]
 async fn test_nipdv_supported_message_kinds_resurface_hidden_dm_for_recipient() {
-    for kind in [9, 40002] {
+    for kind in [9u16, 40002, 45001, 45003] {
         let keys_a = Keys::generate();
         let keys_b = Keys::generate();
         let keys_c = Keys::generate();