update

crates/community/src/cache.rs

@@ -82,6 +82,44 @@ pub async fn purge_expired(client: &Client, channel: &ChannelId, now: Timestamp)
     Ok(purged)
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Observed {
+    pub author: PublicKey,
+    pub at_ms: u64,
+}
+
+/// The cached rumors of `channel`, keyed by the wrap they were opened from.
+pub async fn wrapper_index(
+    client: &Client,
+    channel: &ChannelId,
+) -> Result<BTreeMap<EventId, Observed>> {
+    let filter = Filter::new()
+        .kind(Kind::ApplicationSpecificData)
+        .custom_tag(MARK_TAG, MARK_VALUE)
+        .custom_tag(CHANNEL_TAG, channel.to_hex());
+
+    let mut index = BTreeMap::new();
+
+    for event in client.database().query(filter).await? {
+        let (Some(wrapper_id), Some(author)) = (
+            event.tags.event_ids().next(),
+            event.tags.public_keys().next(),
+        ) else {
+            continue;
+        };
+
+        index.insert(
+            wrapper_id,
+            Observed {
+                author,
+                at_ms: event.created_at.as_secs().saturating_mul(1000),
+            },
+        );
+    }
+
+    Ok(index)
+}
+
 /// Cached rumors for `channel`, newest first, deduplicated by rumor id.
 pub async fn query_rumors(
     client: &Client,