fix(desktop): populate member_count in get_channels so channel browser shows real counts

desktop/src-tauri/src/commands/channels.rs

@@ -116,9 +116,59 @@ pub async fn get_channels(state: State<'_, AppState>) -> Result<Vec<ChannelInfo>
             channels.push(info);
         }
     }
+
+    // Populate member_count by batch-fetching kind:39002 for every listed
+    // channel and counting unique p-tag pubkeys. The kind:40901 summary
+    // sidecar that channel_info_from_event prefers isn't emitted by the
+    // relay today, so without this step every channel reports 0 members
+    // in the channel browser (the active-channel top bar masks this with
+    // its own live members query).
+    let all_d_tags: Vec<String> = channels.iter().map(|c| c.id.clone()).collect();
+    if !all_d_tags.is_empty() {
+        let members_events = query_relay(
+            &state,
+            &[serde_json::json!({
+                "kinds": [39002],
+                "#d": all_d_tags,
+                "limit": all_d_tags.len(),
+            })],
+        )
+        .await
+        .unwrap_or_default();
+
+        let counts = count_members_by_channel(&members_events);
+        for channel in &mut channels {
+            if let Some(count) = counts.get(&channel.id) {
+                channel.member_count = *count;
+            }
+        }
+    }
+
     Ok(channels)
 }
 
+/// Build a `channel_id → unique-member-count` map from a batch of kind:39002
+/// events. Events without a `d` tag are skipped; member dedupe is delegated to
+/// [`nostr_convert::channel_members_from_event`] so the parsing rules match the
+/// per-channel `get_channel_members` path.
+fn count_members_by_channel(events: &[nostr::Event]) -> std::collections::HashMap<String, i64> {
+    let mut counts: std::collections::HashMap<String, i64> =
+        std::collections::HashMap::with_capacity(events.len());
+    for ev in events {
+        let Some(d) = ev.tags.iter().find_map(|t| {
+            let s = t.as_slice();
+            (s.len() >= 2 && s[0] == "d").then(|| s[1].clone())
+        }) else {
+            continue;
+        };
+        let Ok(resp) = nostr_convert::channel_members_from_event(ev) else {
+            continue;
+        };
+        counts.insert(d, resp.members.len() as i64);
+    }
+    counts
+}
+
 #[tauri::command]
 pub async fn get_channel_details(
     channel_id: String,
@@ -415,3 +465,7 @@ pub async fn leave_channel(channel_id: String, state: State<'_, AppState>) -> Re
     submit_event(builder, &state).await?;
     Ok(())
 }
+
+#[cfg(test)]
+#[path = "channels_tests.rs"]
+mod tests;

desktop/src-tauri/src/commands/channels_tests.rs

@@ -0,0 +1,85 @@
+// Tests for commands/channels.rs — split into a sibling file to keep
+// channels.rs under the per-file line cap.
+
+use super::*;
+use nostr::{EventBuilder, Keys, Kind, Tag};
+
+/// Build a signed event for testing with the given kind, content, and tags.
+fn ev(kind: u16, content: &str, tags: Vec<Vec<&str>>) -> nostr::Event {
+    let keys = Keys::generate();
+    let parsed: Vec<Tag> = tags
+        .into_iter()
+        .map(|t| Tag::parse(t).expect("parse tag"))
+        .collect();
+    EventBuilder::new(Kind::from_u16(kind), content)
+        .tags(parsed)
+        .sign_with_keys(&keys)
+        .expect("sign")
+}
+
+// A 64-hex pubkey (nostr p-tags require 32-byte hex).
+const PK_A: &str = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
+const PK_B: &str = "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb";
+const PK_C: &str = "cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc";
+
+#[test]
+fn counts_unique_p_tags_per_channel() {
+    let e1 = ev(
+        39002,
+        "",
+        vec![
+            vec!["d", "chan-1"],
+            vec!["p", PK_A, "", "member"],
+            vec!["p", PK_B, "", "admin"],
+        ],
+    );
+    let e2 = ev(
+        39002,
+        "",
+        vec![vec!["d", "chan-2"], vec!["p", PK_C, "", "member"]],
+    );
+
+    let counts = count_members_by_channel(&[e1, e2]);
+    assert_eq!(counts.get("chan-1"), Some(&2));
+    assert_eq!(counts.get("chan-2"), Some(&1));
+    assert_eq!(counts.len(), 2);
+}
+
+#[test]
+fn dedupes_repeated_pubkeys() {
+    let e = ev(
+        39002,
+        "",
+        vec![
+            vec!["d", "chan-1"],
+            vec!["p", PK_A, "", "member"],
+            vec!["p", PK_A, "", "admin"], // duplicate pubkey, different role
+            vec!["p", PK_B, "", "member"],
+        ],
+    );
+    let counts = count_members_by_channel(&[e]);
+    assert_eq!(counts.get("chan-1"), Some(&2));
+}
+
+#[test]
+fn skips_event_without_d_tag() {
+    let e = ev(39002, "", vec![vec!["p", PK_A, "", "member"]]);
+    let counts = count_members_by_channel(&[e]);
+    assert!(counts.is_empty());
+}
+
+#[test]
+fn zero_member_channel_is_recorded() {
+    // A channel with a members event but no p-tags should report 0,
+    // not be absent from the map (the caller relies on `get` returning
+    // `Some(0)` to overwrite a default).
+    let e = ev(39002, "", vec![vec!["d", "chan-1"]]);
+    let counts = count_members_by_channel(&[e]);
+    assert_eq!(counts.get("chan-1"), Some(&0));
+}
+
+#[test]
+fn empty_input_yields_empty_map() {
+    let counts = count_members_by_channel(&[]);
+    assert!(counts.is_empty());
+}