buddy_list: Include offline users in participants list for large orgs.

web/src/buddy_data.ts

@@ -2,6 +2,7 @@ import assert from "minimalistic-assert";
 
 import * as hash_util from "./hash_util";
 import {$t} from "./i18n";
+import * as message_lists from "./message_lists";
 import * as muted_users from "./muted_users";
 import * as narrow_state from "./narrow_state";
 import {page_params} from "./page_params";
@@ -285,7 +286,11 @@ function user_is_recently_active(user_id: number): boolean {
     return level(user_id) <= 2;
 }
 
-function maybe_shrink_list(user_ids: number[], user_filter_text: string): number[] {
+function maybe_shrink_list(
+    user_ids: number[],
+    user_filter_text: string,
+    conversation_participants: Set<number>,
+): number[] {
     if (user_ids.length <= max_size_before_shrinking) {
         return user_ids;
     }
@@ -310,7 +315,8 @@ function maybe_shrink_list(user_ids: number[], user_filter_text: string): number
     user_ids = user_ids.filter(
         (user_id) =>
             user_is_recently_active(user_id) ||
-            user_matches_narrow(user_id, pm_ids_set, filter_by_stream_id ? stream_id : undefined),
+            user_matches_narrow(user_id, pm_ids_set, filter_by_stream_id ? stream_id : undefined) ||
+            conversation_participants.has(user_id),
     );
 
     return user_ids;
@@ -357,8 +363,12 @@ function filter_user_ids(user_filter_text: string, user_ids: number[]): number[]
     return [...people.filter_people_by_search_terms(persons, user_filter_text)];
 }
 
-function get_filtered_user_id_list(user_filter_text: string): number[] {
-    let base_user_id_list;
+function get_filtered_user_id_list(
+    user_filter_text: string,
+    conversation_participants: Set<number>,
+): number[] {
+    // We always want to show conversation participants even if they're inactive.
+    let base_user_id_list = [...conversation_participants];
 
     if (user_filter_text) {
         // If there's a filter, select from all users, not just those
@@ -399,10 +409,27 @@ function get_filtered_user_id_list(user_filter_text: string): number[] {
     return user_ids;
 }
 
+export function get_conversation_participants(): Set<number> {
+    const participant_ids_set = new Set<number>();
+    if (!narrow_state.stream_id() || !narrow_state.topic() || !message_lists.current) {
+        return participant_ids_set;
+    }
+    for (const message of message_lists.current.all_messages()) {
+        if (
+            !people.is_valid_bot_user(message.sender_id) &&
+            people.is_person_active(message.sender_id)
+        ) {
+            participant_ids_set.add(message.sender_id);
+        }
+    }
+    return participant_ids_set;
+}
+
 export function get_filtered_and_sorted_user_ids(user_filter_text: string): number[] {
     let user_ids;
-    user_ids = get_filtered_user_id_list(user_filter_text);
-    user_ids = maybe_shrink_list(user_ids, user_filter_text);
+    const conversation_participants = get_conversation_participants();
+    user_ids = get_filtered_user_id_list(user_filter_text, conversation_participants);
+    user_ids = maybe_shrink_list(user_ids, user_filter_text, conversation_participants);
     return sort_users(user_ids);
 }
 

web/src/buddy_list.ts

@@ -15,7 +15,6 @@ import type {BuddyUserInfo} from "./buddy_data";
 import {media_breakpoints_num} from "./css_variables";
 import * as hash_util from "./hash_util";
 import {$t} from "./i18n";
-import * as message_lists from "./message_lists";
 import * as message_viewport from "./message_viewport";
 import * as narrow_state from "./narrow_state";
 import * as padded_widget from "./padded_widget";
@@ -90,17 +89,7 @@ function get_render_data(): BuddyListRenderData {
     const total_human_users = people.get_active_human_count();
     const other_users_count = total_human_users - total_human_subscribers_count;
     const hide_headers = should_hide_headers(current_sub, pm_ids_set);
-    const participant_ids_set = new Set<number>();
-    if (current_sub && narrow_state.topic() && message_lists.current) {
-        for (const message of message_lists.current.all_messages()) {
-            if (
-                !people.is_valid_bot_user(message.sender_id) &&
-                people.is_person_active(message.sender_id)
-            ) {
-                participant_ids_set.add(message.sender_id);
-            }
-        }
-    }
+    const participant_ids_set = buddy_data.get_conversation_participants();
 
     return {
         current_sub,

web/tests/buddy_data.test.js

@@ -22,6 +22,8 @@ const presence = zrequire("presence");
 const stream_data = zrequire("stream_data");
 const user_status = zrequire("user_status");
 const buddy_data = zrequire("buddy_data");
+const {Filter} = zrequire("filter");
+const message_lists = zrequire("message_lists");
 
 // The buddy_data module is mostly tested indirectly through
 // activity.test.js, but we should feel free to add direct tests
@@ -109,6 +111,7 @@ function test(label, f) {
         people.add_active_user(me);
         people.initialize_current_user(me.user_id);
         muted_users.set_muted_users([]);
+        message_lists.set_current(undefined);
 
         f(helpers);
 
@@ -376,6 +379,39 @@ test("show offline channel subscribers for small channels", ({override_rewire})
     assert.deepEqual(buddy_data.get_filtered_and_sorted_user_ids(""), [me.user_id, alice.user_id]);
 });
 
+test("get_conversation_participants", ({override_rewire}) => {
+    people.add_active_user(selma);
+
+    const rome_sub = {name: "Rome", subscribed: true, stream_id: 1001};
+    stream_data.add_sub(rome_sub);
+    peer_data.set_subscribers(rome_sub.stream_id, [selma.user_id]);
+
+    const filter = new Filter([
+        {operator: "channel", operand: rome_sub.channel_id},
+        {operator: "topic", operand: "Foo"},
+    ]);
+    message_lists.set_current({
+        data: {
+            filter,
+        },
+        all_messages() {
+            return [
+                {
+                    sender_id: selma.user_id,
+                    id: rome_sub.stream_id,
+                    content: "example content",
+                    topic: "Foo",
+                    type: "stream",
+                },
+            ];
+        },
+    });
+    override_rewire(narrow_state, "stream_id", () => rome_sub.stream_id);
+    override_rewire(narrow_state, "topic", () => "Foo");
+
+    assert.deepEqual(buddy_data.get_conversation_participants(), new Set([selma.user_id]));
+});
+
 test("level", () => {
     realm.server_presence_offline_threshold_seconds = 200;