feat(platform): threadsPanel view + setThreadsPanelIncludeArchived (Phase 75)

Compute threadLastActivity, root message snippets, and threadsPanel payload
for UI sidebar. Exposes threadsPanelIncludeArchived toggle via channel emit.

Co-authored-by: Cursor <[email protected]>

index.js

@@ -82,6 +82,7 @@ const {
   defaultThreadName,
   groupThreadsByParent,
   listForumPostsForParent,
+  buildThreadsPanel,
   isThreadChannel,
   isForumChannel,
   isAnnouncementChannel,
@@ -350,6 +351,7 @@ class PearcordPlatform extends EventEmitter {
     await this.boosts.ready()
     this._forumTagFilter = null
     this._forumIncludeArchived = false
+    this._threadsPanelIncludeArchived = false
     this.guilds = await this.listGuilds()
     void this._finishSessionStartup()
     this.emit('user', user)
@@ -4204,6 +4206,12 @@ class PearcordPlatform extends EventEmitter {
     return thread
   }
 
+  setThreadsPanelIncludeArchived (includeArchived) {
+    this._threadsPanelIncludeArchived = !!includeArchived
+    this.emit('channel')
+    return { includeArchived: this._threadsPanelIncludeArchived }
+  }
+
   async archiveThread (threadId, archived = true) {
     if (!this.guild?.guild) throw new Error('no guild')
     const channels = await this.guild.listChannels()
@@ -4581,13 +4589,42 @@ class PearcordPlatform extends EventEmitter {
     const discoveryStats = this.discovery
       ? await this.discovery.refreshStats()
       : null
-    const threadsByParent = groupThreadsByParent(channels)
+    const threadsByParent = groupThreadsByParent(channels, {
+      includeArchived: this._threadsPanelIncludeArchived
+    })
     const threadMessageCounts = {}
+    const threadLastActivity = {}
+    const threadRootMessages = {}
     for (const ch of channels) {
       if (!isThreadChannel(ch)) continue
       const rows = await this.db.find(COLLECTIONS.MESSAGES, { channelId: ch.id })
       threadMessageCounts[ch.id] = rows.length
+      threadLastActivity[ch.id] = rows.length
+        ? Math.max(...rows.map((m) => m.createdAt || 0))
+        : (ch.createdAt || 0)
+      if (ch.rootMessageId) {
+        let root = await this.db.get(COLLECTIONS.MESSAGES, {
+          channelId: ch.parentId,
+          id: ch.rootMessageId
+        })
+        if (!root) {
+          root = rows.find((m) => m.id === ch.rootMessageId) || null
+        }
+        if (root) threadRootMessages[ch.rootMessageId] = root
+      }
     }
+    const threadsPanel = this.mode === 'guild' && guild
+      ? buildThreadsPanel({
+        channels,
+        threadsByParent,
+        unread,
+        threadMessageCounts,
+        threadLastActivity,
+        rootMessages: threadRootMessages,
+        activeChannelId: this.activeChannelId,
+        includeArchived: this._threadsPanelIncludeArchived
+      })
+      : null
     const activeChannel = channels.find((c) => c.id === this.activeChannelId) || null
     let forumPosts =
       activeChannel && isForumChannel(activeChannel)
@@ -4864,6 +4901,9 @@ class PearcordPlatform extends EventEmitter {
       dmEncryptionEnabled: this.mode === 'dm' && dmEncryptionAvailable(),
       threadsByParent,
       threadMessageCounts,
+      threadLastActivity,
+      threadsPanel,
+      threadsPanelIncludeArchived: this._threadsPanelIncludeArchived,
       threadTypingByParent,
       forumPosts,
       forumPaletteTags,