perf(mesh): bounded swarm flush on joinMesh with background continue

Race flush against PEARCORD_GUILD_SWARM_FLUSH_MS and emit mesh-flush-timeout
when continuing without blocking guild open.

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

README.md

@@ -27,7 +27,7 @@ Create and load guilds in local storage, join peers on `pearcord:guild:{guildId}
 | `PearcordGuild#create({ name, iconHash? })` | New guild + owner member + `general` text + `Voice Lobby`; `nsfwGateEnabled` defaults true (v0.8.174) |
 | `PearcordGuild#joinByInvite(invite, userId)` | Materialize guild/channels from invite; add member; bump invite uses |
 | `PearcordGuild#setActiveGuild(guild)` | Set `this.guild` for list/create operations |
-| `PearcordGuild#joinMesh()` / `#leaveMesh()` | Hyperswarm on `topicToBuffer(guild.topic)` |
+| `PearcordGuild#joinMesh(opts?)` / `#leaveMesh()` | Hyperswarm on `topicToBuffer(guild.topic)`; bounded `flush()` via `PEARCORD_GUILD_SWARM_FLUSH_MS` (default 2.5s) |
 | `PearcordGuild#listChannels()` / `#listMembers()` | DB queries with thread meta attached |
 | `PearcordGuild#createChannel`, `#createCategory`, `#createThread`, `#createForumThread` | Channel tree |
 | `PearcordGuild#reorderChannelsInParent` | Reassign `position` for siblings under one category/root |

index.js

@@ -860,7 +860,7 @@ class PearcordGuild extends EventEmitter {
     broadcastGossip(this, RPC.TYPING_START, payload)
   }
 
-  async joinMesh () {
+  async joinMesh (opts = {}) {
     if (!this.guild) throw new Error('no active guild')
     const topic = topicToBuffer(this.guild.topic)
     this.swarm.removeAllListeners('connection')
@@ -902,7 +902,25 @@ class PearcordGuild extends EventEmitter {
       })
     })
     await this.swarm.join(topic, { server: true, client: true })
-    await this.swarm.flush()
+    const flushMs = Number(
+      opts.flushMs ??
+        process.env.PEARCORD_GUILD_SWARM_FLUSH_MS ??
+        process.env.PEARCORD_SWARM_FLUSH_MS ??
+        2500
+    )
+    if (this.swarm.flush) {
+      let flushed = false
+      await Promise.race([
+        this.swarm.flush().then(() => {
+          flushed = true
+        }),
+        new Promise((resolve) => setTimeout(resolve, flushMs))
+      ])
+      if (!flushed) {
+        this.emit('mesh-flush-timeout', { flushMs, guildId: this.guild.id })
+        void this.swarm.flush().catch(() => {})
+      }
+    }
     return this.guild
   }