Summary

• Adds DiscordMemberAddListener that fires when a user joins a Discord guild and delivers a system event to the matched agent session
• Gated on the existing intents.guildMembers privileged intent flag (must also be enabled in Discord Developer Portal)
• Opt-in per guild via memberJoinNotifications: "on" (default: "off" to avoid high-volume floods on existing deployments)

Motivation

Without this, the only way to react to member joins was a polling cron that called the Discord REST API directly every few minutes — unreliable, leaks the bot token into process args, and caused welcome messages to arrive hours or days late.

Config

{
  "channels": {
    "discord": {
      "intents": { "guildMembers": true },
      "guilds": {
        "YOUR_GUILD_ID": {
          "memberJoinNotifications": "on"
        }
      }
    }
  }
}

Test plan

• pnpm tsgo — no errors
• pnpm test src/discord/monitor/ — 118 tests pass
• Manually verified listener registration log line on gateway restart: [discord] GuildMembers intent enabled — member-add listener registered

Closes #23978

🤖 Generated with Claude Code

Greptile Summary

Adds support for Discord GUILD_MEMBER_ADD events by introducing a new DiscordMemberAddListener that fires system events when users join guilds. The implementation follows existing patterns from the reaction listener, includes proper opt-in configuration (memberJoinNotifications: "on"), and correctly gates the feature on the guildMembers privileged intent.

• Introduced DiscordMemberJoinNotificationMode type with "off" (default) and "on" values
• Added new listener class following the established pattern (timing instrumentation, error handling)
• Routes events to agent sessions using guildId and memberRoleIds for proper agent selection
• Skips bot accounts and the bot user itself
• Conditionally registers listener only when intents.guildMembers is enabled

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The implementation follows established patterns from existing listeners (reactions, presence), includes proper opt-in defaults to prevent spam, respects existing privileged intent gating, and the author confirmed tests pass (118 tests in src/discord/monitor/). No logic errors or security issues detected.
• No files require special attention

_{Last reviewed commit: aa948ec}

_{(3/5) Reply to the agent's comments like "Can you suggest a fix for this @greptileai?" or ask follow-up questions!}