Summary

• Problem: Discord requireMention: true stopped working — the agent responds and shows typing on every guild message even when not mentioned. The root cause is that isDirectMessage was derived solely from channelInfo?.type === ChannelType.DM, ignoring params.data.guild_id. When channelInfo returned ChannelType.DM for a guild channel (stale cache, API inconsistency, or Carbon library change), guild messages were classified as DMs, bypassing the requireMention gate entirely.
• Why it matters: Every Discord guild deployment with requireMention: true is broken — the bot responds to every message, flooding channels.
• What changed: In message-handler.preflight.ts, isDirectMessage and isGroupDm now require !isGuildMessage as a precondition. If guild_id is present, the message is never classified as DM or GroupDM — mirroring the existing pattern in agent-components.ts (line 214-217).
• What did NOT change (scope boundary): resolveDiscordChannelInfo, resolveMentionGatingWithBypass, guild config resolution, and all other preflight checks are untouched.

Change Type (select all)

• Bug fix
• Feature
• Refactor
• Docs
• Security hardening
• Chore/infra

Scope (select all touched areas)

• Gateway / orchestration
• Skills / tool execution
• Auth / tokens
• Memory / storage
• Integrations
• API / contracts
• UI / DX
• CI/CD / infra

Linked Issue/PR

• Closes [Bug]: Discord requireMention not working - agent responds and shows typing even without mention #34353

User-visible / Behavior Changes

Guild messages without an explicit bot mention are correctly dropped when requireMention: true is configured, restoring pre-regression behavior.

Security Impact (required)

• New permissions/capabilities? No
• Secrets/tokens handling changed? No
• New/changed network calls? No
• Command/tool execution surface changed? No
• Data access scope changed? No

Repro + Verification

Environment

• OS: macOS / Linux
• Runtime: Node.js 22+

Steps

1. Configure Discord guild with requireMention: true in guilds.<guildId>.
2. Send a message in a guild channel without mentioning the bot.
3. Observe the agent behavior.

Expected

• Agent ignores the message (no typing, no response).

Actual

• Before: Agent shows typing and responds to every message regardless of mention.
• After: Agent correctly ignores messages without explicit mention.

Evidence

• Failing test/log before + passing after
• Trace/log snippets
• Screenshot/recording
• Perf numbers (if relevant)

New test: "drops guild messages without mention even when channelInfo reports DM type (stale cache)" — simulates a guild message where channelInfo.type incorrectly returns ChannelType.DM, verifies the message is still dropped when requireMention: true.

Human Verification (required)

• Verified scenarios: Guild message with guild_id + stale channelInfo.type=DM dropped. Guild message with correct channelInfo.type=GuildText still works. True DMs (no guild_id, channelInfo.type=DM) still accepted.
• Edge cases checked: guild_id present but channelInfo null results in isDirectMessage = false (correct). GroupDM with guild_id absent still works via channelInfo.type.
• What you did not verify: Live Discord API integration with actual stale channel cache scenario.

Compatibility / Migration

• Backward compatible? Yes
• Config/env changes? No
• Migration needed? No

Failure Recovery (if this breaks)

• How to disable/revert: Revert this commit; isDirectMessage returns to channelInfo?.type === ChannelType.DM.
• Files/config to restore: src/discord/monitor/message-handler.preflight.ts

Risks and Mitigations

• Risk: A guild message where guild_id is absent from the event payload would fail to be recognized as guild.
  • Mitigation: guild_id is a core Discord gateway field always present for guild messages. The same pattern is already proven in agent-components.ts for interactions.