Bug Description

Signal's group policy handling only supports sender-level gating via groupAllowFrom, but does not support group-level allowlisting via a groups config map. This means there is no way to allow a specific Signal group by ID — you can only filter by individual sender phone numbers/UUIDs.

Every other channel that supports group allowlists already has this:

• Telegram: channels.telegram.groups.<chatId> + resolveChannelGroupPolicy
• iMessage: channels.imessage.groups.<chatId> + resolveChannelGroupPolicy
• WhatsApp: channels.whatsapp.groups.<conversationId> + resolveChannelGroupPolicy
• IRC: channels.irc.groups.<channel> + schema support
• BlueBubbles: channels.bluebubbles.groups.<chatId> + schema support

Signal is the only channel that lacks this capability.

Expected Behavior

Users should be able to configure channels.signal.groups.<groupId>: {} to explicitly allow specific Signal groups by ID, bypassing the sender-level groupAllowFrom check. This follows the pattern already established by Telegram, iMessage, WhatsApp, IRC, and BlueBubbles.

{
  channels: {
    signal: {
      groupPolicy: "allowlist",
      groups: {
        "your-signal-group-id": {}  // Allow this specific group
      }
    }
  }
}

Actual Behavior

Signal only checks groupAllowFrom (sender-level) when groupPolicy: "allowlist". There is no groups config option and no call to resolveChannelGroupPolicy in the Signal event handler.

Related

• Previously reported as Signal groupPolicy: allowlist doesn't work with group IDs in groupAllowFrom #4336 (closed as not_planned)
• PR fix(signal): add group-level allowlist support via groups config #4337 addressed this but was closed as stale
• The shared resolveChannelGroupPolicy infrastructure in src/config/group-policy.ts already supports this — Signal just doesn't use it