v1 didn't track is_group separately; db.ts hardcoded `is_group: 1` for
every messaging_group. v2 uses is_group=0 to collapse DM sub-thread
sessions and to drive routing decisions, so getting it wrong is latent
risk on otherwise-working installs.
New helper inferIsGroup(channelType, platformId) lives in shared.ts so
tasks.ts and any future migration step can reuse it. Inferred per
channel:
- whatsapp: `<id>@g.us` is a group, anything else is a DM
- telegram: negative chat IDs are groups, positive are DMs
- everything else: default to 1 (least surprising for chats v1 chose
to register, where DM auto-create paths weren't used)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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