- Report "already subscribed" instead of false success on re-subscribe
- Report "not subscribed" instead of false success on redundant unsubscribe
- Add explicit channel existence check before subscribe/unsubscribe
- Return empty JSON array [] instead of null for no subscribers
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Adds three new subcommands to `gt mail channel`:
- subscribe <name>: Subscribe current identity to a channel
- unsubscribe <name>: Unsubscribe current identity from a channel
- subscribers <name>: List all subscribers to a channel
These commands expose the existing beads.SubscribeToChannel and
beads.UnsubscribeFromChannel functions through the CLI.
Closes gt-77334r
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Add gt mail channel subcommands for beads-native channels:
- gt mail channel [name] - list channels or show messages
- gt mail channel list - list all channels
- gt mail channel show <name> - show channel messages
- gt mail channel create <name> [--retain-count=N] [--retain-hours=N]
- gt mail channel delete <name>
Channels are pub/sub streams for broadcast messaging with retention policies.
Messages are stored with channel:<name> label and retrieved via beads queries.
Part of gt-xfqh1e.12 (channel viewing task).
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
