Unjoined public channel is reported as a private channel

What happened. tdc thread view id:Cef56SqAhC6dgFNn5R4f4 (a thread in a public channel I have not joined) fails with:

NOT_FOUND: This thread belongs to a private channel.
Use --include-private-channels to access it

With the flag it reads fine, and the channel is public.

Why. assertChannelIsPublic checks the channel id against getPublicChannelIds, which is built from client.channels.getChannels({ workspaceId }) (src/lib/public-channels.ts). That list did not contain the channel for me, so anything outside it is reported as private, joined or not. Comms has two levels here, private and public-not-yet-joined, and the message only names one.

Ask. Either of these; the first is enough on its own:

1. Reword the error to what the check actually knows: "This thread is in a channel you have not joined, or a private one. Pass --include-private-channels to read it."
2. Check the channel itself (its public flag) so an unjoined public channel passes the guard without the flag, and only private ones need it.

Why it matters. Agents relay this message as a fact. Mine told me the thread was private twice, once inside a draft reply that warned colleagues the link would not work for them. Version 3.1.0.

Start with src/lib/public-channels.ts and the assertChannelIsPublic check, then reproduce the issue with the tdc thread view id:Cef56SqAhC6dgFNn5R4f4 command. Done means an unjoined public channel is no longer reported as private, or the error accurately distinguishes unjoined public and private channels while the --include-private-channels behavior remains clear.