Each conversation has its own sharing controls. Open the share menu at the top of a conversation to change who can see it. There are two independent settings: who can reach it by default (General access) and the specific people you add.
General access
Invited people only. The default. Only you and the people you add can see the conversation.
Everyone in project [project name]. Anyone with access to the project can see and continue the conversation.
Add specific people
In the share menu, use the Name or email box under Add people.
Search for a teammate, or type any email address to invite someone outside your workspace.
They appear under Who has access. Adding someone does not change your General access setting.
What a guest is
Anyone you add individually who is not a member of the project is a guest. This includes teammates who are in your workspace but not on that project. A guest gets read-only access: they can see the conversation as it is, but they cannot open the underlying documents, reply, continue, or fork it.
People who are members of the project get full access. They can read, reply, continue, and click citations to open the source documents, subject to their project access.
Copy a link
Use Copy link to send the conversation to people who already have access. Each guest also gets their own private link. Links are not public: the project link works for anyone who already has access to the conversation, and each guest link works only for that guest.
Continue a shared conversation
If a teammate shares a conversation with you, you can fork it to create your own continuable copy that keeps the original messages as context. See Continue someone else's conversation. Guests cannot fork.
Stop sharing
Open the share menu, find the person under Who has access, and remove them with the X. They lose access immediately.