A chat needs no project. Open one from the Chats view and you get a real thread with its own history, its own model, and its own attachments, and none of it belongs to a folder.
Nothing you ask in a chat lands in a project you are working in. There is no repository to open, no branch to name, and no thread in a project list that grows because of it.
What a chat keeps
A chat keeps the conversation, in full, for as long as it exists. Open it next week and the whole exchange is still there, with the same model and thinking level you set, because those are saved with the chat rather than with the app.
Attachments stay with it too. A file you attached to a message remains part of that chat, so a later question can refer back to it without attaching it again.
A chat you started but have not sent in yet shows in the list as a draft. Nothing is sent on your behalf to make it appear, and the next New chat starts a separate draft instead of overwriting that one.
What a chat never touches
A chat has no scope and no branch. It cannot change a file in a project thread's checkout, and it does not appear in a project's thread list.
By default a chat is web-only: it answers from what you type and what you attach. That is the state the File System switch starts in, and for research and questions it is the right one, because nothing outside the conversation can be read or changed.
Turning File System on grants that chat file operations. Once it has file access, the permission levels appear in the composer, and the choice of level decides what the chat may change without asking you first. Turning File System off again returns the chat to answering from the conversation alone.
The switch belongs to the chat. Granting file access to one chat does not grant it to another.
Search across chats
The Chats view searches every chat by what was said in it. Type a phrase you remember from an answer, or a word from a question you asked weeks ago, and the matching chats come back.
Search stays inside the family it belongs to. Search in Chats returns chats, search in Threads returns project threads, and search in a scope returns that scope's threads, so a result never turns out to be something from somewhere else.
New chat sits beside the search control in the same header. The actions in that slot change with the view you are in, which means the Chats view always offers the two things a chat needs: a way to start one and a way to find one.
The state of a chat
A chat in the list says what it is doing. A chat with a reply you have not read is unread, a chat that is working says so, and a chat that stopped to ask you something says that instead. You do not have to open each one to find the one that wants you.
That state is also what the bell reports. A finished reply raises its own entry naming the chat it came from, so a long answer stops being something you sit and wait for.
When to use a chat
Use a chat for work that does not need a repository. Research, a question about an error message, a comparison of two approaches before you commit to one, a message you want to draft before it goes anywhere.
Use it when you want an answer without a checkout attached. A chat will not run a command in a project, will not change a file unless you grant file access, and will not leave a diff for you to review afterwards.
Use a project thread when the work has to land somewhere. If the answer will become a file, a fix, or a commit, the thread belongs to the project, because that is where the change is recorded and reviewed.
Use a scope when the work has to land somewhere but must not disturb what is already there. A thread in its own worktree changes a checkout of its own, which a chat cannot do.
A chat is also the cheapest place to test a model. Change the model, ask the same question, and read two answers side by side without touching a single project.
Chats and the rest of the app
Chats are one of the views on the rail, beside Projects, Threads, Assistant, and Browser. The rail is the same in every view, and every view keeps its place while you are away, so leaving a chat for a project and coming back costs nothing.
A chat is not a dead end. An answer in a chat offers Continue in a project: choose the project, and the conversation opens there as a new thread with its history intact. The chat you were in stays where it was, so the original is still there to read.
That is the useful direction. A chat is where a question can be asked without deciding anything, and continuing it into a project is how the answer becomes work. A project thread has no matching action, because the work it did already belongs to a checkout.