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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →To try a different solution without losing your current conversation, fork its session: in Claude Code, run /branch in the active session or resume a saved session with claude --resume <session-id> --fork-session. In Codex, enter /fork in the current chat, or use codex fork to choose a saved session. Each creates a separate conversation history; neither command by itself gives the new conversation an isolated copy of your project files.
Choose the command based on where the conversation is
| Tool | Conversation | How to fork | What happens to the original |
|---|---|---|---|
| Claude Code | Current interactive session | Run /branch. |
The fork starts a separate session; the source session remains available. |
| Claude Code | Saved session | Run claude --resume <session-id> --fork-session. |
The resumed conversation is forked into a new session ID. |
| Codex | Current chat | Enter /fork. |
Codex creates a new chat with a fresh ID and leaves the original transcript untouched. |
| Codex | Saved chat | Run codex fork, then choose a session; or use codex fork --last for the most recent chat. |
The selected chat is copied into a new chat, leaving the source transcript untouched. |
These commands are documented in the Claude Code sessions guidance, the Anthropic Agent SDK session-management cookbook, and the Codex CLI reference. The command forms below follow those references, checked October 7, 2026; product commands can change, so consult the live documentation if your installed version behaves differently.
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Fork a Claude Code session
From the session you have open
- In the interactive Claude Code session, enter
/branch. - Continue in the branched conversation with the alternate approach. Keep using the original session if you need to return to its separate transcript.
From a saved session
- Find the session ID for the saved conversation you want to continue.
- Run
claude --resume <session-id> --fork-session, replacing<session-id>with that ID. - Continue in the new session created from the saved conversation.
The CLI route is useful when you want to resume a particular saved session rather than branch the conversation already on screen. The Agent SDK also supports forking from a selected message ID, so an SDK workflow can start from a point within a transcript rather than carrying forward the entire conversation.
Fork a Codex chat
From the current chat
- Enter
/forkin the active Codex chat. - Continue in the new chat to explore the alternate solution; the original chat transcript remains unchanged.
From a saved chat
- Run
codex forkto open the session picker. - Select the saved chat you want to branch. Codex creates a new chat based on it.
To skip the picker and fork the most recent chat, run codex fork --last. To target a particular saved chat, provide its session ID to codex fork. Add --all to include sessions outside the current working directory in the picker.
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A conversation fork is not a project-file fork
Forking preserves a separate line of chat history. Do not assume it also creates a separate checkout or copy of the files being edited: the session commands described above concern conversation history, while file isolation is a separate repository setup decision.
If you plan to make changes in parallel, arrange project isolation separately—for example, use distinct Git worktrees or branches as appropriate to your workflow. Anthropic specifically recommends separate Git worktrees for multiple concurrent Claude Code sessions. Without file isolation, two conversations may still operate on the same working files, even though their transcripts are distinct.
Quick Recap
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Which route should you use?
- Already in the conversation: use Claude Code
/branchor Codex/fork. - Starting from a saved Claude Code session: use
claude --resume <session-id> --fork-session. - Starting from a saved Codex chat: use
codex forkto pick a session,codex fork --lastfor the latest one, or a session ID to target a specific chat. - Editing code in parallel: separately decide how to isolate the working files; a new transcript alone does not do that.
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