Session forking (resume and fork)
Also called fork a session, fork_session, --fork-session, resume a session, named session
Branching a saved agent conversation so you can try a second approach from the same point, while the original stays as it was.
Long agent work rarely fits in one sitting. Resuming brings back the whole conversation: what the agent read, what it concluded, where it stopped. Forking does the same but as a new session, so you can try a different approach without losing the original line of thought.
The catch is time. A resumed or forked session remembers files as they were when it read them. If the code has moved on, tell it which files changed, or start fresh with a short summary of what still holds.
For example
After an hour of analysing a slow cache, you fork the session: one branch tries a new cache key, the other a longer expiry, both starting from the same findings.
Put it to use
Where you'll meet session forking (resume and fork) in ChatGPT, Gemini and Claude, how to use it there, and the mix-up most people make.
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