--fork-session
A Claude Code CLI flag, read out of the shipped bundle. It has been in the build since v2.1.138, including the newest one read.
What it is
When resuming, create a new session ID instead of reusing the original (use with --resume or --continue)
Anthropic's own wording. Read off CLI reference, captured 2026-08-28.
Presence across releases
| Releases | Reading | Declared type | Default |
|---|---|---|---|
| 2.1.245 – 2.1.250 5 releases | never mined | — | — |
| 2.1.138 – 2.1.243 95 releases | in the build | — | — |
A row reading never mined is a release with no archived bundle behind it. Nothing was read out of it, so nothing here says whether the name was in it. A declared type or a default is only ever what that release's own bundle stated.
Changelog entries naming it
-
v2.1.232--session-id now works with --continue/--resume under an SDK URL
--session-id now works with --continue or --resume when an SDK URL is supplied.
named in this entry
Documentation pages
- CLI reference reference table Claude Code CLI
- Manage multiple agents with agent view mentions it Claude Code CLI
- Checkpointing mentions it Claude Code CLI
- Glossary mentions it Claude Code CLI
- Hooks reference mentions it Claude Code CLI
- How Claude Code works mentions it Claude Code CLI
- Manage sessions mentions it Claude Code CLI
- Run parallel sessions with worktrees mentions it Claude Code CLI
A reference table page is one whose own table defines this name, and it is where the description above came from. A page that mentions it carries the name somewhere in its text and may say nothing about it at all. Every page carrying it.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the CLI flag does. All CLI flags.