What
- Session resume/fork no longer passes
hookMessages/hooksPromisedirectly to the startup path; instead it returns asessionStartHookspromise wired through a new abortable "tail" queue. Resume also gained aprecedingRowsoption, letting a caller resume from a subset of prior transcript rows instead of the full session. - When resuming a session from the picker, the session's recorded
sessionStartHooksare captured and threaded through aspendingHookMessagesinto the resumed UI state. - Resumed sessions now propagate this
sessionStartHooksfield intopendingHookMessageswhen reconstructing state, alongside the existingsessionHooksfield, which was previously missing from the restored-session object.
Why
This ensures SessionStart hooks that fired for a session are correctly carried over when that session is resumed, so hook-driven setup isn't silently lost, and it also enables resuming from a partial transcript.
Names in the bundleSessionStart
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added since
A small documentation edit on Hooks reference touched a line naming SessionStart after this was published.
The same wait applies at launch, including a resumed session: a prompt you send while SessionStart hooks are still running doesn't reach Claude until they finish.hooks see the edit
Confirmed since
Anthropic's documentation has since written up SessionStart, on Claude Code changelog.
* Improved hook feedback: while a SessionStart, UserPromptSubmit, PreToolUse or SessionEnd hook runs, the spinner says so with elapsed time, and Esc cancels a prompt waiting on a SessionStart hookchangelog see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up SessionStart, on Claude Code changelog.