Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
HooksArea: what it touches
Internal ChangesKind: in v2.1.273,
Internal ChangesSection of the release
Unclear What information agentContext carries or what new capability it gives to SessionStart hooks is not stated.
What
A hook is a script you configure to run automatically at certain points in a session. The internal function that runs SessionStart hooks (which fire when a session begins or resumes) and loads plugin hooks now also accepts and passes along a new agentContext parameter, alongside existing options like credentials, the cancellation signal, and whether the session is orphaned.
Why
This gives the hook-running machinery more context about the agent it's running for, though the finding doesn't specify what new behavior this enables for hook authors.
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 sinceA small documentation edit on Use Claude Code in the cloud touched a line naming SessionStart after this was published.* **Time limits**: commands Claude runs and SessionStart hooks have default timeouts you can change, and a setup script is cached only when it finishes in roughly five minutes. See [Time limits](/docs/en/cloud-environments#time-limits)claude-code-on-the-websee the edit
Confirmed sinceAnthropic's documentation has since written up SessionStart, on Configure cloud environments.* **One repository per session**: a session with several repositories doesn't load hooks from any repository's `.claude/settings.json`, so a SessionStart hook you define there doesn't run. Install dependencies for those sessions with a [se…cloud-environmentssee the edit
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtWhat information agentContext carries or what new capability it gives to SessionStart hooks is not stated.
Anthropic's documentation agreesAnthropic's documentation has since written up SessionStart, on Configure cloud environments.
