Source Intelligence

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.221 Home All releases olderv2.1.220 v2.1.222newer

Windows sandbox TLS termination can now use the managed sandbox CA

Not switched on
Useful3 Signal4
Sandbox Notable not in their notes

Windows sandbox TLS interception could use a persistent managed certificate authority, but that path is disabled here.

A Windows managed sandbox CA, installed via /sandbox install, sits behind CLAUDE_CODE_NANKEEN_KESTREL, off by default.

Feature flag
tengu_nankeen_kestrel Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.221: on

These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.

Read once, for one account on one subscription tier, against v2.1.221. It isn't a statement about your account. What a flag value here can and cannot tell you

CLAUDE_CODE_NANKEEN_KESTREL/sandbox installsandbox.network.tlsTerminatecaCertPathcaKeyPath
What

CA resolution for sandbox.network.tlsTerminate was reworked, and on Windows a persistent sandbox-managed CA can be used instead of an ephemeral one, though that path is switched off in this build.

Details
  • Three CA sources now exist: a trusted caCertPath/caKeyPath pair from settings, a "managed" CA, or unavailable, with a certificate-thumbprint check that reads the managed CA cert from disk.
  • On native Windows an ephemeral CA cannot pass the sandbox trust check; the managed CA is set up via /sandbox install, and the settings description documents this.
  • Trust failures now throw typed errors carrying codes rather than plain Error objects.
  • The old refusal message about missing caCertPath/caKeyPath is replaced by one saying the managed CA is gated off.
  • The managed-CA path is Windows-only and gated on CLAUDE_CODE_NANKEEN_KESTREL, else tengu_nankeen_kestrel with an in-source fallback of false, so it is disabled by default here.
Evidence

On native Windows an ephemeral CA cannot pass the sandbox trust check, [sandbox] settings tlsTerminate has no CA paths and the managed sandbox CA is gated off on Windows

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.221 →