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.
The update_environment_variables structured IO control message now enforces an allowlist. Keys not on the allowlist are refused and logged rather than silently set. A debug message is emitted listing the rejected keys.
Evidence
Refusal log message (search for "[structuredIO] refused update_environment_variables for non-allowlisted keys:")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.