Under the hood
ANTHROPIC_BETAS entries are now filtered against a new exclusion list before being applied
What
When Claude Code builds its list of beta headers from the ANTHROPIC_BETAS environment variable (used to opt into experimental Anthropic API features), each entry is now also checked against a new exclusion list. Entries that match are dropped, on top of the existing trimming of blank entries.
Why
Some beta names can now be blocked outright from being applied via ANTHROPIC_BETAS, regardless of what the user sets, beyond the earlier org-compliance-based blocking of the whole variable.
Names in the bundleANTHROPIC_BETAS
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
The finding doesn't say which beta names are on the new exclusion list or why they're excluded.