Group of 3 Nothing to try yet Notable
Auto mode's classifier-only tools can now be allowed-with-warning instead of blocked, and are always routed through the classifier
What
- Tools that declare
classifierOnly()are now always evaluated by the auto mode classifier — saved always-allow rules and hook-based allows are ignored, and outside auto mode such tools are denied with a message naming the tool. - These tools can now set
onBlock: 'flag'. When the classifier would otherwise block the action, refuse to review it, or return no verdict, the action is now delivered (allowed) instead of denied, but annotated with adecisionReasonnoting it was "Flagged by the classifier, delivered with its warning: ...". - A new guard denies the action with an explicit bug message if a classifier-only tool serializes to an empty classifier input, since the classifier would have nothing to judge.
- The core auto-mode permission pipeline now checks each tool's classifier-only config: if
onBlock === "refuse"and a hook asked for a prompt (or the host re-asks on every allow), it denies with an explanation; ifonBlock === "flag", it forces the new allow-with-flag outcome.
Why This lets certain sensitive tools stay strictly gated by the auto-mode classifier (never allowed by saved rules or hooks) while giving them a softer failure mode: instead of silently blocking an action the classifier is unsure about, Claude Code can deliver it with a visible warning explaining why it was flagged.
Names in the bundleonBlock
Documented inapi/api/beta
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.
Confirmed since
Anthropic's documentation has since written up onBlock, on sent_count = len(messages sent in the compaction request).
use Anthropic\Beta\Messages\BetaCompactionBlock;build-with-claude/compaction see the edit
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
Whether `tengu_auto_mode_decision` affects this behavior is unclear, since no reading of that gate has been taken yet.
Anthropic's documentation agrees
Anthropic's documentation has since written up onBlock, on sent_count = len(messages sent in the compaction request).