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 v2.1.179 Home All releases olderv2.1.178 v2.1.181newer
Claude Code v2.1.179

Precompute Compaction Setting [Gradual Rollout]

Feature flag
tengu_sepia_moth Off in both readings

The flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.

This account: off · anonymous baseline: off · compiled default in v2.1.179: 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 v2.1.179. It isn't a statement about your account. What a flag value here can and cannot tell you

What

A new experimental setting precomputeCompactionEnabled allows Claude to precompute the compaction summary in the background before it's actually needed, making context-window compaction faster when it triggers.

Status

Setting infrastructure exists and is wired to the settings UI, but the setting toggle is only shown when the server flag tengu_sepia_moth is enabled. The actual precompute behavior also requires this flag. The setting description reads: "@internal Precompute the compaction summary in the background before it is needed. Only applies when auto-compact is on."

Details
  • Appears in the Experimental section of /settings when enabled
  • Default value is true when the flag is active
  • Emits a tengu_precompute_compaction_setting_changed telemetry event on change
Evidence

Setting description (search for "Precompute the compaction summary in the background") and setting key (search for "precomputeCompactionEnabled")

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

See this entry in the whole of v2.1.179 →