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.

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Claude Code v2.1.105

Reactive Compaction [Gradual Rollout]

Feature flag
tengu_cobalt_raccoon On for this account, and not off by default

The flag server returned on for the one account this site reads, and nothing in this release compiles it off by default. The compiled default is shown below, and says which it is when we cannot read one: a fifth of gates compile in a string or a number rather than on or off, and most published releases have no gate table behind them at all. No client can see what the server returns for your account.

This account: on · anonymous baseline: on · compiled default in v2.1.105: no gate table built for this version

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 v2.1.105. It isn't a statement about your account. What a flag value here can and cannot tell you

What

A new conversation compaction system that automatically summarizes older messages when the prompt exceeds context limits, using binary search to find the optimal compaction boundary.

Status

Feature-flagged behind tengu_cobalt_raccoon (default: false). Disabled in non-interactive mode.

Details
  • Replaces the removed tengu_sm_compact system with a more sophisticated approach
  • Uses binary search to determine how many message groups to preserve vs. summarize
  • Sends older messages to a model fork for summarization
  • Includes retry logic (strips media on size errors), empty-response detection, and PreCompact hook support
  • Extensive telemetry: trigger, success, duration, pre/post token counts, group counts
  • When enabled, triggers automatically during conversation turns when token limits are approached
Evidence

Feature gate (search for "tengu_cobalt_raccoon") returns !1 (false) as default

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

See this entry in the whole of v2.1.105 →