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 v2.1.75 Home All releases olderv2.1.74 v2.1.76newer
Claude Code v2.1.75

Opus 1M Context Window Default

Feature flag
tengu_cobalt_compass 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 v2.1.75: 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 v2.1.75. It isn't a statement about your account. What a flag value here can and cannot tell you

What

First-party Opus users now default to a 1M token context window (5x larger), with automatic migration from the standard Opus setting.

Details
  • Controlled by the tengu_cobalt_compass feature flag (gradual rollout)
  • Users who had "opus" selected are automatically migrated to "opus[1m]"
  • A merge notice is shown up to 6 times: "Opus now defaults to 1M context · 5x more room, same pricing"
  • When Opus 1M is active, Opus no longer triggers "Billed as extra usage" — same pricing as before
  • The model picker now offers an explicit "Opus (1M context)" entry labeled [NEW]
Evidence

Opus 1M migration and display (search for "tengu_cobalt_compass", "Opus now defaults to 1M context", "tengu_opus_to_opus1m_migration")

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

See this entry in the whole of v2.1.75 →