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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 v2.1.68

5 entries read diff v2.1.67 → v2.1.68 Markdown

This release re-enables the "ultrathink" keyword as a way to boost reasoning effort to high for the current turn, complete with a new rainbow shimmer visual effect. It also adds a CLAUDE_CODE_DISABLE_LEGACY_MODEL_REMAP environment variable to let users opt out of automatic model remapping to Opus 4.6, and introduces a redesigned server-controlled effort selection dialog.

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Ultrathink keyword re-enabled as effort boost#

Feature flag
tengu_turtle_carbon 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 v2.1.68: 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 v2.1.68. It isn't a statement about your account. What a flag value here can and cannot tell you

What

Typing "ultrathink" in a message now sets reasoning effort to "high" for that turn. In the previous version, ultrathink was deprecated and showed a dismissive message — it now has real functionality again.

Usage
ultrathink about the architecture of this codebase and suggest improvements
Details
  • When "ultrathink" appears anywhere in your message, effort is automatically set to high for that turn
  • A notification briefly displays: "Effort set to high for this turn"
  • The word "ultrathink" is rendered with a rainbow color shimmer effect in the terminal (cycling through red, orange, yellow, green, blue, indigo, and violet)
  • Controlled by the tengu_turtle_carbon feature flag (defaults to enabled)
  • Replaces the old "Ultrathink no longer does anything. Thinking budget is now max by default." deprecation message
Evidence

Ultrathink effort injection (search for "ultrathink_effort") — rqY() at line ~290076 checks jd() ("tengu_turtle_carbon") and Vf7() (/\bultrathink\b/i)

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Legacy model remap opt-out#

What

Users who were automatically migrated from legacy Opus models to Opus 4.6 can now opt out by setting an environment variable.

Usage
export CLAUDE_CODE_DISABLE_LEGACY_MODEL_REMAP=1
Details
  • When your model is auto-remapped to Opus 4.6, the notification now reads: "Model updated to Opus 4.6 · Set CLAUDE_CODE_DISABLE_LEGACY_MODEL_REMAP=1 to opt out"
  • The notification displays for 8 seconds (up from 3) when the opt-out message is shown, giving you time to read the instructions
  • Setting the environment variable to 1 disables the automatic model remapping entirely
  • The remap behavior is also gated by the tengu_grey_wool feature flag (defaults to enabled)
Evidence

Model remap opt-out (search for "CLAUDE_CODE_DISABLE_LEGACY_MODEL_REMAP") — gy1() at line ~535228

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Effort selection dialog redesigned#

Feature flag
tengu_grey_step2 Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.68: 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 v2.1.68. It isn't a statement about your account. What a flag value here can and cannot tell you

The effort callout dialog for Opus 4.6 users has been redesigned with server-configurable content and a simplified option set.

Details
  • Dialog title and description are now fetched from the server (via tengu_grey_step2 feature flag) instead of being hardcoded
  • Options are simplified to three clear choices:
  • "Use medium effort (recommended)"
  • "Use high effort"
  • "Use low effort" (new — previously only medium and high were offered)
  • Removed verbose per-option descriptions and the "(current)" suffix labeling
  • Uses a separate dismiss state (effortCalloutV2Dismissed) so users who dismissed the old dialog may see the new one
Evidence

Server-controlled effort dialog (search for "tengu_grey_step2") — zb6() at line ~162660, dialog at ohq() line ~588325

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

Removed silent medium-effort auto-migration#

Feature flag
tengu_grey_step2 Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.68: 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 v2.1.68. It isn't a statement about your account. What a flag value here can and cannot tell you

The automatic migration that silently set Opus 4.6 effort to "medium" has been removed.

Details
  • Previously, on startup, the app would set opus46EffortMediumMigrationTimestamp and briefly flash "Opus 4.6 effort updated to medium"
  • This silent migration has been completely removed — effort is no longer changed behind the scenes
  • Default effort for Opus 4.6 is now determined by feature flags (tengu_quartz_falcon, tengu_grey_step2) rather than a one-time migration
Evidence

Removed migration function (search for "opus46EffortMediumMigrationTimestamp" — present in v2.1.67, absent in v2.1.68)

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

Server-controlled effort dialog [Gradual Rollout]#

Feature flag
tengu_grey_step2 Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.68: 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 v2.1.68. It isn't a statement about your account. What a flag value here can and cannot tell you

What

The redesigned effort dialog described above is gated behind the tengu_grey_step2 feature flag, which defaults to { enabled: false }.

Status

Feature-flagged (disabled by default, server-controlled rollout)

Details
  • The tengu_grey_step2 flag controls whether the dialog appears and provides its title and description text
  • A separate tengu_quartz_falcon flag also influences the default effort level for Opus 4.6
  • First-party users who previously dismissed the old effort dialog won't see the new one until tengu_grey_step2 is enabled server-side
  • API users (By() or wb6()) can also be enrolled via the same flag
Evidence

Dialog visibility (search for "effortCalloutV2Dismissed") — zIq() at line ~588370 checks zb6().enabled

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

Verbatim
Official · Anthropic

Anthropic’s official release notes

Published verbatim by Anthropic for v2.1.68. Text is unmodified from the upstream changelog. Everything else on this page came out of the bundle instead, which is why the two lists don't match.

  • Opus 4.6 now defaults to medium effort for Max and Team subscribers. Medium effort works well for most tasks — it's the sweet spot between speed and thoroughness. You can change this anytime with /model
  • Re-introduced the "ultrathink" keyword to enable high effort for the next turn
  • Removed Opus 4 and 4.1 from Claude Code on the first-party API — users with these models pinned are automatically moved to Opus 4.6
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