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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 v2.1.240

10 entries read diff v2.1.239 → v2.1.240 Markdown

This build carries seven pieces of unreleased work, most of it about how the model's thinking is shown. The machinery to pick a thinking display mode is present, but the one path that does anything new, connector text only, needs a server-supplied model capability plus an internal gate before it sends the thinking-display-updates-2026-08-18 API beta, so nothing changes on a stock build; the new three-state CLAUDE_CODE_THINKING_DISPLAY_UPDATES setting lets you force it on or off, and left unset it defers to the remote gate, which is off. Claude Code also now detects thinking blocks the server tagged as narration by reading the block's signature, and counts them for everyone, though hiding them from the live thinking preview and marking them "(summarized)" both sit behind an off-by-default gate. A one-time dialog offering to drop your saved default effort from high to medium is fully wired up, telemetry included, but takes all its wording from the remote config key tengu_radiant_island, which ships empty, so it never renders. Separately, saving a default effort can be scoped to just the model you are using rather than globally, gated off by default.

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5 entries

What probably matters to you

Anything you can use today, anything that visibly changes, and anything worth poking at. One line each, open for detail.

Use it now
Useful4 Signal4
Thinking Display Notable not in their notes

CLAUDE_CODE_THINKING_DISPLAY_UPDATES environment variable#

Set CLAUDE_CODE_THINKING_DISPLAY_UPDATES to force the new thinking display on or off yourself.

CLAUDE_CODE_THINKING_DISPLAY_UPDATES
What

A new three-state environment variable in the settings schema. Set it true to force the new thinking display on, false to force it off; leave it unset and the remote gate decides, which is off by default.

Evidence

CLAUDE_CODE_THINKING_DISPLAY_UPDATES

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.

Not switched on
Useful2 Signal5
Thinking Display Notable not in their notes

Thinking display modes gated behind a server-side model capability#

Claude Code can present thinking as connector text only, but nothing enables it here.

Three thinking display modes and an API beta id are built in, but need a server-supplied capability plus an internal gate, and the mode selector is never called.

Feature flag
tengu_sable_thrush 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 v2.1.240: on

tengu_thinking_display_updates 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 v2.1.240: on

Read once, for one account on one subscription tier, against v2.1.240. It isn't a statement about your account. What a flag value here can and cannot tell you

CLAUDE_CODE_THINKING_DISPLAY_UPDATES
What

Claude Code gains machinery to choose how a model's thinking is presented: thinking plus the short connector text that bridges to the next action, connector text only, or nothing at all. Only the connector-text-only path does anything new, asking the model for streaming thinking updates and attaching the new API beta id thinking-display-updates-2026-08-18 to the request. Reaching that path needs a model capability the server has to supply plus an internal gate, so with no server configuration the beta is never sent, and the selector helper that maps a requested mode onto a display is not called anywhere in this build.

Details
  • Resolution order is: an explicit summarized request wins and shows thinking plus connector text, then omitted shows nothing, then non-interactive sessions show nothing, then the showThinkingSummaries setting gives thinking plus connector text, and last the capability-plus-gate path gives connector text only.
  • The helper's own fallback branch shows connector text only when both the thinking-display-updates gate and the tengu_sable_thrush gate are on, and otherwise shows nothing.
  • Setting the CLAUDE_CODE_THINKING_DISPLAY_UPDATES environment variable short-circuits the check and is returned directly; otherwise the server-supplied model capability or the remote tengu_thinking_display_updates gate decides, with the value compiled into the binary defaulting to off.
  • The outgoing request is only rewritten to carry the beta when the endpoint is first-party and streaming-capable and the CLAUDE_CODE_SIMULATE_PROXY_USAGE environment variable is not set.
Evidence

if (e === "summarized") return "thinking_and_connector_text";, thinking-display-updates-2026-08-18

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.

Not switched on
Useful3 Signal4
Effort Levels Notable

"Switch your default effort to medium?" prompt, complete but with no text to show#

A one-time prompt offering to switch your default effort to medium exists but has no text.

The effort-medium dialog is fully wired into the prompt sequence but its required wording comes from a remote config key that ships empty.

Feature flag
tengu_radiant_island 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 v2.1.240: not a boolean we can read

Read once, for one account on one subscription tier, against v2.1.240. It isn't a statement about your account. What a flag value here can and cannot tell you

What

A one-time dialog offering to change your saved default effort from high to medium, confirming with Effort set to medium and saved as your default or a warning if the write fails. It is fully reachable in the prompt sequence, ahead of the LSP and plugin hints, and marks itself seen so it appears at most once. But its wording comes entirely from the remote config key tengu_radiant_island, whose in-binary value is an empty object and whose body text is required, so with no server value the dialog never appears.

Details
  • Only the body text is required; title, confirm label and cancel label have in-code defaults.
  • You are only eligible if you have no effort pinned anywhere, or have pinned high in your user settings. Any other configuration disqualifies.
  • The parent picks it as effort-medium-nudge in the same chain as the fullscreen upsell and remote callouts.
Evidence

Switch your default effort to medium?

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.

Not switched on
Useful3 Signal4
Effort Levels Notable

Saving a default effort level can now scope it to one model#

Your saved default effort could apply per model instead of everywhere, but that is off.

Per-model effort defaults are implemented behind the tengu_russet_plover gate; with it off you still get one global setting.

Feature flag
tengu_russet_plover 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 v2.1.240: on

Read once, for one account on one subscription tier, against v2.1.240. It isn't a statement about your account. What a flag value here can and cannot tell you

What

Previously, saving a default effort wrote both a global setting and a per-model one. With the tengu_russet_plover gate on, it now writes only the per-model entry, so the default applies to the model you are using rather than everything. With the gate off, which is the built-in default, it writes only the global setting.

Details
  • The gate is remote, tengu_russet_plover, fallback off.
  • Model names that would collide with built-in JavaScript object property names also fall back to the global-only write.
Evidence

{ effortLevel: t, modelSettings: { [r]: { effortLevel: t } } }

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.

Not switched on
Useful2 Signal4
Thinking Display not in their notes

Server-tagged "narration" thinking blocks, counted now and rendered as "(summarized)" later#

Claude Code now spots server-tagged narration thinking, but the display change stays off by default.

Narration detection and per-request counting run for everyone; the "(summarized)" rendering sits behind a gate that is off by default.

Feature flag
tengu_sable_thrush 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 v2.1.240: on

Read once, for one account on one subscription tier, against v2.1.240. It isn't a statement about your account. What a flag value here can and cannot tell you

CLAUDE_CODE_SABLE_THRUSH
What

Claude Code can now tell whether the model's thinking block was tagged by the server as narration, by decoding the block's cryptographic signature and looking for the literal string narration inside it. The count of such blocks per request is reported for everyone on this build. The display changes that depend on it are held behind a gate that is off by default, so on a stock build thinking still renders exactly as before.

Details
  • The classifier caches its result per block, so each block is decoded once.
  • Decode failures are swallowed silently and reported once as narration_classifier_error.
  • The telemetry field counting narration blocks per request existed in 2.1.239 but was wired to a check hardcoded to return nothing, so it never reported; it is now wired to the real check and has no gate.
  • The display-side check additionally requires CLAUDE_CODE_SABLE_THRUSH set true or the remote tengu_sable_thrush gate to be on, with the in-binary fallback off, and it also requires the server to actually be tagging blocks.
  • With the gate on, the main message renderer prints a dimmed, italic (summarized) label above the trimmed thinking text instead of the reasoning itself, the live thinking pane blanks out for such blocks, and a reply whose first block is narration counts as having visible content.
  • Screen readers get a dot column labelled summarized: in place of the visual label.
  • Each of the three display sites checks the classifier helper is present before calling it, so those paths stay inert if it is absent.
Evidence

narration_classifier_error, "aria-label": "summarized:", (summarized)

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.

Were these the right ones to put at the top? 0 answered
Below the fold

Everything else

Smaller changes and internals, grouped as the pipeline found them. Nothing is dropped, it is only further down.

2 entries

In Developmentopen

Not switched on
Useful2 Signal3
Thinking Display

Narration thinking is kept out of the live thinking preview#

Narration thinking would be hidden from the live thinking preview, but that path is switched off.

The streaming preview skips narration blocks only with the sable-thrush gate on, which defaults off.

What

The streaming path used to always show the first thinking block of a reply as the in-progress thinking preview. It now checks whether that block is narration first and shows nothing if so. Only reachable with the sable-thrush gate on, which is off by default.

Details
  • The call site also checks that the narration helper is present before using it, so builds without it behave as before.
Evidence

isNarrationSummaryBlock

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.

Not switched on
Useful1 Signal2
Effort Levels

Telemetry for the effort nudge#

Two events would record the effort prompt and your answer, but it never shows.

Display and choice telemetry for the effort nudge fire only once remote config supplies the dialog text.

Feature flag
tengu_radiant_island 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 v2.1.240: not a boolean we can read

Read once, for one account on one subscription tier, against v2.1.240. It isn't a statement about your account. What a flag value here can and cannot tell you

What

Two events fire only when the effort-medium prompt actually renders, which requires the remote tengu_radiant_island config to supply its text. One records the display and which group you fell into, the other records your choice and the outcome: switched, declined, write_failed or unavailable.

Details
  • Failure paths also record a reason, either unavailable_at_accept or settings_write_failed.
Evidence

tengu_effort_medium_nudge_resolved

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.

3 entries

Internal Changesopen

Under the hood
Useful2 Signal3
Telemetry

Per-message stats count narration thinking blocks#

Per-message character tallies now include narration blocks, so usage stats count a bit more.

What

The routine that tallies text and thinking character counts per message now also counts blocks tagged as narration. This uses the raw signature check with no gate, so it counts on every build where the helper is present.

Evidence

isNarrationTaggedBlock

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

Under the hood
Useful2 Signal1
Elsewhere not in their notes

Version stamped as 2.1.240#

The build now reports itself as version 2.1.240 in version checks and headers.

claude --version
What

The embedded version, build time and commit id moved to the 2.1.240 build. These drive claude --version, update checks, Remote Control minimum-version messages, user-agent headers and analytics fields. No behaviour change beyond the new values.

Evidence

VERSION: "2.1.240"

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.

Under the hood
Useful1 Signal1
Elsewhere

Most of this release is the version stamp and compiler churn#

Nearly all of this release is repeated build-constant updates and renamed variables, not real changes.

What

About 90 of the changes are the same build-constant block re-emitted at each place it is used. The rest, including the GitLab merge-request URL pattern, git worktree paths, test and typecheck command detection, the login-error check and a long tail of reformatting in the MCP and plugin sync code, are identical apart from renamed internal variables.

Evidence

GIT_SHA: "d235569e3f61fc4d9aacd7c85e6d1b6253e03f52"

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 v2.1.240. 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.

  • Bug fixes and reliability improvements
Read it on GitHub →
System prompt

No change to the system prompt since v2.1.239.

Claude Code, interactive mode

Read the prompts for this release →
Documentation

What the docs did around this release

427 documentation changes were recorded within 24 hours either side of this release, nearest first. The closest 12 are below. They're here because they happened near this release in time. That's not a claim that this release caused the edit, or that the page documents anything in it.

routines Changed +1 -1 recorded here claude-code plugins-reference Changed +17 -1 recorded here claude-code errors Changed +35 -0 recorded here claude-code desktop-scheduled-tasks Changed +1 -1 recorded here claude-code desktop Changed +3 -1 recorded here claude-code cloud-environments Changed +1 -1 recorded here claude-code chrome Changed +5 -0 recorded here claude-code claude-tag/users/troubleshooting Changed +2 -2 recorded here claude-docs claude-tag/users/getting-started Changed +3 -3 recorded here claude-docs claude-tag/concepts/security-and-data Changed +1 -1 recorded here claude-docs claude-tag/concepts/how-it-works Changed +3 -3 recorded here claude-docs claude-tag/admins/troubleshooting Changed +1 -1 recorded here claude-docs

Every time above is when this site's poller recorded the change, which is up to half an hour after the edit on an ordinary read and up to a day after it on a full sweep. Upstream's own edit time is used instead wherever a capture carries one. None of these do.

The documentation ledger →
Switches

Every name in this release

The 3 literal strings found in the bundle, with the number of entries that name each one. Picking one searches for it. A name is here because this build's code mentions it, which is not the same as it working or being finished.

Environment variables

Settings and names in the code