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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 v2.1.220

9 entries read diff v2.1.219 → v2.1.220 Markdown

A retry path that would drop the classifier beta after an HTTP 400 and a successful bare retry is present in the build but inert: it keys off a beta constant that is null in both builds, so the latch never fires. Nothing about classifier behaviour changes as a result. Treat it as groundwork rather than a feature you can exercise today.

Refusal fallback no longer lands on Claude Opus 5 when the client cannot see its model entitlements. A new check detects sessions with no entitlement data at all, and the Opus lineup walk used for refusal fallback filters Opus 5 out in that state; a normalization step also rewrites any model whose canonical id is "claude-opus-5" to "claude-opus-4-8" before it is used as a fallback target, so an affected setup now falls back to Claude Opus 4.8. Separately, the permission classifier behind auto mode now attaches a beta descriptor to its API requests, on both classifier stages, where the previous build sent none.

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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.

Not switched on
Useful2 Signal3
Permissions Notable

Classifier beta-rejection latch still keys off a null placeholder#

The automatic retry that would drop a rejected classifier beta can never trigger in this build.

The drop-on-400 latch for the auto-mode classifier beta is keyed on a constant that is null, so the branch and its telemetry are unreachable.

What

The path that drops a classifier beta after an HTTP 400 followed by a successful bare retry is keyed on a beta constant that is null in both builds, so it never fires.

Details
  • The latch bails out early when the constant is null, and the constant is declared as null in 2.1.219 and 2.1.220 alike.
  • The newly-sent auto-mode-classifier beta therefore has no automatic drop-on-400 path in this build.
  • The telemetry it would emit, tengu_auto_mode_beta_latch and permission_auto_mode_classifier, is present but unreachable.
Evidence

tengu_auto_mode_beta_latch

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

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.

1 entry

New Featuresopen

Under the hood
Useful2 Signal0
Permissions

Auto-mode classifier requests now send a new beta header#

Auto mode's permission classifier now tags its requests with a beta marker on Anthropic-hosted sessions.

CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS
What

The permission classifier used by auto mode attaches a beta descriptor to its API requests, where the previous build sent none. Both classifier stages now carry it.

Details
  • Registers WA("auto_mode_classifier", "auto-mode-classifier-2026-07-16") and adds it to the frozen known-betas list, so it is also reachable through the header lookup map.
  • In 2.1.219 the classifier's request builder was a stub that unconditionally returned an empty extraBetas array; it now returns this beta.
  • Gated on provider being "firstParty" and the base URL being api.anthropic.com. Suppressed by CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS or hipaa mode, in which case the list stays empty.
Evidence

auto-mode-classifier-2026-07-16

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.

2 entries

Improvementsopen

You'll notice
Useful3 Signal0
Model Fallback

Opus 5 is skipped when the client cannot see model entitlements#

If your session has no model access info cached, Claude won't fall back to Opus 5.

What

A new predicate detects sessions where Claude Code has no entitlement data at all, and the Opus lineup walk used for refusal fallback filters Opus 5 out in that state.

Details
  • isEntitlementOverlayUnavailable returns true when the provider is first-party, an OAuth token is stored, the profile scope is absent, no Anthropic API key is set, and the cached model-access list is empty.
  • A helper combines that predicate with a canonical-name check against "claude-opus-5"; the candidate scan becomes .find((n) => N1e(lo(n)) && !u2c(n) && r(n)), and a sibling helper substitutes "claude-opus-4-8" in its place.
  • No remote flag is involved. It is driven purely by runtime auth and cache state, so a first-party OAuth session with an empty entitlement cache will not auto-pick Opus 5 as a fallback target.
Evidence

isEntitlementOverlayUnavailable

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.

You'll notice
Useful3 Signal0
Model Fallback

Refusal fallback no longer picks Opus 5 when entitlements are unknown#

When a refusal triggers a model switch and entitlements are unknown, you get Opus 4.8 instead of Opus 5.

What

The refusal and model-fallback picker gained a normalization step that rewrites any model whose canonical id is "claude-opus-5" to "claude-opus-4-8" before it is used as a fallback target. A refusal that used to fall back to Claude Opus 5 on affected setups now falls back to Claude Opus 4.8.

Details
  • The first-party branch went from if (!rm()) return s2c("claude-opus-4-8"); let r = EE(); in 2.1.219 to if (!rm()) return l2c(c2c); let r = d2c(EE());, where c2c is the constant "claude-opus-4-8" and d2c performs the mapping.
  • The next-fallback-model resolver applies the same mapping: l2c(rm() ? r.id : s2c(r.id), "exact") becomes f2c(rm() ? d2c(r.id) : l2c(r.id), "exact").
  • The non-exact candidate scan skips the same models: Gji().find((n) => N1e(lo(n)) && !u2c(n) && r(n)) versus the old Uji().find((n) => N1e(lo(n)) && r(n)).
  • The gate is a runtime condition, not a remote flag. The substitution only applies when the helper body Hn() === "firstParty" && zA() && !bH() && eZ() === null && ZJt().length === 0 holds, the same predicate the build reports elsewhere as entitlement_blind. Otherwise behaviour is unchanged.
Evidence

claude-opus-4-8

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.

5 entries

Internal Changesopen

Under the hood
Useful2 Signal0
Build Metadata

Version bumped to 2.1.220#

The version shown in /status, bug reports and update checks is now 2.1.220.

/status
What

The build-time constant block embedded throughout the bundle carries a new version, timestamp and commit hash, rethreaded through roughly 55 call sites.

Details
  • VERSION 2.1.219 -> 2.1.220, with a new BUILD_TIME of 2026-07-24T22:17:45Z and a new GIT_SHA.
  • Surfaces in the /status version line, the bug-report template's Environment Info, the claude-code/<version> user agent, update-check output (Current version: ), telemetry and analytics payloads, and the npm install/view commands targeting @anthropic-ai/claude-code.
  • The BUILD_REF_NAME suffix helper still returns the empty string, and the JOSE compactDecrypt calls in the OIDC JWE path were re-minified with no behaviour change.
Evidence

VERSION: "2.1.220", BUILD_TIME: "2026-07-24T22:17:45Z"

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 Signal0
Build Metadata

Build stamp moved to 2.1.220#

Version strings in update messages, doctor output and daemon logs were re-stamped to 2.1.220.

claude update
What

The inlined build constants appearing in around 40 user-visible and log strings were re-stamped, with no surrounding logic touched.

Details
  • VERSION 2.1.219 -> 2.1.220, BUILD_TIME 2026-07-24T03:24:19Z -> 2026-07-24T22:17:45Z, GIT_SHA 7006c4c3acac98e554d3997baeda6a7fa4d1ff7c -> 4073f59596e272f39393db4f96abc5f4b10eff21.
  • Affected strings include version output, claude update messages, user agents, doctor output and daemon logs.
Evidence

GIT_SHA: "4073f59596e272f39393db4f96abc5f4b10eff21"

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 Signal0
Permissions

Reworded the classifier beta-rejection warning#

A warning message about a rejected classifier beta was reworded, though you can't reach it.

What

The warn-level log emitted when the auto-mode classifier's beta is rejected changes from "the bare retry succeeded" to "the retry without it succeeded".

Details
  • Log text only, the surrounding logic is unchanged.
  • The branch is currently unreachable because the latch it belongs to is keyed on a null constant.
Evidence

beta rejected (HTTP 400) and the retry without it succeeded

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

Under the hood
Useful1 Signal0
Elsewhere

Prompt text for /code-review, /simplify, skill-saving and credential paths is byte-identical#

Code review, simplify and skill-saving instructions are unchanged despite looking rewritten in the bundle.

/code-review/simplify
What

A large group of apparently new and removed code is pure bundler renaming, with prompt wording unchanged from 2.1.219.

Details
  • Covers the code-review phase prompts including "## Phase 2 \u2014 Verify (1-vote, 3-state)", "## Phase 3 \u2014 Sweep for gaps" and the Artifact publishing block.
  • Also covers the /simplify 4-agent and single-pass prompts, the "# Saving skills" system prompt variants, the background-session shipping policy text, the workflow status strings and the credential file paths.
  • Only the surrounding minified identifiers and the interpolated tool and skill symbols differ. No user-visible behaviour change.
Evidence

## Phase 3 \u2014 Sweep for gaps

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 Signal0
Build Metadata

Bundle-wide reformatting with no behaviour change#

Assorted internal code was reformatted and renamed with nothing you can perceive changing.

What

Several unrelated areas were reflowed or had their module-init closures renamed, with no semantic difference found in any of them.

Details
  • Method-chain reflows in JWT verification, PEM fingerprinting via createHash("sha1") and createHash("sha256"), MCP server-config mapping, the SDK set_model control request, QR-code rendering and several string-splitting sites.
  • Renamed module-init closures for the test and typecheck command regexes and for the git worktree path constants /worktrees/ and config.worktree.lock.
Evidence

failed to validate JWT signature

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.

Verbatim
Official · Anthropic

Anthropic’s official release notes

Published verbatim by Anthropic for v2.1.220. 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 v2.1.219.

Claude Code, interactive mode

Read the prompts for this release →
Switches

Every name in this release

The 5 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.

Slash commands

Environment variables

Settings and names in the code