# Claude Code v2.1.276

> Claude Code v2.1.276, released 18 Sep 2026 (2026-09-18). 2 entries read out of the shipped bundle. Unofficial, and not affiliated with Anthropic.

Web version: https://changelogs.core-directive.com/v/2.1.276

Model-advisor's standby model selection now checks not just whether a fallback model is available but whether the account is actually talking to Anthropic's own API before picking it. Previously the base URL wasn't verified, which meant the standby pick could be selected even when requests were routed elsewhere. The check now confirms the API endpoint before allowing that selection to proceed.

## Bug Fixes

### Model-advisor standby model selection now double-checks the base URL is Anthropic's own

Model-advisor's standby model pick now also requires the account to actually be talking to Anthropic's own API

**Unclear.** Whether the related `tengu_sage_compass2` gate is enabled for any account is unknown; no reading of it has been taken under this release.

**What**

Claude Code has an internal "model-advisor" feature that can automatically switch you to a standby (fallback) model. Previously, this switch only checked that the advisor tool was enabled and that it had ranked a standby model. Now it also checks that the connection is genuinely going to Anthropic's own servers: the account type must be `firstParty`, and either `_CLAUDE_CODE_ASSUME_FIRST_PARTY_BASE_URL` is set, or the effective `ANTHROPIC_BASE_URL` actually resolves to `api.anthropic.com`.

In practice, this means:

- If you're signed in with a first-party Anthropic account but have `ANTHROPIC_BASE_URL` pointed at a custom proxy or gateway, the advisor will no longer silently substitute a standby model.

- The standby-model switch now only kicks in when requests are verifiably reaching Anthropic's own API endpoint.

**Why**

This closes a gap where a proxied or gateway-routed session could still get its model silently swapped out by the advisor, even though it wasn't actually talking to Anthropic's servers. Anyone routing Claude Code through a custom `ANTHROPIC_BASE_URL` should expect the standby-model feature to stay off rather than kick in unexpectedly.

- Flag `tengu_sage_compass2`: Not enough to say (read for one account on one subscription tier against v2.1.276; this account: no value returned, anonymous baseline: no value returned, compiled default: not a boolean we can read) 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.
- Area: Elsewhere
- Names: `_CLAUDE_CODE_ASSUME_FIRST_PARTY_BASE_URL`
- Tier: Under the hood
- Useful: 2/5
- Signal: 2/5

## Internal Changes

### Version bump to 2.1.276

Claude Code updated to version 2.1.276 with no functional changes

**What**

This release bumps Claude Code's internal build metadata (version number, build time, and git commit reference) to 2.1.276.

**Why**

There is no behavior change to be aware of here; only the version stamp embedded throughout the app was updated.

- Area: Elsewhere
- Tier: Under the hood
- Useful: 1/5
- Signal: 0/5