{"version":"2.1.299","anchor":"fast-mode-status-accepts-api-keys-only-if-they-look-like-ant","canonical_anchor":"fast-mode-status-accepts-api-keys-only-if-they-look-like-ant","heading":"Fast mode checks now use only API keys that look like Anthropic keys","tier":"notice","area":"Models","scope":"individual","heads_up":true,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.299\/e\/fast-mode-status-accepts-api-keys-only-if-they-look-like-ant","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.299","markdown":"### Fast mode checks now use only API keys that look like Anthropic keys\n\nFast mode and profile lookups now use an API key only when no OAuth login is available and the key starts with `sk-ant-`\n\n**What**\n\nFast mode is a setting that makes Claude reply faster. To decide its status, Claude Code checks your organization and fetches your profile. It now uses an API key for those checks only when no OAuth login (signing in through your Anthropic account) is available and the key looks like an Anthropic key, starting with `sk-ant-`. Before, any key in that slot was used.\n\nWhen the key does not qualify, the reason given for the fast mode guess is now \"unknown\" instead of \"preference\".\n\n**Why**\n\nIf you put a gateway or proxy token where the API key goes, Claude Code no longer sends it to fast mode and profile requests that would fail with it.\n\n- Flag `tengu_penguins_off`: Not enough to say (read for one account on one subscription tier against v2.1.299; 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.\n- Area: Models\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 2\/5\n- Scope: individual\n- Heads-up: yes"}