{"version":"2.1.307","anchor":"context-window-lookup-simplified","canonical_anchor":"context-window-lookup-simplified","heading":"Unknown models no longer fall back to a one-million-token context window","tier":"notice","area":"Elsewhere","scope":"individual","heads_up":true,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.307\/e\/context-window-lookup-simplified","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.307","markdown":"### Unknown models no longer fall back to a one-million-token context window\n\nLooking up a model's context window no longer falls back to one million tokens when the model is not recognised\n\n**Unclear.** Whether an unrecognised model still gets a default context window from somewhere else is not established.\n\n**What**\n\nThe context window is how much text a model can take in at once. When Claude Code looks up that size for a model, it used to fall back to one million tokens if no size was found. A token is a small piece of text. That fallback has been removed, so a model Claude Code does not recognise now gets no size from this lookup.\n\n**Why**\n\nIf you use a model Claude Code does not recognise, the context size it assumes for that model may be different now.\n\n- Area: Elsewhere\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 2\/5\n- Scope: individual\n- Heads-up: yes"}