{"version":"2.1.315","anchor":"haiku-fallback-model-helper","canonical_anchor":"haiku-fallback-model-helper","heading":"Stricter rule for when Claude Code picks a Haiku model on its own","tier":"notice","area":"Models","scope":"individual","heads_up":true,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.315\/e\/haiku-fallback-model-helper","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.315","markdown":"### Stricter rule for when Claude Code picks a Haiku model on its own\n\nClaude Code now chooses a Haiku model itself only when no small-model variable is set, the provider is Anthropic's own, and the main model is the default\n\n**Unclear.** It is not clear which tasks use the model this rule chooses.\n\n**What**\n\nClaude Code has changed the rule for when it falls back to choosing a Haiku-class model by itself. It now does so only when all of these hold:\n\n- `ANTHROPIC_SMALL_FAST_MODEL` is not set\n\n- `ANTHROPIC_DEFAULT_HAIKU_MODEL` is not set\n\n- Claude Code is talking to Anthropic's own API directly, not through another cloud provider\n\n- the main model is the default one\n\n- a few further checks pass\n\nIf you set either variable, your choice is used instead of this fallback. Environment variables are named values set in your shell before Claude Code starts.\n\n**Why**\n\nThis may change which model handles small or quick tasks for you, so the model you see used for those tasks may differ from before.\n\n- Area: Models\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 2\/5\n- Scope: individual\n- Heads-up: yes"}