{"version":"2.1.310","anchor":"vertex-default-model-fallback-gains-document-driven-targets","canonical_anchor":"vertex-default-model-fallback-gains-document-driven-targets","heading":"Vertex and Bedrock default models can come from a published model document","tier":"notice","area":"Models","scope":"org","heads_up":true,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.310\/e\/vertex-default-model-fallback-gains-document-driven-targets","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.310","markdown":"### Vertex and Bedrock default models can come from a published model document\n\nOn Vertex and Bedrock, default models can now come from a published document per tier, falling back to models mapped in `modelOverrides`\n\n**What**\n\nWhen you use Claude Code through Google Vertex or Amazon Bedrock, it checks which default model it can use for each model tier. Before, the fallbacks came only from a list built into Claude Code. Now:\n\n- Each tier can take its target model from a published model document.\n\n- A model that is too old is treated as unavailable when it was a document default.\n\n- A model your administrator has mapped through `modelOverrides` counts as an accepted fallback.\n\n- Claude Code can check document defaults again and record any that turned out not to work.\n\nOn Vertex, this check is skipped when `CLAUDE_CODE_PROVIDER_MANAGED_BY_HOST` is set.\n\n**Why**\n\nVertex and Bedrock users may see different default models once published documents drive the choice.\n\n- Area: Models\n- Tier: You'll notice\n- Useful: 3\/5\n- Signal: 4\/5\n- Scope: org\n- Heads-up: yes"}