Remove Nova Premier (us.amazon.nova-premier-v1:0) from Studio model picker before its Sept 14, 2026 EOL

[xiehust]

Summary

us.amazon.nova-premier-v1:0 (Amazon Nova Premier) is scheduled for end of life on Amazon Bedrock on September 14, 2026. It is still offered as a selectable model in the Studio model picker. After the EOL date any agent built with it will fail at first invoke with a model-not-available error, so the entry should be removed before then.

anthropic.claude-opus-4-1-20250805-v1:0 (Claude Opus 4.1) is also on the EOL list (January 8, 2027) but is not referenced anywhere in this repo, so no action is needed for it.

Where Nova Premier is referenced (main)

Model catalog entries (user-facing, should be removed):

• frontend/src/studio/lib/models.ts:83 — { model_id: 'us.amazon.nova-premier-v1:0', model_name: 'Amazon Nova Premier v1' }
• apps/studio/src/components/property-panel.tsx:129 — same entry in the legacy Studio app

Model-specific handling (can be removed once the catalog entry is gone, or left as harmless dead branches):

• frontend/src/studio/PropertyPanel.tsx:609 — if (modelId.includes('nova-premier'))
• frontend/src/studio/lib/code-generator.ts:1498 and :1604 — max_tokens clamp to 32000
• frontend/src/studio/lib/graph-code-generator.ts:94 — same clamp
• docs/studio-integration.md:295 — documents the clamp

DEFAULT_MODEL_ID is unaffected (it is Sonnet 5), and no backend, evaluation, A/B, or governance code path references Nova Premier. Impact is limited to users who manually pick it from the dropdown.

Suggested change

1. Remove the two catalog entries so the model can no longer be selected.
2. Drop the nova-premier special-casing in PropertyPanel.tsx, code-generator.ts, graph-code-generator.ts, and the note in docs/studio-integration.md.
3. Optionally, show a warning in the property panel when loading a saved flow whose node still carries us.amazon.nova-premier-v1:0, so existing flows are not silently broken.

Reference

Amazon Bedrock model lifecycle: https://docs.aws.amazon.com/bedrock/latest/userguide/model-lifecycle.html