Summary

• add an opt-in, write-time TypeProvider hook for emitting selected attributes from the previous GA contract without placing them in the normal attribute/visitor/reference-map pipeline
• preserve prior ModelReaderWriterBuildableAttribute entries only when their target and every enclosing type and generic argument remain emitted or otherwise resolvable, while deduplicating entries still generated today
• exclude unrelated attributes such as EditorBrowsableAttribute, removed targets, and any target component marked error-obsolete (Obsolete(..., true))
• recursively collect, deduplicate, and reapply every obsolete and experimental diagnostic suppression required by the target, its declaring types, and its generic arguments
• correctly resolve and render arbitrarily nested target types, including constructed generic declaring types

Validation

• npm run build
• 1,719 Microsoft.TypeSpec.Generator tests
• 1,514 Microsoft.TypeSpec.Generator.ClientModel tests
• npm run cop
• full C# test-library regeneration
• pnpm format:check
• type-aware oxlint