Issue

Fixes #7526 — NativeAttributeValue type resolves to any.

Description

The NativeAttributeValue union exported from @aws-sdk/util-dynamodb (and re-exported by @aws-sdk/lib-dynamodb) included InstanceType<{ new (...args: any[]): any }> as a union member. TypeScript widens InstanceType<{ new (...args: any[]): any }> to any, which collapsed the entire union to any and silently disabled type-checking for every consumer of the DynamoDB Document Client (PutCommand, UpdateCommand, marshall, convertToAttr, etc.).

The maintainer (@kuhe) identified the fix in a comment on the issue: remove that member from the union. This PR removes it and resolves the latent typecheck errors that surfaced inside the package once the implicit any was no longer absorbing them — three small internal cast adjustments in convertToAttr.ts, marshall.ts, and unmarshall.ts. No runtime behavior changes.

Files changed:

• packages-internal/util-dynamodb/src/models.ts — the actual type fix (drop the InstanceType<...> union member that widened to any).
• packages-internal/util-dynamodb/src/convertToAttr.ts — small local-cast adjustment to satisfy the now-stricter union.
• packages-internal/util-dynamodb/src/marshall.ts — small cast adjustment.
• packages-internal/util-dynamodb/src/unmarshall.ts — small cast adjustment.
• packages-internal/util-dynamodb/src/NativeAttributeValue.spec.ts — new regression spec.

Note on breaking-ness: This is a type-only change. Runtime behavior is identical. Downstream users currently passing arbitrary class instances directly into marshall/convertToAttr (relying on convertClassInstanceToMap) will now see compile errors at the call site. The maintainer flagged the original bug as "breaking"; this PR follows their guidance.

generated by AI tools, and reviewed by Mohanraj Venkatesan

Testing

Added packages-internal/util-dynamodb/src/NativeAttributeValue.spec.ts with 16 Vitest cases:

• 13 positive assignments covering every supported native type (string, number, boolean, null, undefined, bigint, NumberValue, Uint8Array, ArrayBuffer, Set variants, map, list).
• 3 // @ts-expect-error regressions that verify the union no longer collapses to any (function, symbol, and a parameter-not-narrowed case).

Verified the regression tests catch the original bug: temporarily restoring the offending union member produces 3 TS2578: Unused '@ts-expect-error' directive errors, exactly as expected.

Local results:

• npx vitest run in packages-internal/util-dynamodb — 388/388 pass (372 pre-existing + 16 new).
• npx tsc --noEmit -p tsconfig.types.json — only pre-existing baseline errors remain (4 @aws-sdk/client-dynamodb module-resolution errors due to missing local dist-*/ outputs, plus one pre-existing unused-directive). No new errors introduced.

Checklist

• Linked to the original issue (NativeAttributeValue type is any #7526).
• Added a regression test that fails on main and passes with this fix.
• All existing tests in the affected package still pass (vitest run: 388/388).
• No new tsc --noEmit errors introduced.
• Husky pre-commit hooks pass (lint-staged, lint:versions, lint:dependencies, lint:api).
• AI disclosure included in Description per repo policy.