fix: align filter input type name casing for index and relational query fields

[sharonyajain]

Description of changes

Amplify Data models whose GraphQL type name does not begin with an uppercase letter (e.g. a model declared as userPrivateSyncItem) produce a schema whose secondary-index (@index queryField) and @hasMany connection query fields declare a filter argument type that the generated client never sends. At runtime AppSync rejects the query with:

Validation error of type VariableTypeMismatch: Variable type 'ModelUserPrivateSyncItemFilterInput'
doesn't match expected type 'ModeluserPrivateSyncItemFilterInput' @ 'userPrivateSyncItemsByDataType'

Root cause: two helpers name the Model<name>FilterInput type with different casing rules:

• The model transformer (regular list query) uses getFilterInputName → toPascalCase(['Model', name, 'FilterInput']), which capitalizes the model name → ModelUserPrivateSyncItemFilterInput.
• The index transformer (GSI query field) and the relational transformer (@hasMany connection field) used ModelResourceIDs.ModelFilterInputTypeName(name), which is a raw `Model${name}FilterInput` with no capitalization → ModeluserPrivateSyncItemFilterInput.

The generated client (@aws-amplify/data-schema) PascalCases the model name, matching the model transformer. So for a lowercase-first model name the base list filter type matches the client, but the GSI / @hasMany filter type does not — hence the mismatch on those fields only.

Fix: align the index and relational transformers to the same getFilterInputName helper the model transformer uses, so the filter input type name is generated consistently.

• packages/amplify-graphql-index-transformer/src/schema.ts
  • makeModelXFilterInputObject now creates the filter input type via getFilterInputName(object.name.value).
  • ensureQueryField aligns the GSI query field's filter argument type to the same name.
• packages/amplify-graphql-relational-transformer/src/schema.ts
  • makeModelConnectionField and makeModelXFilterInputObject now use getFilterInputName(relatedType.name.value).

For model names that already start with an uppercase letter, getFilterInputName returns a string identical to the previous ModelResourceIDs.ModelFilterInputTypeName output, so there is no change for the common case (confirmed by unchanged snapshots). The shared ModelResourceIDs.ModelFilterInputTypeName helper is intentionally left untouched, since it is used by other code paths; only the two affected transformers are changed.

CDK / CloudFormation Parameters Changed

None. This only changes a generated GraphQL type name (and only for model names that do not begin with an uppercase letter).

Issue #, if available

Fixes aws-amplify/amplify-backend#3267

Description of how you validated changes

• Added regression unit tests using a lowercase-first model name:
  • amplify-graphql-index-transformer.test.ts — asserts the GSI query field and the list query field both reference ModelUserPrivateSyncItemFilterInput, and no ModeluserPrivateSyncItemFilterInput type is emitted.
  • amplify-graphql-has-many-transformer.test.ts — asserts the @hasMany connection field's filter arg is ModelOtherPartFilterInput (related model otherPart), and no lowercase variant is emitted.
• yarn build + yarn test on both affected packages:
  • index transformer: 94/94 tests, 30/30 snapshots pass (no snapshot churn).
  • relational transformer: 195/195 tests, 126/126 snapshots pass (no snapshot churn).
• Ran eslint on the four changed files: no new lint findings introduced by this change. Pre-existing lint issues in these files (jsdoc, no-shadow, max-depth, function length, etc.) are unrelated to this fix and left as-is per the repo's iterative-lint policy.
• Not validated against a live AppSync deployment; verification is at the transformer/schema level.

Checklist

• PR description included
• yarn test passes (for the two affected packages)
• E2E test run linked
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced) — n/a
• New AWS SDK calls or CloudFormation actions have been added to relevant test and service IAM policies — n/a
• Any CDK or CloudFormation parameter changes are called out explicitly (none)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[Simone319]

Approved if the e2e tests succeeds.