[Bug]: FilterVisibility to honor extends

[dvv]

Hi!

I upgraded to 1.13.0 and tried to apply the new FilterVisibility type:

import "@typespec/http";

using TypeSpec.Reflection;

@service(#{ })
namespace Rpc;

// -----------------------------------------------------------------------------

model Base {
  @visibility(Lifecycle.Read) id: string,
}

model Auditable extends Base {
  @visibility(Lifecycle.Read) created_at: utcDateTime,
  @visibility(Lifecycle.Read) created_by: string,
  @visibility(Lifecycle.Read) updated_at: utcDateTime,
  @visibility(Lifecycle.Read) updated_by: string,
}

// -----------------------------------------------------------------------------

model User extends Auditable {
  name: string,
}

// -----------------------------------------------------------------------------

@doc("DTO to create {name}", T) model ObjectCreate<T extends Model> is FilterVisibility<T, #{ all: #[Lifecycle.Create] }, "{name}Create"> {}

model UserCreate is ObjectCreate<User> {}

// -----------------------------------------------------------------------------

The resulting spec is somewhat surprising to me:

openapi: 3.0.0
info:
  title: (title)
  version: 0.0.0
tags: []
paths: {}
components:
  schemas:
    Auditable:
      type: object
      required:
        - created_at
        - created_by
        - updated_at
        - updated_by
      properties:
        created_at:
          type: string
          format: date-time
          readOnly: true
        created_by:
          type: string
          readOnly: true
        updated_at:
          type: string
          format: date-time
          readOnly: true
        updated_by:
          type: string
          readOnly: true
      allOf:
        - $ref: '#/components/schemas/Base'
    Base:
      type: object
      required:
        - id
      properties:
        id:
          type: string
          readOnly: true
    User:
      type: object
      required:
        - name
      properties:
        name:
          type: string
      allOf:
        - $ref: '#/components/schemas/Auditable'
    UserCreate:
      type: object
      required:
        - name
      properties:
        name:
          type: string
      allOf:
        - $ref: '#/components/schemas/Auditable'
      description: DTO to create User

That is, Create lifecycle is applied to explicit portion of User model, and inherited properties go on without visibility filter.
Is this the expected behavior?

Then, I made User model to read:

model User extends Auditable {
  @visibility(Lifecycle.Create) login: string, 
  name: string,
}

and encounter the compilation error:
error @typespec/openapi/duplicate-type-name Duplicate type name: 'User'. Check @friendlyName decorators and overlap with types in TypeSpec or service namespace..
Wonder what is the cause of the (rather unexpeced) error?

TIA

Originally posted by @dvv in #11034

[github-actions]

🎯 Issue Triage

Two related bugs with FilterVisibility when used with models that use extends inheritance: (1) visibility filtering is not applied to inherited properties — only direct properties are filtered, and (2) a spurious duplicate-type-name error is emitted when a model has mixed-visibility direct properties and is passed through FilterVisibility.

Category: Bug
Area: lib:http

🔗 [Playground Reproduction]((typespec.io/redacted)

📋 Reproduction code

import "`@typespec/http`";

using TypeSpec.Reflection;

`@service`(#{ })
namespace Rpc;

model Base {
  `@visibility`(Lifecycle.Read) id: string,
}

model Auditable extends Base {
  `@visibility`(Lifecycle.Read) created_at: utcDateTime,
  `@visibility`(Lifecycle.Read) created_by: string,
  `@visibility`(Lifecycle.Read) updated_at: utcDateTime,
  `@visibility`(Lifecycle.Read) updated_by: string,
}

model User extends Auditable {
  name: string,
}

`@doc`("DTO to create {name}", T) model ObjectCreate<T extends Model> is FilterVisibility<T, #{ all: #[Lifecycle.Create] }, "{name}Create"> {}

model UserCreate is ObjectCreate<User> {}

🔍 Analysis

Bug 1 — inherited properties not filtered:
UserCreate in the OpenAPI output still includes allOf: $ref: Auditable which carries readOnly: true (Read-visibility) properties, even though FilterVisibility<User, { all: [Lifecycle.Create] }, ...> should remove all non-Create properties. The filter only applies to the model's own directly-declared properties, not those coming from base models via extends.

Bug 2 — duplicate-type-name diagnostic:
When User has at least one property with Lifecycle.Create visibility, FilterVisibility appears to produce a filtered copy of User that ends up with the same schema name as the original, triggering the duplicate-type-name error. The filtered model is not being renamed correctly (or a naming collision occurs).

Affected components:

• TypeSpec.Reflection.FilterVisibility (compiler standard library)
• typespec/http visibility system (Lifecycle enum)
• openapi3 emitter schema name resolution

📝 Suggested next steps

• Confirm expected behavior: FilterVisibility should apply visibility filtering to all properties including those inherited via extends.
• Investigate FilterVisibility implementation to see whether it recurses into parent models.
• Trace the schema naming logic for filtered models that have mixed-visibility direct properties to fix the duplicate-type-name collision.

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