Fix invalid OpenAPI schema generation for models extending Array

[Copilot]

When a TypeSpec model extends an Array, the generated OpenAPI schema was invalid because it contained both type: "object" and allOf: [{ type: "array", ... }]. This creates a contradictory schema that violates the OpenAPI specification.

Before (Invalid):

model A extends Array<int32> {}

Generated:

A:
  type: object
  allOf:
    - type: array
      items:
        type: integer
        format: int32

After (Valid):

model A extends Array<int32> {}

Generated:

A:
  type: array
  items:
    type: integer
    format: int32

Solution:
Modified modelDeclaration in schema-emitter.ts to detect when a model extends an array type using isArrayModelType. In such cases:

1. Extract the element type from the base array model's indexer
2. Generate an array schema directly instead of an object schema
3. Skip adding the baseModel to allOf for array extensions

This ensures that model A extends Array<T> {} and model A is Array<T> {} generate identical, valid schemas.

Tests Added:

• Verification that extends and is Array generate identical schemas
• Support for complex element types (custom models)
• Edge cases with different primitive types

All existing tests pass, confirming no regression in normal model inheritance or array handling.

Fixes #7519.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• http://168.63.129.16:80/machine/
  • Triggering command: /usr/bin/python3 -u bin/WALinuxAgent-2.13.1.1-py3.9.egg -collect-logs (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[richardpark-msft]

@copilot, we believe this could be simplified.

[Copilot]

Simplified the logic by eliminating code duplication. The array extension check and element type extraction are now combined, and I use a ternary operator to create the appropriate schema directly instead of having separate if/else blocks with redundant object schema creation. Commit 1e5abdd.

[richardpark-msft]

Never mind, go back to the original commit.

[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• http://168.63.129.16:80/machine/
  • Triggering command: /usr/bin/python3 -u bin/WALinuxAgent-2.13.1.1-py3.9.egg -collect-logs (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list