Make apiVersion parameter optional at client initialization

[Copilot]

The apiVersion parameter in client initialization was incorrectly marked as required (optional: false) even when a default value exists.

Changes

• clients.ts: Set optional: true for all apiVersion parameters at client level when isApiVersionParam is true
  • Endpoint template parameters (server URL parameters)
  • Multi-service client scenarios
  • Single-service client scenarios
• Test updates: Updated assertions to expect optional: true for client-level apiVersion parameters in params.test.ts and structure.test.ts, including multi-service test cases
• Changeset: Added changeset file documenting the fix

Before:

{
  name: "apiVersion",
  isApiVersionParam: true,
  clientDefaultValue: "2022-12-01",
  optional: false,  // ❌ Required despite having default
  onClient: true
}

After:

{
  name: "apiVersion",
  isApiVersionParam: true,
  clientDefaultValue: "2022-12-01",
  optional: true,   // ✅ Optional when at client level
  onClient: true
}

The fix ensures that apiVersion parameters are always optional at the client level across all scenarios, including both single-service and multi-service clients.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[TCGC] The apiVersion parameter should be optional at the client</issue_title>
<issue_description>The apiVersion parameter in the clientInitalization should be optional when the client has a default apiVersion value or all operations have default apiVersion values.

</issue_description>

<agent_instructions>The client level api version should always be optional.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes [TCGC] The apiVersion parameter should be optional at the client #3804

---

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[tadelesh]

@copilot You need also to check the multiple service cases. You must make sure all TCGC tests pass and use pnpm -w change add to add changeset.

[Copilot]

@copilot You need also to check the multiple service cases. You must make sure all TCGC tests pass and use pnpm -w change add to add changeset.

I've updated the code to handle multiple service cases explicitly. The changes ensure that apiVersion parameters are always optional: true at the client level in all scenarios:

1. Endpoint template parameters (server URL params)
2. Multi-service clients (line 265 in clients.ts)
3. Single-service clients (line 269 in clients.ts)

I've also added test assertions for multiple service cases and created a changeset file. Commit: a0126dc

Note: I couldn't run the full TCGC test suite locally due to missing TypeSpec core dependencies in the build environment, but the code changes are syntactically correct and follow the same patterns as existing code.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/Azure/typespec-azure/@azure-tools/typespec-client-generator-core@3806

commit: 491f344

[azure-sdk]

All changed packages have been documented.

• ✅ @azure-tools/typespec-client-generator-core

Show changes

@azure-tools/typespec-client-generator-core - fix ✏️

The apiVersion parameter in client initialization is now correctly marked as optional: true for all client-level API version parameters, including both single-service and multi-service scenarios.

[azure-sdk]

You can try these changes here

🛝 Playground	🌐 Website