feat: support HEAD operations as boolean or { body: boolean } in Modular SDK with head-as-boolean and wrap-non-model-return

[Copilot]

A new head-as-boolean option (mirroring HLC's --head-as-boolean) enables boolean return types for HEAD operations with no response body in the Modular SDK. The behavior depends on the combination of head-as-boolean and wrap-non-model-return:

wrap-non-model-return	head-as-boolean	Return type
true	true	Promise<{ body: boolean }>
false	true	Promise<boolean>
true	false	Promise<void>
false	false	Promise<void>

The dedicated head-as-boolean opt-in prevents unintended changes to HEAD operations like headIfModifiedSince (conditional request headers) which must continue to return void.

Changes

rlc-common/src/interfaces.ts

• Added headAsBoolean?: boolean to the RLCOptions interface

typespec-ts/src/lib.ts

• Added "head-as-boolean" emitter option with JSON schema description

typespec-ts/src/transform/transfromRLCOptions.ts

• Wired head-as-boolean emitter option through to headAsBoolean in RLCOptions

typespec-ts/test/util/emitUtil.ts

• Wired head-as-boolean option in the test utility so scenario YAML configs can set it

operationHelpers.ts

• isHeadOperation() — new helper to centralize the HTTP verb check
• checkWrapNonModelReturn() — HEAD + void response returns { shouldWrap: true } only when both wrapNonModelReturn and headAsBoolean are enabled
• buildNonModelResponseTypeDeclaration() — emits { body: boolean } type body for HEAD void operations when both head-as-boolean and wrap-non-model-return are set
• getDeserializePrivateFunction() — two cases:
  • With wrap-non-model-return: true: generates return { body: result.status.startsWith("2") }
  • With wrap-non-model-return: false: generates return result.status.startsWith("2") (plain boolean)
• getOperationFunction() — returns Promise<boolean> when head-as-boolean: true and wrap-non-model-return: false

Examples

With wrap-non-model-return: true and head-as-boolean: true:

export type CheckExistenceResponse = { body: boolean };

export async function _checkExistenceDeserialize(
  result: PathUncheckedResponse,
): Promise<CheckExistenceResponse> {
  const expectedStatuses = ["204", "404"];
  if (!expectedStatuses.includes(result.status)) {
    throw createRestError(result);
  }
  return { body: result.status.startsWith("2") };
}

With wrap-non-model-return: false and head-as-boolean: true:

export async function _headResourceDeserialize(
  result: PathUncheckedResponse,
): Promise<boolean> {
  const expectedStatuses = ["204"];
  if (!expectedStatuses.includes(result.status)) {
    throw createRestError(result);
  }
  return result.status.startsWith("2");
}

HEAD operations without head-as-boolean: true continue to return Promise<void> unchanged.

Tests

Unit test scenarios in wrapNonModelReturn.md cover all four combinations of wrap-non-model-return and head-as-boolean for HEAD operations.

[v-jiaodi]

@copilot Following HLC’s implementation logic https://github.com/Azure/autorest.typescript/blob/main/packages/autorest.typescript/src/generators/modelsGenerator.ts#L224, validate the current fix and resolve the CI failures.

[Copilot]

@copilot Following HLC’s implementation logic https://github.com/Azure/autorest.typescript/blob/main/packages/autorest.typescript/src/generators/modelsGenerator.ts#L224, validate the current fix and...

Following the HLC logic which requires headAsBoolean to be explicitly set (not just any HEAD operation), I've:

1. Added a separate head-as-boolean emitter option (mirroring HLC's head-as-boolean) so only services that explicitly opt-in get { body: boolean } wrapping for HEAD void operations
2. The root cause of the CI failures was that wrap-non-model-return defaults to true for Azure flavor, causing ALL HEAD operations (including headIfModifiedSince for conditional request headers) to incorrectly get boolean wrapping

Key changes in d9b8c91:

• Added headAsBoolean to RLCOptions in rlc-common
• Added head-as-boolean option to lib.ts and wired through transfromRLCOptions.ts
• Updated checkWrapNonModelReturn to require BOTH wrapNonModelReturn and headAsBoolean (matching HLC's headAsBoolean && addedResponses.length === 0)
• headIfModifiedSince now correctly still returns Promise<void> ✓
• All 620 unit tests pass

Warning

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[v-jiaodi]

@copilot According to typespec operation checkExistenceAtManagementGroupScope to add UT https://github.com/Azure/azure-rest-api-specs/blob/99cfa558b8ed9c11464a426f401406531c26d6ce/specification/resources/resource-manager/Microsoft.Resources/deployments/DeploymentExtended.tsp#L447

  checkExistenceAtManagementGroupScope is Extension.CheckExistence<
    Extension.ManagementGroup<"groupId">,
    DeploymentExtended,
    Error = CloudError
  >;

expected response code is xxxResponse and xxxResponse = { body: boolean};

[Copilot]

@copilot According to typespec operation checkExistenceAtManagementGroupScope to add UT https://github.com/Azure/azure-rest-api-specs/blob/99cfa558b8ed9c11464a426f401406531c26d6ce/specification/resour...

Added in d42161e. The new scenario in wrapNonModelReturn.md models the exact ARM pattern from the referenced spec:

@route("/providers/Microsoft.Management/managementGroups/{groupId}/providers/Microsoft.Resources/deployments/{deploymentName}")
@head
op checkExistenceAtManagementGroupScope(
  @path groupId: string,
  @path deploymentName: string,
): { @statusCode _: 204; } | { @statusCode _: 404; };

With wrap-non-model-return: true + head-as-boolean: true, it generates:

• CheckExistenceAtManagementGroupScopeResponse = { body: boolean } ✓
• _checkExistenceAtManagementGroupScopeDeserialize returning { body: result.status.startsWith("2") } ✓

[v-jiaodi]

@copilot revert commit d42161e895c43f302c1ddbf958f338c5b263298d

[Copilot]

@copilot revert commit d42161e895c43f302c1ddbf958f338c5b263298d

Reverted in 7163ccc. The ARM-style checkExistenceAtManagementGroupScope scenario has been removed from wrapNonModelReturn.md.

[lirenhe]

@qiaozha, could you help to review this PR? thanks

[v-jiaodi]

@copilot please resolve comment #3887 (comment) and #3887 (comment)

[Copilot]

@copilot please resolve comment #3887 (comment) and #3887 (comment)

Resolved in 0a49d1d. Both cases are now handled correctly:

• Case 1 (wrap-non-model-return: true + head-as-boolean: true): returns Promise<{ body: boolean }> ✓
• Case 2 (wrap-non-model-return: false + head-as-boolean: true): now returns Promise<boolean> (plain boolean, no wrap) ✓

Changes: getDeserializePrivateFunction and getOperationFunction both check for !response.type && isHeadOperation && headAsBoolean && !shouldWrap to return boolean. The test for wrap-non-model-return: false, head-as-boolean: true is updated accordingly.

[v-jiaodi]

@copilot Run pnpm format to fix ci error.

[Copilot]

@copilot Run pnpm format to fix ci error.

Done in e55eb5f. The formatter wrapped a long conditional in operationHelpers.ts.