[client-generator-core] Allow @clientOption value to reference a TypeSpec model

[iscai-msft]

Fixes #5256

Summary

Extends the @clientOption decorator so its value parameter can reference a TypeSpec model, in addition to the previously supported string, boolean, and number literal values.

@clientOption("composes", OpenAICreateResponseOptions, "csharp")
model FoundryCreateResponseOptions {}

Changes

• lib/decorators.tsp: updated @clientOption's value parameter type to unknown | valueof unknown and added an example/description covering model reference values.
• src/internal-utils.ts: getDecoratorArgValue now routes Model kind decorator arguments through getClientTypeWithDiagnostics (same path already used for EnumMember), so a referenced model is resolved into its SdkType, preserving any customizations such as @alternateType.
• generated-defs/Azure.ClientGenerator.Core.ts: regenerated via pnpm gen-extern-signature.
• Added tests in test/decorators/client-option.test.ts covering:
  • A model reference as the value, verified via getClientOptions.
  • That @alternateType customizations on the referenced model are preserved when resolving the value.
• Added a changeset entry.

Testing

• pnpm vitest run in packages/typespec-client-generator-core — 1405 passed, 2 skipped.
• pnpm build and pnpm lint pass.

Co-authored-by: Copilot App 223556219+Copilot@users.noreply.github.com

[github-actions]

All changed packages have been documented.

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

Show changes

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

@clientOption's value can now reference a TypeSpec model, in addition to string, boolean, and number literal values. The referenced model (including customizations such as @alternateType) is preserved and resolved so scoped emitters can access it via getClientOptions.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@azure-tools/typespec-client-generator-core@5276

commit: 252860d

[github-actions]

📦 Package size report

✅ No notable package size changes compared to the base branch.

13 package(s) with no notable change

Package	Packed (base → head)	Δ Packed	Unpacked (base → head)	Δ Unpacked
@azure-tools/typespec-client-generator-core	228.33 KB → 229.25 KB	+948 B (+0.4%)	1.23 MB → 1.23 MB	+3.38 KB (+0.3%)
@azure-tools/typespec-java	13.51 MB → 13.51 MB	-189 B (-0.0%)	15.03 MB → 15.03 MB	+65 B (+0.0%)
@azure-tools/typespec-go	258.42 KB → 258.44 KB	+29 B (+0.0%)	1.32 MB → 1.32 MB	+95 B (+0.0%)
@azure-tools/typespec-python	42.20 KB → 42.22 KB	+21 B (+0.0%)	164.85 KB → 164.91 KB	+65 B (+0.0%)
@azure-tools/typespec-ts	527.17 KB → 527.17 KB	-1 B (-0.0%)	2.54 MB → 2.54 MB	—
@azure-tools/azure-http-specs	146.63 KB → 146.63 KB	—	1.16 MB → 1.16 MB	—
@azure-tools/typespec-autorest	80.93 KB → 80.93 KB	—	395.06 KB → 395.06 KB	—
@azure-tools/typespec-autorest-canonical	7.42 KB → 7.42 KB	—	26.00 KB → 26.00 KB	—
@azure-tools/typespec-azure-core	129.43 KB → 129.43 KB	—	702.77 KB → 702.77 KB	—
@azure-tools/typespec-azure-portal-core	42.40 KB → 42.40 KB	—	192.91 KB → 192.91 KB	—
@azure-tools/typespec-azure-resource-manager	171.92 KB → 171.92 KB	—	1.04 MB → 1.04 MB	—
@azure-tools/typespec-azure-rulesets	5.16 KB → 5.16 KB	—	32.09 KB → 32.09 KB	—
@azure-tools/typespec-metadata	15.91 KB → 15.91 KB	—	62.26 KB → 62.26 KB	—

_{Packed = gzipped .tgz published to npm. Unpacked = total extracted size. 🆕 added, 🗑️ removed. Packages from the core/ submodule are not included.
🔴 grew · 🟢 shrank — only changes of at least 512 B and 0.5% are marked.}

[azure-sdk-automation]

You can try these changes here

🛝 Playground	🌐 Website