Add operation-aware C# body suffix linting

[haiyuazhang]

Summary

• make csharp-model-suffix operation-aware for direct PATCH and PUT/POST bodies
• use Content for immediate nested request models while stopping at the first named model
• suppress diagnostics when request, response, or HTTP verb roles conflict
• add C#-scoped code fixes, documentation, and comprehensive tests

Addresses the design for #4447.

Detection algorithm

1. Resolve all HTTP operations and collect each model's usage roles:
   • direct PATCH body → patch
   • direct PUT/POST body → content
   • immediate nested model in a PATCH/PUT/POST body → content
   • response body → response
   • direct body for another HTTP verb → other
2. For nested content, inspect only properties directly declared or inherited by the body model. Unwrap arrays, records, tuples, unions, and anonymous models, then stop at the first named model instead of recursively inspecting its properties.
3. Resolve the effective C# model name with getLibraryName(..., "csharp"), including any existing @clientName override.
4. Check only names ending in Parameter, Parameters, or Request:
   • an unambiguous patch role recommends Patch
   • an unambiguous content role recommends Content
5. Produce no diagnostic when roles conflict, such as direct PATCH plus PUT/POST, direct PATCH plus nested content, or request plus response usage. Multiple PATCH uses and combined PUT/POST uses are compatible.
6. Offer a C#-scoped @@clientName code fix when the expected suffix is deterministic.

The rule intentionally does not require every PATCH body name to end in Patch; names with other suffixes remain outside #4447.

Why only Parameter, Parameters, and Request?

This boundary keeps the rule deterministic and aligned with #4447:

• Linter: PATCH body parameter / model must be named [Model]Patch #4447 specifically targets Parameter(s) → Patch/Content.
• Request is included because batch1 normally maps it to Content, while a direct PATCH body must map it to Patch.
• These suffixes support an unambiguous mechanical replacement and deterministic code fix.

A broader rule requiring every PATCH body name to end in Patch would produce approximately 653 existing diagnostics. Many affected names end in Update, Contract, Payload, Resource, or domain-specific terms whose correct replacement requires semantic context. For example, Settings may need to become FaceSettingsPatch, while ResourceUpdateModel may need to become AgriServiceResourcePatch. The linter cannot reliably infer those service or resource prefixes.

The targeted suffix list is therefore a safety boundary: it reports only cases where both the violation and recommended name are deterministic.

Dependency

This PR is stacked on #4867 because it extends the csharp-model-suffix rule introduced there. Until #4867 merges, this PR's diff also includes the batch1 commits. After #4867 merges, the branch will be synchronized with main so only the PATCH/Content changes remain.

[github-actions]

All changed packages have been documented.

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

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

Add csharp-model-suffix and csharp-use-standard-acronyms linter rules for C# SDK model,> naming, including operation-aware Patch and Content suffixes for request body models.

@azure-tools/typespec-azure-rulesets - feature ✏️

Add csharp-model-suffix and csharp-use-standard-acronyms linter rules for C# SDK model,> naming, including operation-aware Patch and Content suffixes for request body models.

[pkg-pr-new]

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npm i https://pkg.pr.new/@azure-tools/typespec-azure-rulesets@5058

npm i https://pkg.pr.new/@azure-tools/typespec-client-generator-core@5058

commit: 14b0392

[azure-sdk-automation]

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