[Mgmt] Add 'resource-name' client option on Read operation

[haiyuazhang]

Summary

Introduces a new resource-name clientOption key, anchored on the ARM resource Read operation, to override the generated SDK resource class names. Supersedes the model-keyed resource-name-mappings design from #59282 per @ArcturusZhang's review feedback.

Decorator surface

Plain rename (ordinary resource):

@@clientOption(FooSettingsOperations.get, "resource-name", "FooConfiguration", "csharp");

Per-parent rename (expandable {parentType} resource):

@@clientOption(EventGridPrivateEndpointConnections.get, "resource-name",
  #{ eventGridTopics: "EventGridTopicPrivateEndpointConnection",
     eventGridDomains: "EventGridDomainPrivateEndpointConnection" },
  "csharp");

Map keys are the enum values substituted for {parentType} (TypeSpec record literal keys must be identifiers).

Implementation notes

• New helpers extractResourceNameOverride / applyResourceNameOverrides / findReadMethod in resource-metadata.ts.
• ResourceMetadata.expansionTypeValue records the enum value that was substituted for {parentType} per expanded resource — that's the override lookup key.
• Override pass runs as the final step in both buildArmProviderSchema (legacy) and resolveArmResources (modern) detection paths.
• Passes the TCGC SdkMethod (a DecoratedType) to getClientOptions; not __raw (TypeSpec Operation does not satisfy DecoratedType).
• Diagnostics: empty value, string-on-expandable misuse, unknown map keys, post-rename name collisions.

Test coverage

• 4 new emitter unit tests (plain rename, expandable map, unused-key diagnostic, string-on-expandable diagnostic). All 133 emitter tests pass.
• Mgmt-TypeSpec project exercises both forms end-to-end:
  • foo.tsp: FooSettings* → FooConfiguration*.
  • routedoperations.tsp: per-parent rename of EventGrid private endpoint connection.
• Mgmt-TypeSpec dotnet build clean, regen clean.

Related

• Supersedes [Mgmt CodeGen] Support customizing resource names via @@clientOption resource-name-mappings #59282.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds a new resource-name @@clientOption (anchored on an ARM resource Read operation) to override generated C# resource class-name roots, including support for expandable {parentType} resources via a per-enum-value map.

Changes:

• Implemented resource-name override parsing and late-stage application in both legacy (buildArmProviderSchema) and modern (resolveArmResources) detection paths.
• Added unit tests covering plain rename, expandable map rename, and diagnostics for misuse/unused keys.
• Updated Mgmt-TypeSpec test project inputs/outputs and added docs describing the new client option.

Reviewed changes

Copilot reviewed 8 out of 22 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/tspCodeModel.json	Updates expected codemodel decorators/metadata to reflect resource-name overrides.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/Models/AzureGeneratorMgmtTypeSpecTestsContext.cs	Updates buildable model registrations to renamed resource types.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/FooSettingsResource.cs	Regenerates resource type with overridden name (FooConfigurationResource).
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/FooSettingsResource.Serialization.cs	Regenerates serialization partial for renamed Foo resource type.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/Extensions/MockableAzureGeneratorMgmtTypeSpecTestsResourceGroupResource.cs	Updates mockable extension surface for renamed Foo resource accessor.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/Extensions/MockableAzureGeneratorMgmtTypeSpecTestsArmClient.cs	Updates mockable ArmClient helpers for renamed Foo/EventGrid expanded resources.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/Extensions/AzureGeneratorMgmtTypeSpecTestsExtensions.cs	Updates public extension methods to match renamed resource types and mockable targets.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/EventGridTopicResource.cs	Updates collection/resource accessors to renamed expanded PEC types.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/EventGridTopicEventGridPrivateEndpointConnectionResource.cs	Regenerates expanded PEC resource type name for Topic parent.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/EventGridTopicEventGridPrivateEndpointConnectionResource.Serialization.cs	Regenerates serialization partial for expanded PEC resource (Topic/Domain).
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/EventGridTopicEventGridPrivateEndpointConnectionCollection.cs	Regenerates expanded PEC collection type name for Topic parent.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/EventGridDomainResource.cs	Updates collection/resource accessors to renamed expanded PEC types.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/EventGridDomainEventGridPrivateEndpointConnectionResource.cs	Regenerates expanded PEC resource type name for Domain parent.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/EventGridDomainEventGridPrivateEndpointConnectionResource.Serialization.cs	Regenerates serialization partial for expanded PEC resource (Topic/Domain).
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/EventGridDomainEventGridPrivateEndpointConnectionCollection.cs	Regenerates expanded PEC collection type name for Domain parent.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/routedoperations.tsp	Adds @@clientOption(..., "resource-name", #{...}) example for expandable {parentType} resource.
eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/foo.tsp	Adds @@clientOption(..., "resource-name", "FooConfiguration") example for plain rename.
eng/packages/http-client-csharp-mgmt/emitter/test/resource-detection.test.ts	Adds 4 unit tests validating override behavior and diagnostics.
eng/packages/http-client-csharp-mgmt/emitter/src/resource-metadata.ts	Introduces override parsing/apply helpers and tracks expansion enum value for lookup.
eng/packages/http-client-csharp-mgmt/emitter/src/resource-detection.ts	Applies overrides as a final step in legacy resource detection.
eng/packages/http-client-csharp-mgmt/emitter/src/resolve-arm-resources-converter.ts	Applies overrides as a final step in modern resource detection.
eng/packages/http-client-csharp-mgmt/docs/client-options.md	Documents the new resource-name client option and its supported forms.

[haiyuazhang]

Phase 1 versioning: passed/not applicable (no SDK package csproj, changelog, or ApiCompatBaseline changes). Phase 2 API review: no SDK package API surface changes; reviewed the mgmt emitter logic/tests and found one non-blocking diagnostic wording issue. Phase 3 ApiCompat: skipped because this PR does not change a released management package. Total inline comments: 1.

[ArcturusZhang]

could we move the diagnostic reporting when we are expanding the resources? this could make the code here more clear.

[haiyuazhang]

Good call on cleaning this up. After investigating I went with a slightly different approach than relocating into expansion — relocating would force expandDynamicParentResourcesInSchema to know about the user-facing decorator's string-vs-map shape (and the map on non-expandable case wouldn't naturally enter the expansion loop, since non-expandable resources hit continue immediately), which felt like the wrong layering.

Instead I adopted the canonical TypeSpec $lib diagnostic pattern that's already used in this emitter (e.g. resource-model-not-associated-with-arm-resource). All six resource-name diagnostics added by this PR are now registered codes in lib/lib.ts with paramMessage templates:

• resource-name-empty-string
• resource-name-bad-entry
• resource-name-empty-record
• resource-name-bad-type
• resource-name-string-on-expandable
• resource-name-map-on-non-expandable

extractResourceNameOverride now takes program?: Program directly. Step 2a's two misuse diagnostics emit via $lib.reportDiagnostic directly, which collapses each call site from a multi-line template literal to ~5 lines, and message text now lives in the central catalog. Net result: the step-2a block is materially shorter and clearer, layering is preserved, and we have proper registered diagnostic codes (useful for future suppression rules and tooling).

Done in 01cefba.