Honor @encode(string) on C# boolean model properties

[Copilot]

The C# emitter ignores @encode(string) on boolean model properties, writing JSON booleans instead of strings and failing the four http/encode/boolean Spector scenarios.

• Encoding: Preserve the boolean-string format through type mapping and emit lowercase "true"/"false" strings.
• Decoding: Parse string values case-insensitively, including "TRUE" and "FaLsE", while rejecting malformed values. Unencoded booleans retain existing behavior.
• Coverage: Add serialization/deserialization baselines and typed Spector coverage for all four scenarios.

model BoolAsStringProperty {
  @encode(string)
  value: boolean;
}

new BoolAsStringProperty(true) serializes as {"value":"true"} rather than {"value":true}.

• Fixes C# emitter ignores @encode(string) on boolean model properties #11691

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).
1 pipeline(s) were filtered out due to trigger conditions.
There may be pipelines that require an authorized user to comment /azp run to run.

[Copilot]

🟢 Approval recommended

The change is scoped to a new serialization format + MRW JSON read/write handling and is covered by both unit baselines and Spector integration tests for the targeted scenarios.

Pull request overview

Fixes the C# HTTP client emitter’s handling of @encode(string) on boolean model properties so JSON serialization uses string booleans (and deserialization accepts mixed-case string values), allowing the http/encode/boolean Spector scenarios to pass.

Changes:

• Adds a new SerializationFormat.Boolean_String and maps boolean + encode: "string" to it in TypeFactory.
• Updates MRW JSON serialization/deserialization to write "true"/"false" strings and parse string booleans via bool.Parse(...) when Boolean_String is selected.
• Adds unit baselines + unit tests for the new boolean-string serialization/deserialization statements, and adds typed Spector coverage for the four encode/boolean scenarios.

File summaries

File	Description
packages/http-client-csharp/generator/TestProjects/Spector.Tests/TestProjects.Spector.Tests.csproj	Adds the Encode.Boolean generated test project reference so the Spector test assembly compiles/tests it.
packages/http-client-csharp/generator/TestProjects/Spector.Tests/Http/Encode/Boolean/EncodeBooleanTests.cs	Adds Spector integration tests for the four http/encode/boolean property scenarios plus negative decoding assertions.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator/src/TypeFactory.cs	Maps InputPrimitiveTypeKind.Boolean with encode == "string" to the new SerializationFormat.Boolean_String.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.Input/src/InputTypes/Serialization/SerializationFormat.cs	Introduces the new Boolean_String serialization format.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/MrwSerializationTypeDefinitions/TestData/MrwSerializationTypeDefinitionTests/TestBooleanSerialization(string).cs	Baseline for boolean-as-string JSON write statement.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/MrwSerializationTypeDefinitions/TestData/MrwSerializationTypeDefinitionTests/TestBooleanSerialization(default).cs	Baseline for default boolean JSON write statement.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/MrwSerializationTypeDefinitions/TestData/MrwSerializationTypeDefinitionTests/TestBooleanDeserialization(string).cs	Baseline for boolean-as-string JSON read expression.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/MrwSerializationTypeDefinitions/TestData/MrwSerializationTypeDefinitionTests/TestBooleanDeserialization(default).cs	Baseline for default boolean JSON read expression.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/MrwSerializationTypeDefinitions/MrwSerializationTypeDefinitionTests.cs	Adds unit tests verifying the generated serialization/deserialization output for boolean (string vs default).
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/MrwSerializationTypeDefinition.cs	Implements boolean string write/read behavior gated by SerializationFormat.Boolean_String.

Review details

• Files reviewed: 10/10 changed files
• Comments generated: 0
• Review effort level: Lite

---

💡 Configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@typespec/http-client-csharp@11882

commit: 494a42e