aot-json-serializer-context

name	aot-json-serializer-context
description	Generate Refitter AOT serializer contexts without regex-only type discovery
domain	code-generation
confidence	high
source	earned

Context

Use this skill when Refitter needs to emit JsonSerializerContext code for generated contracts. The old regex-only approach missed namespaces, nested types, and closed generic usages, and could emit attributes in the wrong place.

Patterns

Parse generated contracts with Roslyn

• Use CSharpSyntaxTree.ParseText() over the generated contracts source.
• Collect declared contract types from BaseTypeDeclarationSyntax.
• Track namespace + containing-type path so nested contracts are emitted as Outer.Inner.

Register only valid serializer targets

• Add all non-generic declared contract types.
• For generic contracts, register only closed usages found in TypeSyntax nodes (for example Envelope<Pet>), never the open declaration (Envelope<T>).
• Skip usages that still reference in-scope type parameters.

Emit the context in the contracts namespace

• Wrap the generated context in namespace {ContractsNamespace ?? Namespace}.
• Place [JsonSerializable(typeof(...))] attributes directly on the partial context class, not before the namespace declaration.
• Derive the context name from Naming.InterfaceName, stripping a conventional leading I (IUsersApi -> UsersApiSerializerContext), and fall back to NamingSettings.DefaultInterfaceName if the name is blank.

Wire both generation paths

• Single-file output: append the serializer context after generated contracts.
• Multi-file output: emit a dedicated {ContextName}.cs file.

Examples

• src/Refitter.Core/JsonSerializerContextGenerator.cs
• src/Refitter.Core/RefitGenerator.cs
• src/Refitter.Tests/JsonSerializerContextGeneratorTests.cs
• src/Refitter.Tests/Scenarios/GenerateJsonSerializerContextTests.cs

Anti-Patterns

• Do not regex-scan emitted C# for type names; this loses namespace/nesting/generic information.
• Do not register open generic declarations with [JsonSerializable].
• Do not emit serializer-context attributes outside the namespace/class declaration they belong to.