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Add two new public overloads of AddAIContentType that accept a baseType parameter, allowing consumers to register AIContent-derived types in custom polymorphic hierarchies (e.g., under ToolCallContent or ToolResultContent, not just AIContent). - Generic: AddAIContentType<TContent>(options, baseType, discriminatorId) - Non-generic: AddAIContentType(options, baseType, contentType, discriminatorId) Updates API baseline and adds comprehensive unit tests. Co-authored-by: jozkee <[email protected]>
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[WIP] Make AddAIContentType method public
Expose AddAIContentType overloads with baseType parameter
Mar 5, 2026
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src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.cs
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Instead of adding new baseType overloads, modify the existing AddAIContentType methods to automatically walk the inheritance chain from the content type up to AIContent, registering against every intermediate base type. This eliminates the need for callers to manually register against each level in the hierarchy. The internal registration of experimental types (CodeInterpreter, ImageGeneration) is simplified from 8 calls to 4, since the chain walker handles intermediate bases (ToolCallContent/ToolResultContent) automatically. Co-authored-by: Copilot <[email protected]>
…lot/make-add-ai-content-type-public # Conflicts: # src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.Defaults.cs
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LGTM. Can you also add a one-liner to the M.E.AI.Abstractions CHANGELOG for this?
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Pull request overview
This PR improves Microsoft.Extensions.AI.Abstractions JSON polymorphic configuration by making AddAIContentType automatically register a custom AIContent-derived type against every base type in its inheritance chain up to AIContent, eliminating the need for callers to register the same derived type multiple times.
Changes:
- Updated
AddAIContentTypeto walk the base-type chain and register polymorphic derived types at each level (e.g.,ToolCallContentandAIContent). - Simplified internal default registration for experimental tool-call / tool-result content types by relying on the chain-walker behavior.
- Added tests covering chain registration for both custom hierarchies and built-in intermediate base types, and for both generic/non-generic overloads.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.cs | Replaces single-base registration with AddAIContentTypeChain that registers derived types for each base up to AIContent. |
| src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.Defaults.cs | Reduces default experimental content registration calls by leveraging the inheritance chain registration behavior. |
| test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Utilities/AIJsonUtilitiesTests.cs | Adds coverage verifying roundtrip polymorphism through custom and built-in base-type chains, for both overload forms. |
Co-authored-by: Copilot <[email protected]>
jozkee
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AddAIContentType automatically registers the content type against every base in the inheritance chain up to AIContent
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Follow-up from #7299 (comment).
Summary
Instead of exposing new
baseTypeoverloads, the existingAddAIContentTypemethods now automatically walk the inheritance chain from the content type up toAIContent, registering the type as a polymorphic derived type at every level. This means a single call likeoptions.AddAIContentType<MyToolCall>("myToolCall")whereMyToolCall : ToolCallContent : AIContentwill register against bothToolCallContentandAIContent.Usage
Changes
AIJsonUtilities.cs— Existing public overloads now callAddAIContentTypeChain, which walks the base type hierarchy using a static local function. No new public API surface added.AIJsonUtilities.Defaults.cs— Internal experimental type registration simplified from 8 calls to 4, since the chain walker handles intermediate bases (ToolCallContent/ToolResultContent) automatically.Microsoft.Extensions.AI.Abstractions.json— Reverted API baseline additions (no new overloads needed).AIJsonUtilitiesTests.cs— Tests verify chain registration through both custom (LeafContent : DerivedAIContent : AIContent) and built-in (DerivedToolCallContent : ToolCallContent : AIContent) hierarchies, usingTheoryto cover both generic and non-generic overloads.💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.
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