.NET: [Breaking] Delete display name property

[SergeyMenshykh]

Motivation and Context

Today, AIAgent.DisplayName does not represent the agent's display name; it is just a fallback mechanism from the agent's name to the agent's Id if no name is specified. This can be confusing, quite opinionated and not necessarily what consumers want for their scenarios. The AIAgent class has Id and Name properties that provide agents with uniqueness and human-readable components. Consumers may use these properties separately or together instead of the DisplayName property to implement their scenarios.

Contributes to: #2542

[Copilot]

Pull request overview

This PR removes the AIAgent.DisplayName property, which was a convenience property that returned Name ?? Id. The removal reduces confusion and allows consumers to directly use the Name and Id properties according to their specific needs.

Key Changes

• Removed the DisplayName property from AIAgent class
• Updated all usages to explicitly use Name ?? Id pattern
• Updated method signatures in A2A module to remove displayName parameter

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
dotnet/src/Microsoft.Agents.AI.Abstractions/AIAgent.cs	Removed the DisplayName property and its documentation
dotnet/src/Microsoft.Agents.AI.A2A/A2AAgent.cs	Removed displayName field and override, updated constructor
dotnet/src/Microsoft.Agents.AI.A2A/Extensions/A2AClientExtensions.cs	Removed displayName parameter from GetAIAgent method
dotnet/src/Microsoft.Agents.AI/OpenTelemetryAgent.cs	Updated activity display name logic to use conditional Name ?? Id pattern
dotnet/src/Microsoft.Agents.AI.Workflows/HandoffsWorkflowBuilder.cs	Updated error messages to use Name ?? Id for agent references
dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/HandoffAgentExecutor.cs	Replaced DisplayName with Name ?? Id pattern in message handling
dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/AgentRunStreamingExecutor.cs	Updated message role change logic to use Name ?? Id
dotnet/src/Microsoft.Agents.AI.Hosting.OpenAI/EndpointRouteBuilderExtensions.ChatCompletions.cs	Updated endpoint agent name to use Name ?? Id
dotnet/src/Microsoft.Agents.AI.Hosting.OpenAI/EndpointRouteBuilderExtensions.Responses.cs	Updated endpoint agent name to use Name ?? Id
dotnet/src/Microsoft.Agents.AI.DevUI/EntitiesApiExtensions.cs	Updated entity name to use Name ?? Id
dotnet/samples/GettingStarted/AgentProviders/Agent_With_CustomImplementation/Program.cs	Updated to use Name instead of DisplayName, adjusted parameter nullability
dotnet/tests/Microsoft.Agents.AI.A2A.UnitTests/A2AAgentTests.cs	Removed displayName-related test assertions and variable
dotnet/tests/Microsoft.Agents.AI.A2A.UnitTests/Extensions/A2AClientExtensionsTests.cs	Removed displayName parameter from test
dotnet/tests/Microsoft.Agents.AI.UnitTests/LoggingAgentTests.cs	Removed DisplayName assertion from test
dotnet/tests/Microsoft.Agents.AI.UnitTests/OpenTelemetryAgentTests.cs	Removed DisplayName assertion, updated activity display name assertions with conditional logic
dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/TestEchoAgent.cs	Updated AuthorName to use Name ?? Id
dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/Sample/12_HandOff_HostAsAgent.cs	Updated AuthorName to use Name ?? Id