.NET: Add observer for OpenAIWebSearch

[westey-m]

Motivation and Context

Description

Updating the console samples with an observer that allows displaying more detail of calls to the OpenAIResponses web_search tool.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[Copilot]

Pull request overview

Updates the .NET Harness “Step01_Research” console sample to display richer streaming details for the OpenAI Responses web_search tool via a dedicated observer.

Changes:

• Register a new OpenAIResponsesWebSearchDisplayObserver in the Step01 Research sample’s observer pipeline.
• Add OpenAIResponsesWebSearchDisplayObserver implementation to render search/query/open/find-in-page activity (and optionally sources) in the console.
• Special-case WebSearchToolCallContent in ToolCallDisplayObserver to avoid duplicate tool-call output.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
dotnet/samples/02-agents/Harness/Harness_Step01_Research/Program.cs	Adds the new web-search display observer to the sample’s observer list.
dotnet/samples/02-agents/Harness/Harness_Step01_Research/OpenAIResponsesWebSearchDisplayObserver.cs	Implements detailed console rendering for OpenAI Responses web search activity.
dotnet/samples/02-agents/Harness/Harness_Shared_Console/Observers/ToolCallDisplayObserver.cs	Attempts to suppress web search tool-call messages to prevent duplication.

Comments suppressed due to low confidence (1)

dotnet/samples/02-agents/Harness/Harness_Step01_Research/OpenAIResponsesWebSearchDisplayObserver.cs:178

• Same issue here: JsonDocument.Parse(data) is being passed the BinaryData returned by ModelReaderWriter.Write(wscri), which isn’t a supported overload and will fail to compile. Convert data to string/bytes first.

            var data = System.ClientModel.Primitives.ModelReaderWriter.Write(wscri);
            using var doc = System.Text.Json.JsonDocument.Parse(data);

[github-actions]

Automated Code Review

Reviewers: 4 | Confidence: 91% | Result: All clear

Reviewed: Correctness, Security Reliability, Test Coverage, Design Approach

---

Automated review by westey-m's agents