Refactor WebSearchTool and move to OpenAI namespace

- Moved ReasoningEffort, Verbosity, and WebSearchTool to Devlooped.Extensions.AI.OpenAI namespace for clarity.
- Refactored WebSearchTool to support explicit properties for Country, Region, City, TimeZone, and AllowedDomains.
- Integrated location and domain filtering logic directly into WebSearchTool.
- Removed WebSearchToolExtensions as its functionality is now in the main class.
- Updated tests to use the new WebSearchTool API and removed obsolete ContextSize usage.

Author: kzu

src/Extensions/ReasoningEffort.cs src/Extensions/OpenAI/ReasoningEffort.cssrc/Extensions/ReasoningEffort.cs renamed to src/Extensions/OpenAI/ReasoningEffort.cs

@@ -1,6 +1,6 @@
 using System.ComponentModel;
 
-namespace Devlooped.Extensions.AI;
+namespace Devlooped.Extensions.AI.OpenAI;
 
 /// <summary>
 /// Effort a reasoning model should apply when generating a response.

src/Extensions/Verbosity.cs src/Extensions/OpenAI/Verbosity.cssrc/Extensions/Verbosity.cs renamed to src/Extensions/OpenAI/Verbosity.cs

@@ -1,4 +1,4 @@
-namespace Devlooped.Extensions.AI;
+namespace Devlooped.Extensions.AI.OpenAI;
 
 /// <summary>
 /// Verbosity determines how many output tokens are generated for models that support it, such as GPT-5.

src/Extensions/OpenAI/WebSearchTool.cs

@@ -0,0 +1,104 @@
+using Microsoft.Extensions.AI;
+using OpenAI.Responses;
+using WebSearch = OpenAI.Responses.WebSearchTool;
+
+namespace Devlooped.Extensions.AI.OpenAI;
+
+/// <summary>
+/// Basic web search tool that can limit the search to a specific country.
+/// </summary>
+public class WebSearchTool : HostedWebSearchTool
+{
+    readonly Dictionary<string, object?> additionalProperties = new();
+    string? country;
+    string? region;
+    string? city;
+    string? timeZone;
+    string[]? allowedDomains;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="WebSearchTool"/> class with the specified country.
+    /// </summary>
+    /// <param name="country">ISO alpha-2 country code.</param>
+    public WebSearchTool(string? country = null) => Country = country;
+
+    /// <summary>
+    /// Sets the user's country for web search results, using the ISO alpha-2 code.
+    /// </summary>
+    public string? Country
+    {
+        get => country;
+        set
+        {
+            country = value;
+            UpdateUserLocation();
+        }
+    }
+
+    /// <summary>
+    /// Optional free text additional information about the region to be used in the search.
+    /// </summary>
+    public string? Region
+    {
+        get => region;
+        set
+        {
+            region = value;
+            UpdateUserLocation();
+        }
+    }
+
+    /// <summary>
+    /// Optional free text additional information about the city to be used in the search.
+    /// </summary>
+    public string? City
+    {
+        get => city;
+        set
+        {
+            city = value;
+            UpdateUserLocation();
+        }
+    }
+
+    /// <summary>
+    /// Optional IANA timezone name to be used in the search.
+    /// </summary>
+    public string? TimeZone
+    {
+        get => timeZone;
+        set
+        {
+            timeZone = value;
+            UpdateUserLocation();
+        }
+    }
+
+    /// <summary>
+    /// Optional list of allowed domains to restrict the web search.
+    /// </summary>
+    public string[]? AllowedDomains
+    {
+        get => allowedDomains;
+        set
+        {
+            allowedDomains = value;
+            if (value is { Length: > 0 })
+                additionalProperties[nameof(WebSearch.Filters)] = new WebSearchToolFilters { AllowedDomains = value };
+            else
+                additionalProperties.Remove(nameof(WebSearch.Filters));
+        }
+    }
+
+    /// <inheritdoc/>
+    public override IReadOnlyDictionary<string, object?> AdditionalProperties => additionalProperties;
+
+    void UpdateUserLocation()
+    {
+        if (country != null || region != null || city != null || timeZone != null)
+            additionalProperties[nameof(WebSearch.UserLocation)] =
+                WebSearchToolLocation.CreateApproximateLocation(country, region, city, timeZone);
+        else
+            additionalProperties.Remove(nameof(WebSearch.UserLocation));
+    }
+}

src/Extensions/OpenAI/WebSearchToolExtensions.cs

@@ -276,11 +276,10 @@ public async Task WebSearchCountryHighContext()
 
         var options = new ChatOptions
         {
-            Tools = [new WebSearchTool("AR")
+            Tools = [new Devlooped.Extensions.AI.OpenAI.WebSearchTool("AR")
             {
                 Region = "Bariloche",
                 TimeZone = "America/Argentina/Buenos_Aires",
-                ContextSize = WebSearchToolContextSize.High
             }]
         };