Rebuilt how AI Studio knows what a model can do (#960)

app/MindWork AI Studio/Provider/HuggingFace/HFModel.cs

@@ -5,4 +5,30 @@ namespace AIStudio.Provider.HuggingFace;
 /// </summary>
 /// <param name="Id">The ID of the model, written as "org/model".</param>
 /// <param name="Providers">The inference providers serving this model.</param>
-public readonly record struct HFModel(string Id, IList<HFModelProvider>? Providers);
+public readonly record struct HFModel(string Id, IList<HFModelProvider>? Providers)
+{
+    /// <summary>
+    /// The window this model has when it is reached the way this user set things up.
+    /// </summary>
+    /// <remarks>
+    /// A window belongs to an inference provider here, not to the model: the same weights run
+    /// behind several of them, each configured by somebody else. Where the user named one, its
+    /// number is the answer. Where they let the router choose, the smallest window among the
+    /// providers currently serving the model is -- nobody knows which one the router will take, and
+    /// a number promising more than the chosen provider delivers would walk a conversation into an
+    /// error the user could not see coming.
+    /// </remarks>
+    /// <param name="providerSlug">The inference provider the user chose, or empty when the router chooses.</param>
+    /// <returns>The window in tokens, or null where nobody stated one.</returns>
+    public int? ContextWindowTokens(string providerSlug)
+    {
+        if (this.Providers is null)
+            return null;
+
+        var serving = this.Providers.Where(provider => provider.IsLive);
+        if (!string.IsNullOrEmpty(providerSlug))
+            serving = serving.Where(provider => string.Equals(provider.Provider, providerSlug, StringComparison.OrdinalIgnoreCase));
+
+        return serving.Where(provider => provider.ContextWindowTokens is > 0).Min(provider => provider.ContextWindowTokens);
+    }
+}