From 7bda6dfd457c4eeff6d1fea10a5ef9e32129444c Mon Sep 17 00:00:00 2001
From: Thorsten Sommer <SommerEngineering@users.noreply.github.com>
Date: Tue, 3 Nov 2026 15:04:37 +0100
Subject: [PATCH] Explained why the trimmed build still keeps the immutable
 collections of .NET

---
 app/Trimming.props | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/app/Trimming.props b/app/Trimming.props
index a8cc4a7c7..81a0516a5 100644
--- a/app/Trimming.props
+++ b/app/Trimming.props
@@ -16,9 +16,11 @@
 
     <!--
         System.Text.Json builds an immutable collection, e.g., the ImmutableHashSet of a chat, through a factory method
-        like ImmutableHashSet.CreateRange, which it finds by reflection at runtime. Nothing calls that method directly,
-        so the trimmer removes it, and every type which holds such a collection fails to load and to save. Only a
-        published build shows this: debug builds and the tests are not trimmed. Hence, we keep the whole assembly.
+        like ImmutableHashSet.CreateRange. The contracts which AI Studio generates for its own options call that method
+        directly, so the trimmer keeps it, and the trim smoke test passes without the line below. A contract which
+        System.Text.Json builds by reflection, as it still does for the JSON of Blazor, finds the method at runtime
+        only, and nothing would keep it then. The whole assembly costs about 70 KB more than its trimmed part, so we
+        keep it, in case such a contract ever meets an immutable collection.
     -->
     <ItemGroup>
         <TrimmerRootAssembly Include="System.Collections.Immutable" />