[dotnet-code] Consolidate truncation removable count

[github-actions]

Summary

Reuse the existing message index helper when truncation calculates removable non-system groups. This keeps the Go truncation internals aligned around the same included/non-system group concept used elsewhere, which should make future .NET-to-Go compaction ports easier to compare. Added a narrow preservation test for system and pre-excluded groups.

.NET Reference

• dotnet/src/Microsoft.Agents.AI/Compaction/TruncationCompactionStrategy.cs - counts removable non-system, non-excluded groups before applying the truncation floor.
• dotnet/tests/Microsoft.Agents.AI.UnitTests/Compaction/TruncationCompactionStrategyTests.cs - covers skipping pre-excluded and system groups during truncation.

Public API and Behavior

No public Go API changed. No intentional behavior change was made.

Tests

• go test ./agent/compaction
• go test ./agent/compaction ./agent/harness/loop ./agent/hosting/workflowhosting

Added TestTruncationStrategy_SkipsPreExcludedAndSystemGroups.

Notes

Rejected dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/AggregateTurnMessagesExecutor.cs because the Go aggregate-turn workflow binding is already structurally close and changing it would be churn. Rejected dotnet/src/Microsoft.Agents.AI.Workflows/FanInEdgeData.cs because Go intentionally uses a unified Edge/EdgeConnection shape and introducing a separate fan-in data type would risk public/internal churn. Rejected dotnet/src/Microsoft.Agents.AI/Harness/Loop/LoopContext.cs because matching the .NET context shape would require public Go API changes.

Generated by .NET-to-Go Code Portability Refactoring Agent · 408 AIC · ⌖ 17.6 AIC · ⊞ 20.8K · ◷

---

Note

This was originally intended as a pull request, but GitHub Actions is not permitted to create or approve pull requests in this repository.
The changes have been pushed to branch dotnet-code/truncation-removable-count-2305220f28c523ce.

Click here to create the pull request

To fix the permissions issue, go to Settings → Actions → General and enable Allow GitHub Actions to create and approve pull requests. See also: gh-aw FAQ

Show patch preview (80 of 80 lines)

From d261ae63e97e2f6b4b4464b13ef2f1d2244fdb5f Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Sat, 27 Jun 2026 22:43:23 +0000
Subject: [PATCH] Consolidate truncation removable count

Reuse the message index helper for counting included non-system groups before truncation and add a preservation test for skipped system and pre-excluded groups.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 agent/compaction/compaction_test.go | 34 +++++++++++++++++++++++++++++
 agent/compaction/truncation.go      |  7 +-----
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/agent/compaction/compaction_test.go b/agent/compaction/compaction_test.go
index 3aa44fea2..08026b43e 100644
--- a/agent/compaction/compaction_test.go
+++ b/agent/compaction/compaction_test.go
@@ -85,6 +85,40 @@ func TestTruncationStrategy_ExcludesOldestGroups(t *testing.T) {
 	}
 }
 
+func TestTruncationStrategy_SkipsPreExcludedAndSystemGroups(t *testing.T) {
+	index := compaction.CreateMessageIndex([]*message.Message{
+		textMessage(message.RoleSystem, "system"),
+		textMessage(message.RoleUser, "u1"),
+		textMessage(message.RoleAssistant, "a1"),
+		textMessage(message.RoleUser, "u2"),
+	}, nil)
+	index.Groups[1].IsExcluded = true
+	strategy := &compaction.TruncationStrategy{
+		MinimumPreservedGroups: 1,
+	}
+
+	compacted, err := strategy.Compact(t.Context(), index)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !compacted {
+		t.Fatal("expected compaction")
+	}
+
+	if index.Groups[0].IsExcluded {
+		t.Fatal("expected system group to be preserved")
+	}
+	if !index.Groups[1].IsExcluded {
+		t.Fatal("expected pre-excluded group to remain excluded")
+	}
+	if !index.Groups[2].IsExcluded {
+		t.Fatal("expected oldest removable group to be excluded")
+	}
+	if index.Groups[3].IsExcluded {
+		t.Fatal("expected minimum preserved group to remain included")
+	}
+}
+
 func TestTruncationStrategy_ZeroValueU
... (truncated)