[dotnet-port] Port TodoList_Complete reason requirement from .NET

[github-actions]

Summary

Aligns the TodoList_Complete tool in agent/harness/todo with the upstream .NET change from PR microsoft/agent-framework#5902. The .NET implementation changed the complete tool's input from a plain list of integer IDs to a structured list of {id, reason} objects, requiring agents to provide a reason describing how each item was completed. This improves auditability of todo item lifecycle events.

Changes made:

• Added CompleteInput struct with ID int and Reason string fields
• Updated TodoList_Complete tool to accept []CompleteInput instead of []int
• Updated tool description to mention the reason field
• Updated default instructions to prompt agents to "Include a reason describing how the items were completed"
• Updated all existing tests to use the new input format
• Added two new tests: TestCompleteTodos_WithReason and TestCompleteToolDescription_MentionsReason

Ported .NET PRs

• .NET: Require TODO finish reason and rename SubAgents to BackgroundAgents agent-framework#5902 - Require TODO finish reason and rename SubAgents to BackgroundAgents

(Only the TodoList_Complete reason requirement is ported here. The SubAgents→BackgroundAgents rename is in .NET-specific Harness infrastructure with no current Go equivalent.)

Breaking Changes

Yes. The TodoList_Complete tool previously accepted []int (a list of IDs). It now accepts []CompleteInput where each entry is {"id": <int>, "reason": "<string>"}. Any agent or integration that calls TodoList_Complete with plain integers will receive a JSON deserialization error. Since the Go SDK is in beta this is acceptable; agents driven by LLMs will naturally adapt once the updated tool description and instructions reach them.

Tests and Examples

• All pre-existing tests in agent/harness/todo updated to use new input format — all pass
• TestCompleteTodos_WithReason: verifies items are marked complete when a reason is supplied
• TestCompleteToolDescription_MentionsReason: verifies the tool description contains "reason"
• Run: go test ./agent/harness/todo/...

Notes

The upstream commit also renames SubAgents* → BackgroundAgents* across the .NET Harness. The Go SDK does not yet have a SubAgents/BackgroundAgents provider, so that rename has no Go counterpart to port. It is tracked in the feature comparison doc as a future addition.

Upstream commit: 7cea5e162a5a80f29dc986bfb324c7bc5bd81c09

Generated by .NET to Go Porting Agent · ● 17.5M · ◷

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Show patch preview (198 of 198 lines)

From 338c8da69aaa6a4455d573089c600d16ab9cd9b9 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Tue, 19 May 2026 10:21:09 +0000
Subject: [PATCH] feat(todo): require reason in TodoList_Complete aligned with
 .NET PR #5902

Port the upstream .NET change that replaces the plain-ID slice in
TodoList_Complete with a structured CompleteInput{ID, Reason} slice.
Agents are now prompted to include a completion reason, which improves
auditability of todo lifecycle events.

Changes:
- Add CompleteInput struct (id + reason fields)
- Update completeTool to accept []CompleteInput instead of []int
- Update tool description to mention the reason field
- Update default instructions to ask agents to include a reason
- Update all existing tests to use the new input format
- Add TestCompleteTodos_WithReason and TestCompleteToolDescription_MentionsReason

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 agent/harness/todo/todo.go      | 19 ++++++----
 agent/harness/todo/todo_test.go | 63 +++++++++++++++++++++++++++++----
 2 files changed, 69 insertions(+), 13 deletions(-)

diff --git a/agent/harness/todo/todo.go b/agent/harness/todo/todo.go
index 17ca2a14..25b15370 100644
--- a/agent/harness/todo/todo.go
+++ b/agent/harness/todo/todo.go
@@ -36,7 +36,7 @@ When a user changes the topic or changes their mind, ensure that you update the
 
 Use these tools to manage your tasks:
 - Use TodoList_Add to break down complex work into trackable items (supports adding one or many at once).
-- Use TodoList_Complete to mark items as done when finished (supports one or many at once).
+- Use TodoList_Complete to mark items as done when finished (supports one or many at once). Include a reason describing how the items were completed.
 - Use TodoList_GetRemaining to check what work is still pending.
 - Use TodoList_GetAll to review the full list including completed items.
 - Use TodoList_Remove to remove items that are no lo
... (truncated)