From 160d2e0b1f6255e8fabc31a7f47524eb2847ca05 Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Tue, 29 Sep 2026 15:30:56 +0000
Subject: [PATCH 1/2] Lock SetActiveProfile and DeleteProfile so a delete
 cannot leave a stale active id [patch]

SetActiveProfile checked the profile existed and then wrote the active id as
two steps. A DeleteProfile landing between them removed the profile before
the id was set, so its clear was skipped and the active id kept naming the
deleted profile; a profile later recreated with that id became active on its
own. Run the check-and-set and the remove-and-clear under the manager's lock.

Fixes #120

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WAdbE4VMmkBh1tzMGpC9Wy
---
 .../ProfileActivateDeleteConcurrencyTests.cs  | 54 +++++++++++++++++++
 Keybinding/Services/ProfileManager.cs         | 32 +++++++----
 2 files changed, 75 insertions(+), 11 deletions(-)
 create mode 100644 Keybinding.Test/ProfileActivateDeleteConcurrencyTests.cs

diff --git a/Keybinding.Test/ProfileActivateDeleteConcurrencyTests.cs b/Keybinding.Test/ProfileActivateDeleteConcurrencyTests.cs
new file mode 100644
index 0000000..3c50645
--- /dev/null
+++ b/Keybinding.Test/ProfileActivateDeleteConcurrencyTests.cs
@@ -0,0 +1,54 @@
+// Copyright (c) 2023-2026 ktsu-dev contributors
+
+namespace ktsu.Keybinding.Test;
+
+using ktsu.Keybinding.Core.Services;
+
+[TestClass]
+public class ProfileActivateDeleteConcurrencyTests
+{
+	private const int Trials = 10000;
+
+	public TestContext TestContext { get; set; } = null!;
+
+	[TestMethod]
+	public void SetActiveProfile_RacingDeleteProfile_NeverLeavesTheDeletedIdActive()
+	{
+		int stale = 0;
+		for (int trial = 0; trial < Trials; trial++)
+		{
+			ProfileManager profiles = new();
+			profiles.CreateProfile("x", "X");
+			using Barrier barrier = new(2);
+
+			Thread activate = new(() =>
+			{
+				barrier.SignalAndWait(TestContext.CancellationToken);
+
+				// Keep activating until the delete lands, so the activation is in flight when it does
+				while (profiles.SetActiveProfile("x"))
+				{
+				}
+			});
+			Thread delete = new(() =>
+			{
+				barrier.SignalAndWait(TestContext.CancellationToken);
+				profiles.DeleteProfile("x");
+			});
+
+			activate.Start();
+			delete.Start();
+			activate.Join();
+			delete.Join();
+
+			// A profile recreated with the deleted id must not become active on its own
+			profiles.CreateProfile("x", "Recreated");
+			if (profiles.GetActiveProfile() is not null)
+			{
+				stale++;
+			}
+		}
+
+		Assert.AreEqual(0, stale, $"{stale} of {Trials} trials left the active id pointing at the deleted profile.");
+	}
+}
diff --git a/Keybinding/Services/ProfileManager.cs b/Keybinding/Services/ProfileManager.cs
index 923182d..d9df93a 100644
--- a/Keybinding/Services/ProfileManager.cs
+++ b/Keybinding/Services/ProfileManager.cs
@@ -57,15 +57,22 @@ public bool DeleteProfile(string profileId)
 		}
 
 		string normalizedId = profileId.Trim();
-		bool removed = _profiles.TryRemove(normalizedId, out _);
 
-		// Clear active profile if it was the one being deleted
-		if (removed && _activeProfileId == normalizedId)
+		// Remove and clear under the lock SetActiveProfile checks and sets under, so an activation
+		// cannot land between them and leave the active id naming the deleted profile
+		// (ktsu-dev/Keybinding#120)
+		lock (_lock)
 		{
-			_activeProfileId = null;
-		}
+			bool removed = _profiles.TryRemove(normalizedId, out _);
 
-		return removed;
+			// Clear active profile if it was the one being deleted
+			if (removed && _activeProfileId == normalizedId)
+			{
+				_activeProfileId = null;
+			}
+
+			return removed;
+		}
 	}
 
 	/// <inheritdoc/>
@@ -102,13 +109,16 @@ public bool SetActiveProfile(string profileId)
 
 		string normalizedId = profileId.Trim();
 
-		if (!_profiles.ContainsKey(normalizedId))
+		lock (_lock)
 		{
-			return false;
-		}
+			if (!_profiles.ContainsKey(normalizedId))
+			{
+				return false;
+			}
 
-		_activeProfileId = normalizedId;
-		return true;
+			_activeProfileId = normalizedId;
+			return true;
+		}
 	}
 
 	/// <inheritdoc/>

From a4ac0c66e1e0733691ffebb6b17f26f7affd0ea9 Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Tue, 29 Sep 2026 15:36:34 +0000
Subject: [PATCH 2/2] Comment the intentionally empty activation loop in the
 race test

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WAdbE4VMmkBh1tzMGpC9Wy
---
 Keybinding.Test/ProfileActivateDeleteConcurrencyTests.cs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Keybinding.Test/ProfileActivateDeleteConcurrencyTests.cs b/Keybinding.Test/ProfileActivateDeleteConcurrencyTests.cs
index 3c50645..f8f276f 100644
--- a/Keybinding.Test/ProfileActivateDeleteConcurrencyTests.cs
+++ b/Keybinding.Test/ProfileActivateDeleteConcurrencyTests.cs
@@ -28,6 +28,7 @@ public void SetActiveProfile_RacingDeleteProfile_NeverLeavesTheDeletedIdActive()
 				// Keep activating until the delete lands, so the activation is in flight when it does
 				while (profiles.SetActiveProfile("x"))
 				{
+					// Intentionally empty: each iteration is another activation racing the delete
 				}
 			});
 			Thread delete = new(() =>