fix(launcher): Campaign LA LA3 review fixes — contract paths omission, probe composition, graceful stop, hygiene

Opus review of LA3 returned FIX FIRST; this addresses every finding in
scope (F1-F5, F7-F12; F6 CI-lane addition excluded per instructions):

- F1 (CRITICAL): SessionProcessSettings.Paths is now nullable and left
  null by SessionConfigComposer unless a caller supplies overrides, so
  the JSON key is entirely absent instead of "paths":{} — the App-side
  loader's strict UnmappedMemberHandling.Disallow would otherwise reject
  every gui/guiSelect session-config document at load.
- F2: added SessionConfigComposer.ComposeProbe and a nullable
  SessionDescriptor.Mode field ("probe", omitted for normal play) per
  the pinned contract — no character/policy/plugins/loginCommands.
- F3: LauncherProcessSupervisor.Stop now tries
  ILauncherChildProcess.TryRequestGracefulStop (Linux: libc SIGINT via
  LibraryImport, K4-proven graceful headless logout) before
  CloseMainWindow. Windows has no reliable no-window-console equivalent
  today; filed docs/ISSUES.md #397 with the CREATE_NEW_PROCESS_GROUP +
  CTRL_BREAK fix direction. Stop()'s blocking-timeout contract is now
  documented for LA4.
- F4: LauncherProfileStore.Save chmods the Linux temp file to 0600
  immediately after creation, before any credential is serialized;
  failure paths and Load() clean up a stale .tmp.
- F5: added LauncherCoreDependencyBoundaryTests asserting Launcher.Core
  references exactly AcDream.Platform and no packages.
- F7: StatusEventParser.Parse no longer throws on a whitespace/null
  line; StatusFileTailer.ReadNewEvents swallows the File.Exists/open
  TOCTOU window (FileNotFoundException/DirectoryNotFoundException/
  IOException) instead of throwing.
- F8: Start() now kills (entire process tree) and disposes a child that
  started successfully but failed while being fed its stdin password,
  instead of orphaning it.
- F9: SetState is monotonic — once Exited, no later transition applies
  or fires StateChanged, closing a Start()-path race where a
  synchronously-exiting child could be "resurrected" to Running.
- F10: CharacterIdFormat.TryParse now requires the "0x" prefix (an
  unprefixed hand-typed decimal id is also valid hex and was silently
  misread); a parsed id of 0 is treated as unusable and falls back to
  the name selector; LauncherProfileStore.MergeRoster normalizes both
  sides through TryParse/ToHexString instead of raw string equality, so
  a legacy unprefixed-hex row self-heals via name match instead of
  duplicating.
- F11: StatusCharacterEntry.SecondsGreyedOut is now uint, matching
  CharacterRosterEntry and the host writer.
- F12: added MalformedStatusEvent, returned for a recognized `e` whose
  payload doesn't match its shape, distinguished from UnknownStatusEvent
  (an unrecognized `e`).

AllowUnsafeBlocks was added to AcDream.Launcher.Core.csproj — required
by the LibraryImport source generator's function-pointer marshalling
stub for F3's Linux SIGINT P/Invoke.

Verification: dotnet build AcDream.slnx -c Release green (0 errors);
dotnet test tests/AcDream.Launcher.Core.Tests -c Release green at 94/94
on native Windows and under WSL (Ubuntu, verified across multiple runs
for the timing-sensitive SIGINT/sharing-violation tests, no flakes
observed).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/AcDream.Launcher.Core.Tests/LauncherCoreDependencyBoundaryTests.cs

@@ -0,0 +1,79 @@
+using System.Runtime.CompilerServices;
+using System.Xml.Linq;
+
+namespace AcDream.Launcher.Core.Tests;
+
+// Campaign LA plan §LA3 review finding F5: AcDream.Launcher.Core's entire
+// premise (spec §LA3, SessionConfigDocument.cs's "PINNED CONTRACT" remarks)
+// is being the BCL-plus-Platform-only assembly the external Avalonia
+// launcher (LA4) can reference without pulling in any game-solution
+// dependency. That contract is what this guard enforces — the csproj must
+// declare exactly one ProjectReference (AcDream.Platform) and zero
+// PackageReference entries, forever, in the same spirit as Platform's,
+// Runtime's, and Headless's dependency-boundary guards.
+public sealed class LauncherCoreDependencyBoundaryTests
+{
+    [Fact]
+    public void LauncherCoreProjectReferencesOnlyPlatformAndDeclaresNoPackages()
+    {
+        string repositoryRoot = FindRepositoryRoot();
+        string projectPath = Path.Combine(
+            repositoryRoot,
+            "src",
+            "AcDream.Launcher.Core",
+            "AcDream.Launcher.Core.csproj");
+        var project = XDocument.Load(projectPath);
+
+        var projectReferences = project.Descendants("ProjectReference")
+            .Select(element => element.Attribute("Include")?.Value)
+            // The csproj is authored with Windows-style "..\Foo\Foo.csproj"
+            // separators; Path.GetFileName only recognizes the platform's
+            // own separator, so on Linux it would return the whole
+            // relative path unchanged instead of just the filename.
+            // Normalizing to '/' first keeps this assertion
+            // platform-agnostic (this project's tests run under both
+            // native Windows and WSL — see Campaign LA plan §LA3 review
+            // finding F5's acceptance).
+            .Select(include => include is null
+                ? null
+                : Path.GetFileName(include.Replace('\\', '/')))
+            .ToList();
+
+        Assert.Equal(["AcDream.Platform.csproj"], projectReferences);
+        Assert.Empty(project.Descendants("PackageReference"));
+    }
+
+    private static string FindRepositoryRoot(
+        [CallerFilePath] string sourcePath = "")
+    {
+        string[] starts =
+        {
+            Path.GetDirectoryName(sourcePath) ?? string.Empty,
+            Directory.GetCurrentDirectory(),
+            AppContext.BaseDirectory,
+        };
+        foreach (string start in starts)
+        {
+            if (string.IsNullOrEmpty(start))
+            {
+                continue;
+            }
+
+            var directory = new DirectoryInfo(start);
+            while (directory is not null)
+            {
+                if (File.Exists(Path.Combine(
+                        directory.FullName,
+                        "AcDream.slnx")))
+                {
+                    return directory.FullName;
+                }
+
+                directory = directory.Parent;
+            }
+        }
+
+        throw new DirectoryNotFoundException(
+            "Could not find AcDream.slnx above the source, working, or output directory.");
+    }
+}

tests/AcDream.Launcher.Core.Tests/Launching/LauncherProcessSupervisorTests.cs

@@ -109,6 +109,132 @@ public sealed class LauncherProcessSupervisorTests
         Assert.Equal(0, fake.KillCallCount);
     }
 
+    [Fact]
+    public void StopAttemptsTheGracefulStopSignalBeforeCloseMainWindow()
+    {
+        var factory = new FakeChildProcessFactory(exitsWithinStopTimeout: true);
+        using var supervisor = new LauncherProcessSupervisor(factory);
+        supervisor.Start(Spec(), "pw");
+
+        supervisor.Stop(TimeSpan.FromMilliseconds(50));
+
+        FakeChildProcess fake = factory.LastCreated!;
+        Assert.Equal(1, fake.TryRequestGracefulStopCallCount);
+        Assert.Equal(["gracefulStop", "closeMainWindow"], fake.CallOrder);
+    }
+
+    [Fact]
+    public void GracefulStopSignalSendsSigintToARealChildOnLinux()
+    {
+        // Review finding F3, proven end to end against the real
+        // SystemChildProcess: Stop() sends SIGINT before falling back to
+        // CloseMainWindow/Kill, and the trapped child exits gracefully
+        // with code 0 well within the timeout. A hard SIGKILL fallback
+        // (or a signal arriving before the shell's trap is even armed,
+        // which falls back to the shell's default SIGINT disposition —
+        // terminate with exit 128+2=130) would not produce this clean
+        // exit code, so ExitCode == 0 is a hermetic proof the graceful
+        // path is what actually stopped the child.
+        if (!OperatingSystem.IsLinux())
+            return;
+
+        string readyMarker = Path.Combine(
+            Path.GetTempPath(), "acdream-la3-sigint-" + Guid.NewGuid().ToString("N"));
+        try
+        {
+            using var supervisor = new LauncherProcessSupervisor();
+            var exited = new ManualResetEventSlim(false);
+            supervisor.StateChanged += (_, s) =>
+            {
+                if (s == LauncherSessionState.Exited)
+                    exited.Set();
+            };
+
+            supervisor.Start(
+                new LauncherProcessSpec(
+                    "/bin/bash",
+                    [
+                        "-c",
+                        "trap 'kill $child 2>/dev/null; exit 0' INT; "
+                            + "sleep 30 & child=$!; "
+                            + $"touch '{readyMarker}'; "
+                            + "wait $child",
+                    ]),
+                password: null);
+
+            // Wait for the child to prove its SIGINT trap is armed AND
+            // its background `sleep` is tracked (touch runs after both,
+            // in program order) before sending the signal — otherwise
+            // this test would race the shell's own startup and
+            // intermittently observe the shell's default SIGINT
+            // disposition instead of the trap, or leave an untracked
+            // orphaned `sleep`.
+            DateTime readyDeadline = DateTime.UtcNow + TimeSpan.FromSeconds(5);
+            while (!File.Exists(readyMarker) && DateTime.UtcNow < readyDeadline)
+            {
+                Thread.Sleep(10);
+            }
+
+            Assert.True(
+                File.Exists(readyMarker),
+                "child did not signal trap-armed readiness in time");
+
+            supervisor.Stop(TimeSpan.FromSeconds(10));
+
+            Assert.True(exited.Wait(TimeSpan.FromSeconds(5)));
+            Assert.Equal(0, supervisor.ExitCode);
+        }
+        finally
+        {
+            try
+            {
+                File.Delete(readyMarker);
+            }
+            catch (IOException)
+            {
+            }
+        }
+    }
+
+    [Fact]
+    public void StartKillsAndDisposesTheChildWhenFeedingStdinThrowsAfterTheProcessHasStarted()
+    {
+        var factory = new FakeChildProcessFactory(
+            exitsWithinStopTimeout: true,
+            throwOnStandardInputWrite: true);
+        using var supervisor = new LauncherProcessSupervisor(factory);
+
+        Assert.ThrowsAny<Exception>(() => supervisor.Start(Spec(), "pw"));
+
+        FakeChildProcess fake = factory.LastCreated!;
+        Assert.True(fake.Started);
+        Assert.Equal(1, fake.KillCallCount);
+        Assert.True(fake.Disposed);
+    }
+
+    [Fact]
+    public void SetStateIsMonotonicAndIgnoresATransitionAfterExited()
+    {
+        // Simulates the child exiting synchronously from inside
+        // process.Start() itself (a child that dies immediately) — the
+        // trailing SetState(Running) at the end of Start() must not
+        // resurrect State from the terminal Exited it already reached,
+        // nor fire a spurious StateChanged(Running).
+        var factory = new FakeChildProcessFactory(
+            exitsWithinStopTimeout: true,
+            exitDuringStart: true);
+        using var supervisor = new LauncherProcessSupervisor(factory);
+        var states = new List<LauncherSessionState>();
+        supervisor.StateChanged += (_, s) => states.Add(s);
+
+        supervisor.Start(Spec(), "pw");
+
+        Assert.Equal(LauncherSessionState.Exited, supervisor.State);
+        Assert.Equal(
+            [LauncherSessionState.Starting, LauncherSessionState.Exited],
+            states);
+    }
+
     [Fact]
     public void LauncherProcessSpecCarriesNoCredentialLikeMember()
     {
@@ -162,22 +288,34 @@ public sealed class LauncherProcessSupervisorTests
         // because this test is itself running under `dotnet test`.
         OperatingSystem.IsWindows() ? "dotnet.exe" : "dotnet";
 
-    private sealed class FakeChildProcessFactory(bool exitsWithinStopTimeout)
+    private sealed class FakeChildProcessFactory(
+        bool exitsWithinStopTimeout,
+        bool exitDuringStart = false,
+        bool throwOnStandardInputWrite = false)
         : ILauncherChildProcessFactory
     {
         public FakeChildProcess? LastCreated { get; private set; }
 
         public ILauncherChildProcess Create(LauncherProcessSpec spec)
         {
-            LastCreated = new FakeChildProcess(spec, exitsWithinStopTimeout);
+            LastCreated = new FakeChildProcess(
+                spec,
+                exitsWithinStopTimeout,
+                exitDuringStart,
+                throwOnStandardInputWrite);
             return LastCreated;
         }
     }
 
-    private sealed class FakeChildProcess(LauncherProcessSpec spec, bool exitsWithinStopTimeout)
+    private sealed class FakeChildProcess(
+        LauncherProcessSpec spec,
+        bool exitsWithinStopTimeout,
+        bool exitDuringStart = false,
+        bool throwOnStandardInputWrite = false)
         : ILauncherChildProcess
     {
         private readonly RecordingTextWriter _standardInput = new();
+        private readonly ThrowingTextWriter _throwingStandardInput = new();
 
         public LauncherProcessSpec Spec { get; } = spec;
 
@@ -191,27 +329,59 @@ public sealed class LauncherProcessSupervisorTests
 
         public int CloseMainWindowCallCount { get; private set; }
 
+        public int TryRequestGracefulStopCallCount { get; private set; }
+
         public int KillCallCount { get; private set; }
 
+        public bool Disposed { get; private set; }
+
+        /// <summary>Records the order <see cref="TryRequestGracefulStop"/>,
+        /// <see cref="CloseMainWindow"/>, and <see cref="Kill"/> were
+        /// actually invoked in — review finding F3's ordering guarantee.
+        /// </summary>
+        public List<string> CallOrder { get; } = [];
+
         public bool HasExited { get; private set; }
 
         public int ExitCode { get; private set; }
 
-        public TextWriter StandardInput => _standardInput;
+        public TextWriter StandardInput =>
+            throwOnStandardInputWrite ? _throwingStandardInput : _standardInput;
 
         public event EventHandler? Exited;
 
-        public void Start() => Started = true;
+        public void Start()
+        {
+            Started = true;
+
+            if (exitDuringStart)
+            {
+                // Simulates a child that dies synchronously from inside
+                // Process.Start() itself (review finding F9's race).
+                HasExited = true;
+                ExitCode = 0;
+                Exited?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        public bool TryRequestGracefulStop()
+        {
+            TryRequestGracefulStopCallCount++;
+            CallOrder.Add("gracefulStop");
+            return false;
+        }
 
         public bool CloseMainWindow()
         {
             CloseMainWindowCallCount++;
+            CallOrder.Add("closeMainWindow");
             return true;
         }
 
         public void Kill()
         {
             KillCallCount++;
+            CallOrder.Add("kill");
             HasExited = true;
             ExitCode = -1;
             Exited?.Invoke(this, EventArgs.Empty);
@@ -230,6 +400,7 @@ public sealed class LauncherProcessSupervisorTests
 
         public void Dispose()
         {
+            Disposed = true;
         }
     }
 
@@ -243,4 +414,16 @@ public sealed class LauncherProcessSupervisorTests
             base.Dispose(disposing);
         }
     }
+
+    /// <summary>Simulates a broken stdin pipe (review finding F8): the
+    /// child process started successfully, but feeding it the password
+    /// fails.</summary>
+    private sealed class ThrowingTextWriter : StringWriter
+    {
+        public override void Write(string? value) =>
+            throw new IOException("simulated broken stdin pipe");
+
+        public override void Write(char value) =>
+            throw new IOException("simulated broken stdin pipe");
+    }
 }

tests/AcDream.Launcher.Core.Tests/Launching/SessionConfigComposerTests.cs

@@ -135,6 +135,45 @@ public sealed class SessionConfigComposerTests
         Assert.Equal("+Acdream", (string?)session["character"]!["name"]);
     }
 
+    [Fact]
+    public void GuiModeFallsBackToNameSelectorWhenIdIsAHandTypedDecimalWithoutThe0xPrefix()
+    {
+        // Review finding F10: an 8-digit all-decimal-digit string is ALSO
+        // a syntactically valid hex number. Without requiring the "0x"
+        // prefix, this used to silently reinterpret a hand-typed decimal
+        // id as hex and select the wrong character; it must now fall
+        // through to the name selector instead of guessing.
+        ComposedSessionConfig composed = SessionConfigComposer.Compose(
+            Server(),
+            Account(),
+            Character(LaunchMode.Gui, id: "12345678"),
+            Install,
+            Paths,
+            sessionId: "session-gui-decimal-id");
+
+        JsonObject session = SingleSession(composed);
+        Assert.Null(session["character"]!["id"]);
+        Assert.Equal("+Acdream", (string?)session["character"]!["name"]);
+    }
+
+    [Fact]
+    public void GuiModeFallsBackToNameSelectorWhenTheParsedIdIsZero()
+    {
+        // Review finding F10: both host loaders reject `id: 0` outright,
+        // so a parsed-but-zero id is not a usable selector either.
+        ComposedSessionConfig composed = SessionConfigComposer.Compose(
+            Server(),
+            Account(),
+            Character(LaunchMode.Gui, id: "0x00000000"),
+            Install,
+            Paths,
+            sessionId: "session-gui-zero-id");
+
+        JsonObject session = SingleSession(composed);
+        Assert.Null(session["character"]!["id"]);
+        Assert.Equal("+Acdream", (string?)session["character"]!["name"]);
+    }
+
     [Fact]
     public void PluginsAndLoginCommandsAreOmittedWhenEmptyRatherThanEmptyArrays()
     {
@@ -156,7 +195,7 @@ public sealed class SessionConfigComposerTests
     }
 
     [Fact]
-    public void ProcessContentCarriesInstallRecordAndPathsIsAlwaysPresent()
+    public void ProcessContentCarriesInstallRecordAndPathsIsOmittedByDefault()
     {
         ComposedSessionConfig composed = SessionConfigComposer.Compose(
             Server(),
@@ -169,11 +208,15 @@ public sealed class SessionConfigComposerTests
         JsonObject root = ParseRoot(composed);
         Assert.Equal(1, (int?)root["version"]);
         JsonObject process = root["process"]!.AsObject();
-        AssertKeys(process, "paths", "content");
 
-        // Paths is always present as an object; every member is omitted
-        // when unset (hosts resolve their own default ApplicationPathSet).
-        Assert.Empty(process["paths"]!.AsObject());
+        // PINNED CONTRACT (review finding F1): process.paths is OMITTED
+        // entirely — not an empty object — unless a caller explicitly
+        // supplies overrides. The App-side loader parses with strict
+        // UnmappedMemberHandling.Disallow and has no `paths` member of
+        // its own, so an emitted "paths":{} would reject the whole
+        // document at config load for every gui/guiSelect launch.
+        AssertKeys(process, "content");
+        Assert.False(process.ContainsKey("paths"));
 
         JsonObject content = process["content"]!.AsObject();
         AssertKeys(content, "datDirectory", "preparedAssetPath");
@@ -181,6 +224,92 @@ public sealed class SessionConfigComposerTests
         Assert.Equal(Install.PreparedAssetPath, (string?)content["preparedAssetPath"]);
     }
 
+    [Fact]
+    public void NormalPlaySessionsOmitTheModeFieldEntirely()
+    {
+        foreach (LaunchMode mode in new[] { LaunchMode.Gui, LaunchMode.GuiSelect, LaunchMode.Headless })
+        {
+            ComposedSessionConfig composed = SessionConfigComposer.Compose(
+                Server(),
+                Account(),
+                Character(mode),
+                Install,
+                Paths,
+                sessionId: $"session-mode-omit-{mode}");
+
+            JsonObject session = SingleSession(composed);
+            Assert.False(session.ContainsKey("mode"));
+        }
+    }
+
+    [Fact]
+    public void ProbeModeSetsModeAndOmitsCharacterPolicyPluginsAndLoginCommands()
+    {
+        ComposedSessionConfig composed = SessionConfigComposer.ComposeProbe(
+            Server(),
+            Account(),
+            Install,
+            Paths,
+            sessionId: "session-probe");
+
+        JsonObject session = SingleSession(composed);
+
+        AssertKeys(
+            session,
+            "id", "mode", "endpoint", "account", "credential", "statusFile");
+
+        Assert.Equal("session-probe", (string?)session["id"]);
+        Assert.Equal("probe", (string?)session["mode"]);
+        Assert.Equal("127.0.0.1", (string?)session["endpoint"]!["host"]);
+        Assert.Equal(9000, (int?)session["endpoint"]!["port"]);
+        Assert.Equal("testaccount", (string?)session["account"]);
+        Assert.Equal("standardInput", (string?)session["credential"]!["provider"]);
+        Assert.False(session.ContainsKey("character"));
+        Assert.False(session.ContainsKey("policy"));
+        Assert.False(session.ContainsKey("plugins"));
+        Assert.False(session.ContainsKey("loginCommands"));
+        Assert.False(session.ContainsKey("loginCommandDelayMs"));
+        Assert.Equal(
+            Path.Combine(
+                Paths.CacheDirectory, "launcher", "sessions", "session-probe", "status.jsonl"),
+            (string?)session["statusFile"]);
+    }
+
+    [Fact]
+    public void ProbeModeDocumentNeverContainsThePassword()
+    {
+        AccountProfile account = Account();
+
+        ComposedSessionConfig composed = SessionConfigComposer.ComposeProbe(
+            Server(),
+            account,
+            Install,
+            Paths,
+            sessionId: "session-probe-pw");
+
+        string json = SessionConfigComposer.Serialize(composed.Document);
+        Assert.DoesNotContain(account.Password, json, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void ProbeModeProcessSettingsMatchNormalComposition()
+    {
+        ComposedSessionConfig composed = SessionConfigComposer.ComposeProbe(
+            Server(),
+            Account(),
+            Install,
+            Paths,
+            sessionId: "session-probe-content");
+
+        JsonObject root = ParseRoot(composed);
+        JsonObject process = root["process"]!.AsObject();
+        AssertKeys(process, "content");
+
+        JsonObject content = process["content"]!.AsObject();
+        Assert.Equal(Install.DatDirectory, (string?)content["datDirectory"]);
+        Assert.Equal(Install.PreparedAssetPath, (string?)content["preparedAssetPath"]);
+    }
+
     [Fact]
     public void ComposedDocumentNeverContainsThePassword()
     {

tests/AcDream.Launcher.Core.Tests/Profiles/CharacterIdFormatTests.cs

@@ -14,8 +14,8 @@ public sealed class CharacterIdFormatTests
     [Theory]
     [InlineData("0x5000000A", 0x5000000Au)]
     [InlineData("0x5000000a", 0x5000000Au)]
-    [InlineData("5000000A", 0x5000000Au)]
-    public void TryParseAcceptsWithAndWithoutPrefixAndCase(string text, uint expected)
+    [InlineData("0X5000000A", 0x5000000Au)]
+    public void TryParseAcceptsThe0xPrefixCaseInsensitively(string text, uint expected)
     {
         Assert.True(CharacterIdFormat.TryParse(text, out uint id));
         Assert.Equal(expected, id);
@@ -26,8 +26,15 @@ public sealed class CharacterIdFormatTests
     [InlineData("")]
     [InlineData("   ")]
     [InlineData("not-hex")]
-    public void TryParseRejectsNullEmptyOrNonHex(string? text)
+    [InlineData("5000000A")]
+    [InlineData("12345678")]
+    public void TryParseRejectsNullEmptyNonHexOrAnUnprefixedString(string? text)
     {
+        // "5000000A"/"12345678" are all-hex-digit strings that would
+        // parse fine as hex WITHOUT the "0x" prefix — review finding F10
+        // requires the prefix precisely so a hand-typed decimal id (which
+        // is ALSO syntactically valid hex) is never silently
+        // misinterpreted as one.
         Assert.False(CharacterIdFormat.TryParse(text, out uint id));
         Assert.Equal(0u, id);
     }

tests/AcDream.Launcher.Core.Tests/Profiles/LauncherProfileStoreTests.cs

@@ -1,3 +1,4 @@
+using System.Threading;
 using AcDream.Launcher.Core.Profiles;
 
 namespace AcDream.Launcher.Core.Tests.Profiles;
@@ -284,4 +285,105 @@ public sealed class LauncherProfileStoreTests : IDisposable
             UnixFileMode.UserRead | UnixFileMode.UserWrite,
             mode);
     }
+
+    [Fact]
+    public void SaveNeverLeavesTheTempFileWorldOrGroupReadableDuringTheWrite()
+    {
+        // Review finding F4: the temp file used to be created with the
+        // process's default umask and only chmod'd AFTER the atomic
+        // rename, leaving a window where the plaintext-credential temp
+        // file could be world/group-readable. The fix chmods the temp
+        // file immediately after creation, BEFORE any content (including
+        // the password) is serialized into it. A large document makes
+        // the write take long enough for a concurrent poller to have a
+        // real chance at observing a regression.
+        if (!OperatingSystem.IsLinux())
+            return;
+
+        var store = new LauncherProfileStore(_filePath);
+        store.Load();
+        store.AddServer("Local ACE", "127.0.0.1", 9000);
+        for (int i = 0; i < 300; i++)
+        {
+            store.AddAccount("Local ACE", $"account{i}", new string('x', 4096));
+        }
+
+        string tempPath = _filePath + ".tmp";
+        bool observedLooseMode = false;
+        bool stop = false;
+        var poller = new Thread(() =>
+        {
+            while (!Volatile.Read(ref stop))
+            {
+                if (File.Exists(tempPath))
+                {
+                    try
+                    {
+                        // The platform-compat analyzer can't see the
+                        // enclosing test method's `OperatingSystem.IsLinux()`
+                        // guard across this lambda boundary; suppressed
+                        // rather than restructured, since the guard is
+                        // real and this whole method is a no-op off Linux.
+#pragma warning disable CA1416
+                        UnixFileMode mode = File.GetUnixFileMode(tempPath);
+#pragma warning restore CA1416
+                        if ((mode & ~(UnixFileMode.UserRead | UnixFileMode.UserWrite)) != 0)
+                        {
+                            observedLooseMode = true;
+                        }
+                    }
+                    catch (IOException)
+                    {
+                        // Renamed/deleted between the Exists check and
+                        // GetUnixFileMode — not a finding, just keep
+                        // polling.
+                    }
+                }
+            }
+        });
+        poller.Start();
+
+        store.Save();
+
+        Volatile.Write(ref stop, true);
+        poller.Join();
+
+        Assert.False(observedLooseMode);
+    }
+
+    [Fact]
+    public void SaveDeletesTheStaleTempFileWhenTheFinalRenameFails()
+    {
+        // Review finding F4: force the rename step to fail (the
+        // destination path names an existing DIRECTORY, which
+        // File.Move(..., overwrite: true) refuses to replace — Windows
+        // reports this as UnauthorizedAccessException, Linux as
+        // IOException, so the assertion below accepts either) and assert
+        // the temp file — which still carries the just-serialized
+        // plaintext credentials — doesn't linger on disk afterward.
+        Directory.CreateDirectory(_filePath);
+        var store = new LauncherProfileStore(_filePath);
+        store.Load();
+        store.AddServer("Local ACE", "127.0.0.1", 9000);
+        store.AddAccount("Local ACE", "testaccount", "testpassword");
+
+        Assert.ThrowsAny<Exception>(() => store.Save());
+
+        Assert.False(File.Exists(_filePath + ".tmp"));
+    }
+
+    [Fact]
+    public void LoadDeletesAStaleTempFileLeftBehindByACrashedSave()
+    {
+        // Review finding F4: a Save() that crashed between creating the
+        // temp file and the atomic rename leaves a ".tmp" carrying the
+        // same plaintext credentials as the real store. Load() cleans it
+        // up opportunistically the next time the store is opened.
+        File.WriteAllText(_filePath + ".tmp", """{"version":1,"servers":[]}""");
+
+        var store = new LauncherProfileStore(_filePath);
+        store.Load();
+
+        Assert.False(File.Exists(_filePath + ".tmp"));
+    }
 }

tests/AcDream.Launcher.Core.Tests/Profiles/RosterMergeTests.cs

@@ -126,6 +126,32 @@ public sealed class RosterMergeTests
         Assert.Contains(characters, c => c.Name == "+PendingDelete");
     }
 
+    [Fact]
+    public void MergeNormalizesAnUnprefixedHexIdInsteadOfCreatingADuplicateRow()
+    {
+        // Review finding F10: a hand-edited row can carry an id without
+        // the "0x" prefix (e.g. copy-pasted from somewhere that dropped
+        // it). CharacterIdFormat.TryParse now REJECTS that string
+        // outright (it no longer guesses hex-without-a-prefix), so the
+        // old raw string-equality comparison against the roster's
+        // canonical "0x..." form would never match and would add a
+        // second row forever. The name-fallback match must still
+        // recognize this as the SAME character and self-heal its id.
+        LauncherProfileStore store = NewStoreWithServerAndAccount();
+        store.Document.Servers.Single().Accounts.Single().Characters.Add(
+            new CharacterProfile { Id = "5000000A", Name = "+Acdream" });
+
+        store.MergeRoster(
+            "Local ACE",
+            "testaccount",
+            [new CharacterRosterEntry(0x5000000A, "+Acdream", 0)]);
+
+        CharacterProfile character = Assert.Single(
+            store.Document.Servers.Single().Accounts.Single().Characters);
+        Assert.Equal("0x5000000A", character.Id);
+        Assert.Equal("+Acdream", character.Name);
+    }
+
     [Fact]
     public void MergeThrowsForUnknownServerOrAccount()
     {

tests/AcDream.Launcher.Core.Tests/Status/StatusEventParserTests.cs

@@ -46,9 +46,9 @@ public sealed class StatusEventParserTests
         Assert.Equal(2, list.Characters.Count);
         Assert.Equal(1342177290u, list.Characters[0].Id);
         Assert.Equal("+Acdream", list.Characters[0].Name);
-        Assert.Equal(0, list.Characters[0].SecondsGreyedOut);
+        Assert.Equal(0u, list.Characters[0].SecondsGreyedOut);
         Assert.Equal(1342177291u, list.Characters[1].Id);
-        Assert.Equal(1, list.Characters[1].SecondsGreyedOut);
+        Assert.Equal(1u, list.Characters[1].SecondsGreyedOut);
     }
 
     [Fact]
@@ -112,14 +112,59 @@ public sealed class StatusEventParserTests
         Assert.IsType<UnknownStatusEvent>(e);
     }
 
-    [Fact]
-    public void KnownEValueWithMissingRequiredFieldSurfacesAsUnknownEventRatherThanThrowing()
+    [Theory]
+    [InlineData("")]
+    [InlineData("   ")]
+    [InlineData("\t")]
+    public void WhitespaceOrEmptyLineSurfacesAsUnknownEventRatherThanThrowing(string line)
     {
-        // characterList without "characters" — a shape mismatch, not
-        // just an unrecognized e value.
-        var e = StatusEventParser.Parse(
-            """{"v":1,"e":"characterList","t":"2026-08-14T12:00:09Z","sessionId":"s1","accountName":"a","slotCount":6}""");
+        // Review finding F7: ArgumentException.ThrowIfNullOrWhiteSpace
+        // used to guard this method BEFORE the try/catch, so a
+        // whitespace-only line (e.g. a stray blank line the tailer
+        // happens to hand over) escaped as an uncaught exception instead
+        // of degrading like every other malformed-input case.
+        var e = StatusEventParser.Parse(line);
 
         Assert.IsType<UnknownStatusEvent>(e);
     }
+
+    [Fact]
+    public void NullLineSurfacesAsUnknownEventRatherThanThrowing()
+    {
+        var e = StatusEventParser.Parse(null!);
+
+        Assert.IsType<UnknownStatusEvent>(e);
+    }
+
+    [Fact]
+    public void KnownEValueWithMissingRequiredFieldSurfacesAsMalformedEventRatherThanThrowing()
+    {
+        // characterList without "characters" — a shape mismatch on a
+        // KNOWN event name. Review finding F12: this must be
+        // distinguishable from an unrecognized e value, so it now
+        // surfaces as MalformedStatusEvent rather than UnknownStatusEvent.
+        var e = StatusEventParser.Parse(
+            """{"v":1,"e":"characterList","t":"2026-08-14T12:00:09Z","sessionId":"s1","accountName":"a","slotCount":6}""");
+
+        var malformed = Assert.IsType<MalformedStatusEvent>(e);
+        Assert.Equal("characterList", malformed.E);
+        Assert.Equal("s1", malformed.SessionId);
+        Assert.False(string.IsNullOrWhiteSpace(malformed.Error));
+    }
+
+    [Fact]
+    public void KnownEValueWithAFieldOfTheWrongJsonKindSurfacesAsMalformedEvent()
+    {
+        // "characters" present but not an array — this throws
+        // InvalidOperationException out of JsonElement.EnumerateArray()
+        // rather than the FormatException a missing/wrong-kind scalar
+        // field throws, so it exercises the parser's other malformed-
+        // payload catch path.
+        var e = StatusEventParser.Parse(
+            """{"v":1,"e":"characterList","t":"2026-08-14T12:00:10Z","sessionId":"s1","accountName":"a","slotCount":6,"characters":"not-an-array"}""");
+
+        var malformed = Assert.IsType<MalformedStatusEvent>(e);
+        Assert.Equal("characterList", malformed.E);
+        Assert.False(string.IsNullOrWhiteSpace(malformed.Error));
+    }
 }

tests/AcDream.Launcher.Core.Tests/Status/StatusFileTailerTests.cs

@@ -141,6 +141,33 @@ public sealed class StatusFileTailerTests : IDisposable
         Assert.IsType<ConnectedStatusEvent>(secondPoll[0]);
     }
 
+    [Fact]
+    public void ReadNewEventsReturnsEmptyRatherThanThrowingOnASharingViolation()
+    {
+        // A deterministic proxy for the File.Exists -> new FileStream
+        // TOCTOU window (review finding F7): Windows enforces FileShare
+        // at the OS level, so holding an exclusive (FileShare.None)
+        // handle open while the tailer tries to open the same path
+        // reliably reproduces the IOException the tailer must now
+        // swallow instead of throwing out of a method documented never
+        // to throw. (.NET's FileStream doesn't apply mandatory locking
+        // on Linux by default, so this specific scenario isn't
+        // reproducible there — the fix itself is platform-agnostic, only
+        // this particular deterministic trigger is Windows-only.)
+        if (!OperatingSystem.IsWindows())
+            return;
+
+        AppendShared(Line("started", "s1"));
+        using var exclusiveHandle = new FileStream(
+            _path, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
+
+        var tailer = new StatusFileTailer(_path);
+
+        IReadOnlyList<StatusEvent> events = tailer.ReadNewEvents();
+
+        Assert.Empty(events);
+    }
+
     [Fact]
     public void RestartsFromTheTopWhenTheFileIsTruncatedOrReplaced()
     {