diff --git a/src/ClaudeDo.Ui/Services/PtyTerminalSession.cs b/src/ClaudeDo.Ui/Services/PtyTerminalSession.cs
index aa1f5750..e9f6b43f 100644
--- a/src/ClaudeDo.Ui/Services/PtyTerminalSession.cs
+++ b/src/ClaudeDo.Ui/Services/PtyTerminalSession.cs
@@ -25,7 +25,21 @@ public sealed class PtyTerminalSession : IDisposable
     // inherits the other's env (e.g. CLAUDEDO_PLANNING_TOKEN, breaking that session's own MCP
     // auth). Process-wide env leakage AFTER a launch has forked remains a documented limitation
     // — Porta.Pty has no per-launch env seam, so the vars stay set on the whole UI process.
+    // The wait is bounded (see WaitForLaunchGateAsync) — a hung launch (slow disk, AV scanning
+    // claude.exe, a Porta.Pty/ConPTY hiccup) must not freeze every other pane open behind it.
     private static readonly SemaphoreSlim s_launchGate = new(1, 1);
+    private static readonly TimeSpan s_launchGateTimeout = TimeSpan.FromSeconds(30);
+
+    /// <summary>
+    /// Waits on <paramref name="gate"/> for at most <paramref name="timeout"/>, throwing
+    /// <see cref="TimeoutException"/> instead of blocking forever. Never acquires the gate on
+    /// timeout, so callers must not release it in that case.
+    /// </summary>
+    internal static async Task WaitForLaunchGateAsync(SemaphoreSlim gate, TimeSpan timeout, CancellationToken ct)
+    {
+        if (!await gate.WaitAsync(timeout, ct))
+            throw new TimeoutException("Another terminal launch is still starting up. Please retry in a moment.");
+    }
 
     private TerminalControl? _control;
     private bool _disposed;
@@ -50,7 +64,7 @@ public sealed class PtyTerminalSession : IDisposable
         control.Args = new List<string>(descriptor.Args);
         control.StartingDirectory = descriptor.Cwd;
 
-        await s_launchGate.WaitAsync(ct);
+        await WaitForLaunchGateAsync(s_launchGate, s_launchGateTimeout, ct);
         try
         {
             foreach (var (key, value) in descriptor.Env)
diff --git a/tests/ClaudeDo.Ui.Tests/Services/PtyTerminalSessionTests.cs b/tests/ClaudeDo.Ui.Tests/Services/PtyTerminalSessionTests.cs
new file mode 100644
index 00000000..5e6f23fc
--- /dev/null
+++ b/tests/ClaudeDo.Ui.Tests/Services/PtyTerminalSessionTests.cs
@@ -0,0 +1,38 @@
+using System.Threading;
+using ClaudeDo.Ui.Services;
+using Xunit;
+
+namespace ClaudeDo.Ui.Tests.Services;
+
+public class PtyTerminalSessionTests
+{
+    [Fact]
+    public async Task WaitForLaunchGateAsync_ThrowsTimeoutException_WhenGateStaysHeld()
+    {
+        using var gate = new SemaphoreSlim(0, 1); // never released — simulates a hung launch
+
+        await Assert.ThrowsAsync<TimeoutException>(() =>
+            PtyTerminalSession.WaitForLaunchGateAsync(gate, TimeSpan.FromMilliseconds(50), CancellationToken.None));
+    }
+
+    [Fact]
+    public async Task WaitForLaunchGateAsync_DoesNotReleaseGate_ItNeverAcquired()
+    {
+        using var gate = new SemaphoreSlim(0, 1);
+
+        await Assert.ThrowsAsync<TimeoutException>(() =>
+            PtyTerminalSession.WaitForLaunchGateAsync(gate, TimeSpan.FromMilliseconds(50), CancellationToken.None));
+
+        Assert.Equal(0, gate.CurrentCount); // still held; a bad fix would Release() what it never acquired
+    }
+
+    [Fact]
+    public async Task WaitForLaunchGateAsync_AcquiresGate_WhenAvailable()
+    {
+        using var gate = new SemaphoreSlim(1, 1);
+
+        await PtyTerminalSession.WaitForLaunchGateAsync(gate, TimeSpan.FromSeconds(5), CancellationToken.None);
+
+        Assert.Equal(0, gate.CurrentCount); // acquired
+    }
+}