Add live debugger frontend and mutex stall recovery (#383)

src/SharpEmu.Debugger/Session/IDebugTarget.cs

@@ -0,0 +1,51 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+namespace SharpEmu.Debugger.Session;
+
+/// <summary>
+/// The inspection and control surface a debugger front-end (for example a
+/// network server) drives. Register and memory accessors succeed only while the
+/// target is <see cref="DebuggerRunState.Paused"/>; they return <c>false</c>
+/// otherwise so callers never read torn state from a running guest.
+/// </summary>
+public interface IDebugTarget
+{
+    /// <summary>The current execution state.</summary>
+    DebuggerRunState State { get; }
+
+    /// <summary>The most recent stop, or null if the target has not stopped yet.</summary>
+    DebugStopEvent? LastStop { get; }
+
+    /// <summary>Reads the integer register file. Fails unless paused.</summary>
+    bool TryGetRegisters(out DebugRegisterFile registers);
+
+    /// <summary>Writes a single register. Fails unless paused.</summary>
+    bool TrySetRegister(DebugRegisterId id, ulong value);
+
+    /// <summary>Reads guest memory into <paramref name="destination"/>. Fails unless paused.</summary>
+    bool TryReadMemory(ulong address, Span<byte> destination);
+
+    /// <summary>Writes guest memory from <paramref name="source"/>. Fails unless paused.</summary>
+    bool TryWriteMemory(ulong address, ReadOnlySpan<byte> source);
+
+    /// <summary>Reads a 128-bit XMM register. Fails unless paused.</summary>
+    bool TryReadXmm(int registerIndex, out ulong low, out ulong high);
+
+    /// <summary>
+    /// Resumes a paused target. Returns false when the target was not paused.
+    /// </summary>
+    bool Continue();
+
+    /// <summary>
+    /// Resumes a paused target and stops again at the next frame boundary.
+    /// Returns false when the target was not paused.
+    /// </summary>
+    bool StepFrame();
+
+    /// <summary>
+    /// Requests that a running target stop at the next frame boundary. Has no
+    /// effect if the target is already paused or terminated.
+    /// </summary>
+    void RequestPause();
+}