Add debug foundation

SLICE3.MD

@@ -17,14 +17,14 @@ This slice does not implement the real hero, weapons, enemies, clusters, or miss
 - [x] (2026-04-21 17:43Z) Read repository rules, Windows rules, `PLANS.md`, `CODE.md`, `SLICE2.MD`, current debug scripts, current root scene, current content browser, and `godot/project.godot`.
 - [x] (2026-04-21 17:43Z) Verified that Slice 2 has committed content definitions, validation tests, content browser boot mode, and a clean worktree.
 - [x] (2026-04-21 17:43Z) Created this Slice 3 ExecPlan.
-- [ ] Implement pure debug runtime state and command service.
-- [ ] Add unit tests for debug commands and validation behavior.
-- [ ] Add Godot debug command node, upgraded overlay, clickable debug panel, and debug sandbox scene.
-- [ ] Add debug sandbox boot mode and input actions.
-- [ ] Add headless debug foundation smoke script.
-- [ ] Run formatting for touched C# files with `jb cleanupcode --build=False`.
-- [ ] Validate with .NET tests, .NET build, Godot solution build, debug sandbox smoke boot, content browser smoke boot, and existing smoke boot.
-- [ ] Commit the completed slice.
+- [x] (2026-04-21 19:18Z) Implemented pure debug runtime state and command service.
+- [x] (2026-04-21 19:18Z) Added unit tests for debug commands and validation behavior.
+- [x] (2026-04-21 19:18Z) Added Godot debug command node, upgraded overlay, clickable debug panel, and debug sandbox scene.
+- [x] (2026-04-21 19:18Z) Added debug sandbox boot mode and input actions.
+- [x] (2026-04-21 19:18Z) Added headless debug foundation smoke script.
+- [x] (2026-04-21 19:18Z) Ran formatting for touched C# files with `jb cleanupcode --build=False`.
+- [x] (2026-04-21 19:18Z) Validated with .NET tests, .NET build, Godot solution build, debug sandbox smoke boot, content browser smoke boot, and existing smoke boot.
+- [x] (2026-04-21 19:18Z) Commit the completed slice.
 
 ## Surprises & Discoveries
 
@@ -40,6 +40,9 @@ This slice does not implement the real hero, weapons, enemies, clusters, or miss
 - Observation: Content definitions and tests are available for difficulty ids, enemy ids, and mission timeline marker names.
   Evidence: `godot/scripts/content/samples/SampleContent.cs` creates `difficulty.easy`, `difficulty.normal`, `difficulty.hard`, `enemy.serial`, `enemy.parallel`, and mission markers such as `cluster.opening`.
 
+- Observation: Godot generated script UID files for the new Godot-facing debug node scripts during the headless project scan.
+  Evidence: `godot/scripts/debug/DebugCommandNode.cs.uid`, `godot/scripts/debug/DebugPanelController.cs.uid`, and `godot/scripts/debug/DebugSandboxController.cs.uid` appeared after `.\godot --headless --path godot --build-solutions --quit`.
+
 ## Decision Log
 
 - Decision: Implement debug command rules as plain C# first, with a Godot node wrapper for engine effects.
@@ -60,7 +63,31 @@ This slice does not implement the real hero, weapons, enemies, clusters, or miss
 
 ## Outcomes & Retrospective
 
-Not started. When this slice is completed, update this section with the exact files created, commands run, validation output, and any remaining risks.
+Completed. Slice 3 added the pure debug command foundation under `godot/scripts/debug/commands/`, xUnit coverage in `tests/SideScrollerGame.Content.Tests/DebugCommandServiceTests.cs`, the Godot bridge node `DebugCommandNode`, the upgraded overlay, the clickable sandbox panel, the debug sandbox controller, the `DebugSandbox` scene, the `DebugSandbox` boot mode, and debug input actions in `godot/project.godot`.
+
+Validation completed from `D:\Code\zfxaction26_1`:
+
+    dotnet test SideScrollerGame.sln
+      Passed! - Failed: 0, Passed: 22, Skipped: 0, Total: 22
+
+    dotnet build SideScrollerGame.sln
+      Build succeeded.
+      0 Warning(s)
+      0 Error(s)
+
+    .\godot --headless --path godot --build-solutions --quit
+      Exited successfully after project scan, .NET build, and script class registration.
+
+    .\godot --headless --path godot -- --debug-boot=debug-sandbox --debug-script=foundation-smoke --seed=333
+      Debug foundation smoke succeeded
+
+    .\godot --headless --path godot -- --debug-boot=content-browser --content-validate-only
+      Content validation succeeded
+
+    .\godot --headless --path godot -- --debug-boot=smoke --seed=12345
+      Smoke scene loaded
+
+Remaining risk: frame-step behavior is covered through the command service request counter and debug node bridge, but it has not been manually observed in the editor UI in this headless-only iteration.
 
 ## Context and Orientation