Launching Godot with --automation=<dir> activates an AutomationHarness
node that polls <dir>/inbox/ for JSON command files, executes them via
a thin facade over existing public surfaces (GameSim, InputMapper,
EventAnimator, ControlBar, PieceStockPanel), and writes results plus
screenshots back to disk. The black-box simulation boundary is not
crossed — every command routes through the same signals/methods a real
player would trigger.
A stdlib-only Python helper (tools/automation/harness.py) wraps the
protocol for test scripts and interactive REPLs. Smoke test passes
end-to-end: load mission, place a piece, step 10 turns, capture 14
1280x720 PNGs, handle rejections, quit cleanly. Existing 102 engine
unit tests still green.
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