FlatRedBall2: Skill for Claude Code

Automation Mode in FlatRedBall2

Automation mode lets an external process control a running game via NDJSON (newline-delimited JSON) over stdin/stdout — one command per line in, one response per line out. The primary use case is AI agents that need to observe and interact with the game the way Playwright interacts with a browser.

Debug builds only. EnableAutomationMode() is a no-op in Release. This is intentional — automation mode exposes internal state and allows arbitrary value forcing.

Setup

// Game.Initialize, after base.Initialize():
FlatRedBallService.Default.EnableAutomationMode();

The call itself does nothing unless --frb-auto is present in the command-line args. Ship the call unconditionally; the flag controls activation.

dotnet run -- --frb-auto

That's the entire required wiring. Entities and their public properties are auto-discovered — no per-property registration.

Deterministic randomness

When automation activates, FlatRedBallService.Random is replaced with a deterministic GameRandom so recorded NDJSON sessions reproduce exactly. Pass an explicit seed to choose which run.

FlatRedBallService.Default.EnableAutomationMode(seed: 1234);

--frb-auto flag	seed: param	Result
absent	(any)	time-based — automation off, seed param ignored
present	omitted	seed 0
present	1234	seed 1234

The seed is only applied when --frb-auto activates automation; without the flag, ship-time seed values have no effect on a normal run.

Game code that constructs its own Random/GameRandom is not seeded by the engine — route gameplay randomness through FlatRedBallService.Random (or derive your own seed from it) if you want it included in the deterministic run.

Command Protocol

Each command is a JSON object terminated by \n. Each response is a JSON object on its own line, always containing ok and frame.

Command	JSON
Step N frames	{"cmd":"step"} or {"cmd":"step","count":5}
Key down/up	{"cmd":"input","type":"key","key":"Space","down":true}
Gamepad button	{"cmd":"input","type":"gamepad","player":0,"button":"A","down":true}
Gamepad axis	{"cmd":"input","type":"axis","player":0,"axis":"LeftStickX","value":0.8}
Cursor (screen px)	{"cmd":"input","type":"cursor","x":120,"y":80,"primary":true}
Cursor (world coords)	{"cmd":"input","type":"cursor","x":0,"y":0,"space":"world","primary":true}
Query active screen	{"cmd":"query","target":"screen"}
Query all entities	{"cmd":"query","target":"entities"}
Query one entity type	{"cmd":"query","target":"Player"}
Force a value	{"cmd":"set","entity":"Player","prop":"X","value":100.0}
Screenshot next Draw	{"cmd":"record_next_screenshot","path":"shot.png"}
Quit	{"cmd":"quit"}