playtesting-a-feature

Run the game and walk the feature with a RunVerification probe sent through summer_batch. The probe presses real inputs, reads state across physics frames, saves rendered frames, and writes results.json, which you combine with summer_get_diagnostics before claiming the feature done.

Clean diagnostics after boot only prove the game started, not that the feature fired. Runtime behaviors like auto-fire weapons, level transitions, and input handling only surface errors during actual play, so the feature must be exercised with a probe or live playthrough.

Extend SummerProbeBase and use report, save_frame, press, key, and finish. Always await press and key since they are coroutines, assert inequalities on physics-frame-derived state rather than exact values, and call finish before max_seconds elapses.

Yes, pin the launch with summer_play seed and fixed_fps parameters. Seed pins only the global RNG, not RandomNumberGenerator instances or randomize calls, and you must check determinism.applied in the result to confirm the pins took effect.

Run the probe directly from the shell using the Summer binary with --summer-verify, --summer-verify-out, and --summer-verify-max flags, then read results.json and saved frames from the output directory. The probe must extend the probe base class copied into the project.

Only for genuinely experiential judgments: whether the game feels right, looks good, or is fun. Input simulation is never a reason to involve the user, since probes press real actions and keys and save rendered frames for visual review.