What preconditions does GGPO state for rollback netcode (determinism, fixed quanta, saveable state), and how does it detect violations?

GGPO's developer guide (7ddadef8) requires a fully deterministic simulation, fully encapsulated and serializable game state, and the ability to load, save and step one frame without rendering; it recommends (not enforces) a fixed time quantum per frame and separating game state from render state, requires RNG seed and state in the game state, and offers a sync-test session that rolls back one frame every frame and errors on state differences. Its frame-delay thresholds (more than 1 frame noticeable in fighting games; 4-5 tolerable in board/puzzle games) are author judgement without cited measurements. Curator qualifications: Curator note: the rollback-glitch example in the same section says a 2-frame flash and then calls it a '2-second flash' (documentation slip); do not quote that sentence. Sync test covers same-machine re-execution only (producer synthesis); cross-machine divergence detection not established. README statements (S28) not re-read. Documentation reading only; no GGPO build or session run. Limitations: Library documentation at one commit. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://github.com/pond3r/ggpo/blob/7ddadef8546a7d99ff0b3530c6056bc8ee4b9c0a/doc/DeveloperGuide.md",
      "note": "doc/DeveloperGuide.md lines 19-21, 176-180, 204-212, 226-236, 281-283 at 7ddadef8"
    },
    {
      "url": "https://github.com/pond3r/ggpo/blob/7ddadef8546a7d99ff0b3530c6056bc8ee4b9c0a/doc/README.md",
      "note": "doc/DeveloperGuide.md lines 19-21, 176-180, 204-212, 226-236, 281-283 at 7ddadef8"
    }
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