Round fairness

GET /api/s2s/rounds/{roundPublicId}/fairness returns one settled round’s verifiable detail: the commitment it was drawn against, plus each reel’s raw draw and resolved item. It is the data a player needs to reproduce — and so trust — the outcome. Use it to render a per-round “provably fair” view in your own history surface.

See provably fair for the verification recipe.

Request

GET https://{operator}.app.lootboxsolutions.com/api/s2s/rounds/r_01J…/fairness?playerExternalId=u_8431

Parameter	In	Required	Notes
roundPublicId	path	✅	The round to verify — the publicId from a purchase win or history.
playerExternalId	query	✅	Must own the round; another player’s round returns 404.

Response — 200

{
  "round": {
    "publicId": "r_01J…",
    "gameKey": "mystery_box",
    "status": "settled",
    "settledAt": "2026-06-16T12:00:00Z",
    "fairness": {
      "serverSeedHash": "3a7bd3…",
      "serverSeed": null,
      "clientSeed": "bF3kQ9",
      "nonce": 7,
      "algorithmKey": "hmac_sha256_v1"
    },
    "reels": [
      {
        "reelIndex": 0,
        "rawDraw": 1234567,
        "chanceUnits": 250000,
        "chancePercent": 2.5,
        "result": { "itemId": 906, "name": "Golden Sword" }
      }
    ]
  }
}

Field	Notes
fairness.serverSeedHash	The commitment this round was drawn against.
fairness.serverSeed	The plaintext seed — present only once the pair has been rotated/revealed; null while it is still active (revealing it early would expose unplayed rounds).
fairness.clientSeed / fairness.nonce / fairness.algorithmKey	The client seed, the nonce this round consumed, and the RNG algorithm.
reels[].reelIndex	The reel’s position — also the cursor mixed into the draw.
reels[].rawDraw	The integer the RNG produced for this reel.
reels[].chanceUnits / chancePercent	The won item’s odds in the box version it was drawn from.
reels[].result	The resolved item: its catalog itemId and name.

To verify a round (once the seed is revealed): recompute the RNG output from serverSeed, clientSeed, nonce and reelIndex, map it through the box version’s odds table, and confirm it lands on result.

Errors

code	HTTP	when
ROUND_NOT_FOUND	404	no round with that public id, or it is not owned by playerExternalId

A bad signature returns 401 (see authentication).