.mtgr

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0010: Multi-game matches ​

Status: Accepted. Item 1 amended by decision 0012.

Context ​

The prototype writes match headers followed by [Game "1"], [Game "2"], and so on. Each game has its own headers, card table, and instance IDs restarting at #1. There is a single DeckId and DeckName for the match and nothing about sideboarding between games. When MTGO does not report the decklist, the file says [Issue "deckUnavailable: ..."]. Cards fetched from the sideboard during a game (for example Liquimetal Coating via Karn, the Great Creator) are written as "appears in hand from sideboard". Game results use loose Termination values (normal, concede).

Decision ​

  1. A match is a match header followed by self-contained games. Each game has its own headers and card table, and instance IDs restart for each game. Any game can be read on its own.
  2. The perspective player's full decklist, main deck and sideboard, is recorded at the start of each game when known. Sideboarding is not recorded separately; readers infer it by comparing consecutive decklists. The opponent's decklist is hidden information (decision 0001), and their cards appear as they are revealed. An unknown decklist is a defined incompleteness.
  3. Cards entering a game from outside it are recorded as coming from outside the game, labelled with where they were (for example the sideboard), with a cause.
  4. Each game records who chose to play or draw, and the choice.
  5. Game results use a defined list of reasons based on the ways to win, lose, and draw in the CR (life total, drawing from an empty library, poison, concession, card effects, and so on), plus source-level endings such as a clock running out or a disconnect.

Rules basis ​

Checked against the Comprehensive Rules effective 2026-09-25.

  • 100.4: a sideboard is "a group of additional cards the player may use to modify their deck between games of a match". The deck can change between games, so it is recorded per game.
  • 103.1: "In a match of several games, the loser of the previous game chooses who takes the first turn." Who chose and what they chose is recorded per game.
  • 400.11: "An object is outside the game if it isn't in any of the game's zones. Outside the game is not a zone." The sideboard is not a zone, so cards arriving from it come from outside the game.
  • 104.2, 104.3, 104.4: the ways to win, lose, and draw a game. These define the result reasons that come from the game rules. Endings like clock timeouts come from the source, not the CR, and are listed separately.

Alternatives rejected ​

  • An explicit change list between games ("-2 Island, +2 Spell Snare"). Rejected: two ways to state the same deck invites disagreement. A full list per game is self-contained and the change list is derivable.
  • One decklist per match. Rejected: cannot represent sideboarding.
  • Instance IDs continuing across games. Rejected: games are separate, and continuing IDs would stop a game being readable on its own.

Consequences ​

  • The spec must define the per-game decklist section, the "outside the game" origin, and the list of result reasons.
  • DeckId, DeckName, and Termination from the prototype are replaced or redefined.