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hasLuckyRounds

8.0.0 engine API transition

This method is a candidate for removal from production governors and engine exports at 8.0.0. Its 7.x route has not been removed. Final removal and standalone package-export decisions require the per-method review and external-integrator confirmation described in the transition index.

Source-local contract​

The declaration below is copied from the pinned source revision; referenced types are defined there. It is an implementation signature, not a package import example.

/**
 * Detect whether a structure contains "lucky rounds" — rounds where the matchUp count
 * transitions from odd to even, meaning one participant advances without playing.
 * This is the definitive test for a lucky-style structure, regardless of stage.
 */
export function hasLuckyRounds({ structure, matchUps }: { structure?: Structure; matchUps?: MatchUp[] });

Engine effects​

State writes: not yet assessed. Notices: not yet assessed. Governor query/mutate placement is not proof of purity; review the implementation and engine path before deciding exposure.

Consumer evidence​

The refreshed source-name scan found no name mentions in the scanned product source files. This does not establish external-integrator non-use. The manifest records repository revisions and scan exclusions. External-integrator confirmation is pending.

Availability and ownership​

  • Production governor declarations: drawsGovernor, queryGovernor.
  • Standalone package API after 8.0.0: decision pending; this page does not establish a supported import.
  • Implementation: src/query/drawDefinition/isLucky.ts — hasLuckyRounds. Source paths and aliases are not package import paths.
  • Replacement workflow: not yet established; no supported replacement is promised.
  • Test-only adapters: may exercise this implementation independently of production engine exports; this is not evidence of product use.

Preserved 7.x reference​

The passages below preserve the existing governor documentation. Engine examples describe 7.x availability, not an 8.x replacement. Source contracts take precedence where an explicitly noted correction applies.

From governors/draws-governor.md​

Determines whether a structure contains "lucky rounds" — rounds where the matchUp count transitions from odd to even, meaning one participant advances without playing. This is the definitive structural test for lucky-style draws, independent of drawType or stage.

const result = engine.hasLuckyRounds({
  structure, // optional — structure object with matchUps
  matchUps, // optional — array of matchUps (alternative to structure)
});
// returns boolean

A lucky round is identified when round N has an odd matchUp count and round N+1 has an even count. Qualifying structures with non-power-of-2 draw sizes are correctly identified as non-lucky because their round transitions don't follow this pattern.