A* With Stable Tie-Breaking

On a grid, many paths have identical cost. A standard A* returns whichever the heap happened to pop, so the path flips between equal-cost routes on recomputation. Units visibly jitter, shuffle between two routes, or take a different path each frame. It looks like an AI bug and it is heap ordering. Worse, it makes paths non-reproducible across runs and platforms, which breaks replays.

VERIFIED: 36 tests, 6/6 mutations caught. Optimality is checked against BFS and Dijkstra rather than asserted, stability is checked by repeated runs and by differently-ordered but equivalent inputs, and diagonal movement is checked not to cut blocked corners.

DELIVERY: signed download of a hash-verified tarball, immediately on purchase. Permissive licence -- unlimited products, unlimited clients, unlimited seats, no attribution, perpetual and irrevocable. One restriction: do not republish the source as source.

Interface

What you call, and what comes back. Types and signatures only — the implementation ships with the source.

  export function octileDistance(dx: number, dy: number): number;
  export function manhattanDistance(dx: number, dy: number): number;
  export function findPath(grid: Grid, start: Point, goal: Point, options: PathOptions = {}): PathResult;