Under review at INFORMS Journal on Computing.

PrecPack is an open-source exact solver for bin packing with generalized precedence constraints, including assembly line balancing and precedence-constrained bin packing as special cases. It extends branch-bound-and-remember search to arbitrary nonnegative precedence weights, retaining restrictions that remain active across future bins. The solver combines dominance rules and conflict-aware lower bounds with optional root column generation, using fixed-point arithmetic to obtain numerically valid bounds. Its C++ implementation provides programming and command-line interfaces, independent solution checking, explicit termination statuses, and reproducible batch execution. Same-machine, single-threaded comparisons show improved solution times and more optimality proofs than leading source-available BBR implementations on classical assembly-line benchmarks. The core search requires no commercial optimization software.