Cloud Cost Allocator with Honest Unallocated

Allocates shared cloud spend to owners by tag rules, in integer minor units, with what it CANNOT allocate reported rather than absorbed.

THE SILENT FAILURE. Showback and chargeback reports always reconcile, because anything unattributable is quietly spread or dropped. Untagged resources are the largest line item in most real accounts, so a report that absorbs them tells every team a number wrong in the same direction. Splitting by percentages that do not sum to exactly 100 silently loses or invents money. Doing it in floating point loses fractions of a cent per row, which across a million rows is a discrepancy nobody can trace. A resource matching two rules is charged twice or once depending on iteration order.

UNALLOCATED IS A FIRST-CLASS BUCKET and is never redistributed silently -- redistribution is explicit and reported separately. The split reconciles EXACTLY, with the integer-division remainder assigned by a documented largest-remainder rule so the parts always sum to the whole. Overlapping rules are REFUSED rather than resolved by iteration order.

TWO REAL BUGS FOUND BEFORE RELEASE. The reconciliation gate -- the function the README tells you to call right before a number reaches a human -- compared three pre-aggregated integers to each other and never read the line items, so a forged result claiming ten million in the array alongside a summary of one hundred was certified as correct. And once that was fixed, a forgery caught by the per-owner check still reported difference zero beside not-ok, which is a refusal that cannot say what is wrong. Reconciliation now recomputes from the arrays AND names the failing check with its real numbers.

VERIFIED: 87 tests. Every mutation was observed FAILING before the source was restored -- a test never seen to fail is a decoration. Independently reviewed by a verifier whose job was to find what is wrong, not to agree.

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.

This is an engineering tool, not legal, tax or accounting advice. It computes and reports; a human decides.

Interface

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

  export function isNonNegativeSafeInteger(n: number): boolean;
  export function assertNonNegativeSafeInteger(n: number, label: string): void;
  export function splitByWeights(total: number, weights: readonly number[]): number[];
  export function sumMinorUnits(amounts: readonly number[]): number;
  export function allocateByPercentage( totalMinorUnits: number, shares: readonly PercentageShare[], toleranceBasisPoints = 0, ): PercentageAllocationResult;
  export function reconcileAllocation(result: AllocationResult): ReconciliationReport;
  export function assertAllocationReconciles(result: AllocationResult): void;
  export function reconcilePercentageSplit(result: PercentageAllocationResult): ReconciliationReport;
  export function assertPercentageSplitReconciles(result: PercentageAllocationResult): void;
  export function reconcileRedistribution(result: RedistributionResult): ReconciliationReport;
  export function assertRedistributionReconciles(result: RedistributionResult): void;
  export function redistributeUnallocated( base: AllocationResult, strategy: RedistributionStrategy, ): RedistributionResult;

  export type UnallocatedReason = "no_matching_rule";
  export type RedistributionStrategy = "equal" | "proportional";