FA-60211 / Inventory cost layering / Open access

Inter-warehouse transfer of cost layers: exhausted layer test · case 01

A zero-cost free-goods layer is dropped from the source after a partial draw, losing units.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Layer removal tests the remaining value instead of the remaining quantity.

THE FAILURE

Layer removal tests the remaining value instead of the remaining quantity.

Unsuccessful approach: Removing when either quantity or value is zero still drops zero-cost layers with units left.

Case contract

Layers are [qty, total value]. A transfer of qty draws FIFO from src; a partial draw takes floor(t*value/qty) and leaves the residue in src; a layer is removed when its quantity reaches zero. Freight is split across the drawn pieces by quantity (floor), residual cents to the first piece, and each piece is appended to dst in draw order as the newest layers. qty<=0 or qty above src stock returns {"error"}. Return {src, dst}.

Why this case matters

Inventory valuation and cost-of-goods decisions depend on this rule.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    src = [list(l) for l in x['src']]
    dst = [list(l) for l in x['dst']]
    q = x['qty']
    if q <= 0 or q > sum(l[0] for l in src):
        return {'error': 'invalid quantity'}
    pieces = []
    while q > 0:
        lq, lv = src[0]
        t = min(q, lq)
        val = lv if t == lq else t * lv // lq
        pieces.append([t, val])
        src[0] = [lq - t, lv - val]
        if src[0][1] == 0:
            src.pop(0)
        q -= t
    fr = x['freight']
    tq = x['qty']
    shares = [fr * p[0] // tq for p in pieces]
    shares[0] += fr - sum(shares)
    for p, s in zip(pieces, shares):
        dst.append([p[0], p[1] + s])
    return {'src': src, 'dst': dst}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['span layers', {'src': [[3, 100], [5, 260]], 'dst': [[2, 90]], 'qty': 6, 'freight': 101}, {'src': [[2, 104]], 'dst': [[2, 90], [3, 151], [3, 206]]}], ['partial residue', {'src': [[3, 101], [4, 77]], 'dst': [], 'qty': 2, 'freight': 11}, {'src': [[1, 34], [4, 77]], 'dst': [[2, 78]]}], ['odd layer value', {'src': [[4, 99], [1, 5]], 'dst': [], 'qty': 3, 'freight': 1}, {'src': [[1, 25], [1, 5]], 'dst': [[3, 75]]}], ['free goods layer', {'src': [[5, 0], [2, 40]], 'dst': [[1, 10]], 'qty': 2, 'freight': 8}, {'src': [[3, 0], [2, 40]], 'dst': [[1, 10], [2, 8]]}], ['uneven freight', {'src': [[1, 50], [1, 60], [5, 300]], 'dst': [], 'qty': 5, 'freight': 14}, {'src': [[2, 120]], 'dst': [[1, 54], [1, 62], [3, 188]]}], ['insufficient', {'src': [[2, 20]], 'dst': [], 'qty': 4, 'freight': 5}, {'error': 'invalid quantity'}], ['nothing requested', {'src': [[2, 20]], 'dst': [], 'qty': 0, 'freight': 5}, {'error': 'invalid quantity'}], ['exact all', {'src': [[2, 21], [1, 12]], 'dst': [[4, 44]], 'qty': 3, 'freight': 0}, {'src': [], 'dst': [[4, 44], [2, 21], [1, 12]]}]], [['span layers', {'src': [[3, 100], [5, 260]], 'dst': [[2, 90]], 'qty': 5, 'freight': 101}, {'src': [[3, 156]], 'dst': [[2, 90], [3, 161], [2, 144]]}], ['partial residue', {'src': [[3, 101], [4, 77]], 'dst': [], 'qty': 2, 'freight': 12}, {'src': [[1, 34], [4, 77]], 'dst': [[2, 79]]}], ['odd layer value', {'src': [[4, 99], [1, 5]], 'dst': [], 'qty': 3, 'freight': 2}, {'src': [[1, 25], [1, 5]], 'dst': [[3, 76]]}], ['free goods layer', {'src': [[5, 0], [2, 40]], 'dst': [[1, 10]], 'qty': 2, 'freight': 9}, {'src': [[3, 0], [2, 40]], 'dst': [[1, 10], [2, 9]]}], ['uneven freight', {'src': [[1, 50], [1, 60], [5, 300]], 'dst': [], 'qty': 5, 'freight': 15}, {'src': [[2, 120]], 'dst': [[1, 53], [1, 63], [3, 189]]}], ['insufficient', {'src': [[2, 20]], 'dst': [], 'qty': 5, 'freight': 5}, {'error': 'invalid quantity'}], ['nothing requested', {'src': [[2, 20]], 'dst': [], 'qty': 0, 'freight': 5}, {'error': 'invalid quantity'}], ['exact all', {'src': [[2, 21], [1, 13]], 'dst': [[4, 44]], 'qty': 3, 'freight': 0}, {'src': [], 'dst': [[4, 44], [2, 21], [1, 13]]}]], [['span layers', {'src': [[3, 100], [5, 260]], 'dst': [[2, 90]], 'qty': 6, 'freight': 101}, {'src': [[2, 104]], 'dst': [[2, 90], [3, 151], [3, 206]]}], ['partial residue', {'src': [[3, 101], [4, 77]], 'dst': [], 'qty': 2, 'freight': 13}, {'src': [[1, 34], [4, 77]], 'dst': [[2, 80]]}], ['odd layer value', {'src': [[4, 99], [1, 5]], 'dst': [], 'qty': 3, 'freight': 3}, {'src': [[1, 25], [1, 5]], 'dst': [[3, 77]]}], ['free goods layer', {'src': [[5, 0], [2, 40]], 'dst': [[1, 10]], 'qty': 2, 'freight': 10}, {'src': [[3, 0], [2, 40]], 'dst': [[1, 10], [2, 10]]}], ['uneven freight', {'src': [[1, 50], [1, 60], [5, 300]], 'dst': [], 'qty': 5, 'freight': 16}, {'src': [[2, 120]], 'dst': [[1, 54], [1, 63], [3, 189]]}], ['insufficient', {'src': [[2, 20]], 'dst': [], 'qty': 6, 'freight': 5}, {'error': 'invalid quantity'}], ['nothing requested', {'src': [[2, 20]], 'dst': [], 'qty': 0, 'freight': 5}, {'error': 'invalid quantity'}], ['exact all', {'src': [[2, 21], [1, 14]], 'dst': [[4, 44]], 'qty': 3, 'freight': 0}, {'src': [], 'dst': [[4, 44], [2, 21], [1, 14]]}]], [['span layers', {'src': [[3, 100], [5, 260]], 'dst': [[2, 90]], 'qty': 5, 'freight': 101}, {'src': [[3, 156]], 'dst': [[2, 90], [3, 161], [2, 144]]}], ['partial residue', {'src': [[3, 101], [4, 77]], 'dst': [], 'qty': 2, 'freight': 14}, {'src': [[1, 34], [4, 77]], 'dst': [[2, 81]]}], ['odd layer value', {'src': [[4, 99], [1, 5]], 'dst': [], 'qty': 3, 'freight': 4}, {'src': [[1, 25], [1, 5]], 'dst': [[3, 78]]}], ['free goods layer', {'src': [[5, 0], [2, 40]], 'dst': [[1, 10]], 'qty': 2, 'freight': 11}, {'src': [[3, 0], [2, 40]], 'dst': [[1, 10], [2, 11]]}], ['uneven freight', {'src': [[1, 50], [1, 60], [5, 300]], 'dst': [], 'qty': 5, 'freight': 17}, {'src': [[2, 120]], 'dst': [[1, 54], [1, 63], [3, 190]]}], ['insufficient', {'src': [[2, 20]], 'dst': [], 'qty': 7, 'freight': 5}, {'error': 'invalid quantity'}], ['nothing requested', {'src': [[2, 20]], 'dst': [], 'qty': 0, 'freight': 5}, {'error': 'invalid quantity'}], ['exact all', {'src': [[2, 21], [1, 15]], 'dst': [[4, 44]], 'qty': 3, 'freight': 0}, {'src': [], 'dst': [[4, 44], [2, 21], [1, 15]]}]], [['span layers', {'src': [[3, 100], [5, 260]], 'dst': [[2, 90]], 'qty': 6, 'freight': 101}, {'src': [[2, 104]], 'dst': [[2, 90], [3, 151], [3, 206]]}], ['partial residue', {'src': [[3, 101], [4, 77]], 'dst': [], 'qty': 2, 'freight': 15}, {'src': [[1, 34], [4, 77]], 'dst': [[2, 82]]}], ['odd layer value', {'src': [[4, 99], [1, 5]], 'dst': [], 'qty': 3, 'freight': 5}, {'src': [[1, 25], [1, 5]], 'dst': [[3, 79]]}], ['free goods layer', {'src': [[5, 0], [2, 40]], 'dst': [[1, 10]], 'qty': 2, 'freight': 12}, {'src': [[3, 0], [2, 40]], 'dst': [[1, 10], [2, 12]]}], ['uneven freight', {'src': [[1, 50], [1, 60], [5, 300]], 'dst': [], 'qty': 5, 'freight': 18}, {'src': [[2, 120]], 'dst': [[1, 55], [1, 63], [3, 190]]}], ['insufficient', {'src': [[2, 20]], 'dst': [], 'qty': 8, 'freight': 5}, {'error': 'invalid quantity'}], ['nothing requested', {'src': [[2, 20]], 'dst': [], 'qty': 0, 'freight': 5}, {'error': 'invalid quantity'}], ['exact all', {'src': [[2, 21], [1, 16]], 'dst': [[4, 44]], 'qty': 3, 'freight': 0}, {'src': [], 'dst': [[4, 44], [2, 21], [1, 16]]}]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
span layers	`{'dst': [[2, 90], [3, 151], [3, 206]], 'src': [[2, 104]]}`	`{'dst': [[2, 90], [3, 151], [3, 206]], 'src': [[2, 104]]}`	Passed
partial residue	`{'dst': [[2, 78]], 'src': [[1, 34], [4, 77]]}`	`{'dst': [[2, 78]], 'src': [[1, 34], [4, 77]]}`	Passed
odd layer value	`{'dst': [[3, 75]], 'src': [[1, 25], [1, 5]]}`	`{'dst': [[3, 75]], 'src': [[1, 25], [1, 5]]}`	Passed
free goods layer	`{'dst': [[1, 10], [2, 8]], 'src': [[2, 40]]}`	`{'dst': [[1, 10], [2, 8]], 'src': [[3, 0], [2, 40]]}`	Failed
uneven freight	`{'dst': [[1, 54], [1, 62], [3, 188]], 'src': [[2, 120]]}`	`{'dst': [[1, 54], [1, 62], [3, 188]], 'src': [[2, 120]]}`	Passed
insufficient	`{'error': 'invalid quantity'}`	`{'error': 'invalid quantity'}`	Passed
nothing requested	`{'error': 'invalid quantity'}`	`{'error': 'invalid quantity'}`	Passed
exact all	`{'dst': [[4, 44], [2, 21], [1, 12]], 'src': []}`	`{'dst': [[4, 44], [2, 21], [1, 12]], 'src': []}`	Passed

SHA-256 / f39598cbd4d136642d60cd429d703a52a84a2fcb040d0818d14908792afdbc71

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    src = [list(l) for l in x['src']]
    dst = [list(l) for l in x['dst']]
    q = x['qty']
    if q <= 0 or q > sum(l[0] for l in src):
        return {'error': 'invalid quantity'}
    pieces = []
    while q > 0:
        lq, lv = src[0]
        t = min(q, lq)
        val = lv if t == lq else t * lv // lq
        pieces.append([t, val])
        src[0] = [lq - t, lv - val]
        if src[0][0] <= 0 or src[0][1] <= 0:
            src.pop(0)
        q -= t
    fr = x['freight']
    tq = x['qty']
    shares = [fr * p[0] // tq for p in pieces]
    shares[0] += fr - sum(shares)
    for p, s in zip(pieces, shares):
        dst.append([p[0], p[1] + s])
    return {'src': src, 'dst': dst}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['span layers', {'src': [[3, 100], [5, 260]], 'dst': [[2, 90]], 'qty': 6, 'freight': 101}, {'src': [[2, 104]], 'dst': [[2, 90], [3, 151], [3, 206]]}], ['partial residue', {'src': [[3, 101], [4, 77]], 'dst': [], 'qty': 2, 'freight': 11}, {'src': [[1, 34], [4, 77]], 'dst': [[2, 78]]}], ['odd layer value', {'src': [[4, 99], [1, 5]], 'dst': [], 'qty': 3, 'freight': 1}, {'src': [[1, 25], [1, 5]], 'dst': [[3, 75]]}], ['free goods layer', {'src': [[5, 0], [2, 40]], 'dst': [[1, 10]], 'qty': 2, 'freight': 8}, {'src': [[3, 0], [2, 40]], 'dst': [[1, 10], [2, 8]]}], ['uneven freight', {'src': [[1, 50], [1, 60], [5, 300]], 'dst': [], 'qty': 5, 'freight': 14}, {'src': [[2, 120]], 'dst': [[1, 54], [1, 62], [3, 188]]}], ['insufficient', {'src': [[2, 20]], 'dst': [], 'qty': 4, 'freight': 5}, {'error': 'invalid quantity'}], ['nothing requested', {'src': [[2, 20]], 'dst': [], 'qty': 0, 'freight': 5}, {'error': 'invalid quantity'}], ['exact all', {'src': [[2, 21], [1, 12]], 'dst': [[4, 44]], 'qty': 3, 'freight': 0}, {'src': [], 'dst': [[4, 44], [2, 21], [1, 12]]}]], [['span layers', {'src': [[3, 100], [5, 260]], 'dst': [[2, 90]], 'qty': 5, 'freight': 101}, {'src': [[3, 156]], 'dst': [[2, 90], [3, 161], [2, 144]]}], ['partial residue', {'src': [[3, 101], [4, 77]], 'dst': [], 'qty': 2, 'freight': 12}, {'src': [[1, 34], [4, 77]], 'dst': [[2, 79]]}], ['odd layer value', {'src': [[4, 99], [1, 5]], 'dst': [], 'qty': 3, 'freight': 2}, {'src': [[1, 25], [1, 5]], 'dst': [[3, 76]]}], ['free goods layer', {'src': [[5, 0], [2, 40]], 'dst': [[1, 10]], 'qty': 2, 'freight': 9}, {'src': [[3, 0], [2, 40]], 'dst': [[1, 10], [2, 9]]}], ['uneven freight', {'src': [[1, 50], [1, 60], [5, 300]], 'dst': [], 'qty': 5, 'freight': 15}, {'src': [[2, 120]], 'dst': [[1, 53], [1, 63], [3, 189]]}], ['insufficient', {'src': [[2, 20]], 'dst': [], 'qty': 5, 'freight': 5}, {'error': 'invalid quantity'}], ['nothing requested', {'src': [[2, 20]], 'dst': [], 'qty': 0, 'freight': 5}, {'error': 'invalid quantity'}], ['exact all', {'src': [[2, 21], [1, 13]], 'dst': [[4, 44]], 'qty': 3, 'freight': 0}, {'src': [], 'dst': [[4, 44], [2, 21], [1, 13]]}]], [['span layers', {'src': [[3, 100], [5, 260]], 'dst': [[2, 90]], 'qty': 6, 'freight': 101}, {'src': [[2, 104]], 'dst': [[2, 90], [3, 151], [3, 206]]}], ['partial residue', {'src': [[3, 101], [4, 77]], 'dst': [], 'qty': 2, 'freight': 13}, {'src': [[1, 34], [4, 77]], 'dst': [[2, 80]]}], ['odd layer value', {'src': [[4, 99], [1, 5]], 'dst': [], 'qty': 3, 'freight': 3}, {'src': [[1, 25], [1, 5]], 'dst': [[3, 77]]}], ['free goods layer', {'src': [[5, 0], [2, 40]], 'dst': [[1, 10]], 'qty': 2, 'freight': 10}, {'src': [[3, 0], [2, 40]], 'dst': [[1, 10], [2, 10]]}], ['uneven freight', {'src': [[1, 50], [1, 60], [5, 300]], 'dst': [], 'qty': 5, 'freight': 16}, {'src': [[2, 120]], 'dst': [[1, 54], [1, 63], [3, 189]]}], ['insufficient', {'src': [[2, 20]], 'dst': [], 'qty': 6, 'freight': 5}, {'error': 'invalid quantity'}], ['nothing requested', {'src': [[2, 20]], 'dst': [], 'qty': 0, 'freight': 5}, {'error': 'invalid quantity'}], ['exact all', {'src': [[2, 21], [1, 14]], 'dst': [[4, 44]], 'qty': 3, 'freight': 0}, {'src': [], 'dst': [[4, 44], [2, 21], [1, 14]]}]], [['span layers', {'src': [[3, 100], [5, 260]], 'dst': [[2, 90]], 'qty': 5, 'freight': 101}, {'src': [[3, 156]], 'dst': [[2, 90], [3, 161], [2, 144]]}], ['partial residue', {'src': [[3, 101], [4, 77]], 'dst': [], 'qty': 2, 'freight': 14}, {'src': [[1, 34], [4, 77]], 'dst': [[2, 81]]}], ['odd layer value', {'src': [[4, 99], [1, 5]], 'dst': [], 'qty': 3, 'freight': 4}, {'src': [[1, 25], [1, 5]], 'dst': [[3, 78]]}], ['free goods layer', {'src': [[5, 0], [2, 40]], 'dst': [[1, 10]], 'qty': 2, 'freight': 11}, {'src': [[3, 0], [2, 40]], 'dst': [[1, 10], [2, 11]]}], ['uneven freight', {'src': [[1, 50], [1, 60], [5, 300]], 'dst': [], 'qty': 5, 'freight': 17}, {'src': [[2, 120]], 'dst': [[1, 54], [1, 63], [3, 190]]}], ['insufficient', {'src': [[2, 20]], 'dst': [], 'qty': 7, 'freight': 5}, {'error': 'invalid quantity'}], ['nothing requested', {'src': [[2, 20]], 'dst': [], 'qty': 0, 'freight': 5}, {'error': 'invalid quantity'}], ['exact all', {'src': [[2, 21], [1, 15]], 'dst': [[4, 44]], 'qty': 3, 'freight': 0}, {'src': [], 'dst': [[4, 44], [2, 21], [1, 15]]}]], [['span layers', {'src': [[3, 100], [5, 260]], 'dst': [[2, 90]], 'qty': 6, 'freight': 101}, {'src': [[2, 104]], 'dst': [[2, 90], [3, 151], [3, 206]]}], ['partial residue', {'src': [[3, 101], [4, 77]], 'dst': [], 'qty': 2, 'freight': 15}, {'src': [[1, 34], [4, 77]], 'dst': [[2, 82]]}], ['odd layer value', {'src': [[4, 99], [1, 5]], 'dst': [], 'qty': 3, 'freight': 5}, {'src': [[1, 25], [1, 5]], 'dst': [[3, 79]]}], ['free goods layer', {'src': [[5, 0], [2, 40]], 'dst': [[1, 10]], 'qty': 2, 'freight': 12}, {'src': [[3, 0], [2, 40]], 'dst': [[1, 10], [2, 12]]}], ['uneven freight', {'src': [[1, 50], [1, 60], [5, 300]], 'dst': [], 'qty': 5, 'freight': 18}, {'src': [[2, 120]], 'dst': [[1, 55], [1, 63], [3, 190]]}], ['insufficient', {'src': [[2, 20]], 'dst': [], 'qty': 8, 'freight': 5}, {'error': 'invalid quantity'}], ['nothing requested', {'src': [[2, 20]], 'dst': [], 'qty': 0, 'freight': 5}, {'error': 'invalid quantity'}], ['exact all', {'src': [[2, 21], [1, 16]], 'dst': [[4, 44]], 'qty': 3, 'freight': 0}, {'src': [], 'dst': [[4, 44], [2, 21], [1, 16]]}]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
span layers	`{'dst': [[2, 90], [3, 151], [3, 206]], 'src': [[2, 104]]}`	`{'dst': [[2, 90], [3, 151], [3, 206]], 'src': [[2, 104]]}`	Passed
partial residue	`{'dst': [[2, 78]], 'src': [[1, 34], [4, 77]]}`	`{'dst': [[2, 78]], 'src': [[1, 34], [4, 77]]}`	Passed
odd layer value	`{'dst': [[3, 75]], 'src': [[1, 25], [1, 5]]}`	`{'dst': [[3, 75]], 'src': [[1, 25], [1, 5]]}`	Passed
free goods layer	`{'dst': [[1, 10], [2, 8]], 'src': [[2, 40]]}`	`{'dst': [[1, 10], [2, 8]], 'src': [[3, 0], [2, 40]]}`	Failed
uneven freight	`{'dst': [[1, 54], [1, 62], [3, 188]], 'src': [[2, 120]]}`	`{'dst': [[1, 54], [1, 62], [3, 188]], 'src': [[2, 120]]}`	Passed
insufficient	`{'error': 'invalid quantity'}`	`{'error': 'invalid quantity'}`	Passed
nothing requested	`{'error': 'invalid quantity'}`	`{'error': 'invalid quantity'}`	Passed
exact all	`{'dst': [[4, 44], [2, 21], [1, 12]], 'src': []}`	`{'dst': [[4, 44], [2, 21], [1, 12]], 'src': []}`	Passed

SHA-256 / a17500da3aef179db7e1ef35810ad38982ca8fa909646446488446bfed09d2bd

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 8 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Verification & scope

Stipulated bounded teaching model with explicit toy rules; not an accounting-standard implementation. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:46:43.449550+00:00.

Case digest / 555b93f4fce3034168f1c9307ed23754487475a83d46706695fdab6c27c05804