FA-100556 / Mixture of experts dispatch / Open access

Overflow tokens disappear despite available alternatives · case 01

Overflow tokens disappear despite available alternatives.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Each token commits to its first choice before capacity is checked.

THE FAILURE

Each token commits to its first choice before capacity is checked.

Unsuccessful approach: Overflow is rerouted to an alternate expert without checking that the alternate has remaining capacity.

Case contract

Each token has ranked (expert,score) alternatives; in token order assign its highest ranked expert with remaining per-expert capacity, or omit it.

Why this case matters

A deterministic toy router makes this dispatch decision independently inspectable.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(choices,capacity):
    return [[i,max(row,key=lambda x:x[1])[0]] for i,row in enumerate(choices) if row]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
e='e'+str(N); f='f'+str(N); rows=[[(e,9),(f,8)],[(e,7),(f,6)],[(f,5),(e,4)]]
check('fallback used',solve(rows,1),[[0,e],[1,f]])
check('fallback capacity respected',solve([[(e,5),(f,4)],[(e,3),(f,2)],[(e,1),(f,0)]],1),[[0,e],[1,f]])
check('capacity two',solve(rows,2),[[0,e],[1,e],[2,f]])
check('zero capacity',solve(rows,0),[])
check('empty batch',solve([],N),[])
check('single route',solve([[(e,1)]],1),[[0,e]])
check('no alternatives',solve([[],[(e,1)]],1),[[1,e]])
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
fallback used	`[[0, 'e1'], [1, 'e1'], [2, 'f1']]`	`[[0, 'e1'], [1, 'f1']]`	Failed
fallback capacity respected	`[[0, 'e1'], [1, 'e1'], [2, 'e1']]`	`[[0, 'e1'], [1, 'f1']]`	Failed
capacity two	`[[0, 'e1'], [1, 'e1'], [2, 'f1']]`	`[[0, 'e1'], [1, 'e1'], [2, 'f1']]`	Passed
zero capacity	`[[0, 'e1'], [1, 'e1'], [2, 'f1']]`	`[]`	Failed
empty batch	`[]`	`[]`	Passed
single route	`[[0, 'e1']]`	`[[0, 'e1']]`	Passed
no alternatives	`[[1, 'e1']]`	`[[1, 'e1']]`	Passed

SHA-256 / 369fd8278ca1aedd1054fb4478eaba30c05d1d74d903b3be77022109a33d9873

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(choices,capacity):
    out=[]; used={}
    for i,row in enumerate(choices):
     ranked=sorted(row,key=lambda x:(-x[1],x[0]))
     if not ranked: continue
     primary=ranked[0][0]
     if used.get(primary,0)<capacity:
      out.append([i,primary]); used[primary]=used.get(primary,0)+1
     elif len(ranked)>1:
      out.append([i,ranked[1][0]])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
e='e'+str(N); f='f'+str(N); rows=[[(e,9),(f,8)],[(e,7),(f,6)],[(f,5),(e,4)]]
check('fallback used',solve(rows,1),[[0,e],[1,f]])
check('fallback capacity respected',solve([[(e,5),(f,4)],[(e,3),(f,2)],[(e,1),(f,0)]],1),[[0,e],[1,f]])
check('capacity two',solve(rows,2),[[0,e],[1,e],[2,f]])
check('zero capacity',solve(rows,0),[])
check('empty batch',solve([],N),[])
check('single route',solve([[(e,1)]],1),[[0,e]])
check('no alternatives',solve([[],[(e,1)]],1),[[1,e]])
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
fallback used	`[[0, 'e1'], [1, 'f1'], [2, 'f1']]`	`[[0, 'e1'], [1, 'f1']]`	Failed
fallback capacity respected	`[[0, 'e1'], [1, 'f1'], [2, 'f1']]`	`[[0, 'e1'], [1, 'f1']]`	Failed
capacity two	`[[0, 'e1'], [1, 'e1'], [2, 'f1']]`	`[[0, 'e1'], [1, 'e1'], [2, 'f1']]`	Passed
zero capacity	`[[0, 'f1'], [1, 'f1'], [2, 'e1']]`	`[]`	Failed
empty batch	`[]`	`[]`	Passed
single route	`[[0, 'e1']]`	`[[0, 'e1']]`	Passed
no alternatives	`[[1, 'e1']]`	`[[1, 'e1']]`	Passed

SHA-256 / ea2d5027afe932a3ec60f30fe8fc7a12dfa63fa7e2253b8e490282034d0a20a6

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 7 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.

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Verification & scope

Inputs are finite toy scores and routes; the contract does not model a production model, accelerator, or learned routing quality. 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 2026-09-30T16:48:36.731021+00:00.

Case digest / a1812701cba4d313d8fa0a0aba3c445fe01b7873ef3da07d123c8801faaf49c3