- duplicate detection now groups by (txid, direction), catching two CONFIRMED
  bookings of one transaction under different idempotency keys
- a CONFIRMED entry against a merely broadcast transaction is reported instead
  of silently leaving an unexplained gap in the balance equation
- attribute matching resolves the most constrained entry first, so an ambiguous
  pairing no longer strands a second entry
- grounding validator now judges 0x-prefixed hashes, lower-case identifiers and
  asset symbols, and space-separated thousands

Each fix carries a regression test named after the situation.