Same defect class as the import-key fix: a hardcoded prefix/length pre-filter
layered over the checksum validators rejected valid addresses before the daemon
saw them. The send-screen recipient gate required a[0]=='R', and the payment-URI
parser accepted only 'R'/'t' with rigid length bands — so every valid P2SH /
multisig address (DragonX SCRIPT_ADDRESS=85 → 'b…') was silently refused, leaving
the Send button disabled with no usable recipient.
Centralize recipient recognition in util/address_validation:
- isTransparentAddress: Base58Check with a 21-byte version+hash160 payload —
covers P2PKH ('R…', v60) AND P2SH ('b…', v85) on every network, rejects WIF
keys / typos by real checksum.
- isShieldedAddress: Bech32 + a Sapling payment-address HRP (zs / ztestsapling /
zregtestsapling), distinguishing a payment address from a viewing key.
- isValidRecipientAddress: either of the above.
send_tab's two validity helpers (the single choke point for all 5 call sites) and
the payment-URI format check now route through these. The URI parser now
checksum-validates the recipient (fail-fast on transcription errors) rather than
being prefix/length-only.
Tests use real checksummed vectors (P2PKH/P2SH/shielded, WIF- and typo-rejection);
testPaymentUri updated off its old fake fixed-char addresses. Suite green (1/1).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
DanS
c3e81a5fa6