The T6 MVP core: both halves of a channel co-signed self-custodially, each party holding
only its own key. Validated on chipnet + BTC signet.
- Phase 1 — engine library (scripts/lib/t6-engine.mjs): T6Board with open/pay/settleHtlc/
readState behind a clean API + injected per-party signers. Demo t6-engine-demo.mjs
(open + 2 pays + read on chipnet).
- Phase 2 — self-custodial BCH board (contracts/BchChannelBoardUni.cash +
t6-selfcustody-uni-demo.mjs): a state update is authorized by BOTH parties' checkDataSig
over the state MESSAGE (channelId||state||balances), signed independently with each own
key — no transaction co-signing. Sidesteps cashscript's inability to co-sign a tx across
two key-holders (the both-signed board would need the WalletConnect signing path). channelId
is a bytes32 constructor arg both sides control (no VM tokenCategory byte-order ambiguity;
makes the address unique per channel = anti-replay). Validated update 932ad30d.
- Phase 3 — self-custodial BTC 2-of-2 (scripts/lib/t6-btc.mjs +
t6-btc-selfcustody-close.mjs): real signet 2-of-2 funded + cooperatively closed to the
board's agreed split, co-signed via bitcoinjs PSBT (Alice signs → base64 → Bob signs →
finalize). Neither party holds the other's key. PSBT multi-party signing is native/clean,
unlike the BCH board. Fund 98fa1d2d, close 413e52f8 (Alice 5700 / Bob 3800).
The transport carries only a PSBT (base64) or a 64-byte state signature — small, dumb, non-LN.
Remaining: Phase 4 (self-custodial wallet UI). Snapshots 0185, 0186.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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