Until now every Cashu proof this node held was backed by a secret drawn
from OsRng and written to exactly one file. Losing wallet/ecash.json
lost the coins outright — no phrase to write down, and nothing the mint
could do about it. Ecash is a bearer instrument, so "one file, no
backup" was the sharpest edge in the wallet.
NUT-13 derives each proof's secret and blinding factor from (seed,
keyset id, counter) instead. The wallet becomes a phrase, and the coins
can be re-derived and re-claimed — here or in any other NUT-13 wallet.
The phrase is its own 24 words, derived from the node master seed over a
fixed HKDF path. Both halves matter: it is still covered by the node's
recovery phrase, so there is nothing extra to write down; but it is
portable, so restoring ecash into Minibits or cdk-cli does not mean
handing over the key to the entire node.
It sits on disk unencrypted, deliberately. The master seed needs the
operator's password to open, which no background mint or swap can ask
for; and this file lives beside wallet/ecash.json, which already holds
spendable bearer secrets in plaintext. It regenerates exactly those
secrets, so it is the same sensitivity class as the file next to it.
0600, like identity/nostr_secret, which is derived and persisted the
same way.
Counters are reserved *before* the mint call and never rolled back. A
gap costs a restore scan a few extra probes; a reused counter costs a
coin, because two proofs with the same secret can only be spent once.
Restore is the half that cannot be done offline: a re-derived secret is
not money until the mint's signature over it exists. /v1/restore returns
those signatures; unblinding reconstitutes the proofs. It is additive
and idempotent — coins already held are skipped by secret, spent ones
are counted but not added — so it is safe to press on a working wallet,
which is when someone is most likely to reach for it.
Existing nodes activate on the first visit to Settings → Ecash backup
phrase: that password prompt is the only moment the master seed can
legitimately be opened. New nodes get it at onboarding. Until then the
behaviour is exactly as before — valid proofs, no backup — and the card
says so rather than implying a backup already exists.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Redeeming ecash reported success as one line of small green text, while an
on-chain or Lightning payment got the full moment — amount, verb, and the
identifiers you can copy. That asymmetry matters most for ecash: it leaves
no public ledger entry, so if the payment is ever questioned there is
nothing to look up afterwards. Whatever isn't copyable at that instant is
simply gone.
The success pane is extracted from SendBitcoinModal into a shared
PaymentSuccessPane so Cashu and Fedimint show the *same* screen rather
than a lookalike, and the copyable-row treatment is defined once. Each
caller passes the identifiers its protocol actually has; ecash receive now
shows the issuing mint (newly returned by wallet.ecash-receive) and the
redeemed token itself, clamped so a long token doesn't flood the pane.
Also: the test-ecash switch is a proper toggle (role="switch", keyboard
focusable) rather than a checkbox — it selects which purse the wallet is
looking at, so it should read as a mode you are in.
SendBitcoinModal still carries its own copy of the markup; consolidating it
onto the shared component is a follow-up, deliberately not done in the same
change as the money-path wiring.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Executes steps 1-3 of docs/cashu-cdk-migration-plan.md, plus the test-coin
switch needed to exercise these routes without spending real sats.
Protocol layer: depend on `cashu` 0.17.5 (MIT, the crate CDK is built on,
default-features off, `wallet` only). Keyset ids now go through upstream's
`Id::from_short_keyset_id` / `ShortKeysetId` instead of the prefix match
hand-rolled in 2277fc46 — same repair, but implemented by the reference
code that defines the rule, so the next spec turn is a version bump rather
than another incident. `MintClient` feeds it the mint's `/v1/keysets` in
upstream's own `KeySetInfo` shape, parsing entries individually so one
keyset in an unmodelled unit can't block resolving the id we need.
Adding the crate required relaxing `bip39 = "=2.1.0"` to `"2.1"` (resolves
2.2.2): the exact pin held `unicode-normalization` at 0.1.22 and no
resolution existed otherwise. The pin carried no recorded rationale; seed
tests cover the bump.
Network switch: `wallet.ecash-network` / `wallet.ecash-set-network`, with a
Test mode toggle in Wallet Settings → Cashu. Cashu has no testnet, so this
points the wallet at the public `testnut` mint — but crucially each network
gets its OWN wallet and accepted-mints file, because test and real proofs
in one purse would be spendable interchangeably and the balance would be a
lie. Mainnet keeps the original filenames, so existing funds files are
untouched and switching is reversible: tests assert a real balance survives
a round trip through test mode.
Headless coverage: scripts/test-ecash-routes.sh drives every ecash RPC over
the real HTTP path (network get/set, balance, history, mint quote + claim,
send, receive, double-redeem refusal, garbage input, melt quote), restores
the node's original network on exit, and exits non-zero with the failure
count.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
