Each machine handles exactly one currency today (operator-set on
`dca_machines.fiat_code`). The deposit's currency is fully determined
by the machine it's recorded against, so it shouldn't be operator-
chooseable in the first place.
Surfaced during 2026-05-16 E2E testing: Jordan had a "15 USD" deposit
recorded against an EUR Sintra (operator typo in the freeform currency
input). The balance summary is currency-blind (`SUM(amount)` over
mixed currencies), so on the next cash-out the system distributed
15 EUR worth of sats on the strength of that 15 USD row. Worked out
by chance; could have over-paid by ~10% if the actual EUR/USD rate
had been further off.
Fix:
- `CreateDepositData` / `UpdateDepositData` no longer carry a
`currency` field. Any client-submitted value is silently dropped
at Pydantic validation, before reaching the handler.
- `api_create_deposit` resolves the machine's `fiat_code` and
passes it to `create_deposit(..., currency=...)` as a required
keyword arg. The deposit row's `currency` column always matches
the machine going forward.
- UI: the freeform `<q-input label="Currency">` becomes a read-only
`<q-chip>` slot on the amount field, sourced from the new
`depositMachineFiatCode` computed (resolves via the selected
client's machine).
- `m005_lock_deposit_currency_to_machine_fiat_code` migration
backfills existing rows: every `dca_deposits.currency` gets
rewritten to match its joined `dca_machines.fiat_code`. Greg's
stray `15 USD` row becomes `15 EUR` (the right answer at today's
invariant).
Multi-currency-per-machine support is explicitly out of scope here;
when hardware ships that reads multiple denominations across
currencies, the relevant changes are documented in issue #26's
"Future" section (dca_machines.fiat_codes set, currency-aware
balance summary, etc.). The current fix is "lock the input side";
that future work is "unlock it but constrained to the machine's
declared set".
3 new unit tests (`tests/test_deposit_currency.py`) lock in the
model-contract guarantees. Total suite 89 passing.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
