## Problem
A paying user reported that "Save & Sync" on the account mapping screen
did nothing — no error, no navigation, nothing.
EnableBanking returned their Société Générale card (`CB Visa`) with
`uid: null`:
```json
{"uid": null, "name": "CB Visa", "cash_account_type": "CARD", "account_id": {"iban": null, "other": {"scheme_name": "CPAN", "identification": "************8210"}}}
```
The page renders one mapping row per pending account, so the form posted
`bank_account_uid: null`. `MapAccountsRequest` requires it, the request
422'd, and since the page never rendered validation errors the button
looked dead. The user retried the connection six times.
A second problem kept them from doing what they actually wanted: both
accounts reported `currency: "XXX"` — ISO 4217 for "no currency".
`getCompatibleAccounts` filtered their existing EUR accounts against
`"XXX"`, matched nothing, and the "Link to existing account" option was
never rendered. The backend already knew `XXX` isn't a currency
(`AccountUserCurrencyService::resolveImportedCurrency`); the frontend
didn't.
## Fix
- Accounts without a uid are filtered out of the mapping screen. They
can never be synced anyway — every sync service early-returns on an
empty `external_account_id` — and `CreatesAccountsFromPending` already
skipped them during onboarding. That rule now lives in one place,
`BankingConnection::mappablePendingAccounts()`.
- The skipped accounts are named on the page, so users don't go hunting
for an account they can see in their bank app.
- A connection where *no* account has a uid is closed out instead of
parking on a mapping page that could only ever 422.
- Validation errors surface as a toast, with app-authored messages in
`MapAccountsRequest::messages()` instead of raw field paths.
- `XXX` (and a blank/lowercase variant) is treated as "unknown
currency": the code isn't displayed, and it no longer filters out every
linkable account.
## Scope
One user affected in production (the reporter). Their connection has one
valid account alongside the card, so this fix unblocks them on deploy —
no data change needed.
## Testing
- `tests/Feature/OpenBanking` — 315 passed, including two new cases:
uid-less accounts are hidden and named, and an all-uid-less connection
is closed rather than left awaiting mapping.
- Browser QA against a local reproduction of the exact production
payload: only `Compte Bancaire` is offered, `CB Visa` is named as
skipped, "Link to existing account" appears despite the `XXX` currency,
submitting without picking an account toasts the error, and picking
`Dany SG` links it (`external_account_id` set, connection `active`).
## Demo
https://github.com/user-attachments/assets/6275834a-a518-47b9-9015-a698e5926d71
<!-- PLACEHOLDER: drag account-mapping-fix-qa.mp4 here -->
## Not in this PR
`AuthorizationController::refreshAccountIds()` consumes the raw pending
list on reconnect; its positional fallback can pair a legacy account
with a uid-less entry. Not reachable for any account in production
today, it belongs to a different flow, and it deserves its own test —
filed separately rather than smuggled in here.
eb60f2eb30