feat: stale manual balance detection — nudge to update or snooze

[tomfunk]

Problem

Manual accounts (createManualAccount — type='other', subtype='manual') and CSV accounts only get a new balance_history row when the user edits the value by hand (updateAccountValue writes a row for today). Every net worth / health query (core/health.ts, getNetWorthHistory, getAccountsWithBalances) uses each account's latest balance row regardless of age, so a manual balance entered six months ago silently distorts net worth, runway, FIRE progress, and the Health page — with no indication anything is stale.

The Accounts screens (TUI + GUI) already show "synced " per account via last_synced (getLinkedAccounts computes MAX(date) from balance_history), but nothing warns when that date is old, and manual accounts will always go stale without user action.

Proposed solution

• Staleness threshold for manually-maintained balances (manual + CSV accounts), e.g. default 30–60 days, configurable via the settings table.
• Accounts screen: stale badge / warning color on the "synced " text for accounts past the threshold, with a quick path to the existing edit-value flow.
• Health page: a small notice when any included (non-excluded) manual balance is stale, e.g. "2 manual balances are >60 days old — net worth may be inaccurate", so the numbers on that page carry a caveat.
• Snooze: per-account "remind me later" that suppresses the warning until a date. Could be a stale_snooze_until column on accounts or a settings key per account id. Snoozing should be cheap — the point is a nudge, not nagging (same principle as Plaid sync health warnings #21: in-context, not modal).
• MCP: list_accounts could include daysSinceUpdate / needsAttention so the agent can prompt too — dovetails with the flags proposed in Plaid sync health warnings #21.

Notes

• Plaid sync health warnings #21 covers Plaid-linked accounts failing to sync (link errors, expired tokens). This issue is the complement: accounts that are designed to be updated by hand and have no sync to fail.
• An alternative to snooze-per-account: let the user mark an account "slow-moving" (e.g. house value) with a longer threshold instead of repeatedly snoozing.

[john-frandsen]

One angle worth considering on the design here: the staleness problem hits a very different severity depending on geography.

For US accounts, Plaid-linked accounts (covered by #21) are the sync path, and manual/CSV is the fallback. But for European/UK users, the situation inverts — Plaid's EU bank coverage is sparse and expensive, so every bank account effectively becomes a "manual" account with the exact stale-balance distortion this issue describes. The nudge UX is the right immediate fix, but the root cause for those accounts is the absence of an automated sync path.

The barrier is PSD2/eIDAS certificate requirements — most EU/UK bank-data aggregators require a Qualified Certificate of Authentication (QWAC/QCert) that costs €2-10K/year and takes months to obtain, which is why personal finance apps tend to skip EU sync entirely. There are cert-free alternatives (I maintain open-banking.io, a PSD2 aggregation layer that doesn't require the eIDAS cert) but the broader point is that fungible's stale-balance UX is going to matter most for exactly the accounts that can't get Plaid sync.

For the implementation, a couple of notes:

• daysSinceUpdate in the MCP list_accounts response is a great call — it lets the agent proactively flag "your net worth includes 2 accounts not updated in 90+ days" without the user having to open the Accounts screen.
• For the snooze column: stale_snooze_until on accounts is simpler than a per-account settings key. One UPDATE accounts SET stale_snooze_until = date('now', '+30 days') WHERE id = ? on snooze, and the staleness check becomes WHERE last_synced < date('now', '-{threshold} days') AND (stale_snooze_until IS NULL OR stale_snooze_until < date('now')).
• The threshold might want to be per-account-type rather than global — investment/retirement accounts legitimately update quarterly, while checking accounts going 30+ days stale likely indicate a sync failure or abandoned account.

Happy to help scope an EU/UK sync provider if there's interest down the road.