Sync Status: per-source ingestion health page with nav warning badge

The n8n flows fail invisibly from the app's perspective (review UX-17,
the top trust gap). /api/v1/sync-status derives last-received + cadence
thresholds for BAC, salary, municipal, pensions and exchange rate from
existing data — no n8n integration needed. New Sincronización page
shows per-source freshness and a hint to check n8n; the sidebar item
gets an amber dot when any source is stale. Verified live against the
dev DB (correctly flags its stale BAC data at 43 days).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/app/api/v1/endpoints/sync_status.py

@@ -0,0 +1,20 @@
+from fastapi import APIRouter, Depends
+from sqlmodel import Session
+
+from app.auth import get_current_user
+from app.db import get_session
+from app.services.sync_status import compute_sync_status
+
+router = APIRouter(prefix="/sync-status", tags=["sync-status"])
+
+
+@router.get("/")
+def sync_status(
+    session: Session = Depends(get_session),
+    _user: str = Depends(get_current_user),
+):
+    sources = compute_sync_status(session)
+    return {
+        "sources": sources,
+        "warnings": sum(1 for s in sources if s["status"] in ("warning", "never")),
+    }

backend/app/api/v1/router.py

@@ -14,6 +14,7 @@ from app.api.v1.endpoints import (
     salarios,
     savings_accrual,
     settings,
+    sync_status,
     tokens,
     transactions,
 )
@@ -34,3 +35,4 @@ api_router.include_router(salarios.router)
 api_router.include_router(pensions.router)
 api_router.include_router(municipal_receipts.router)
 api_router.include_router(savings_accrual.router)
+api_router.include_router(sync_status.router)

backend/app/services/sync_status.py

@@ -0,0 +1,94 @@
+"""Per-source ingestion health, derived from existing data (review UX-17).
+
+The n8n flows fail silently from the app's perspective — a parser break just
+looks like missing data. This derives "when did we last receive something from
+each source" plus a cadence threshold, so a stalled flow becomes visible
+in-app without any n8n integration.
+"""
+
+from dataclasses import dataclass
+
+from sqlmodel import Session, func, select
+
+from app.models.models import (
+    Bank,
+    ExchangeRate,
+    MunicipalReceipt,
+    PensionSnapshot,
+    Transaction,
+    TransactionSource,
+    TransactionType,
+)
+from app.timeutil import utcnow
+
+
+@dataclass
+class SourceSpec:
+    key: str
+    label: str
+    warn_after_days: float
+    description: str
+
+
+# Cadences: BAC emails arrive near-daily with normal card use; salary is
+# biweekly/monthly; municipal and pension are monthly; rates refresh every 6h.
+SOURCES: list[SourceSpec] = [
+    SourceSpec("bac_credit_card", "BAC Tarjeta de Crédito", 7,
+               "Correos de compra parseados por n8n"),
+    SourceSpec("salary", "Depósitos de Salario", 35,
+               "Correos de depósito parseados por n8n"),
+    SourceSpec("municipal", "Recibos Municipales", 40,
+               "PDF mensual vía n8n (cron)"),
+    SourceSpec("pensions", "Estados de Pensión", 40,
+               "PDFs diarios/mensuales vía n8n"),
+    SourceSpec("exchange_rate", "Tipo de Cambio", 1,
+               "Actualización automática cada 6 horas"),
+]
+
+
+def _last_received(session: Session, key: str):
+    if key == "bac_credit_card":
+        return session.exec(
+            select(func.max(Transaction.created_at)).where(
+                Transaction.source == TransactionSource.CREDIT_CARD,
+                Transaction.bank == Bank.BAC,
+            )
+        ).one()
+    if key == "salary":
+        return session.exec(
+            select(func.max(Transaction.created_at)).where(
+                Transaction.transaction_type == TransactionType.SALARY
+            )
+        ).one()
+    if key == "municipal":
+        return session.exec(select(func.max(MunicipalReceipt.created_at))).one()
+    if key == "pensions":
+        return session.exec(select(func.max(PensionSnapshot.created_at))).one()
+    if key == "exchange_rate":
+        return session.exec(select(func.max(ExchangeRate.fetched_at))).one()
+    raise ValueError(f"unknown sync source: {key}")
+
+
+def compute_sync_status(session: Session) -> list[dict]:
+    now = utcnow()
+    out: list[dict] = []
+    for spec in SOURCES:
+        last = _last_received(session, spec.key)
+        if last is None:
+            status = "never"
+            age_days = None
+        else:
+            age_days = (now - last).total_seconds() / 86400
+            status = "ok" if age_days <= spec.warn_after_days else "warning"
+        out.append(
+            {
+                "key": spec.key,
+                "label": spec.label,
+                "description": spec.description,
+                "last_received": last.isoformat() if last else None,
+                "age_days": round(age_days, 1) if age_days is not None else None,
+                "warn_after_days": spec.warn_after_days,
+                "status": status,
+            }
+        )
+    return out