Add integration test suite

113 passing tests + 3 skipped + 8 xfailed across 10 files, covering user
expense and income flow, admin receivable/revenue, settings + auth gates,
void/reject, manual payment requests, balance display, Lightning auth
paths, reconciliation API, and pure-function units. Runs against a real
Fava subprocess and full LNbits app via asgi_lifespan; the harness
captures the auth-flow / settings / env-var disciplines surfaced during
build-out (see tests/README.md and tests/conftest.py docstring).

Eight xfailed/skipped tests carry full implementations gated behind issues
#38, #39, #40 — they flip back on automatically when those land.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_smoke.py

@@ -0,0 +1,66 @@
+"""Smoke test: validates the test harness end-to-end.
+
+If this passes, the rest of the test files can be trusted to actually exercise
+real code paths (Fava up, app up, Libra activated, FavaClient pointed at the
+test instance, BQL round-trips working, libra wallet configured, user wallet
+configured, account exists, permission granted).
+
+If this fails, no point running anything else — fix the harness first.
+"""
+import pytest
+
+from .helpers import approve_entry, get_balance, post_expense
+
+
+@pytest.mark.anyio
+async def test_smoke_submit_approve_and_see_balance(
+    client, super_user_headers, configured_user, standard_accounts,
+):
+    """Full stack round-trip: user submits an expense, admin approves it,
+    balance reflects it.
+
+    Exercises: libra wallet config (session fixture), user wallet config
+    (configured_user fixture), permission grant (configured_user fixture),
+    Beancount entry construction, Fava add_entries HTTP call, pending→cleared
+    flag transition via the source-slice mutation path, BQL balance query
+    (which filters by flag = '*' so the approve step is load-bearing).
+    """
+    _, wallet = configured_user
+
+    # User pays 50 EUR for groceries — entry posted with flag `!` (pending).
+    entry = await post_expense(
+        client,
+        wallet_inkey=wallet.inkey,
+        user_wallet_id=wallet.id,
+        amount="50.00",
+        currency="EUR",
+        description="Smoke test expense",
+        expense_account=standard_accounts["expense_food"]["name"],
+    )
+    entry_id = entry.get("id")
+    assert entry_id, f"expense response missing id: {entry}"
+
+    # Pending entries are excluded from the cleared-only balance query —
+    # confirm balance is still zero at this point.
+    pending_balance = await get_balance(client, wallet_inkey=wallet.inkey)
+    pending_eur = pending_balance.get("fiat_balances", {}).get("EUR")
+    assert pending_eur in (None, 0, "0", "0.00"), (
+        f"pending expense should not affect cleared balance, got {pending_eur}"
+    )
+
+    # Admin approves the pending entry, flipping its flag from `!` to `*`.
+    await approve_entry(
+        client, super_user_headers=super_user_headers, entry_id=entry_id,
+    )
+
+    # Balance now reflects the 50 EUR Libra owes the user.
+    # Sign convention (per get_user_balance_bql docstring): the API returns
+    # the balance from libra's perspective — negative on Liabilities:Payable
+    # means libra owes the user. So a 50 EUR expense surfaces as -50 EUR.
+    balance = await get_balance(client, wallet_inkey=wallet.inkey)
+    fiat = balance.get("fiat_balances", {})
+    eur = fiat.get("EUR")
+    assert eur is not None, f"expected EUR in fiat_balances after approve, got {balance}"
+    assert float(eur) == pytest.approx(-50.0), (
+        f"expected EUR balance of -50.00 (libra-owes-user) after approve, got {eur}"
+    )