fix: persist and propagate key constraints from Lightning invoices

LightningInvoice had no columns for balance_limit, balance_limit_reset,
or validity_date. SQLModel silently dropped these constructor kwargs, so
create_api_key_from_invoice always produced an unconstrained key.

Add the three columns to LightningInvoice with a migration, and wire them
through to the ApiKey in create_api_key_from_invoice, matching the pattern
already used in the child key creation path.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

migrations/versions/a2b3c4d5e6f7_add_constraints_to_lightning_invoices.py

@@ -0,0 +1,26 @@
+"""Add balance_limit, balance_limit_reset, validity_date to lightning_invoices
+
+Revision ID: a2b3c4d5e6f7
+Revises: f1a2b3c4d5e6
+Create Date: 2026-06-03 00:00:00.000000
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+revision = "a2b3c4d5e6f7"
+down_revision = "f1a2b3c4d5e6"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("lightning_invoices", sa.Column("balance_limit", sa.Integer(), nullable=True))
+    op.add_column("lightning_invoices", sa.Column("balance_limit_reset", sa.String(), nullable=True))
+    op.add_column("lightning_invoices", sa.Column("validity_date", sa.Integer(), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("lightning_invoices", "validity_date")
+    op.drop_column("lightning_invoices", "balance_limit_reset")
+    op.drop_column("lightning_invoices", "balance_limit")

routstr/core/db.py

@@ -140,6 +140,18 @@ class LightningInvoice(SQLModel, table=True):  # type: ignore
     )
     expires_at: int = Field(description="Unix timestamp when invoice expires")
     paid_at: int | None = Field(default=None, description="Unix timestamp when paid")
+    balance_limit: int | None = Field(
+        default=None,
+        description="Max spendable msats for the created key",
+    )
+    balance_limit_reset: str | None = Field(
+        default=None,
+        description="Reset policy for balance limit (daily, weekly, monthly)",
+    )
+    validity_date: int | None = Field(
+        default=None,
+        description="Unix timestamp after which the created key expires",
+    )
 
 
 class CashuTransaction(SQLModel, table=True):  # type: ignore

routstr/lightning.py

@@ -269,6 +269,9 @@ async def create_api_key_from_invoice(
         balance=invoice.amount_sats * 1000,  # Convert to msats
         refund_currency="sat",
         refund_mint_url=settings.primary_mint,
+        balance_limit=invoice.balance_limit,
+        balance_limit_reset=invoice.balance_limit_reset,
+        validity_date=invoice.validity_date,
     )
 
     session.add(api_key)

tests/integration/test_lightning_invoice_constraints.py

@@ -0,0 +1,159 @@
+"""Integration tests for Lightning invoice key constraint fields.
+
+Covers two things:
+- The three constraint fields (balance_limit, balance_limit_reset, validity_date)
+  are persisted on LightningInvoice and survive a DB round-trip.
+- create_api_key_from_invoice propagates those fields to the created ApiKey,
+  so the constraints are actually enforced when the key is used.
+"""
+
+from __future__ import annotations
+
+import time
+from unittest.mock import AsyncMock, patch
+
+import pytest
+from sqlmodel.ext.asyncio.session import AsyncSession
+
+from routstr.core.db import ApiKey, LightningInvoice
+from routstr.lightning import create_api_key_from_invoice
+
+
+def _make_invoice(**kwargs: object) -> LightningInvoice:
+    base = dict(
+        id="inv_test_001",
+        bolt11="lnbc1000n1test",
+        amount_sats=1000,
+        description="test invoice",
+        payment_hash="deadbeef" * 8,
+        status="paid",
+        purpose="create",
+        expires_at=int(time.time()) + 3600,
+        paid_at=int(time.time()),
+    )
+    base.update(kwargs)
+    return LightningInvoice(**base)  # type: ignore[arg-type]
+
+
+@pytest.fixture(autouse=True)
+def mock_wallet_mint() -> object:
+    with patch("routstr.lightning.get_wallet") as mock_get_wallet:
+        wallet = AsyncMock()
+        wallet.mint = AsyncMock(return_value=[])
+        mock_get_wallet.return_value = wallet
+        yield mock_get_wallet
+
+
+# ---------------------------------------------------------------------------
+# Persistence
+# ---------------------------------------------------------------------------
+
+@pytest.mark.asyncio
+async def test_invoice_persists_balance_limit(
+    integration_session: AsyncSession,
+) -> None:
+    invoice = _make_invoice(balance_limit=5000)
+    integration_session.add(invoice)
+    await integration_session.commit()
+
+    stored = await integration_session.get(LightningInvoice, invoice.id)
+    assert stored is not None
+    assert stored.balance_limit == 5000
+
+
+@pytest.mark.asyncio
+async def test_invoice_persists_balance_limit_reset(
+    integration_session: AsyncSession,
+) -> None:
+    invoice = _make_invoice(balance_limit=5000, balance_limit_reset="daily")
+    integration_session.add(invoice)
+    await integration_session.commit()
+
+    stored = await integration_session.get(LightningInvoice, invoice.id)
+    assert stored is not None
+    assert stored.balance_limit_reset == "daily"
+
+
+@pytest.mark.asyncio
+async def test_invoice_persists_validity_date(
+    integration_session: AsyncSession,
+) -> None:
+    expiry = int(time.time()) + 86400
+    invoice = _make_invoice(validity_date=expiry)
+    integration_session.add(invoice)
+    await integration_session.commit()
+
+    stored = await integration_session.get(LightningInvoice, invoice.id)
+    assert stored is not None
+    assert stored.validity_date == expiry
+
+
+# ---------------------------------------------------------------------------
+# Propagation to ApiKey
+# ---------------------------------------------------------------------------
+
+@pytest.mark.asyncio
+async def test_created_key_receives_balance_limit(
+    integration_session: AsyncSession,
+) -> None:
+    invoice = _make_invoice(balance_limit=8000)
+    integration_session.add(invoice)
+    await integration_session.flush()
+
+    api_key = await create_api_key_from_invoice(invoice, integration_session)
+    await integration_session.commit()
+
+    stored_key = await integration_session.get(ApiKey, api_key.hashed_key)
+    assert stored_key is not None
+    assert stored_key.balance_limit == 8000
+
+
+@pytest.mark.asyncio
+async def test_created_key_receives_balance_limit_reset(
+    integration_session: AsyncSession,
+) -> None:
+    invoice = _make_invoice(balance_limit=8000, balance_limit_reset="monthly")
+    integration_session.add(invoice)
+    await integration_session.flush()
+
+    api_key = await create_api_key_from_invoice(invoice, integration_session)
+    await integration_session.commit()
+
+    stored_key = await integration_session.get(ApiKey, api_key.hashed_key)
+    assert stored_key is not None
+    assert stored_key.balance_limit_reset == "monthly"
+
+
+@pytest.mark.asyncio
+async def test_created_key_receives_validity_date(
+    integration_session: AsyncSession,
+) -> None:
+    expiry = int(time.time()) + 86400
+    invoice = _make_invoice(validity_date=expiry)
+    integration_session.add(invoice)
+    await integration_session.flush()
+
+    api_key = await create_api_key_from_invoice(invoice, integration_session)
+    await integration_session.commit()
+
+    stored_key = await integration_session.get(ApiKey, api_key.hashed_key)
+    assert stored_key is not None
+    assert stored_key.validity_date == expiry
+
+
+@pytest.mark.asyncio
+async def test_created_key_without_constraints_has_none_fields(
+    integration_session: AsyncSession,
+) -> None:
+    invoice = _make_invoice()
+    integration_session.add(invoice)
+    await integration_session.flush()
+
+    api_key = await create_api_key_from_invoice(invoice, integration_session)
+    await integration_session.commit()
+
+    stored_key = await integration_session.get(ApiKey, api_key.hashed_key)
+    assert stored_key is not None
+    assert stored_key.balance_limit is None
+    assert stored_key.balance_limit_reset is None
+    assert stored_key.validity_date is None