Merge pull request #411 from Routstr/408-fix-swap

fix swapping the primary mint

routstr/balance.py

@@ -154,9 +154,23 @@ async def topup_wallet_endpoint(
             raise HTTPException(status_code=400, detail="Token already spent")
         elif "invalid" in error_msg.lower() or "decode" in error_msg.lower():
             raise HTTPException(status_code=400, detail="Invalid token format")
+        elif "insufficient" in error_msg.lower() or "melt fee" in error_msg.lower():
+            raise HTTPException(
+                status_code=400,
+                detail=f"Token value is too small to cover swap fees. {error_msg}",
+            )
+        elif "failed to melt" in error_msg.lower():
+            raise HTTPException(
+                status_code=400,
+                detail=f"Failed to swap foreign mint token. {error_msg}",
+            )
         else:
-            raise HTTPException(status_code=400, detail="Failed to redeem token")
-    except Exception:
+            raise HTTPException(status_code=400, detail=f"Failed to redeem token: {error_msg}")
+    except Exception as e:
+        logger.error(
+            "topup_wallet_endpoint: unhandled error",
+            extra={"error": str(e), "error_type": type(e).__name__},
+        )
         raise HTTPException(status_code=500, detail="Internal server error")
     return {"msats": amount_msats}
 

routstr/wallet.py

@@ -64,11 +64,12 @@ async def swap_to_primary_mint(
     token_obj: Token, token_wallet: Wallet
 ) -> tuple[int, str, str]:
     logger.info(
-        "swap_to_primary_mint",
+        "swap_to_primary_mint: starting",
         extra={
-            "mint": token_obj.mint,
-            "amount": token_obj.amount,
+            "foreign_mint": token_obj.mint,
+            "token_amount": token_obj.amount,
             "unit": token_obj.unit,
+            "primary_mint": settings.primary_mint,
         },
     )
     # Ensure amount is an integer
@@ -91,16 +92,105 @@ async def swap_to_primary_mint(
         minted_amount = int(amount_msat_after_fee // 1000)
     else:
         minted_amount = int(amount_msat_after_fee)
+
+    logger.info(
+        "swap_to_primary_mint: fee estimation",
+        extra={
+            "token_amount_sat": amount_msat // 1000,
+            "estimated_fee_sat": estimated_fee_sat,
+            "minted_amount": minted_amount,
+            "minted_unit": settings.primary_mint_unit,
+        },
+    )
+
     mint_quote = await primary_wallet.request_mint(minted_amount)
+    logger.info(
+        "swap_to_primary_mint: mint quote received",
+        extra={"mint_quote_id": mint_quote.quote},
+    )
 
     melt_quote = await token_wallet.melt_quote(mint_quote.request)
-    _ = await token_wallet.melt(
-        proofs=token_obj.proofs,
-        invoice=mint_quote.request,
-        fee_reserve_sat=melt_quote.fee_reserve,
-        quote_id=melt_quote.quote,
+    total_needed = melt_quote.amount + melt_quote.fee_reserve
+    logger.info(
+        "swap_to_primary_mint: melt quote received",
+        extra={
+            "melt_quote_id": melt_quote.quote,
+            "melt_amount": melt_quote.amount,
+            "melt_fee_reserve": melt_quote.fee_reserve,
+            "total_needed": total_needed,
+            "token_amount": token_amount,
+        },
+    )
+
+    if total_needed > token_amount:
+        logger.warning(
+            "swap_to_primary_mint: insufficient token amount for melt fees",
+            extra={
+                "token_amount": token_amount,
+                "melt_amount": melt_quote.amount,
+                "melt_fee_reserve": melt_quote.fee_reserve,
+                "total_needed": total_needed,
+                "shortfall": total_needed - token_amount,
+            },
+        )
+        raise ValueError(
+            f"Token amount ({token_amount} {token_obj.unit}) is insufficient to cover "
+            f"melt fees. Needed: {total_needed} {token_obj.unit} "
+            f"(amount: {melt_quote.amount} + fee: {melt_quote.fee_reserve})"
+        )
+
+    try:
+        _ = await token_wallet.melt(
+            proofs=token_obj.proofs,
+            invoice=mint_quote.request,
+            fee_reserve_sat=melt_quote.fee_reserve,
+            quote_id=melt_quote.quote,
+        )
+    except Exception as e:
+        logger.error(
+            "swap_to_primary_mint: melt failed",
+            extra={
+                "error": str(e),
+                "error_type": type(e).__name__,
+                "foreign_mint": token_obj.mint,
+                "token_amount": token_amount,
+                "melt_quote_id": melt_quote.quote,
+                "total_needed": total_needed,
+            },
+        )
+        raise ValueError(
+            f"Failed to melt token from foreign mint {token_obj.mint}: {e}"
+        ) from e
+
+    logger.info(
+        "swap_to_primary_mint: melt succeeded, minting on primary",
+        extra={"minted_amount": minted_amount, "mint_quote_id": mint_quote.quote},
+    )
+
+    try:
+        _ = await primary_wallet.mint(minted_amount, quote_id=mint_quote.quote)
+    except Exception as e:
+        logger.error(
+            "swap_to_primary_mint: mint on primary failed after successful melt",
+            extra={
+                "error": str(e),
+                "error_type": type(e).__name__,
+                "minted_amount": minted_amount,
+                "mint_quote_id": mint_quote.quote,
+            },
+        )
+        raise
+
+    logger.info(
+        "swap_to_primary_mint: completed successfully",
+        extra={
+            "foreign_mint": token_obj.mint,
+            "primary_mint": settings.primary_mint,
+            "original_amount": token_amount,
+            "minted_amount": minted_amount,
+            "unit": settings.primary_mint_unit,
+        },
     )
-    _ = await primary_wallet.mint(minted_amount, quote_id=mint_quote.quote)
 
     return int(minted_amount), settings.primary_mint_unit, settings.primary_mint
 

tests/unit/test_wallet.py

@@ -108,6 +108,92 @@ async def test_credit_balance() -> None:
             assert mock_session.refresh.called
 
 
+@pytest.mark.asyncio
+async def test_swap_to_primary_mint_insufficient_for_fees() -> None:
+    """Token amount is less than melt_quote.amount + melt_quote.fee_reserve."""
+    from routstr.wallet import swap_to_primary_mint
+
+    mock_token = Mock()
+    mock_token.mint = "http://foreign:3338"
+    mock_token.unit = "sat"
+    mock_token.amount = 404
+    mock_token.keysets = ["keyset1"]
+    mock_token.proofs = [{"amount": 404}]
+
+    mock_token_wallet = Mock()
+    mock_token_wallet.load_mint = AsyncMock()
+    mock_token_wallet.load_proofs = AsyncMock()
+
+    mock_primary_wallet = Mock()
+    mock_primary_wallet.load_mint = AsyncMock()
+    mock_primary_wallet.load_proofs = AsyncMock()
+
+    mock_mint_quote = Mock()
+    mock_mint_quote.quote = "mint_quote_123"
+    mock_mint_quote.request = "lnbc1..."
+    mock_primary_wallet.request_mint = AsyncMock(return_value=mock_mint_quote)
+
+    mock_melt_quote = Mock()
+    mock_melt_quote.quote = "melt_quote_123"
+    mock_melt_quote.amount = 400
+    mock_melt_quote.fee_reserve = 12  # total needed: 412 > 404
+    mock_token_wallet.melt_quote = AsyncMock(return_value=mock_melt_quote)
+
+    from routstr.core.settings import settings
+
+    with patch.object(settings, "primary_mint", "http://primary:3338"):
+        with patch.object(settings, "primary_mint_unit", "sat"):
+            with patch("routstr.wallet.get_wallet", return_value=mock_primary_wallet):
+                with pytest.raises(ValueError, match="insufficient to cover melt fees"):
+                    await swap_to_primary_mint(mock_token, mock_token_wallet)
+
+    # melt should never have been called
+    mock_token_wallet.melt.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_swap_to_primary_mint_melt_error_wrapped() -> None:
+    """Melt failure from cashu lib is wrapped as ValueError."""
+    from routstr.wallet import swap_to_primary_mint
+
+    mock_token = Mock()
+    mock_token.mint = "http://foreign:3338"
+    mock_token.unit = "sat"
+    mock_token.amount = 5000
+    mock_token.keysets = ["keyset1"]
+    mock_token.proofs = [{"amount": 5000}]
+
+    mock_token_wallet = Mock()
+    mock_token_wallet.load_mint = AsyncMock()
+    mock_token_wallet.load_proofs = AsyncMock()
+
+    mock_primary_wallet = Mock()
+    mock_primary_wallet.load_mint = AsyncMock()
+    mock_primary_wallet.load_proofs = AsyncMock()
+
+    mock_mint_quote = Mock()
+    mock_mint_quote.quote = "mint_quote_456"
+    mock_mint_quote.request = "lnbc1..."
+    mock_primary_wallet.request_mint = AsyncMock(return_value=mock_mint_quote)
+
+    mock_melt_quote = Mock()
+    mock_melt_quote.quote = "melt_quote_456"
+    mock_melt_quote.amount = 4940
+    mock_melt_quote.fee_reserve = 50  # total 4990 < 5000, passes fee check
+    mock_token_wallet.melt_quote = AsyncMock(return_value=mock_melt_quote)
+    mock_token_wallet.melt = AsyncMock(
+        side_effect=Exception("Provided: 5000, needed: 5100 (Code: 11000)")
+    )
+
+    from routstr.core.settings import settings
+
+    with patch.object(settings, "primary_mint", "http://primary:3338"):
+        with patch.object(settings, "primary_mint_unit", "sat"):
+            with patch("routstr.wallet.get_wallet", return_value=mock_primary_wallet):
+                with pytest.raises(ValueError, match="Failed to melt token"):
+                    await swap_to_primary_mint(mock_token, mock_token_wallet)
+
+
 @pytest.mark.asyncio
 async def test_recieve_token_untrusted_mint() -> None:
     mock_wallet = Mock()