Is your feature request related to a problem? Please describe.
When using static Loop In (loop static in ... --last_hop <pubkey>) with more than one channel open to the same last-hop peer, there's currently no way to force the payment to split across those channels. LND's pathfinding only attempts to shard a payment when no single route/channel can carry the full HTLC — if one channel happens to be big enough on its own, LND will always prefer the single-HTLC route, even if the user would rather spread liquidity across both channels.
This matters for users actively managing inbound liquidity across multiple channels to the same peer (e.g. Loop's own routing node) — right now the only way to force a split is to manually shrink the swap amount below the capacity of any single channel, which isn't practical for larger swaps or automated tooling.
Describe the solution you'd like
Add a max-fee argument to the loop-in request (e.g. --max_fee_sat / --max_fee_ppm at the routing/HTLC level, distinct from the existing --max_swap_fee_sat / --max_swap_fee_ppm which caps Loop's service fee).
Setting a low-enough max routing fee would eliminate the single-HTLC route from consideration (a single larger HTLC generally costs more in routing fees than an equivalent smaller shard), forcing the payment to split across the available channels as a side effect — without needing to build new explicit splitting/shard-count logic.
An alternative would be an explicit shard-count argument on the loop-in request, but the max-fee approach seems simpler since it reuses a lever that already exists conceptually in LND's payment API rather than requiring new splitting logic.
(Note for maintainers: in LND terms this means the payment falls back to its existing MPP shard-splitting behavior once the single-HTLC route is priced out of consideration.)
Describe alternatives you've considered
MPP?
Additional context
Static Loop In user with 2 channels open to the Loop peer, wanting a large loop-in swap (static or normal) to route inbound liquidity across both channels rather than concentrating it on whichever single channel happens to have enough capacity.
Is your feature request related to a problem? Please describe.
When using static Loop In (
loop static in ... --last_hop <pubkey>) with more than one channel open to the same last-hop peer, there's currently no way to force the payment to split across those channels. LND's pathfinding only attempts to shard a payment when no single route/channel can carry the full HTLC — if one channel happens to be big enough on its own, LND will always prefer the single-HTLC route, even if the user would rather spread liquidity across both channels.This matters for users actively managing inbound liquidity across multiple channels to the same peer (e.g. Loop's own routing node) — right now the only way to force a split is to manually shrink the swap amount below the capacity of any single channel, which isn't practical for larger swaps or automated tooling.
Describe the solution you'd like
Add a max-fee argument to the loop-in request (e.g.
--max_fee_sat/--max_fee_ppmat the routing/HTLC level, distinct from the existing--max_swap_fee_sat/--max_swap_fee_ppmwhich caps Loop's service fee).Setting a low-enough max routing fee would eliminate the single-HTLC route from consideration (a single larger HTLC generally costs more in routing fees than an equivalent smaller shard), forcing the payment to split across the available channels as a side effect — without needing to build new explicit splitting/shard-count logic.
An alternative would be an explicit shard-count argument on the loop-in request, but the max-fee approach seems simpler since it reuses a lever that already exists conceptually in LND's payment API rather than requiring new splitting logic.
(Note for maintainers: in LND terms this means the payment falls back to its existing MPP shard-splitting behavior once the single-HTLC route is priced out of consideration.)
Describe alternatives you've considered
MPP?
Additional context
Static Loop In user with 2 channels open to the Loop peer, wanting a large loop-in swap (static or normal) to route inbound liquidity across both channels rather than concentrating it on whichever single channel happens to have enough capacity.