LoopMinRequiredLndVersion was 0.17.0, a value that only ever tracked the
go.mod lnd dependency rounded down and was never updated as the client
started depending on newer lnd RPC APIs. The client today uses RPC
fields that do not exist in 0.17.0:
- routerrpc.SendPaymentRequest.first_hop_custom_records and
lnrpc.Route.custom_channel_data, used by asset loop outs in
loopout.go: both added in lnd v0.18.4-beta.
- walletrpc.EstimateFeeResponse.min_relay_fee_sat_per_kw, read by the
sweep batcher fee floor via lndclient WalletKit.MinRelayFee
(sweepbatcher/, loopd/sweep_htlc.go): added in lnd v0.18.3-beta. On
older lnd it silently decodes to 0, disabling the min-relay floor.
Raise the floor to the highest of these (v0.18.4-beta) so loopd fails
fast at startup rather than misbehaving at runtime, and document in
AGENTS.md the rule to keep this value pinned to the lnd APIs the client
actually uses instead of tracking go.mod.
The whole project was analyzed by AI and the context was saved to the file.
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