Changelog

Changes to the .proto definitions, newest first. Dates are the dates the change landed in the canonical proto source.

The proto files served from /proto and the per-service docs on this site track these changes. The auto-generated API Reference lags until it is regenerated — when in doubt, the live rpc.discover method on a running Hydra App is authoritative.

2026-05-19

Swap — counterparty invoice-window handling and convergence retry in the simple-swap flow (server-side behavior; no request/response shape change for clients).

2026-05-10 — Payment timing (CLTV) overhaul

Breaking field renames on the Node API payment RPCs. If you send keysend payments or create invoices, update your code.

Node

• SendChannelPaymentRequest: expiry_timeout_secs → cltv_buffer_secs. (KeySend has no separate invoice-validity knob; the buffer alone bounds the HTLC.)
• EstimateSendPaymentFeeRequest: expiry_timeout_secs → cltv_buffer_secs; new optional max_total_cltv_secs (clamp the route's max-total-CLTV; for atomic-swap-correct timing pass the invoice's cltv_buffer_secs, otherwise omit).
• SendPaymentRequest: same change as EstimateSendPaymentFeeRequest.
• CreateInvoiceRequest: expiry_timeout_secs keeps its meaning (BOLT-11 x — invoice validity window) and gains a new optional cltv_buffer_secs (BOLT-11 c — extra HTLC lifetime past invoice expiry the receiver requires).
• EstimatePayInvoiceFeeRequest, PayInvoiceRequest, EstimatePayEmptyInvoiceFeeRequest, PayEmptyInvoiceRequest: new optional max_total_cltv_secs.

Payment

• Invoice: new field min_final_cltv_expiry_secs — the minimum CLTV buffer (seconds) the receiver requires for the incoming HTLC. The HTLC's effective deadline is expiry_timestamp + min_final_cltv_expiry_secs.

2026-05-06 — Lease API: read-only discovery

Liquidity — four new read-only RPCs (no funds move):

• GetLiquidityServiceInfo — server-wide capacity bounds, durations, per-asset fee config, and the LP's per-network node pubkeys.
• GetLeaseableAssetInfo — per-asset liquidity bounds + fee ratio for one (network, asset).
• GetLeases — the caller's active leases on a network.
• GetLeaseExpiries — lease expiry per (channel_id, asset_id) from the local cache (no LP round-trip).

Also: ChannelReleaseOperation.CooperativeClose gained asset_ids — empty closes every asset channel; otherwise only the listed ones.

2026-05-05 — Lease API: tx_fee_rate removed (breaking)

Liquidity / Swap — the liquidity service now prices the underlying transaction work itself. The client no longer supplies a chain fee rate.

• RequestChannelLiquidityRequest: removed tx_fee_rate (remaining fields renumbered).
• RequestChannelReleaseRequest: removed tx_fee_rate (remaining fields renumbered).
• ReceivingChannelLease (swap): removed tx_fee_rate (remaining fields renumbered).

Action required: delete tx_fee_rate / txFeeRate / TxFeeRate from any Lease request you build. Sending it now returns -32602 unknown field 'txFeeRate'. The Lease API examples have been updated.

2026-05-03 — Channel close flag + client order IDs

Channel

• AssetChannelStatus.Closed gained force_closed (bool). false = cooperative close (in lithium the channel slot can be reused for further deposits); true = unilateral / disputed close (slot is permanently dead — open a new channel).

Orderbook

• CreateOrderRequest gained optional client_order_id (max 64 chars). When set and unique among your open orders, the orderbook stores it, returns the original order_id on retries with the same value (idempotent order creation), and exposes it on subsequent reads.
• Order gained optional client_order_id.
• New RPC GetOrderByClientId — fetch an order by the client_order_id you supplied at creation.
• SwapRole enum reordered: SWAP_ROLE_TAKER moved from 0 to 3. SWAP_ROLE_UNSPECIFIED is 0. If you persisted raw enum integers, re-map them.

2026-04-29 — Swappable-amount estimation

Swap — new RPC EstimateSimpleSwappableAmounts: given two currencies, returns the smallest and largest amounts that can currently be simple-swapped, accounting for wallet balances, orderbook liquidity, and the LP's leaseable capacity. Returns an empty amounts field when the pair has no orderbook liquidity; all-zero fields when the pair has liquidity but no swap is currently feasible.

2026-04-27 — New SimpleSwap estimate variant

Swap — SimpleSwapEstimate gained the InsufficientSendingBalance variant ({ available: DecimalString }). Distinct from NoLiquidity: the market is fine, but the wallet has nothing to send (no active channel and no usable on-chain funds after fees). If you match/switch on the estimate one-of, add a branch for it.

Earlier

The 2026-04 reconciliation aligned every doc with the then-current proto, including the rename of the old RentalService to LiquidityService (the Lease API). The rental_* JSON-RPC namespace no longer exists — it is liquidity_*. See the Lease API.

How this list is maintained

Each entry corresponds to a proto-touching commit in the Hydra App source. When the protos in /proto are refreshed, this page and the affected per-service docs are updated together. The single source of truth for a running server is its rpc.discover output — see JSON-RPC: Discovering methods.