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Introduce a state-machine-based approach to managing LSPS2 JIT channel sessions. The FSM tracks payment collection from initial channel open through HTLC forwarding to completion, replacing the previous ad-hoc state tracking. Also adds Sum trait for Msat and PartialEq for protocol types needed by the FSM. Changelog-Experimental: LSPS2 session state machine for JIT channels
Introduce a session actor that runs the FSM in an async task and communicates side effects through an ActionExecutor trait. This separates state machine logic from I/O concerns like RPC calls and datastore writes.
Add SessionManager that routes incoming HTLCs to the correct session actor by payment hash, replacing the previous handler-based approach. Reworks the policy plugin API and integrates the CLN RPC executor, unifies HTLC handling into the session FSM, and removes the now deprecated handler.rs.
Add integration tests covering the full session lifecycle: channel opening, HTLC forwarding, payment collection, and session completion.
Implement crash recovery for LSPS2 sessions so that in-progress JIT channel sessions survive plugin restarts. Adds recovery traits and datastore methods, a RecoveryProvider implementation for ClnApiRpc, forward monitoring for recovered sessions, and integration tests for recovery scenarios. Makes broadcast_tx and abandon_session idempotent to handle replayed actions safely.
Reduce DatastoreProvider from many methods to 5, with the actor owning the DatastoreEntry and driving all writes through the actor loop. This makes the datastore boundary simpler and testable.
Add an EventSink trait that decouples session event reporting from the transport layer. Includes a composite sink and a channel-based implementation. Wires EventSink through SessionActor and SessionManager, and persists payment_hash in DatastoreEntry.
Replace CLN-specific types (cln_rpc PublicKey, ShortChannelId alias) with standalone alternatives, feature-gate CLN dependencies behind a "cln" feature flag, split ClnApiRpc into focused adapter structs, and refactor Lsps2ServiceHandler generics for cleaner trait boundaries. This makes the lsps2 core reusable outside of CLN.
Merge BlockheightProvider into Lsps2PolicyProvider, extract check_cltv_timeout helper in the session FSM, flatten recovery branching in SessionManager, simplify the actor loop with convert_input and tokio::select!, and remove the unused CollectTimeout ActorInput variant.
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We actually only use this in tests Signed-off-by: Peter Neuroth <pet.v.ne@gmail.com>
After restart, recovered session actors were stored in a separate recovery_handles Vec, unreachable by the forward_event notification path that routes via the sessions HashMap. This caused intermittent CI failures where on_payment_settled could not find the session and the internal forward-monitoring loop failed to detect settlement. Register recovered sessions in the sessions HashMap keyed by payment_hash so forward_event notifications reach them directly. For already-settled forwards, recover into Broadcasting state so the actor self-drives to completion without needing forward_event re-delivery. Remove the now-redundant internal polling loop (get_forward_activity + wait_for_forward_resolution).
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Important
26.04 FREEZE March 11th: Non-bugfix PRs not ready by this date will wait for 26.06.
RC1 is scheduled on March 23rd
The final release is scheduled for April 15th.
Checklist
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tools/lightning-downgradeIntroduces a state-machine-based approach to managing LSPS2 JIT channel sessions, replacing the previous ad-hoc state tracking with a structured FSM that tracks payment collection from initial channel open through HTLC forwarding to completion.