[Jossec101]

• Swap limits per provider. Loop, 40swap and Spark each have their own min and max swap size and their own max swaps in flight on the node, instead of one shared set. So Loop can run one swap at a time while Spark runs several.
  • Existing nodes keep their settings: the shared values become Loop's and 40swap's, and Spark's max swaps in flight.
  • Spark's default to SPARK_SWAP_MIN_SATS (50,000) and SPARK_SWAP_MAX_SATS (2,000,000).
  • Auto-liquidity now picks the provider first, among those below their max swaps in flight, then swaps the most that provider takes.
  • The Nodes page shows and edits them per provider, and the grid has a column for each.
• One exit for many swaps. An exit costs the same whatever its size. So paid swaps now wait in their Spark wallet until it's full (no room for another swap under its max balance), then leave together in one on-chain transaction.
  • One exit per destination wallet, with up to 100 leaves each.
  • The exit fee is shared between the swaps, in proportion to what each brought in.
  • Spark's max swaps in flight counts a swap only while it's being paid.
  • To exit a wallet's swaps earlier, lower its max balance.
• Fix: payments save their own result. Since Spark swaps: payment timeout, no waiting on create, a Transactions tab and slow exits #640, a Spark swap's background payment used the services of the request that created the swap. When that request ended, saving the payment's result failed, and the monitor recorded it a few minutes later instead. The payment now runs in a scope of its own.
• One migration for the whole PR: AddPerProviderSwapLimitsAndSparkExitBatches.
• Tests. Unit tests for each part. The Spark E2E now checks that two swaps share one exit: 7 leaves and one 209-sat fee, the same fee a single-swap exit pays.

[markettes]

LGTM