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We add an event when a payment could not be relayed and indicates that we may need to add liquidity towards the next node. It is really hard to figure it out in the context of a single payment though, so this event does not by itself mean that liquidity should be allocated. The listeners should collect several events and regularly query the state of existing channels with our peers, and network graph data for remote nodes, to create good heuristics for allocating liquidity. Otherwise, it would be trivial for malicious senders to game routing nodes into allocating liquidity "for free" towards them, which could result in financial loss.
We add an event whenever we're unable to send a given HTLC through an outgoing channel. Note that this may happen multiple times for a single payment, since we iterate through our channels and retry on failure.
pm47
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Jan 27, 2026
eclair-core/src/main/scala/fr/acinq/eclair/payment/relay/ChannelRelay.scala
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pm47
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Jan 28, 2026
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We add an event when a payment could not be relayed and indicates that we may need to add liquidity towards the next node. It is really hard to figure it out in the context of a single payment though, so this event does not by itself mean that liquidity should be allocated. The listeners should collect several events and regularly query the state of existing channels with our peers, and network graph data for remote nodes, to create good heuristics for allocating liquidity. Otherwise, it would be trivial for malicious senders to game routing nodes into allocating liquidity "for free" towards them, which could result in financial loss.