Post-quantum Lightning Network upgrade PQLN proposed

• —Gossip (BOLT7) carries ML-DSA and ML-KEM keys, while transport (BOLT8) moves to a hybrid handshake with two ML-KEM encapsulations
• —The 2420-byte ML-DSA-44 signature must be split across four invoice fields due to the 639-byte limit
• —The main cost is bandwidth: a node downloads 10x and stores 9x more data, while ML-DSA signing takes just 0.33 ms
• —Open issues include pinning, rust-lightning's 1024-byte MAX_EXCESS_BYTES_FOR_RELAY limit and unassigned feature bits