Bitcoin Optech: Newsletter #423 Recap

<p>Mark “Murch” Erhardt, Gustavo Flores Echaiz, and Mike Schmidt are joined by Davidson Souza, Eric Price, and PortlandHODL to discuss <a href="https://bitcoinops.org/en/newsletters/2026/09/18/">⁠Newsletter #423⁠</a>.</p><p><br></p><p><strong>News</strong></p><p>● Vardiff controllers that strand slowing miners (23:06) </p><p>● Improvements in Utreexo initial block download (1:18) </p><p>● New BIP draft for unspendable internal keys (1:17:51) </p><p><br></p><p><strong>Changes to services and client software</strong></p><p>● BitBoxApp adds Spark-based Lightning payments (1:24:09) </p><p>● Covenants.diy script editor (1:28:40) </p><p>● EntropyLab offline key calculator (59:46) </p><p><br></p><p><strong>Releases and release candidates</strong></p><p>● Eclair 0.14.3 (1:31:10) </p><p><br></p><p><strong>Notable code and documentation changes</strong></p><p>● Bitcoin Core #35445 (1:33:34) </p><p>● Bitcoin Core #36076 (1:38:51) </p><p>● Bitcoin Core #36150 (1:42:18) </p><p>● Bitcoin Core #36174 (1:44:37) </p><p>● Bitcoin Core #34743 (1:46:13) </p><p>● Bitcoin Core #36081 (1:48:07) </p><p>● Bitcoin Core #35975 (1:48:59) </p><p>● BIPs #2241 (1:50:04) </p><p>● BIPs #2258 (1:53:09) </p><p>● Eclair #3380 (1:56:33) </p><p>● Eclair #3376 (1:57:37) </p><p>● Eclair #3372 (2:04:34) </p><p>● LND #11163 (2:05:57) </p><p>● BDK #2246 (2:07:44) </p>