mining: add coinbase locktime, sequence and version fields to getblocktemplate RPC #34419

1. 
   Sjors commented at 2:17 pm on January 27, 2026: member

   BIP54 proposes contraining the cointbase transaction nLockTime and nSequence fields. Our internal mining code has been doing this since #32155, but currently the fields are only communicated to IPC clients (see e.g. #33819).

   This PR extends the getblocktemplate RPC to provide these fields.

   Additionally it adds the nVersion field. Although unrelated to BIP54, it’s trivial to add and makes getblocktemplate now cover all coinbase transaction fields.

   Accompanying proposed extension to BIP54: https://github.com/bitcoin/bips/pull/2097

   Even if BIP54 never activates, it makes sense to serve these new fields.

2. refactor: use CoinbaseTx for coinbasevalue a73c41a1dc
3. DrahtBot added the label Mining on Jan 27, 2026
4. 
   DrahtBot commented at 2:17 pm on January 27, 2026: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/34419.

   Reviews

   See the guideline for information on the review process. A summary of reviews will appear here.

5. mining: add coinbase locktime and sequence fields

   Expand the getblocktemplate RPC result with two fields to prepare
   for a possible BIP54 deployment in the future.

   90025e8597
6. Sjors force-pushed on Jan 27, 2026
7. mining: add coinbase_version field to GBT faa8b518fe
8. DrahtBot added the label CI failed on Jan 27, 2026
9. 
   Sjors commented at 3:03 pm on January 27, 2026: member

   Added the coinbase nVersion.
10. Sjors renamed this:
    mining: add coinbase locktime and sequence fields to getblocktemplate RPC
    mining: add coinbase locktime, sequence and version fields to getblocktemplate RPC
    on Jan 27, 2026
11. DrahtBot removed the label CI failed on Jan 27, 2026
12. Sjors marked this as ready for review on Feb 9, 2026

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Sjors DrahtBot

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Mining