bip138: clarify receive-only descriptor set, 0 birth time, and BIP32 range #2298

pull Sjors wants to merge 5 commits into bitcoin:master from Sjors:2026/09/bip138-metadata changing 2 files +32 −4

Sjors commented at 12:08 PM on September 23, 2026: member
This PR makes a couple of clarifications around the descriptor (and bip388 policy) sets.

It adds one test vector, but shouldn't be a breaking change.

Three middle commits:
- clarify receive-only descriptor sets: add a test vector importing just a receive descriptor, with no metadata
- clarify derivation ranges using BIP32: clarifies bounds for range
- bip138: clarify zero and omitted birth times: importers SHOULD rescan from the wallet birthday if known, otherwise from genesis.
The first commit introduces a changelog. I'm reusing that commit across a few parallel pull requests.

The last commit updates the changelog; I'll update that depending on merge order.

bip138: introduce changelog at version 0.1.0

Record the initial published draft using the BIP3 document-version
and changelog convention.

bf63783c10

bip138: clarify receive-only descriptor sets

Make change_descriptor explicitly optional for non-multipath descriptors.
Add a receive-only document vector with no change descriptor or optional
metadata; the existing vectors cover a receive/change pair and multipath.

51995cc228

bip138: clarify derivation ranges using BIP32

Identify range bounds as BIP32 non-hardened child indexes, ordered from
start to end.

399ea2a091

bip138: clarify zero and omitted birth times

Explain that zero and omission both mean the birth time is unknown.
Recommend scanning from the wallet birthday if known, otherwise from
genesis.

ffa6bf4944

bip138: record metadata clarifications in changelog

Record this branch's clarifications and test vectors under draft document
version 0.1.1. Keep the initial-publication entry in the shared first commit.

8c1314949e

Sjors commented at 12:09 PM on September 23, 2026: member

cc @pythcoiner
jonatack added the label Metadata Update on Sep 23, 2026
jonatack added the label Fixups on Sep 23, 2026
murchandamus commented at 4:22 PM on September 23, 2026: member

Mostly fixup, but changes the semantics of change_descriptor.
Sjors referenced this in commit 9facc6aab1 on Sep 23, 2026
Sjors referenced this in commit e3cf2e1764 on Sep 23, 2026
pythcoiner commented at 6:41 AM on September 24, 2026: contributor

ACK 8c131494
Sjors commented at 8:49 AM on September 24, 2026: member

changes the semantics of change_descriptor.

I've always understood and implemented it in the way described here: it's optional.
pythcoiner commented at 11:27 AM on September 24, 2026: contributor

I also had implemented it optional
jonatack commented at 7:18 PM on September 24, 2026: member

ACK
jonatack merged this on Sep 24, 2026
jonatack closed this on Sep 24, 2026
Sjors deleted the branch on Sep 25, 2026

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