wallet: Store information about created and imported multipath descriptors #36444

The wallet does not store any information about multipath descriptors. When a multipath descriptor is imported, it is first expanded, then the expansion descriptors are imported into the wallet.

This PR adds a field to WalletDescriptor which stores the IDs of the ScriptPubKeyMans of the descriptors that are part of the expansion, in the order that they are expanded. This allows us to use ReconstructMultipath to produce the multipath descriptor when necessary.

This is useful for working with hardware wallets that require policy registration, particularly those that require resending the descriptor that was registered.

listdescriptors is updated to include a multipath_descriptor field which contains the multipath descriptor for each individual descriptor if it originally came from a multipath descriptor.

Lastly, the automatically generated descriptors are now produced and stored as multipath descriptors, so listdescriptors will provide a multipath_descriptor for everything that the wallet automatically generates.

Note that the IDs stored in the wallet are ScriptPubKeyMan IDs, which we cannot compute from a descriptor as we assume to be opaque blobs since #35445.

Alternative to #36133, depends on #36442 and #36443

<!--e57a25ab6845829454e8d69fc972939a-->

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

<!--006a51241073e994b41acfe9ec718e94-->

External sites

• Code coverage & benchmarks: https://corecheck.dev/bitcoin/bitcoin/pulls/36444
• Ralph review <img src=https://review.fish.foo/assets/bitcoin/bitcoin/36444.png alt="Ralph review status"> https://git.fish.foo/bitcoin/bitcoin/pulls/36444#author-ralph

<!--021abf342d371248e50ceaed478a90ca-->

Reviews

See the guideline and AI policy for information on the review process.

If your review is incorrectly listed, please copy-paste <code>&lt;!--meta-tag:bot-skip--&gt;</code> into the comment that the bot should ignore.

<!--174a7506f384e20aa4161008e828411d-->

Conflicts

Reviewers, this pull request conflicts with the following ones:

• #36447 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/36447.svg">} (test: Misc fixes for pending validation events races by maflcko)
• #36402 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/36402.svg">} (refactor: wallet_importdescriptors to separate run_test() contents into specific functions by nebula-21)
• #36236 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/36236.svg">} (wallet, rpc: add verify_balance option to importdescriptors by musaHaruna)
• #36122 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/36122.svg">} (BIP460: CISA for Taproot key path spends by fjahr)
• #36070 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/36070.svg">} (wallet: Add deriveHDKey interface by PraneethGunas)
• #35444 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/35444.svg">} (wallet: make descriptor SPKM mutex non-recursive by w0xlt)
• #35377 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/35377.svg">} (wallet: Allow importing of descriptors without private keys when the wallet has the private keys by achow101)
• #35170 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/35170.svg">} (test: Better test coverage for ParseHDKeypath() by optout21)
• #34909 _{<img src="https://drahtbot.space/ack_count/bitcoin/bitcoin/34909.svg">} (wallet, refactor: modularise wallet by extracting out legacy wallet migration by rkrux)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

<!--5faf32d7da4f0f540f40219e4f7537a3-->

LLM Linter (✨ experimental)

Possible typos and grammar issues:

• Failed reconstrcted to private string: -> Failed reconstructed to private string: [misspelled word]
• Get the KeyPath of single KeyPathElements for a give multipath position -> Get the KeyPath of single KeyPathElements for a given multipath position [“give” is the wrong word; intended meaning is unclear until corrected]

Possible places where named args for integral literals may be used (e.g. func(x, /*named_arg=*/0) in C++, and func(x, named_arg=0) in Python):

• Parse(descriptor_str, keys, error, true) in src/wallet/walletutil.h
• Parse(desc_str, keys, error, false) in src/wallet/walletutil.cpp
• Parse(desc_str, keys, error, false) in src/wallet/test/util.cpp
• Parse(desc_str.value(), keys, error, false) in src/wallet/test/fuzz/scriptpubkeyman.cpp
• Parse(desc_str, provider, error, false) in src/wallet/scriptpubkeyman.cpp
• WalletDescriptor(std::move(desc), 0, 0, 1, 1) in src/qt/test/wallettests.cpp
• WalletDescriptor(std::move(desc), 0, 0, 10, 0) in src/test/psbt_tests.cpp
• WalletDescriptor(std::move(desc), 0, 0, 1, 1) in src/wallet/test/util.cpp
• WalletDescriptor(std::move(desc), 0, 0, 1, 1) in src/wallet/test/wallet_tests.cpp
• WalletDescriptor(std::move(desc), creation_time, 0, 0, 0) in src/wallet/test/walletload_tests.cpp
• WalletDescriptor(std::move(desc), creation_time, 0, 0, 0) in src/wallet/wallet.cpp

^{2026-10-05 22:36:14}

<!--85328a0da195eb286784d51f73fa0af9-->

🚧 At least one of the CI tasks failed. _{Task lint: https://github.com/bitcoin/bitcoin/actions/runs/37382356159/job/112007221776} _{LLM reason (✨ experimental): CI failed the Python lint check: wallet_importdescriptors.py has undefined extended_key/xpub names, and wallet_listdescriptors.py has an unused import.}

<details><summary>Hints</summary>

Try to run the tests locally, according to the documentation. However, a CI failure may still happen due to a number of reasons, for example:

• Possibly due to a silent merge conflict (the changes in this pull request being incompatible with the current code in the target branch). If so, make sure to rebase on the latest commit of the target branch.

• A sanitizer issue, which can only be found by compiling with the sanitizer and running the affected test.

• An intermittent issue.

Leave a comment here, if you need help tracking down a confusing failure.

</details>

<!--cf906140f33d8803c4a75a2196329ecb-->

🐙 This pull request conflicts with the target branch and needs rebase.

Concept ACK