wallet: fix imported tapscript address behavior in watch-only mode

[guggero]

Depends on btcsuite/btcwallet#1022.

Demonstrates the base issue that causes lightninglabs/lightning-terminal#1123 and #10120.
Not yet sure what the issue is, perhaps this demonstration case can help find it.
@yyforyongyu you're digging deep into the wallet, perhaps you have an idea?

To see the difference between running the test in a normal setup and in a remote-signing one, you can run:

Normal:

$ make itest icase=taproot_import_scripts

--- PASS: TestLightningNetworkDaemon (5.76s)
    --- PASS: TestLightningNetworkDaemon/tranche00/118-of-302/btcd/taproot_import_scripts (4.57s)
PASS

With a remote signer:

$ make itest icase=remote_signer-tapscript_import

    lnd_taproot_test.go:1161: p2tr outpoint: e05bd624e15ca2227390dfac5f25ff8a86d2272bf4f598e514b0bc56a1cf016c:1
    harness_assertion.go:2617: 
                Error Trace:    /home/guggero/projects/go/src/github.com/lightningnetwork/lnd/lntest/harness_assertion.go:2617
                                                        /home/guggero/projects/go/src/github.com/lightningnetwork/lnd/itest/lnd_taproot_test.go:1166
                                                        /home/guggero/projects/go/src/github.com/lightningnetwork/lnd/itest/lnd_remote_signer_test.go:240
                                                        /home/guggero/projects/go/src/github.com/lightningnetwork/lnd/itest/lnd_remote_signer_test.go:250
                                                        /home/guggero/projects/go/src/github.com/lightningnetwork/lnd/lntest/harness.go:315
                                                        /home/guggero/projects/go/src/github.com/lightningnetwork/lnd/itest/lnd_test.go:130
                Error:          Received unexpected error:
                                tx with hash 6c01cfa156bcb014e598f5f42b27d2868aff255facdf907322a25ce124d65be0 not found
                Test:           TestLightningNetworkDaemon/tranche00/227-of-302/btcd/remote_signer-tapscript_import
                Messages:       outpoint txid_bytes:"l\x01ϡV\xbc\xb0\x14\xe5\x98\xf5\xf4+'҆\x8a\xff%_\xacߐs\"\xa2\\\xe1$\xd6[\xe0"  output_index:1 not found in WatchOnly's wallet

EDIT: This behavior is fixed with btcsuite/btcwallet#1022, so we update to that PR here.

[gemini-code-assist]

Summary of Changes

Hello @guggero, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new integration test case designed to reproduce and investigate a specific issue where imported Tapscript addresses behave unexpectedly when LND is operating in watch-only mode with a remote signer. The new test specifically focuses on the scenario of funding a Partially Signed Bitcoin Transaction (PSBT) using a UTXO from such an imported address.

Highlights

• New Tapscript PSBT Funding Test: I've added a new test function, testTaprootImportTapscriptFullKeyFundPsbt, which simulates importing a Taproot address where only the full key is known, and then attempts to fund and sign a Partially Signed Bitcoin Transaction (PSBT) using a UTXO associated with this imported address. This test is crucial for verifying wallet behavior with imported Tapscript outputs.
• Remote Signer Tapscript Import Test: I've introduced a new remote signer integration test, testRemoteSignerTapscriptImport, which wraps the new Tapscript PSBT funding test (and other existing Tapscript import tests) to run them specifically in a remote signer environment. This is intended to expose the reported discrepancy in behavior.
• PSBT Funding Test Refactoring: I've refactored the existing testFundPsbt into a reusable helper runFundPsbt to allow its inclusion in other test scenarios, specifically within the remote signer tests to cover pay-join scenarios.

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[gemini-code-assist]

Code Review

This pull request adds a new integration test to demonstrate an issue with imported tapscript addresses in watch-only mode. The changes involve refactoring an existing test to reuse its logic and adding new test cases for remote signing and taproot script imports.

My review focuses on improving code quality and adherence to the project's style guide. I've identified a couple of areas for improvement:

• A new test function is missing a comment, which is required by the style guide.
• There's significant code duplication between a new test function and an existing one, which could be refactored to improve maintainability.

Overall, the changes are clear and focused on demonstrating the issue. Addressing the feedback will help maintain the codebase's quality.

Referenced style guide elements:

• All functions must have comments that start with the function name and describe the function's purpose and assumptions (lines 15-16).

[yyforyongyu]

Did quite some digging and found out that, well, this imported account was never created when it was watch-only. In fact, if you change ht.AssertUTXOInWallet(alice, p2trOutputRPC, "imported") to ht.AssertUTXOInWallet(alice, p2trOutputRPC, "default") then it will pass.

This is now fixed in btcsuite/btcwallet#1022

[yyforyongyu]

LGTM🦾

[guggero]

Updated and rebased after merging btcsuite/btcwallet#1022.

[ellemouton]

lgtm!