wallet: Fix Taproot descriptor weight calculation #34386

1. 
   tboy1337 commented at 4:04 am on January 23, 2026: none

   Problem

   The MaxSatisfactionWeight method for Taproot descriptors was incorrectly assuming only keypath spends, leading to significant underestimations of transaction weight. This could cause fee estimation failures for Taproot descriptors with script paths that are more expensive than the key path.

   Solution

   • Fixed weight calculation: Updated MaxSatisfactionWeight to properly calculate the maximum weight across all Taproot script leaves, not just the key path

   Changes

   • src/script/descriptor.cpp: Implemented proper weight calculation that iterates through all descriptor leaves to find the maximum satisfaction weight
   • src/test/descriptor_tests.cpp: Added comprehensive test case descriptor_tr_max_satisfaction_weight covering various Taproot scenarios
   • test/functional/wallet_taproot.py: Updated tests to handle higher fee rates for complex script paths and improved assertions

   Testing

   • Added unit tests verifying correct weight calculation for Taproot descriptors with script paths heavier than key paths
   • Updated functional tests to use appropriate fee rates for edge cases involving large Taproot scripts
   • All existing tests continue to pass

   This fix ensures wallets can properly estimate fees for all Taproot spending scenarios, preventing transaction failures due to underestimated fees.

2. DrahtBot added the label Wallet on Jan 23, 2026
3. 
   DrahtBot commented at 4:04 am on January 23, 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/34386.

   Reviews

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4. 
   fanquake commented at 9:28 am on January 23, 2026: member

   Same as #34314?
5. Fix Taproot descriptors and adjust weight calculation 06d07571f3
6. tboy1337 force-pushed on Jan 23, 2026
7. fanquake closed this on Jan 23, 2026

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Contributors
tboy1337 DrahtBot fanquake

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