When signing with fewer parties than keygen (e.g., 2-of-3 signing with only 2 parties),
the TSS-lib requires filtered save data containing only the participating parties.
Without this fix, signing fails with "U doesn't equal T" error because:
- Keygen creates save data for all N parties (e.g., 3 parties with indices 0, 1, 2)
- Sign uses only T parties (e.g., 2 parties with indices 1, 2)
- TSS-lib internal index validation fails due to mismatch
Changes:
- pkg/tss/signing.go: Use len(sortedPartyIDs) for partyCount and call BuildLocalSaveDataSubset
- tss-party/main.go: Add BuildLocalSaveDataSubset call for Electron app
- tss-wasm/main.go: Add BuildLocalSaveDataSubset call for WASM builds
This fix is backward compatible - when all parties participate, the subset equals the original data.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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