refactor(mint): split monolithic ledger.py into ledger/ package

[KvngMikey]

Fixes #865

Summary

Extracts the monolithic 1413-line cashu/mint/ledger.py into a package with focused mixin classes, making the code easier to navigate and understand. Each mixin inherits from the mixin that provides the methods it calls, this way all existing imports continue to work unchanged.

Changes

• cashu/mint/ledger.py has been replaced with a cashu/mint/ledger/ package containing focused submodules.
• ledger/__init__.py barrel exports from .ledger import Ledger.
• No logic was changed. Existing test suite passes without modification.

[Copilot]

Pull request overview

Note

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Refactors the mint ledger implementation from a single large module into a structured package, separating mint/melt/swap and blind-signature logic while adding protocol typing for watchdog functionality.

Changes:

• Split cashu/mint/ledger.py into multiple modules under cashu/mint/ledger/ (mint, melt, swap, blind_signatures, ledger).
• Introduced SupportsWatchdog protocol to type the watchdog balance/fee API used during mint quoting.
• Added cashu.mint.ledger package export via __init__.py.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
cashu/mint/protocols.py	Adds SupportsWatchdog protocol and supporting imports for typed watchdog integration.
cashu/mint/ledger/ledger.py	New composed Ledger class wiring together split ledger mixins and startup/shutdown routines.
cashu/mint/ledger/blind_signatures.py	Extracts blind signature storage/signing + fee-change promise generation.
cashu/mint/ledger/mint.py	Extracts mint quote, mint, and batch mint flows into a dedicated mixin.
cashu/mint/ledger/melt.py	Extracts melt quoting and payment execution logic into a dedicated mixin.
cashu/mint/ledger/swap.py	Extracts swap + restore logic into a dedicated mixin.
cashu/mint/ledger/init.py	Exposes the new package-level Ledger import.
cashu/mint/ledger.py	Removes the previous monolithic ledger module.

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[codecov]

Codecov Report

❌ Patch coverage is 84.80620% with 98 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.23%. Comparing base (2376e47) to head (a62789b).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
cashu/mint/ledger/melt.py	82.64%	42 Missing ⚠️
cashu/mint/ledger/mint.py	79.88%	35 Missing ⚠️
cashu/mint/ledger/ledger.py	92.66%	8 Missing ⚠️
cashu/mint/ledger/blind_signatures.py	90.00%	7 Missing ⚠️
cashu/mint/ledger/swap.py	85.36%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1032      +/-   ##
==========================================
+ Coverage   75.04%   75.23%   +0.19%     
==========================================
  Files         111      116       +5     
  Lines       12244    12288      +44     
==========================================
+ Hits         9188     9245      +57     
+ Misses       3056     3043      -13     

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