feat: compute epoch length from byron genesis

[nicolasLuduena]

This pull request updates how Byron epoch length is calculated in the Cardano codebase to use the correct slot-based formula instead of a fixed time-based value. The changes ensure that epoch length is now determined by the number of slots per epoch as specified in the Byron genesis protocol constants, improving accuracy and alignment with the official Cardano node implementation. Source of information for the formula.

Byron epoch length calculation updates:

• Replaced the time-based constant FIVE_DAYS_IN_SECONDS with the slot-based constant BYRON_EPOCH_SLOTS_PER_K in crates/cardano/src/forks.rs, reflecting that Byron epochs last 10k slots per protocol constant k from the genesis file.
• Updated the epoch length calculation in both from_byron_genesis and protocol_constants functions to use BYRON_EPOCH_SLOTS_PER_K * k instead of dividing by slot duration, ensuring correctness and consistency with Cardano node behavior.

Summary by CodeRabbit

• Chores
  • Updated Byron epoch length calculation to use dynamic values based on protocol parameters instead of a fixed constant.

[coderabbitai]

📝 Walkthrough

Walkthrough

The PR modifies the Byron epoch length calculation in the forks module, replacing a fixed 5-day-based calculation with one derived from the number of slots per k multiplied by the genesis k value. This change affects both the standard and minimal-version code paths.

Changes

Cohort / File(s)	Summary
Byron Epoch Calculation crates/cardano/src/forks.rs	Replaced epoch length calculation from fixed 5 days in seconds with formula: BYRON_EPOCH_SLOTS_PER_K × byron.protocol_consts.k for both standard and minimal genesis paths.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• fix(cardano): interpret Byron epoch length correctly #748: Also modifies Byron epoch-length calculation in the same file but uses an alternative approach deriving from FIVE_DAYS_IN_SECONDS and slot duration.

Suggested reviewers

• scarmuega

Poem

🐰 Byron's epochs now dance with k,
No more fixed days for thee,
SLOTS_PER_K times genesis rules the way,
Making blockchain rhythms sway! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat: compute epoch length from byron genesis' directly and clearly describes the main change in the pull request: updating Byron epoch length calculation to use genesis-based computation instead of fixed time values.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch byron-epoch-length-computation

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