fix(cardano): align proptest epochs with strict assertions

[scarmuega]

Problem

Running cargo test --workspace --all-features produced 14 test failures in dolos-cardano lib tests (115 passed; 14 failed).

All failures panicked at #[cfg(feature = "strict")] assertions in crates/cardano/src/model/epoch_value.rs (schedule, live_mut, replace, transition), which enforce that a delta's epoch equals the entity's current EpochValue epoch.

Root cause

The strict feature (enabled by --all-features) turns on epoch-alignment assertions that guard a production invariant: ESTART transitions every entity in lockstep with the ledger epoch, so a delta constructed at epoch E is always applied to an entity whose EpochValue is also at epoch E.

The proptest strategies violated this invariant by generating the entity and the delta with independently randomized epochs — both drawn from any_epoch() (3u64..1_000_000u64). When the two epochs disagreed (almost always), apply tripped the strict assertion.

Failing tests (14)

Module	Tests
accounts	stake_delegation_roundtrip, stake_delegation_serde_roundtrip, vote_delegation_roundtrip, vote_delegation_serde_roundtrip, stake_deregistration_roundtrip, stake_deregistration_serde_roundtrip, pool_delegator_retire_roundtrip, drep_delegator_drop_roundtrip, account_transition_roundtrip
epochs	epoch_stats_update_roundtrip, epoch_transition_roundtrip, epoch_transition_v2_roundtrip
pools	pool_registration_roundtrip, pool_transition_roundtrip

Fix

Add epoch-parameterized strategy variants that pin the EpochValue to a caller-chosen epoch, and rewire the 14 failing tests to share a single epoch between entity and delta via prop_flat_map.

For transition deltas (AccountTransition, PoolTransition, EpochTransition, EpochTransitionV2), the entity is generated at epoch and the delta at epoch + 1, matching the assert_eq!(self.epoch + 1, next_epoch) invariant.

New strategies

• any_epoch_value_at(epoch, inner) / any_epoch_value_no_next_at(epoch, inner) — epoch_value.rs
• any_account_state_at(epoch) — accounts.rs
• any_pool_state_at(epoch) — pools.rs
• any_epoch_state_at(epoch) / any_epoch_state_no_rolling_next_at(epoch) — epochs.rs
• *_at(epoch) delta strategies for each affected delta

This models the production invariant the strict feature is meant to guard, rather than disabling the assertions.

Verification

cargo test -p dolos-cardano --all-features
test result: ok. 129 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

cargo clippy --workspace --all-targets --all-features
Finished `dev` profile [unoptimized + debuginfo] target(s)

The dolos-minibf workspace-level failure is pre-existing and unrelated (passes when run independently: 212 passed; 0 failed).

Summary by CodeRabbit

• Bug Fixes
  • Improved consistency in epoch-related account, epoch, and pool state handling.
  • Strengthened roundtrip checks for state changes across epoch boundaries, reducing the chance of hidden edge-case regressions.
  • Expanded test coverage for transitions, registrations, and serialized data paths to better validate real-world epoch-matched scenarios.

[coderabbitai]

Caution

Review failed

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/strict-proptest-epoch-alignment

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