fix(programs): reject rent_payment < 2 for CMint decompression (L-10)

[ananas-block]

Summary

• Certora audit L-10: rent_payment = 0 was accepted for CMint decompression, but only rent_payment = 1 was rejected. A CMint with 0 epochs of rent prepayment would immediately be eligible for reclamation.
• Fix: Require at least 2 epochs of rent prepayment by rejecting rent_payment < 2.

Changes

• decompress_mint.rs: Changed validation from rent_payment == 1 to rent_payment < 2, updated error to InvalidRentPayment.

Summary by CodeRabbit

• Changes

  • Increased minimum rent prepayment for mint creation to 2 epochs.
  • Compression becomes available only after a 2-epoch waiting period.
  • Validation now rejects rent payments less than 2 epochs.

• Tests

  • Updated tests to advance the clock by 2 epochs and reflect the new timing and assertions.

[coderabbitai]

📝 Walkthrough

Walkthrough

The pull request raises the required rent prepayment for mint compression operations from 0 to 2 epochs, updates program-side validation to enforce the >=2 requirement, and adjusts tests to warp the clock and assert compressibility only after the 2-epoch rent period elapses.

Changes

Cohort / File(s)	Summary
Tests forester/tests/test_compressible_mint.rs, forester/tests/test_indexer_interface.rs	Rent prepayment values changed from 0 to 2 epochs. Tests now import SLOTS_PER_EPOCH and warp the clock forward by 2 epochs before asserting compressibility; assertions and comments updated to reflect the delayed compressibility timing.
Validation Logic programs/compressed-token/program/src/compressed_token/mint_action/actions/decompress_mint.rs	Replaced the special-case rejection for exactly 1 epoch with a generic minimum check requiring rent_payment >= 2. Error returned changed from OneEpochPrefundingNotAllowed to InvalidRentPayment; docs/comments updated accordingly.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• chore: clean load client helpers #2173 — touches mint decompression rent prepayment handling and introduces client-side APIs / DEFAULT_RENT_PAYMENT that align with the program-side >=2-epoch validation.

Suggested reviewers

• sergeytimoshin
• SwenSchaeferjohann

Poem

🕰️ Two epochs wait, then the mint may breathe,
Locks loosen slowly, not one tick too brief,
Tests march time-forward, clocks bend to the rule,
Validation tightened, crisp as a tool,
Compression waits patient — steady and chief.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and specifically describes the main change: rejecting rent_payment < 2 for CMint decompression, addressing the Certora audit finding L-10.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 70.00%.

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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 jorrit/fix-certora-l10-rent-payment-zero

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