Add packLossless zero-exponent identity fuzz test

[thedavidmeister]

Summary

• Adds a fuzz test asserting Float.unwrap(packLossless(x, 0)) == bytes32(x) for non-negative integers that fit in int224
• This identity property is relied on by the interpreter's EVM block opcodes which store raw integers and use packLossless in differential testing

Test plan

• testPackLosslessZeroExponentIdentity passes with 5096 fuzz runs

🤖 Generated with Claude Code

Summary by CodeRabbit

• Tests
  • Added test coverage for decimal float packing behavior with zero exponent scenarios.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: e640d05b-0fdd-4833-ba1a-b27fac342765

📥 Commits

Reviewing files that changed from the base of the PR and between 7f72d82 and f8524c6.

📒 Files selected for processing (1)

• test/src/lib/LibDecimalFloat.pack.t.sol

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Walkthrough

A new pure test function testPackLosslessZeroExponentIdentity was added to verify that LibDecimalFloat.packLossless produces a bitwise identity result (where the wrapped float equals the input as bytes32) when the exponent parameter is zero.

Changes

Cohort / File(s)	Summary
LibDecimalFloat Pack Test test/src/lib/LibDecimalFloat.pack.t.sol	Added new test function testPackLosslessZeroExponentIdentity(uint256 value) that validates bitwise identity behavior when packing with zero exponent, using bounded values fitting within int224.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

🚥 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 describes the main change: a new fuzz test for the packLossless function's zero-exponent identity property.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 2026-03-23-pack-identity

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