Agent-Skills.md

Agent Skills: Differential Review

Reviewing changes between versions of SCs (Upgradeability checks).

UncategorizedID: multiversx/mx-ai-skills/diff_review

Repository

multiversx/mx-ai-skills
multiversxLicense: MIT
104

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pnpm dlx add-skill https://github.com/multiversx/mx-ai-skills/tree/HEAD/antigravity/skills/diff_review

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antigravity/skills/diff_review/SKILL.md

Skill Metadata

Name
diff_review
Description
Reviewing changes between versions of SCs (Upgradeability checks).

Differential Review

This skill helps you analyze the difference between two versions of a codebase, focusing on security implications of changes.

1. Upgradeability Checks (MultiversX)

When reviewing a diff between v1 and v2 of a Smart Contract:

  • Storage Layout:
    • Critical: Did the order of fields in a struct stored in a VecMapper or SingleValueMapper change?
    • Result: Usage of existing data will interpret bytes incorrectly (Memory Corruption).
    • Fix: Append new fields to the end of structs, never reorder.
  • Initialization:
    • Critical: Does v2 introduce new Storage Mappers?
    • Check: Are they initialized in #[upgrade]? (Remember #[init] is NOT called on upgrade).

2. Regression Testing

  • New Features: Do they break old invariants?
  • Deleted Code: Was a check removed? Why?

3. Workflow

  1. Generate Diff: git diff v1..v2.
  2. Filter Noise: Ignore formatting/style changes.
  3. Trace Data: Follow the flow of changed data structures.