Audit Skill

Audit and code review guidance for Solidity smart contracts. For detailed vulnerability patterns, see bundled references.

Bundled References

Reference	Content	When to Read
.claude/skills/audit/references/vulnerability-checklist.md	17 vulnerability categories	During security reviews
.claude/skills/audit/references/audit-workflow.md	Step-by-step audit process	When conducting formal audits
.claude/skills/audit/references/pre-audit-checklist.md	Code quality + testing prep	Before external audit

Workflow: Use pre-audit-checklist to prepare → vulnerability-checklist to review → audit-workflow for formal process.

Review Types

Type	Purpose	Depth	When to Use
Self-Review	Pre-submission sanity check	Quick	Before creating a PR
PR Review	Verify changes meet standard	Moderate	When reviewing others' PRs
Deep Review	Thorough security analysis	Deep	Before mainnet deployment
Audit	Comprehensive security audit	Thorough	Pre-launch or after major change

---

Self-Review Checklist

Code Quality

• Code compiles without warnings
• All tests pass
• No commented-out code or debug statements
• No hardcoded test values in production code

Style & Conventions

• Follows naming conventions
• Imports ordered: external → internal → local
• Functions ordered: external → public → internal → private
• NatSpec complete for public/external functions

Logic

• Edge cases handled (zero amounts, empty arrays)
• Error messages are descriptive
• Events emitted for all state changes
• Access control is appropriate

Security

• CEI pattern followed (no state changes after external calls)
• SafeERC20 used for token transfers
• No unchecked arithmetic on user input
• No unbounded loops

Tests

• New functionality has tests
• Edge cases tested
• BTT tree updated (if applicable)

---

PR Review Issues

Issue	Detection
Missing access control	New external functions without modifiers
State after external	.call{}/transfer followed by state changes
Unchecked return values	.call() without checking success
Missing events	State changes without event emission
Incomplete error info	Errors without diagnostic parameters
Test coverage gaps	New code paths without corresponding tests
Breaking changes	Interface modifications without deprecation
Gas regression	New loops, storage operations in hot paths

---

Severity Classification

Severity	Definition
Critical (C)	Direct fund loss or permanent freeze
High (H)	Significant loss under specific conditions
Medium (M)	Limited loss or functionality impairment
Low (L)	Minor issues, deviations from best practices
Informational	Suggestions and observations

---

Quick Vulnerability Reference

Full checklist: See .claude/skills/audit/references/vulnerability-checklist.md for comprehensive patterns.

Severity	Key Checks
Critical	Reentrancy (CEI), Access control, Unchecked .call(), Delegatecall targets, Signature replay
High	Flash loan assumptions, Oracle manipulation, Front-running, Integer overflow, Price inflation
Medium	Fee-on-transfer tokens, Rebasing tokens, Unbounded loops, Timestamp dependence

---

Comment Prefixes

Prefix	Meaning
BLOCKING:	Must fix before merge
IMPORTANT:	Should fix, but can be follow-up
SUGGESTION:	Nice to have, optional
NIT:	Minor style preference
QUESTION:	Clarification needed

---

Protocol Invariants

Security properties that MUST always hold. Read the authoritative invariants from the codebase.

Invariant README Locations

Package	Location
Lockup	lockup/tests/invariant/README.md
Flow	flow/tests/invariant/README.md

What to Verify

When reviewing code, read the package's invariant README and verify:

1. No new code violates existing invariants
2. New features have corresponding invariants added
3. State transitions follow documented valid paths
4. Aggregate amounts remain consistent

Universal Invariants (all protocols)

Category	Check
Value conservation	Total in = total out + total remaining
Monotonic state	Withdrawn/streamed amounts never decrease
Access control	Only authorized roles modify state
State machine	Only valid transitions occur (see README)

---

Final Checklists

Before Approving Any Code

• Compiles without warnings
• All tests pass
• Follows project conventions
• No obvious security issues
• Adequate test coverage

For Security-Critical Code

• CEI pattern followed
• Access control verified
• External calls checked
• Edge cases handled
• Static analysis clean

Before Marking Audit Complete

• All external entry points reviewed
• All state-changing functions checked for reentrancy
• Access control verified on every sensitive function
• External call return values handled
• Token integration patterns validated
• Oracle dependencies assessed
• Flash loan attack vectors considered
• Slither run with no unreviewed findings

---

Example Invocations

Test this skill with these prompts:

1. PR review: "Review this PR for security issues: [diff content]"
2. Self-review: "Run through the self-review checklist for my new withdraw function"
3. Deep review: "Perform a security audit of the SablierFlow.sol contract"
4. Invariant check: "Verify this code doesn't violate the value conservation invariant"