review-verification-protocol

Review Verification Protocol

This protocol MUST be followed before reporting any code review finding. Skipping these steps leads to false positives that waste developer time and erode trust in reviews.

Pre-Report Verification Checklist

Before flagging ANY issue, verify:

• I read the actual code - Not just the diff context, but the full function/impl block
• I searched for usages - Before claiming "unused", searched all references
• I checked surrounding code - The issue may be handled elsewhere (trait impls, error propagation)
• I verified syntax against current docs - Rust edition, crate versions, and API changes
• I distinguished "wrong" from "different style" - Both approaches may be valid
• I considered intentional design - Checked comments, CLAUDE.md, architectural context

Verification by Issue Type

"Unused Variable/Function"

Before flagging, you MUST:

1. Search for ALL references in the codebase (grep/find)
2. Check if it's pub and used by other crates in the workspace
3. Check if it's used via derive macros, trait implementations, or conditional compilation (#[cfg])
4. Verify it's not a trait method required by the trait definition

Common false positives:

• Trait implementations where the method is defined by the trait
• #[cfg(test)] items only used in test builds
• Derive-generated code that uses struct fields
• Types used via From/Into conversions

"Missing Error Handling"

Before flagging, you MUST:

1. Check if the error is handled at a higher level (caller propagates with ?)
2. Check if the crate has a top-level error type that wraps this error
3. Verify the unwrap() isn't in test code or after a safety-ensuring check

Common false positives:

• unwrap() in tests and examples (expected pattern)
• expect("reason") after validation (e.g., regex::Regex::new on a literal)
• Error propagation via ? (the caller handles it)
• let _ = tx.send(...) — intentional when receiver may have dropped

"Unnecessary Clone"

Before flagging, you MUST:

1. Confirm the clone is actually avoidable (borrow checker may require it)
2. Check if the value needs to be moved into a closure/thread/task
3. Verify the type isn't Copy (clone on Copy types is a no-op)
4. Check if the clone is in a hot path (test/setup code cloning is fine)

Common false positives:

• Arc::clone(&arc) — this is the recommended explicit clone for Arc
• Clone before tokio::spawn — required for 'static bound
• Clone in test setup — clarity over performance

"Potential Race Condition"

Before flagging, you MUST:

1. Verify the data is actually shared across threads/tasks
2. Check if Mutex, RwLock, or atomic operations protect the access
3. Confirm the type doesn't already guarantee thread safety (e.g., Arc<Mutex<T>>)
4. Check if the "race" is actually benign (e.g., logging, metrics)

Common false positives:

• Arc<Mutex<T>> — already thread-safe
• Tokio channel operations — inherently synchronized
• std::sync::atomic operations — designed for concurrent access

"Performance Issue"

Before flagging, you MUST:

1. Confirm the code runs frequently enough to matter
2. Verify the optimization would have measurable impact
3. Check if the compiler already optimizes this (iterator fusion, inlining)

Do NOT flag:

• Allocations in startup/initialization code
• String formatting in error paths
• Clone in test code
• .collect() on small iterators

Severity Calibration

Critical (Block Merge)

ONLY use for:

• unsafe code with unsound invariants
• SQL injection via string interpolation
• Use-after-free or memory safety violations
• Data races (concurrent mutation without synchronization)
• Panics in production code paths on user input

Major (Should Fix)

Use for:

• Missing error context across module boundaries
• Blocking operations in async runtime
• Mutex guards held across await points
• Missing transaction for multi-statement database writes

Minor (Consider Fixing)

Use for:

• Missing doc comments on public items
• String parameters where &str would work
• Suboptimal iterator patterns
• Missing #[must_use] on functions with important return values

Informational (No Action Required)

Use for:

• Suggestions for newtypes, builder patterns, or type state
• Performance optimizations without measured impact
• Suggestions to add #[non_exhaustive]
• Refactoring ideas for trait design

These are NOT review blockers.

Do NOT Flag At All

• Style preferences where both approaches are valid (e.g., if let vs match for single variant)
• Optimizations with no measurable benefit
• Test code not meeting production standards
• Generated code or macro output
• Clippy lints that the project has intentionally suppressed

Valid Patterns (Do NOT Flag)

Rust

Pattern	Why It's Valid
unwrap() in tests	Standard test behavior — panics on unexpected errors
.clone() in test setup	Clarity over performance
use super::* in test modules	Standard pattern for accessing parent items
Box<dyn Error> in binaries	Not every app needs custom error types
String fields in structs	Owned data is correct for struct fields
Arc::clone(&x)	Explicit Arc cloning is idiomatic and recommended
#[allow(clippy::...)] with reason	Intentional suppression is valid

Async/Tokio

Pattern	Why It's Valid
std::sync::Mutex for short critical sections	Tokio docs recommend this for non-async locks
tokio::spawn without join	Valid for background tasks with shutdown signaling
select! with default branch	Non-blocking check, intentional pattern
#[tokio::test] without multi_thread	Default single-thread is fine for most tests

Testing

Pattern	Why It's Valid
expect() in tests	Acceptable for test setup/assertions
#[should_panic] with expected	Valid for testing panic behavior
Large test functions	Integration tests can be long
let _ = ... in test cleanup	Cleanup errors are often unactionable

General

Pattern	Why It's Valid
todo!() in new code	Valid placeholder during development
#[allow(dead_code)] during development	Common during iteration
Multiple impl blocks for one type	Organized by trait or concern
Type aliases for complex types	Reduces boilerplate, improves readability

Context-Sensitive Rules

Ownership

Flag unnecessary .clone() ONLY IF:

• In a hot path (not test/setup code)
• A borrow or reference would work
• The clone is not required for Send/'static bounds
• The type is not Copy

Error Handling

Flag missing error context ONLY IF:

• Error crosses a module boundary
• The error type doesn't already carry context (thiserror messages)
• Not in test code
• The bare ? loses meaningful information about what operation failed

Unsafe Code

Flag unsafe ONLY IF:

• Safety comment is missing or doesn't explain the invariant
• The unsafe block is broader than necessary
• The invariant is not actually upheld by surrounding code
• A safe alternative exists with equivalent performance

Before Submitting Review

Final verification:

1. Re-read each finding and ask: "Did I verify this is actually an issue?"
2. For each finding, can you point to the specific line that proves the issue exists?
3. Would a Rust domain expert agree this is a problem, or is it a style preference?
4. Does fixing this provide real value, or is it busywork?
5. Format every finding as: [FILE:LINE] ISSUE_TITLE
6. For each finding, ask: "Does this fix existing code, or does it request entirely new code that didn't exist before?" If the latter, downgrade to Informational.
7. If this is a re-review: ONLY verify previous fixes. Do not introduce new findings.

If uncertain about any finding, either:

• Remove it from the review
• Mark it as a question rather than an issue
• Verify by reading more code context