Find Mismatch

Walk through every file. Focus only on runtime failures/bugs. Do NOT report style, formatting, performance suggestions, docs/tests, or "consider using X".

1. Process

JS/TS (Pre-check): Run static analysis.
- Check if installed:
```
fallow --version
```
  .
- Install globally if missing:
```
npm install -g fallow
```
  .
- Execute audit:
```
fallow audit --format json --quiet
```
  .
- Filter findings by git status:
```
git diff --staged --name-only
```
  .
- If staged: auto-apply safe fixes, re-run audit to verify.
- If unstaged: report-only (no modification).
Review Checklist: Apply checklist to all changes.
Report: Format findings using the specified template.

2. Checklist Categories

1. Cross-Boundary Contracts

Calling mismatch: Check RPC, HTTP, IPC, event name/subject match receiver.
Param names/types:
```
userId
```
vs
```
user_id
```
, string vs number, flat vs wrapped.
Return type: Field accesses (
```
result.field
```
) must match return signature.

2. Serialization & Deserialization

Casing:
```
snake_case
```
in DB/backend vs
```
camelCase
```
in JSON/frontend.
Optionals: Field expected by receiver but optional in producer.
Enums/discriminators: Discriminant fields (
```
type
```
,
```
kind
```
) and variants match.
Base64: Double-encoding layers.

3. Logic Bugs

Double counting: Counters incremented both in loop/branch and outside.
Off-by-one: Index, pagination bounds (
```
page <= total
```
vs
```
page < total
```
).
Conditions: Redundant/dead flags, unreachable statements, shadowed variables.

4. Property & Method Access

Null derefs: Method calls or array index access (
```
items[0].name
```
) without null/length checks.
Optional chaining: Stop check too early (e.g.
```
user?.address.street
```
still crashes if
```
address
```
is null).
This context: Callback bindings in classes.

5. Async & Concurrency

Race conditions: Shared mutable states, parallel filesystem accesses without coordination.
Missing
```
await
```
: Promise ignored, silent errors.
Leaks: File/DB/network connections not closed in error paths.

6. CSS & Styling

HSL variables: Raw HSL components (
```
0 0% 100%
```
) instead of functional format (
```
hsl(0 0% 100%)
```
) fail in Tailwind v4 (unlike v3).
Inline themes: Circular references, selector mismatch (class vs data-theme).

7. Placeholder & Stub Code

Unused declarations/files/dependencies, TODO comments, empty catch blocks.

3. Language-Specific Pitfalls

Python: Hallucinated library methods (pandas, numpy, requests), sync/asyncio confusion, mutable default arguments (
```
def f(x=[])
```
), silent indentation drops.
JS/TS: Backend (Node) vs Frontend (Browser) API mix-ups,
```
any
```
abuse, type-only import mismatches, barrel file false positives (exported but unused in production, used in tests/libraries).
C++: Raw vs smart pointer mix-ups, missing standard library header
```
#include
```
, uninitialized variables, buffer overflows.
Rust: Borrow checker lifetime overcomplication,
```
unwrap()
```
on
```
None
```
/
```
Err
```
, locking across
```
.await
```
yield points.
Java / .NET: Hallucinated annotations/attributes, LINQ N+1 queries, Entity Framework model snapshot drift / missing migrations (check model changes under
```
Entities/
```
against
```
Migrations/
```
).
Go: WaitGroup/Channel deadlocks, unexported struct fields in JSON, defer in loop, map concurrent access.
PHP: Loose type comparisons (
```
==
```
vs
```
===
```
), array vs object access, key undefined.

4. Fallow Finding Mapping & Fixes

Fallow Type	Checklist Category	Auto-Fix Action
`unused_exports`	Placeholder & Stub	Remove `export` (if used locally) or entire declaration.
`unused_files`	Placeholder & Stub	Delete file (check dynamic imports first).
`unused_dependencies`	Placeholder & Stub	Remove dependency from `package.json` .
`circular_dependencies`	Cross-Boundary	Defer to manual review (causes init bugs).
`complexity` / `duplication`	Logic Bugs	Defer to manual review.

5. Output Format

Include

## Review Summary

header (only if JS/TS project):

## Review Summary
- **Manual review bugs found**: N
- **Fallow auto-fixed**: N findings (staged files only)
- **Fallow non-auto-fixable**: N findings
- **Fallow verdict**: pass / fail

Format individual findings (add

[fallow]

tag for fallow-sourced bugs):

## Bug #1
- **File**: <path>:<line>
- **Category**: <category>
- **What's wrong**: <description>
- **Runtime effect**: <effect>
- **Fix**: <code>

find-mismatch

NPX Install

Tags

SKILL.md Content