React effects audit

Target: $ARGUMENTS

React Effects Audit

Overview

Scan React codebases to detect unnecessary useEffect usage based on official React documentation ("You Might Not Need an Effect"). Reports anti-patterns with severity, location, and recommended fixes.

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Agent Workflow (MANDATORY)

PHASE 1: Scan target files (Glob *.tsx, *.jsx, *.ts, *.js)
PHASE 2: Detect anti-patterns (Grep detection rules)
PHASE 3: Analyze context (Read flagged files)
PHASE 4: Generate report with fixes

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Anti-Pattern Summary

#	Anti-Pattern	Severity	Detection
1	Derived state in Effect	WARNING	useEffect + setState from other state/props
2	Expensive calculation in Effect	WARNING	useEffect + setState with filter/map/reduce
3	State reset via Effect	WARNING	useEffect resets state when prop changes
4	Event logic in Effect	CRITICAL	User interaction logic inside useEffect
5	Parent notification via Effect	WARNING	useEffect calls parent onChange/onUpdate
6	Effect chains	CRITICAL	Multiple useEffect triggering each other
7	Missing cleanup in fetch	CRITICAL	useEffect fetch without cleanup/AbortController
8	Manual store subscription	WARNING	addEventListener/subscribe in useEffect
9	App init in Effect	INFO	One-time init logic in useEffect(fn, [])

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Severity Levels

Level	Meaning	Action
CRITICAL	Bugs, race conditions, memory leaks	Fix immediately
WARNING	Performance issues, unnecessary re-renders	Fix same session
INFO	Readability, minor inefficiency	Fix if time allows

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Reference Guide

Skill References

Reference	When to Consult
anti-patterns.md	Understanding each anti-pattern
detection-rules.md	Grep patterns for scanning
fix-patterns-core.md	Fix examples #1-5
fix-patterns-advanced.md	Fix examples #6-9
report-format.md	Generating audit report

SOLID Cross-References (MANDATORY)

This audit complements existing SOLID skills. Always cross-reference:

Project Type	SOLID Skill	Key Rule
Next.js	fuse-nextjs:solid-nextjs	No useEffect for data fetching; use Server Components
React	fuse-react:solid-react	No useEffect for data fetching; use TanStack Query

Integration: When auditing a Next.js or React project, also load the corresponding SOLID skill to check architecture-level violations (file size, interface separation, business logic in components).

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Quick Start

1. Glob **/*.{tsx,jsx} in target directory
2. Detect project type (next.config.* → Next.js, package.json → React)
3. Load corresponding SOLID skill references if applicable
4. For each detection rule in detection-rules.md:
   → Grep pattern across all files
   → Read flagged files for context analysis
   → Confirm or dismiss (false positive check)
5. For each confirmed finding:
   → Identify severity from anti-patterns.md
   → Propose fix from fix-patterns-core.md or fix-patterns-advanced.md
   → Cross-check with SOLID rules (SRP, file size, hooks separation)
6. Output report using report-format.md

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React 19+ Considerations

Feature	Impact on Audit
React Compiler	Auto-memoizes; useMemo less needed but Effect anti-patterns still apply
useEffectEvent	Stable in 19.2; solves stale closure in Effects without adding deps
Activity API	Alternative to conditional rendering; reduces mount/unmount Effects
useSyncExternalStore	Replaces manual subscription Effects (anti-pattern #8)
Server Components	Eliminates many data-fetching Effects entirely

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Forbidden Behaviors

• Do NOT auto-fix without showing the finding first
• Do NOT flag Effects that synchronize with external systems (valid use)
• Do NOT flag data fetching Effects that have proper cleanup
• Do NOT ignore context: always Read the file before confirming a finding