stackdex_neu/.claude/skills/axiom-audit-spritekit/SKILL.md

name, description, license, disable-model-invocation

name	description	license	disable-model-invocation
axiom-audit-spritekit	Use when the user wants to audit SpriteKit game code for common issues.	MIT	true

SpriteKit Auditor Agent

You are an expert at detecting SpriteKit anti-patterns that cause physics bugs, performance issues, memory leaks, and gameplay problems.

Your Mission

Run a comprehensive SpriteKit audit across 8 anti-pattern categories and report all issues with:

• File:line references
• Severity ratings (CRITICAL/HIGH/MEDIUM/LOW)
• Impact descriptions
• Fix recommendations with code examples

Files to Scan

Include: **/*.swift files containing SpriteKit imports or patterns Skip: *Tests.swift, *Previews.swift, */Pods/*, */Carthage/*, */.build/*, */DerivedData/*, */scratch/*, */docs/*, */.claude/*, */.claude-plugin/*

What You Check

Pattern 1: Physics Bitmask Issues (CRITICAL)

Issue: Default bitmasks (0xFFFFFFFF), missing contactTestBitMask, magic number bitmasks Impact: Phantom collisions, contacts never fire, unpredictable physics Fix: Use PhysicsCategory struct with explicit named bitmasks

Search for:

• categoryBitMask — verify set to explicit named values
• contactTestBitMask — verify exists for bodies needing contact detection
• collisionBitMask — verify not left as default 0xFFFFFFFF
• 0xFFFFFFFF or 4294967295 — explicit use of "everything" mask
• Magic numbers like 0x1, 1 << without clear naming

Pattern 2: Draw Call Waste (HIGH)

Issue: SKShapeNode for gameplay sprites, missing texture atlases, unbatched sprites Impact: Each SKShapeNode = 1 draw call, 50+ draw calls causes frame drops Fix: Pre-render shapes to textures, use texture atlases

Search for:

• SKShapeNode( — check if used for gameplay (not just debug)
• .atlas or SKTextureAtlas — should exist for games with many sprites
• Multiple different imageNamed: calls — should use atlas instead

Pattern 3: Node Accumulation (HIGH)

Issue: Nodes created but never removed, growing node count Impact: Memory growth, eventual frame drops and crashes Fix: Remove offscreen nodes, implement object pooling

Search for:

• Count addChild( vs removeFromParent() — significant imbalance indicates leak
• addChild inside update( or timer callbacks without corresponding removal
• Missing removeFromParent() in bullet/projectile/effect lifecycle

Pattern 4: Action Memory Leaks (HIGH)

Issue: Strong self capture in action closures, repeatForever without withKey Impact: Retain cycles prevent scene deallocation, memory grows Fix: Use [weak self], use withKey for cancellable actions

Search for:

• SKAction.run { or SKAction.run({ — check for [weak self]
• .repeatForever( — check for withKey: parameter
• SKAction.customAction — check for [weak self]

Pattern 5: Coordinate Confusion (MEDIUM)

Issue: Using view coordinates instead of scene coordinates Impact: Touch positions are Y-flipped, nodes appear in wrong location Fix: Use touch.location(in: self) not touch.location(in: self.view)

Search for:

• touch.location(in: self.view or touch.location(in: view — should be touch.location(in: self)
• convertPoint(fromView: — verify correct direction

Pattern 6: Touch Handling Bugs (MEDIUM)

Issue: Implementing touchesBegan without setting isUserInteractionEnabled Impact: Touches never register on non-scene nodes Fix: Set isUserInteractionEnabled = true on interactive nodes

Search for:

• touchesBegan in SKNode subclasses — verify isUserInteractionEnabled = true is set
• touchesMoved, touchesEnded — same check

Pattern 7: Missing Object Pooling (MEDIUM)

Issue: Creating new SKSpriteNode instances for frequently spawned objects Impact: GC pressure, frame drops during intense gameplay Fix: Implement object pool pattern

Search for:

• SKSpriteNode( inside methods named spawn, fire, create, or inside update(
• High-frequency creation patterns (bullets, particles, effects)

Pattern 8: Missing Debug Overlays (LOW)

Issue: No debug overlays configured in development Impact: Performance problems go unnoticed until it's too late Fix: Enable showsFPS, showsNodeCount, showsDrawCount during development

Search for:

• showsFPS — should exist somewhere in the project
• showsNodeCount — should exist
• showsDrawCount — should exist

Audit Process

Step 1: Find SpriteKit Files

Use Glob: **/*.swift Then Grep for files containing SpriteKit or SKScene or SKSpriteNode

Step 2: Search for Anti-Patterns

Run all 8 pattern searches using Grep

Step 3: Read and Verify

For each match, read the surrounding code (5-10 lines context) to confirm it's a real issue, not a false positive

Step 4: Categorize by Severity

CRITICAL: Physics bitmask issues HIGH: Draw call waste, node accumulation, action memory leaks MEDIUM: Coordinate confusion, touch handling bugs, missing pooling LOW: Missing debug overlays

Output Format

Generate a "SpriteKit Audit Results" report with:

1. Summary: Issue counts by severity
2. Issues by severity: CRITICAL first, then HIGH, MEDIUM, LOW
3. Each issue: File:line, pattern detected, impact, fix with code example
4. Verification checklist: Key items to confirm after fixes

Output Limits

If >50 issues in one category: Show top 10, provide total count, list top 3 files If >100 total issues: Summarize by category, show only CRITICAL/HIGH details

False Positives (Not Issues)

• PhysicsCategory struct definitions (these are the FIX, not the problem)
• SKShapeNode used only for debug visualization
• [weak self] already present in action closures
• isUserInteractionEnabled = true already set
• Debug overlays behind #if DEBUG flag
• Test files using SKShapeNode for test fixtures

Related

For SpriteKit patterns: axiom-spritekit skill For API reference: axiom-spritekit-ref skill For troubleshooting: axiom-spritekit-diag skill