Explain code, concepts, or system behavior with adjustable depth levels.
Purpose
Get clear explanations of:
- How specific code works
- Why certain patterns are used
- What a system/module does
- Architectural decisions and trade-offs
Instructions
Step 1: Determine scope
Identify what needs explanation:
- File: Entire file structure and purpose
- Function/Method: Specific implementation details
- Concept: Architectural pattern or design decision
- Flow: How data/control moves through the system
Step 2: Assess complexity
Simple (1-2 min read) → Quick summary, key points only
Standard (3-5 min read) → Purpose, how it works, key decisions
Deep (10+ min read) → Full breakdown, alternatives, trade-offs
Step 3: Gather context
# For file explanations
head -50 "$FILE" # See imports and structure
# For function explanations
grep -A 30 "function $NAME\|def $NAME\|fn $NAME" "$FILE"
# For module explanations
ls -la "$DIR"
cat "$DIR/index.ts" 2>/dev/null || cat "$DIR/__init__.py" 2>/dev/null
Step 4: Structure the explanation
Output format
📖 Explanation: [Target]
Scope: [file/function/concept/flow] Depth: [simple/standard/deep]
What it does
[1-3 sentences describing the purpose]
How it works
[Step-by-step breakdown appropriate to depth level]
Key decisions
| Decision | Why | Alternative |
|---|---|---|
| [choice made] | [reasoning] | [what else could work] |
Example usage
// How to use this correctly
Related code
path/to/related.ts- [relationship]path/to/dependency.ts- [relationship]
💡 Learning Notes (if --learn flag)
[Additional context for understanding the broader pattern]
Depth levels
Simple (/explain --simple)
**validateUser()** checks if the user object has required fields
(email, password) and returns a boolean. Uses regex for email format.
Standard (/explain - default)
**validateUser(user: User): ValidationResult**
**Purpose**: Validates user input before database operations.
**Flow**:
1. Check required fields exist (email, password)
2. Validate email format with regex
3. Check password meets requirements (8+ chars, special char)
4. Return { valid: boolean, errors: string[] }
**Used by**: signup(), updateProfile()
Deep (/explain --deep)
[All of standard, plus:]
**Design Decisions**:
- Returns ValidationResult instead of throwing to allow batch validation
- Regex chosen over library for zero dependencies
- Password rules configurable via config.ts
**Trade-offs**:
- Pro: Fast, no dependencies
- Con: Regex email validation isn't RFC-compliant
**Alternatives Considered**:
- Zod schema: More powerful but adds 50KB
- Class-validator: Better for decorators but OOP-heavy
Usage examples
Explain a file:
/explain src/auth/middleware.ts
Explain a function:
/explain the handleWebhook function in payments.ts
Explain a concept:
/explain how our event sourcing works
Explain with specific depth:
/explain --deep the authentication flow
/explain --simple what useCallback does
Explain for learning:
/explain --learn the repository pattern used here
Tips
- Be specific: "Explain line 45-60" > "Explain this file"
- State your level: "I'm new to TypeScript" helps calibrate
- Ask follow-ups: "Why not use X instead?" deepens understanding
- Request analogies: "Explain like I'm familiar with Python but not TS"
$ARGUMENTS