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+---
+name: error-handling-patterns
+description: Master error handling patterns across languages including exceptions, Result types, error propagation, and graceful degradation to build resilient applications. Use when implementing error handling, designing APIs, or improving application reliability.
+---
+
+# Error Handling Patterns
+
+Build resilient applications with robust error handling strategies that gracefully handle failures and provide excellent debugging experiences.
+
+## When to Use This Skill
+
+- Implementing error handling in new features
+- Designing error-resilient APIs
+- Debugging production issues
+- Improving application reliability
+- Creating better error messages for users and developers
+- Implementing retry and circuit breaker patterns
+- Handling async/concurrent errors
+- Building fault-tolerant distributed systems
+
+## Core Concepts
+
+### 1. Error Handling Philosophies
+
+**Exceptions vs Result Types:**
+
+- **Exceptions**: Traditional try-catch, disrupts control flow
+- **Result Types**: Explicit success/failure, functional approach
+- **Error Codes**: C-style, requires discipline
+- **Option/Maybe Types**: For nullable values
+
+**When to Use Each:**
+
+- Exceptions: Unexpected errors, exceptional conditions
+- Result Types: Expected errors, validation failures
+- Panics/Crashes: Unrecoverable errors, programming bugs
+
+### 2. Error Categories
+
+**Recoverable Errors:**
+
+- Network timeouts
+- Missing files
+- Invalid user input
+- API rate limits
+
+**Unrecoverable Errors:**
+
+- Out of memory
+- Stack overflow
+- Programming bugs (null pointer, etc.)
+
+## Detailed patterns and worked examples
+
+Detailed pattern documentation lives in `references/details.md`. Read that file when the navigation tier above is insufficient.
+
+## Best Practices
+
+1. **Fail Fast**: Validate input early, fail quickly
+2. **Preserve Context**: Include stack traces, metadata, timestamps
+3. **Meaningful Messages**: Explain what happened and how to fix it
+4. **Log Appropriately**: Error = log, expected failure = don't spam logs
+5. **Handle at Right Level**: Catch where you can meaningfully handle
+6. **Clean Up Resources**: Use try-finally, context managers, defer
+7. **Don't Swallow Errors**: Log or re-throw, don't silently ignore
+8. **Type-Safe Errors**: Use typed errors when possible
+
+```python
+# Good error handling example
+def process_order(order_id: str) -> Order:
+    """Process order with comprehensive error handling."""
+    try:
+        # Validate input
+        if not order_id:
+            raise ValidationError("Order ID is required")
+
+        # Fetch order
+        order = db.get_order(order_id)
+        if not order:
+            raise NotFoundError("Order", order_id)
+
+        # Process payment
+        try:
+            payment_result = payment_service.charge(order.total)
+        except PaymentServiceError as e:
+            # Log and wrap external service error
+            logger.error(f"Payment failed for order {order_id}: {e}")
+            raise ExternalServiceError(
+                f"Payment processing failed",
+                service="payment_service",
+                details={"order_id": order_id, "amount": order.total}
+            ) from e
+
+        # Update order
+        order.status = "completed"
+        order.payment_id = payment_result.id
+        db.save(order)
+
+        return order
+
+    except ApplicationError:
+        # Re-raise known application errors
+        raise
+    except Exception as e:
+        # Log unexpected errors
+        logger.exception(f"Unexpected error processing order {order_id}")
+        raise ApplicationError(
+            "Order processing failed",
+            code="INTERNAL_ERROR"
+        ) from e
+```
+
+## Common Pitfalls
+
+- **Catching Too Broadly**: `except Exception` hides bugs
+- **Empty Catch Blocks**: Silently swallowing errors
+- **Logging and Re-throwing**: Creates duplicate log entries
+- **Not Cleaning Up**: Forgetting to close files, connections
+- **Poor Error Messages**: "Error occurred" is not helpful
+- **Returning Error Codes**: Use exceptions or Result types
+- **Ignoring Async Errors**: Unhandled promise rejections