Python Execution Fallback Workflow

This skill provides a systematic debugging approach when inline Python code execution fails, particularly in heredoc or shell_agent contexts.

Pattern Overview

When Python code execution fails, follow this recovery workflow:

1. Attempt inline execution first - Try running Python code directly
2. Write script to file on failure - Persist the code to a .py file
3. Execute the file - Run the saved script via shell
4. Validate output - Verify results are correct and complete

When to Use

Apply this pattern when:

• Inline Python execution fails with syntax or runtime errors
• Heredoc-based code execution encounters parsing issues
• Working with complex multi-line scripts that need debugging
• Need systematic approach to isolate execution failures
• Spreadsheet/data generation tasks fail in inline mode

Step-by-Step Instructions

Step 1: Attempt Inline Execution

Try executing Python code inline first (using execute_code_sandbox or similar):

# Example: Attempt inline execution
import pandas as pd
import openpyxl

df = pd.read_excel("input.xlsx")
# Process data...
df.to_excel("output.xlsx", index=False)

If this succeeds, proceed. If it fails, move to Step 2.

Step 2: Write Script to File (On Failure)

When inline execution fails, write the complete script to a persistent file:

# Capture the script content
script_content = '''
import pandas as pd
import openpyxl
import sys

try:
    # Your original code here
    df = pd.read_excel("input.xlsx")
    
    # Processing logic
    result_df = df.groupby("category").sum()
    
    # Output
    result_df.to_excel("output.xlsx", index=False)
    print("SUCCESS: File generated")
    
except Exception as e:
    print(f"ERROR: {e}", file=sys.stderr)
    sys.exit(1)
'''

# Write to file
with open("script.py", "w") as f:
    f.write(script_content)

print("Script written to script.py")

Step 3: Execute the File

Run the saved script using shell execution:

python script.py

Or with error capture:

python script.py 2>&1 | tee execution.log

This approach:

• Avoids heredoc parsing issues
• Provides clearer error messages
• Allows script inspection and modification
• Enables re-execution without rewriting

Step 4: Validate Output

Verify the results are correct:

# Validation script
import pandas as pd
import os

# Check file exists
if os.path.exists("output.xlsx"):
    df = pd.read_excel("output.xlsx")
    print(f"Rows: {len(df)}, Columns: {len(df.columns)}")
    print(df.head())
    print("VALIDATION: PASSED")
else:
    print("VALIDATION: FAILED - Output file missing")

Code Example: Complete Workflow

# Full fallback workflow example
def generate_spreadsheet_fallback(data, output_path):
    """Generate spreadsheet with fallback workflow"""
    
    # Step 1: Try inline
    inline_script = f'''
import pandas as pd
data = {data}
df = pd.DataFrame(data)
df.to_excel("{output_path}", index=False)
'''
    
    try:
        # Attempt inline execution
        result = execute_code_sandbox(code=inline_script)
        if "error" not in result.lower():
            return "SUCCESS_INLINE"
    except Exception as e:
        pass
    
    # Step 2: Write to file
    file_script = f'''
import pandas as pd
import sys

try:
    data = {data}
    df = pd.DataFrame(data)
    df.to_excel("{output_path}", index=False)
    print("SUCCESS")
except Exception as e:
    print(f"ERROR: {{e}}", file=sys.stderr)
    sys.exit(1)
'''
    
    with open("generate.py", "w") as f:
        f.write(file_script)
    
    # Step 3: Execute file
    shell_result = run_shell(command="python generate.py")
    
    # Step 4: Validate
    if os.path.exists(output_path):
        return "SUCCESS_FILE"
    else:
        return "FAILED"

Best Practices

1. Include error handling in file-based scripts (try/except with sys.stderr)
2. Add success indicators (print statements) to confirm execution
3. Preserve original logic when converting from inline to file
4. Check return codes when executing scripts via shell
5. Clean up temporary files after successful validation
6. Log both stdout and stderr for debugging

Common Failure Scenarios

This pattern helps resolve:

• Heredoc string escaping issues
• Multi-line code formatting problems
• Import path resolution failures
• Environment variable access issues
• Complex indentation in inline code

Related Patterns

• Combine with retry-with-modification for iterative debugging
• Use alongside output-validation-check for result verification
• Pair with error-log-analysis for root cause identification