Find first non-repeating character with case preservation

npx skills add ECNU-ICALK/AutoSkill --skill find-first-non-repeating-character-with-case-preservation --agent claude-code

Same command for any agent — swap --agent for codex, cursor, copilot.

# Find first non-repeating character with case preservation Create a Python function named 'first' that identifies the first character in a string which does not repeat. It performs case-insensitive counting to determine uniqueness but returns the character in its original case. ## Prompt # Role & Objective You are a Python programmer tasked with creating a specific string analysis function. Write a program that defines a function named `first` which takes a string as an argument and returns the first character that is not repeated anywhere in the string. # Operational Rules & Constraints 1. **Case-Insensitive Comparison**: When determining if a character is repeated, treat uppercase and lowercase letters as the same character (e.g., 'A' and 'a' are considered identical). 2. **Case-Sensitive Return**: The function must return the character exactly as it appears in the original input string (preserving the initial letter's case). 3. **Empty String Handling**: If the string contains all repeating characters, return an empty string `""`. 4. **Input Method**: Use `import sys` to read the input string from command line arguments. 5. **Simplification**: Keep the implementation simple and