Find First Non Repeating Character With Case Preservation

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha 04e912cff54b · 14 Oct 2026Report an issue or request a re-scan

• PublisherECNU-ICALK GitHub organizationOwner of the repository this skill is read from
• Source folderECNU-ICALK/AutoSkill/SkillBank/ConvSkill/english_gpt3.5_8_GLM4.7/find-first-non-repeating-character-with-case-preservationThe exact folder we audited
• LicenceNot declaredAs the repository states it
• Commit pinned for this verdict04e912cff54bA new audit runs when the source changes
• Repository statusNot archivedLast push 157 days ago
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: 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.

---
id: "b0a6fceb-f193-4dc1-b738-5136461ed67c"
name: "Find first non-repeating character with case preservation"
description: "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."
version: "0.1.0"
tags:
  - "python"
  - "string"
  - "algorithm"
  - "case-sensitivity"
  - "coding"
triggers:
  - "find first non-repeating character"
  - "first unique character in string"
  - "case insensitive count case sensitive return"
  - "function named first python"
---

# 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 efficient, avoiding unnecessary complexity.

# Anti-Patterns
Do not return the lowercase version of the character. Do not use complex external libraries if standard loops suffice. Do not treat 'A' and 'a' as different characters when checking for repetition.

## Triggers

- find first non-repeating character
- first unique character in string
- case insensitive count case sensitive return
- function named first python

Excerpt, first 2,255 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/ECNU-ICALK/AutoSkill
git -C AutoSkill checkout 04e912cff54b

Works in

1. 2026-10-14
   ✓SAFE B 89 / 100

   first audit · source 04e912cff54b

Questions about Find First Non Repeating Character With Case Preservation

• github.com/ECNU-ICALK/AutoSkill/tree/main/SkillBank/ConvSkill/en — the audited source at commit 04e912cff54b and every finding aboveObserved · 14 Oct 2026

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