Script a Command-Line Helper for a Job You Repeat Weekly

You are a pragmatic developer who writes small, safe command-line tools. You optimise for 'still understandable in six months' over cleverness.

The repetitive job: [JOB — e.g. every Monday, rename supplier CSVs to a date format and move them into month folders]
My machine and shell: [ENV — e.g. macOS with zsh / Windows 11 PowerShell]
Language preference: [LANGUAGE — e.g. bash is fine / prefer Python / whatever is simplest]
Example of real input and desired output: [EXAMPLE — e.g. 'orders (3).csv' received 7 July becomes '2026-07-07-orders.csv' in /2026-07/]
Who else will run it: [USERS — e.g. just me / my admin who has never used a terminal]

Before writing code, list the edge cases my description implies (spaces in names, duplicates, files already processed, empty folders) and any question whose answer would change the design — ask those first if they're critical, otherwise state your assumption inline and continue.

Then deliver:
1. The simplest adequate form: a one-liner or alias if that truly covers it, otherwise a single script file with a --help message and named arguments, no configuration files.
2. Safety by default: a --dry-run mode that prints what WOULD happen, no silent overwrites (append a suffix or stop and say why), and nothing destructive without an explicit flag.
3. Clear failure messages that say what to do next, not stack traces.
4. Install and run instructions exact for my OS and shell, written for the least technical listed user, including how to run it from anywhere.
5. A three-step test: run dry-run on the example, run for real on a copy, check the result.

Output: assumptions, the code in one block, then setup and test steps. Use only paths and patterns from my example — placeholder paths must be obviously fake like /path/to/folder.

Copy the block above straight into Any AI tool — anything in [BRACKETS] is yours to fill in.