A coding agent reads your project, edits files and runs commands while you say in plain language what needs to happen. This topic is about working with one every day, mostly with Claude Code.
If you are just starting, read Claude Code in PhpStorm first for installing the CLI and the plugin, and then Using Claude Code effectively: keeping the context clean, planning first and letting Claude check its own work. If the agent has to keep working on its own for longer, Letting Claude Code work autonomously helps. Claude Code Routines shows how a task runs in the cloud on a schedule.
Claude Code is not the only one. In OpenCode you choose the model yourself, and Mistral Vibe is the European, open-source option, with a side-by-side comparison with Claude Code. Claude plugins and Superpowers and the four Karpathy rules against AI code that does too much are about working to a fixed method.