Package a commit-message skill as a Tessl plugin

Background

You are working inside an existing repository that already uses Tessl. The team wants a reusable Tessl plugin that helps an agent write Conventional Commits style commit messages: one skill that, given a staged diff, produces a properly formatted commit message (type, optional scope, imperative summary, body, and footer).

This is a simple, self-contained workflow, so a single skill is the right shape.

Your task

Create the plugin on disk in this repository, ready to validate:

• Scaffold a Tessl plugin named commit-writer in the tessl workspace, with a single skill that writes Conventional Commits messages.
• Author the skill's SKILL.md with a strong description (what it does and when to reach for it) and a few ordered steps.
• Run the appropriate Tessl CLI validation to confirm the plugin is structurally sound.

Do not publish. Leave the finished plugin on disk in the repository.