Project Scaffold Skill

Generates a complete, ready-to-open Python project: devcontainer config, VS Code settings and extensions, a full Makefile, pytest setup, commit-msg hook, and GitHub SSH wiring - everything configured and consistent from the first commit.

Step 1: Gather Requirements

Ask the user for the following. Collect all answers before generating anything.

Required:

• Project name -- used for the root folder name and package identifiers

Optional (ask, but have sensible defaults):

• Devcontainer build mode -- ask:

_"Do you want a Dockerfile-based devcontainer (pre-baked image, fast container startup -- recommended) or a base image + postCreate script (standard, pulls fresh each time)?"_ Default: Dockerfile-based.

• GitHub SSH private key path -- for cloning private repos inside the devcontainer.

Ask: _"Do you have a GitHub SSH private key you'd like wired into the devcontainer? If so, what's the path on your host machine (e.g. ~/.ssh/id_ed25519)?"_ Default: skip if not provided.

• Extra VS Code extensions -- beyond the Python defaults.

Ask: _"Any extra VS Code extensions you want pre-installed?"_

• Project root folder for the new scaffolded project:
• Default: ~/Code -- ask the user only if they want a different location

Step 2: Choose Devcontainer Build Mode

Based on the user's answer:

Dockerfile-based (recommended default)

Generate a .devcontainer/Dockerfile alongside devcontainer.json. The Dockerfile bakes all heavy system-level installs into image layers (cached after first build). The postCreate.sh is trimmed to only project-specific runtime steps (SSH key perms, workspace dirs, shell aliases, exporting and adding environment variables to the shell ~/.zshrc and ~/.bashrc files).

In devcontainer.json, replace "image": "..." with:

"build": {
  "dockerfile": "Dockerfile",
  "context": ".."
}

See references/python.md for the Dockerfile template.

Base image + postCreate script (standard)

Use "image": "..." in devcontainer.json and run the full postCreate.sh on every new container. Simpler but slower -- every postCreate.sh run re-downloads and installs everything.

Step 3: Read the Reference Files

Read all of these before generating anything:

Step 4: Generate the Project

Create all files under ~/Code/<project-name> (or the user-specified root).

Project structure

<project-name>/
├── .devcontainer/
│   ├── devcontainer.json
│   ├── Dockerfile              <- only if Dockerfile-based mode chosen
│   └── scripts/
│       └── postCreate.sh
├── .vscode/
│   ├── extensions.json
│   └── settings.json
├── .github/
│   └── (empty, ready for workflows)
├── src/
│   └── __init__.py
├── tests/
│   ├── __init__.py
│   └── test_sample.py
├── Makefile
├── .gitignore
├── .githooks/
│   └── commit-msg
├── pyproject.toml
├── requirements.txt
├── requirements-dev.txt
├── .python-version
└── README.md

Step 5: Makefile

Always generate a Makefile. See references/common.md -> makefile.template.md for the full template.

Required targets (all projects):

• make help -- prints available targets (always first, always default)
• make check-sys-deps -- verify required system packages are on PATH
• make check-venv -- verify the virtual environment is activated
• make venv -- creates .venv using the correct Python version
• make install -- installs requirements.txt + requirements-dev.txt into the active venv
• make format -- runs black + isort
• make lint -- runs ruff + mypy
• make typecheck -- runs mypy
• make test -- runs pytest with coverage
• make ci -- runs format + lint + typecheck + test in sequence
• make clean -- removes build artifacts, caches, .venv

Conditional targets:

• make github-check -- include only if the user provided an SSH key path

Step 6: GitHub SSH Setup

If the user provided an SSH key path

Extract the filename from the path (e.g. ~/.ssh/id_ed25519 -> id_ed25519). Call that <SSH_KEY_FILENAME> -- substitute it everywhere below.

devcontainer.json -- mount only that file, not the whole ~/.ssh directory:

"mounts": [
  "source=<key-path>,target=/home/vscode/.ssh/<SSH_KEY_FILENAME>,type=bind,consistency=cached"
]

postCreate.sh -- replace the SSH_KEY=<SSH_KEY_FILENAME> placeholder with the actual filename. The if block in the template then handles permissions and known_hosts automatically.

Makefile -- add the github-check target (see references/makefile.template.md).

If no SSH key was provided

• Skip the SSH mount in devcontainer.json entirely -- do not mount ~/.ssh
• Remove the SSH_KEY / if block from postCreate.sh
• Omit the github-check Makefile target

Step 7: Git Init

After generating all files:

1. .gitignore -- from references/gitignore.template.md, use as-is
2. .githooks/commit-msg -- from references/commit-msg.template.sh, copy verbatim, chmod +x
3. README.md -- from references/readme.template.md, substitute <PROJECT_NAME>; remove the GitHub SSH section if no key was configured
4. Tell the user to run:

    cd <project-name>
    git init
    git config core.hooksPath .githooks
    git add .
    git commit -m "chore: initial scaffold"

Lite Mode: Clone / Reset an Existing Scaffold

Use this mode when the user wants to copy an existing scaffolded project to a new name -- no questions about devcontainer mode, SSH keys, or extensions. Everything is copied from the source project and the project name is substituted throughout.

Trigger phrases

• "clone this scaffold as <name>"
• "copy this project to <name>"
• "reset project / clean copy"
• "lite scaffold for <name>"
• "new copy of this project"

Step L1: Gather Requirements

Ask only:

• New project name -- used for the destination folder and all <PROJECT_NAME> substitutions
• Source project path -- default: current working directory
• Destination root -- default: same parent directory as the source project

Step L2: Copy and Substitute

1. Copy the entire source project tree to <destination-root>/<new-project-name>/
2. Exclude: .venv/, __pycache__/, .mypy_cache/, .ruff_cache/, .pytest_cache/,

dist/, build/, *.egg-info/, .coverage, htmlcov/, *.pyc, .git/

1. In every copied file, replace all occurrences of the old project name with the new project name.

Files to update (at minimum):

• Makefile -- comment header
• pyproject.toml -- name, [tool.mypy] source root if present
• README.md -- title and any references
• src/__init__.py -- docstring
• .devcontainer/devcontainer.json -- "name" field
• .devcontainer/scripts/postCreate.sh -- any echo banners
• .devcontainer/scripts/postStartCommand.sh -- comment header

Step L3: Reset Git History

After copying:

1. Delete the copied .git/ directory (start clean)
2. Tell the user to run:

    cd <new-project-name>
    git init
    git config core.hooksPath .githooks
    git add .
    git commit -m "chore: initial scaffold"

Step L4: Output (Lite Mode)

Print a one-line confirmation:

Cloned scaffold -> <destination-root>/<new-project-name>/
Substituted project name: <old-name> -> <new-name>
Git history reset -- run the commands above to initialise a fresh repo.

Output

Print a summary tree of everything created, then list the make targets available. Remind the user:

• Open the folder in VS Code and it will prompt to Reopen in Container
• Activate venv: source .venv/bin/activate
• Run make install to install dependencies
• Run make test to verify everything works
• If SSH was configured, run make github-check to verify connectivity