Cli Shell

You are working on the CLI shell — the entry point that wires Commander subcommands, prints the welcome screen, warns about missing Claude hooks, dispatches to handlers, and translates CliError into a clean exit. Also the public programmatic surface re-exported from src/index.js.

Domain purpose

This layer is what a user actually invokes (aspens …) and what programmatic consumers import. It owns argument parsing, top-level error handling, and the welcome UX. All real work lives in src/commands/*.js — the shell only routes.

Business rules / invariants

• Handlers must throw CliError, never call process.exit(). The top-level handler in bin/cli.js:250 catches it, prints Error: (unless logged: true) in red, and exits with err.exitCode (default 1). Plain Error falls through to the same printer but always exits 1.
• logged: true means "I already printed a user-friendly message" — top level then exits silently with the given code. Use it when the handler rendered a clack outro or multi-line failure already.
• checkMissingHooks(repoPath) runs before doc sync, add, and customize — warns (does not throw) when .claude/skills/ exists but .claude/hooks/skill-activation-prompt.sh or .claude/skills/skill-rules.json is absent. Skipped entirely when .claude/skills/ is missing (nothing to activate).
• No-command invocation shows showWelcome() — listing essential commands, generate/sync, Claude add-ons, utilities, options, typical workflow, and target notes. Adding a new subcommand requires updating this screen too.
• Template counts in the welcome are filesystem-derived — countTemplates(subdir) reads src/templates/{agents,commands,hooks} and filters dotfiles; returns '?' on read failure (never throws).
• Version comes from package.json at runtime via readFileSync; falls back to '0.0.0' silently if parse/read fails. Do not hardcode.
• Numeric option parsers throw InvalidArgumentError (Commander-native) — parsePositiveInt rejects ≤0/NaN; parseCommits additionally caps at 50.
• Signal handlers exit with conventional codes — SIGINT→130, SIGTERM→143. Used to clean up spawned claude -p / codex exec children.

Non-obvious behaviors

• Action wrappers chain checkMissingHooks before the handler for doc sync, add, customize — done inline via arrow (args, options) => { checkMissingHooks(resolve(path)); return handler(...) }. Don't move this into the handler — the warning should fire even if the handler later fails or short-circuits.
• program.parseAsync() is required (not .parse()) — handlers are async; .catch() on the returned promise is the only place plain errors are surfaced.
• src/index.js is the public programmatic API — only re-exports scanRepo, runClaude, loadPrompt, parseFileOutput, writeSkillFiles, buildContext, buildBaseContext, buildDomainContext, analyzeImpact. Adding/removing a re-export is a breaking change for embedders; treat it as such.

Critical files

• bin/cli.js — Commander setup, option parsers, welcome screen, signal handlers, top-level CliError catch.
• src/lib/errors.js — CliError class with exitCode and logged options (plus optional cause).
• src/index.js — Stable programmatic surface for library consumers.

Critical Rules

• New subcommand → register on program (or the doc subgroup) and add it to showWelcome() so users discover it.
• Never swallow a handler error in the action wrapper — let it bubble to program.parseAsync().catch().
• When a handler renders its own failure UX (clack/picocolors), throw new CliError(msg, { logged: true, exitCode }) so the top level does not double-print.

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Last Updated: 2026-05-11

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: aspenkit
• Source: aspenkit/aspens
• License: MIT
• Homepage: https://www.npmjs.com/package/aspens

Install and usage instructions live in the source repository linked above.