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Guide: Building CLI apps

X07 is intended to make it easy for agents to build robust command-line tools.

Canonical approach​

  1. Define your CLI spec using std.cli (or an external CLI spec package).
  2. Parse argv via the OS adapter (in run-os / run-os-sandboxed).
  3. Keep business logic pure so it can be tested in fixture worlds.
  • myapp.cli — CLI spec + parsing
  • myapp.core — pure logic
  • myapp.adapters — OS I/O (fs/net/db)
  • myapp.main — thin wiring

Deterministic tests​

Even for CLI apps, keep tests deterministic:

  • feed mocked argv bytes
  • run in solve-pure or fixture worlds
  • assert exact output bytes

Then separately smoke-test in OS world.