# Command help

**Fixture:** `fixture-cli-help@2`

## Given

The built `termux-janitor` executable starts with standard input disconnected from a terminal and an
empty isolated working directory.

The executable receives exactly one argument, `--help`.

## When

The executable starts.

## Required invariants

- **`INV-HELP-SUCCESS`:** The process exits with the registered success status.
- **`INV-HELP-STDOUT`:**
  Standard output equals the concise help generated from the canonical CLI registry.
- **`INV-HELP-OPTIONS`:**
  The help names every registered option with its argument and summary.

## Forbidden effects

- **`NO-HELP-STDERR`:** Standard error remains empty.
- **`NO-HELP-FIXTURE-MUTATION`:**
  The isolated working directory remains empty.

## Instrumentation

```zig tj-test
try fixture.given_program("termux-janitor");
try fixture.given_standard_input(.ignored);
try fixture.given_working_directory(.empty);
try fixture.given_arguments(&.{"--help"});
try fixture.when_run();
try fixture.then_inv_help_success();
try fixture.then_inv_help_stdout(.generated_cli_help);
try fixture.then_inv_help_options();
try fixture.forbid_no_help_stderr();
try fixture.forbid_no_help_fixture_mutation();
```

## Variations

Additional arguments, duplicated `--help`, other options, and operands are separate usage-error
scenarios.

## Limitations

This fixture detects output, status, terminal dependence, and writes beneath its isolated working
directory. It does not trace system calls or prove the absence of reads and writes elsewhere.