# Design CLI Output

> Design terminal output for a CLI tool with chalk colors, Unicode glyphs, multiple verbosity levels (human, verbose, quiet, JSON), and consistent voice rules. Covers color palette selection, status indicator design, reporter function architecture, ceremony/narrative output variants, and cross-terminal compatibility. Use when building a new CLI reporter module, adding warm narrative output to an existing tool, standardizing output across multiple commands, or designing machine-readable JSON alongside human-readable text.

- Skill: `pjt222/design-cli-output-10` (Agent Skill)
- Install (CLI): `npx skillmds@latest add pjt222/design-cli-output-10`
- Raw SKILL.md: https://api.skillmd.com/api/skills/pjt222/design-cli-output-10/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Design & Media
- License: MIT
- Author: pjt222 (https://skillmd.com/u/pjt222)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/pjt222/design-cli-output-10

---


# Design CLI Output

Consistent multi-level terminal output for CLI.

## Use When

- New reporter module → CLI
- Warm/narrative alongside transactional
- Std across commands
- JSON machine parallel to human
- Colors, glyphs, verbosity for new tool

## In

- **Required**: CLI name + audience (devs, ops, end users)
- **Required**: Commands needing formatting
- **Optional**: Ceremony/narrative variant?
- **Optional**: Branding (palette, tone)

## Do

### Step 1: Color palette

chalk → named palette.

**Load chalk behind no-color fallback.** Fallback must stand in for every call shape palette uses — more than passing strings thru:

```javascript
// A factory returns a *function*; a direct style returns a string. Enumerate
// this list against the installed chalk, not from memory — chalk 6 added the
// three underline* variants, and a list that omits them is wrong for those names.
const FACTORIES = new Set(['ansi256', 'bgAnsi256', 'bgHex', 'bgRgb', 'hex',
  'rgb', 'underlineAnsi256', 'underlineHex', 'underlineRgb']);

function makeChalkStub() {
  return new Proxy((text) => text, {
    get(target, prop) {
      if (prop === 'then') return undefined;   // must not be a thenable
      if (prop === 'level') return 0;          // no color support, truthfully
      if (typeof prop === 'symbol') return Reflect.get(target, prop);
      return FACTORIES.has(prop) ? () => makeChalkStub() : makeChalkStub();
    },
  });
}

let chalk;
try { chalk = (await import('chalk')).default; }
catch { chalk = makeChalkStub(); }
```

4 invariants, shorter stub gets each wrong:

1. **Proxy target callable** — `(text) => text`, not `{}`. Chain (`chalk.bold.cyan('x')`) → every hop indexable + callable.
2. **Factories return fn.** `new Proxy({}, { get: () => (s) => s })` OK for direct styles, breaks factories: `chalk.hex('#FF6B35')` = *string* `'#FF6B35'`, call it → `TypeError: ... is not a function`. Palettes built at module load → that fallback kills tool at import time — exactly where degrading to plain text was the point.
3. **`then` = `undefined`.** Stub answering every prop w/ fn → `await chalk` hangs forever: runtime calls `.then`, waits for callback nobody fires. Node: `Detected unsettled top-level await`, exit 13.
4. **`level` = number.** Capability gates read `chalk.level >= 1`; truthy stub opens them w/ no color behind.

Build palette from whichever obj survived that import.

**Standard** (transactional):

```javascript
// Status colors
const ok = chalk.green;       // success
const fail = chalk.red;       // errors
const warn = chalk.yellow;    // warnings
const info = chalk.cyan;      // identifiers, names
const dim = chalk.dim;        // secondary info, paths
const bold = chalk.bold;      // headers
```

**Warm** (ceremony/narrative):

```javascript
const C = {
  flame: chalk.hex('#FF6B35'),   // active elements, fire
  amber: chalk.hex('#FFB347'),   // arriving items, warm highlights
  spark: chalk.hex('#FFF4E0'),   // individual items (sparks/skills)
  ember: chalk.hex('#8B4513'),   // cold/dormant states
  warm:  chalk.hex('#D4A574'),   // neutral warm text
  dim:   chalk.dim,              // background, secondary
  fail:  chalk.red,              // errors stay red (honest)
};
```

Rules:
- Always no-color fallback + check it vs call shapes palette really uses — warm palette above near-all factories
- Hex for custom (`chalk.hex('#FF6B35')`)
- Fail/err → red regardless
- Name by semantic role not visual
- Share 1 stub across modules, no rebuild per import site → else same defect hunted + fixed in every copy

→ Palette obj w/ named entries + fallback that ran, not merely written.

If err: Exercise fallback path direct; palette = wrong place to find it broken. Stub in scope:

```javascript
console.assert(chalk.dim('x') === 'x');            // direct style
console.assert(chalk.hex('#fff')('x') === 'x');    // factory — the usual defect
console.assert(chalk.bold.cyan('x') === 'x');      // chain
console.assert(chalk.level === 0);                 // capability gate stays shut
await chalk;                                       // must not hang
```

`NO_COLOR=1` no cover this. It runs *working* chalk choosing no escapes; fallback runs chalk that failed import. 2 paths share no code. See [More Ex](references/EXAMPLES.md#step-1-the-no-color-chalk-fallback) → annotated prod stub, defect repro, runnable ver of checks above.

### Step 2: Status indicators

Unicode glyphs or ASCII:

**ASCII (max compat):**

```text
+  created/installed (green)
-  removed/deleted (red)
=  skipped/unchanged (dim)
!  error/warning (red)
```

**Unicode (richer, UTF-8 term):**

```text
✦  item/skill/practice (spark)
◉  active/burning state
◎  cooling/embers state
○  cold/dormant state
◌  available/not installed
✗  failed item
✓  success (use sparingly — not all terminals render it well)
```

Criteria:
- ASCII → CI/piped
- Unicode → interactive
- Both via `--ascii` flag or `NO_COLOR`
- Test: macOS Terminal, Windows Terminal, VS Code, SSH

→ Glyph set communicates status at glance w/o color alone.

If err: Glyph renders `?` or box → ASCII equiv. `+/-/=/!` works everywhere.

### Step 3: Verbosity levels

Every cmd supports 4:

| Level | Flag | Audience | Content |
|---|---|---|---|
| **Default** | (none) | Human at terminal | Formatted, colored, informative |
| **Verbose** | `--verbose` or `--ceremonial` | Human wanting detail | Per-item breakdown, arrival sequences |
| **Quiet** | `--quiet` | Scripts, CI | Minimal lines, status icons, no decoration |
| **JSON** | `--json` | Machine consumers | Structured, parseable, complete |

Pattern:

```javascript
function output(data, options) {
  if (options.json) {
    console.log(JSON.stringify(data, null, 2));
    return;
  }
  if (options.quiet) {
    for (const item of data.items) {
      const icon = item.ok ? '+' : '!';
      console.log(`${icon} ${item.id}`);
    }
    return;
  }
  // Default (or verbose) human output
  printFormatted(data, { verbose: options.verbose });
}
```

JSON rules:
- Always valid (no mix w/ human text)
- Include all human data + machine fields
- Consistent keys across cmds
- Exit 0 success, 1 err (regardless of mode)

→ 4 clear levels, consistent behavior across cmds.

If err: Verbose too noisy → opt-in (`--ceremonial`) not graduated.

### Step 4: Voice rules

Tone + style. Prevents inconsistency.

Ex (campfire reporter):

1. **Present tense, active**: "mystic arrives" not "mystic has been installed"
2. **No exclamation**: Quiet confidence.
3. **Metaphor replaces jargon**: "practices" not "dependencies" (ceremony only)
4. **Failures honest, not catastrophic**: "A spark was lost" not "ERROR: installation failed with exit code 1"
5. **Closing line reflects state**: Every op ends summary
6. **No emoji**: Unicode glyphs carry visual weight w/o decorative
7. **Every word info**: If no understanding → remove

Standard (non-ceremony):
- Concise, factual lines
- Status icon + item ID + ctx
- Summary line w/ counts
- Err msgs suggest actions

→ 3-7 voice rules output fns follow.

If err: Rules arbitrary → test. Write same output w/ + w/o rule. If no change → rule not needed.

### Step 5: Reporter fns

Module w/ focused fns:

```javascript
// reporter.js — standard output
export function printResults(results) { ... }
export function printItemTable(items) { ... }
export function printDetections(detections) { ... }
export function printAudit(auditResults) { ... }
export function printDryRun() { ... }
export function warn(msg) { ... }
export function error(msg) { ... }
export { chalk };
```

Each fn:
1. Handle empty/null gracefully
2. Compute layout (col widths, padding)
3. Output w/ palette
4. Summary line at bottom

Ceremony → separate module:

```javascript
// campfire-reporter.js — warm narrative output
export function printArrival({ teamId, agents, results, ceremonial }) { ... }
export function printScatter({ teamId, agents, results }) { ... }
export function printTend(fires) { ... }
export function printCampfireList({ teams, state, reg }) { ... }
export function printFireSummary({ team, fireData, reg }) { ... }
export function printJson(data) { ... }
```

→ Independent fns, handle own formatting w/o caller state.

If err: Fn >~50 lines → extract helpers. Reviewable in isolation.

### Step 6: Test across envs

```bash
# With colors (interactive terminal)
node cli/index.js list --domains

# Without colors (piped)
node cli/index.js list --domains | cat

# With NO_COLOR environment variable
NO_COLOR=1 node cli/index.js list --domains

# JSON mode (parseable)
node cli/index.js campfire --json | jq .

# In CI (typically no TTY)
CI=true node cli/index.js audit

# The no-color fallback. A failed import cannot be provoked with an env var, so
# assert on the stub itself in the suite rather than reaching it through the CLI.
# Pass a glob, not a directory: `node --test <dir>` stopped expanding at Node 22.
node --test 'cli/test/*.test.js'
```

Check:
- Colors in interactive
- No ANSI leaks in piped
- JSON valid (`jq .`)
- Unicode in target terminals
- Col align w/ varying widths
- No-color fallback answers every call shape palette uses, asserted in suite not hand-demoed once

→ Output correct in all 6 contexts.

If err: ANSI leaks → chalk respects `NO_COLOR`. Unicode breaks → ASCII fallback. Green suite says nothing about color either way: test runners pipe stdout → `chalk.level` 0 → colored + uncolored out byte-identical, assertions hold w/ color fully broken. Prove color works → `FORCE_COLOR=3` + assert on escape seq.

## Check

- [ ] Palette has no-color fallback + fallback ran: direct style, factory, chain, `level === 0`, `await` all checked
- [ ] Status indicators work color + no-color
- [ ] All 4 verbosity levels useful
- [ ] JSON valid + `jq`-parseable
- [ ] Voice rules docs + followed
- [ ] Reporter fns handle empty/null
- [ ] Tested: terminal, piped, NO_COLOR, CI

## Traps

- **No-color fallback covering direct styles only**: `new Proxy({}, { get: () => (s) => s })` reads complete, does cover `chalk.dim` + `chalk.red`, but every factory then returns string caller immediately tries to call. Palettes built at module load → `TypeError` lands at import time — fallback fails hardest in the 1 case it exists for. Step 1 lists 4 invariants stub must satisfy.
- **Mix human + JSON**: `--json` only valid JSON. Stray line ("DRY RUN") breaks parsers. Suppress human in JSON mode.
- **Hardcoded col widths**: Varies. `Math.max(...items.map(i => i.id.length))` dyn.
- **Color w/o meaning**: Color-only → colorblind + piped lose info. Pair w/ text (`+`, `OK`, `ERR`).
- **Ceremony wrong ctx**: Interactive only. CI/scripts/`--quiet` = noise. Gate behind flags.
- **Forget summary**: Users scan last line first. 1-line summary (counts).

## →

- `scaffold-cli-command` — cmds using this output
- `test-cli-application` — test output matches
- `build-cli-plugin` — plugins report results