design-cli-output
About
This skill provides patterns for designing CLI terminal output with features like colored text, status indicators, and multiple verbosity levels including JSON. It covers architecture for reporter functions, cross-terminal compatibility, and maintaining a consistent narrative voice. Use it when building or enhancing a CLI tool to standardize human-readable and machine-parsable output.
Quick Install
Claude Code
Recommendednpx skills add pjt222/agent-almanac -a claude-code/plugin add https://github.com/pjt222/agent-almanacgit clone https://github.com/pjt222/agent-almanac.git ~/.claude/skills/design-cli-outputCopy and paste this command in Claude Code to install this skill
Documentation
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:
Standard (transactional):
let chalk;
try { chalk = (await import('chalk')).default; }
catch { chalk = new Proxy({}, { get: () => (s) => s }); }
// 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):
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:
- No-color fallback (Proxy pattern)
- Hex for custom (
chalk.hex('#FF6B35')) - Fail/err → red regardless
- Name by semantic role not visual
→ Palette obj w/ named entries + no-color fallback.
If err: chalk unavailable (piped, CI) → Proxy returns strings unchanged. Test NO_COLOR=1.
Step 2: Status indicators
Unicode glyphs or ASCII:
ASCII (max compat):
+ created/installed (green)
- removed/deleted (red)
= skipped/unchanged (dim)
! error/warning (red)
Unicode (richer, UTF-8 term):
✦ 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
--asciiflag orNO_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:
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):
- Present tense, active: "mystic arrives" not "mystic has been installed"
- No exclamation: Quiet confidence.
- Metaphor replaces jargon: "practices" not "dependencies" (ceremony only)
- Failures honest, not catastrophic: "A spark was lost" not "ERROR: installation failed with exit code 1"
- Closing line reflects state: Every op ends summary
- No emoji: Unicode glyphs carry visual weight w/o decorative
- 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:
// 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:
- Handle empty/null gracefully
- Compute layout (col widths, padding)
- Output w/ palette
- Summary line at bottom
Ceremony → separate module:
// 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
# 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
Check:
- Colors in interactive
- No ANSI leaks in piped
- JSON valid (
jq .) - Unicode in target terminals
- Col align w/ varying widths
→ Output correct in all 5 contexts.
If err: ANSI leaks → chalk respects NO_COLOR. Unicode breaks → ASCII fallback.
Check
- Palette has no-color fallback
- 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
- Mix human + JSON:
--jsononly 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 outputtest-cli-application— test output matchesbuild-cli-plugin— plugins report results
GitHub Repository
Related Skills
content-collections
MetaThis skill provides a production-tested setup for Content Collections, a TypeScript-first tool that transforms Markdown/MDX files into type-safe data collections with Zod validation. Use it when building blogs, documentation sites, or content-heavy Vite + React applications to ensure type safety and automatic content validation. It covers everything from Vite plugin configuration and MDX compilation to deployment optimization and schema validation.
polymarket
MetaThis skill enables developers to build applications with the Polymarket prediction markets platform, including API integration for trading and market data. It also provides real-time data streaming via WebSocket to monitor live trades and market activity. Use it for implementing trading strategies or creating tools that process live market updates.
creating-opencode-plugins
MetaThis skill helps developers create OpenCode plugins that hook into 25+ event types like commands, files, and LSP operations. It provides the plugin structure, event API specifications, and implementation patterns for JavaScript/TypeScript modules. Use it when you need to intercept, monitor, or extend the OpenCode AI assistant's lifecycle with custom event-driven logic.
sglang
MetaSGLang is a high-performance LLM serving framework that specializes in fast, structured generation for JSON, regex, and agentic workflows using its RadixAttention prefix caching. It delivers significantly faster inference, especially for tasks with repeated prefixes, making it ideal for complex, structured outputs and multi-turn conversations. Choose SGLang over alternatives like vLLM when you need constrained decoding or are building applications with extensive prefix sharing.
