capture-screens— agent skill

Preferences

_On startup, use Read to load ~/.claude/skills/capture-screens/preferences.md. If missing, use defaults below._

Defaults:

• url: http://localhost:3000
• output: screenshots
• viewport: 1440x900
• highlight: true
• highlight-color: #FF4B4B
• wait-ms: 800

Context

_On startup, use Bash to detect the current working directory. Use this for default output path resolution._

Command routing

Check $ARGUMENTS:

• help → show help, stop
• config → run config flow, stop
• reset → delete preferences file, confirm, stop
• anything else → run the skill

Help

capture-screens — Automated contextual screenshot capture via Playwright

Usage:
  /capture-screens [context]                          Interactive — prompts for missing inputs
  /capture-screens [context] --url <url>              App URL to capture
  /capture-screens [context] --features <f1,f2,...>   Comma-separated routes or feature names
  /capture-screens [context] --output <dir>           Output directory (default: screenshots/)
  /capture-screens [context] --no-highlight           Skip CSS highlight injection
  /capture-screens [context] --viewport <WxH>         Viewport size (default: 1440x900)
  /capture-screens [context] --auth <instructions>    How to authenticate, e.g. "login as [email protected] / pass123"
  /capture-screens [context] --inject-js <file>       Path to a JS file to evaluate before capturing (e.g. to seed state)
  /capture-screens config                             Set persistent preferences
  /capture-screens reset                              Clear preferences
  /capture-screens help                               This help

Context argument:
  Free-text description of what you're capturing. Used to generate semantic
  filenames and manifest descriptions. Example:
  "Checkout flow — cart summary, shipping form, payment step, confirmation"

Examples:
  /capture-screens "Settings page — profile tab, notifications, billing"
  /capture-screens "Onboarding flow" --url https://staging.myapp.com --auth "skip login, go to /onboarding"
  /capture-screens "Admin dashboard" --url http://localhost:3000 --no-highlight --output docs/screenshots
  /capture-screens "Product tour" --inject-js seed-demo-state.js

Output:
  {output}/                    ← semantically-named PNGs
  {output}/manifest.json       ← filename → description map (for downstream skills)
  {output}/capture-report.md   ← human-readable summary with descriptions

Current preferences:
  (shown from preferences.md)

Config

Use AskUserQuestion to collect:

1. Default URL — what URL does your app run on? (default: http://localhost:3000)
2. Default output directory — where to save screenshots? (default: screenshots)
3. Viewport size — browser viewport? (default: 1440x900)
4. Highlight color — CSS color for element highlights? (default: #FF4B4B)
5. Default wait — ms to wait after navigation before screenshot? (default: 800)

Save to ~/.claude/skills/capture-screens/preferences.md.

Reset

Delete ~/.claude/skills/capture-screens/preferences.md and confirm: "Preferences cleared. Using defaults."

First-time detection

If no preferences file exists, show:

First time using /capture-screens? Run /capture-screens config to set your defaults, or continue — sensible defaults will be used.

Then proceed.

Workflow

Step 1 — Gather inputs

Parse $ARGUMENTS for:

• Context description — free text before any --flag
• --url <url> — app URL (fallback: preferences → http://localhost:3000)
• --features <list> — comma-separated routes or feature names
• --output <dir> — output directory (fallback: preferences → screenshots)
• --no-highlight — skip CSS highlight injection
• --viewport <WxH> — e.g., 1440x900
• --auth <instructions> — how to authenticate (e.g., "login as [email protected] / password")
• --inject-js <file> — path to a JS file to evaluate before capturing (for any custom state setup: localStorage, cookies, mocked APIs, etc.)

If context description is missing, ask:

What are you capturing? Describe the product area and key states to document. Example: "Checkout flow — cart, shipping, payment, confirmation page"

If features are missing, derive a capture plan from the context description. Ask to confirm:

Based on your description, I'll capture: [list of routes/states]. Anything to add or remove?

Step 2 — Prepare output directory

Create the output directory:

mkdir -p {output}

Step 3 — Open browser and set viewport

1. Navigate to --url via browser_navigate
2. Resize via browser_resize to {viewport}
3. Take a baseline browser_snapshot to verify the page loaded

Authentication — if the page requires login:

• If --auth was provided, follow those instructions using browser_type and browser_click
• Otherwise ask: "The page requires login. How should I authenticate? (provide credentials or 'skip' to continue unauthenticated)"
• Wait for the authenticated state before continuing

Step 4 — Inject custom JS (if --inject-js provided)

If --inject-js <file> was provided:

1. Read the file contents with Read
2. Evaluate via browser_evaluate
3. Reload the page via browser_navigate to let the app pick up any injected state
4. Wait for the page to stabilize

This is the escape hatch for any app-specific state seeding — localStorage, sessionStorage, cookies, API mocking, feature flags, etc. The skill itself has no opinion about what the JS does.

Step 5 — Inject highlight utility (skip if --no-highlight)

Inject once into the page via browser_evaluate:

const style = document.createElement('style');
style.id = '__capture-highlight-style';
style.textContent = `
  [data-capture-highlight] {
    outline: 3px solid {highlight-color} !important;
    outline-offset: 3px !important;
    border-radius: 4px !important;
    box-shadow: 0 0 0 6px {highlight-color}22 !important;
  }
`;
document.head.appendChild(style);

window.__captureHighlight = (selector) => {
  document.querySelectorAll('[data-capture-highlight]')
    .forEach(el => el.removeAttribute('data-capture-highlight'));
  const el = selector ? document.querySelector(selector) : null;
  if (el) {
    el.setAttribute('data-capture-highlight', '');
    el.scrollIntoView({ block: 'center', behavior: 'instant' });
  }
};

window.__captureClearHighlight = () => {
  document.querySelectorAll('[data-capture-highlight]')
    .forEach(el => el.removeAttribute('data-capture-highlight'));
};

Step 6 — Capture each feature/state

For each item in the capture plan:

1. Navigate to the route via browser_navigate (or browser_click for tabs/buttons within the same page)
2. Wait for content via browser_wait_for — target a meaningful selector (main content area, data table, heading) or fall back to {wait-ms} ms
3. Snapshot via browser_snapshot to understand the current page structure
4. Identify key element to highlight — the most visually significant element for this state (active tab, primary action, key data component). Skip if nothing meaningful to highlight.
5. Highlight via browser_evaluate: window.__captureHighlight('{selector}')
6. Screenshot via browser_take_screenshot
7. Generate semantic filename from context (see Filename rules below)
8. Save to {output}/{filename}.png
9. Record in manifest: { filename, description, route, timestamp }
10. Clear highlight via browser_evaluate: window.__captureClearHighlight()

Within-page states (tabs, modals, dropdowns, hover states):

• Use browser_click to open the state, screenshot, then restore to neutral state before moving on

On failure: log the error and skip — never abort the full session for one bad step.

Step 7 — Write outputs

`{output}/manifest.json`:

{
  "capturedAt": "{ISO timestamp}",
  "url": "{app url}",
  "viewport": "{WxH}",
  "context": "{context description}",
  "screenshots": [
    {
      "filename": "settings-profile-tab-overview.png",
      "description": "Settings page — Profile tab showing name, avatar, and account details",
      "route": "/settings/profile",
      "selector": ".profile-form"
    }
  ]
}

`{output}/capture-report.md`:

# Screenshot Capture Report
**Context:** {context description}
**URL:** {url}
**Captured:** {timestamp}
**Count:** {N} screenshots → `{output}/`

## Screenshots

### {Feature Area}
**File:** `{filename}.png`
**Route:** `{route}`
**Description:** {description}

---

Step 8 — Report

Captured {N} screenshots → {output}/
  ✓ {filename1}.png — {description}
  ✓ {filename2}.png — ...

Manifest: {output}/manifest.json
Report:   {output}/capture-report.md

List any skipped steps and their errors at the end.

Filename generation rules

• Format: {feature}-{sub-feature}-{state}.png (2-3 levels, kebab-case)
• Specific: checkout-payment-form-filled.png not checkout-3.png
• State-aware: append -open, -empty, -active, -selected, -error when the UI state matters
• Unique: if two shots of the same feature, differentiate by state — never append -2
• Max 60 chars excluding .png
• Derive names from: context description + current route + page title visible in snapshot + key elements visible

Principles

1. App-agnostic by default — no assumptions about framework, auth method, or state management; ask or accept instructions rather than guessing
2. Snapshot before screenshot — always browser_snapshot first to understand page structure before deciding what to highlight and capture
3. Name from what you see, not sequence — derive filenames from the actual content visible in the snapshot, not from a counter
4. `--inject-js` is the escape hatch — any app-specific state setup (localStorage, cookies, API mocks) belongs in an external JS file the user provides; the skill doesn't know or care what it does
5. Graceful continuation — a failed step is logged and skipped; the session completes as much as possible