storybook-screenshot

name	storybook-screenshot
description	Launch the Storybook dev server and use Playwright to take screenshots of component stories. Use when you need visual verification of UI component designs or want to iterate on a component's appearance.

Storybook Screenshot

This skill describes how to start the Storybook dev server, then use Playwright to navigate to specific component stories and take screenshots.

CRITICAL: What NOT To Do

DO NOT use any of these approaches:

• Running npm run storybook as a foreground Bash command — it runs forever and will block Claude indefinitely
• Using shell backgrounding (&) with $! — PID tracking is unreliable across Bash tool calls

Prerequisites

• node_modules/ must exist in sculptor/frontend/
• The src/api/ generated types must exist (Storybook strips the generate-types vite plugin, so they must be pre-generated)

If node_modules/ doesn't exist, install dependencies first:

cd sculptor/frontend
npm install

If src/api/ doesn't exist, generate it first:

cd sculptor/frontend
npm run generate-api

Step 1: Set up environment

Create a unique log file and determine the workspace screenshots directory. The workspace root is the parent of code/ (which is your current working directory). Screenshots go in attachments/screenshots/ within that workspace root.

LOG_FILE=$(mktemp)
WORKSPACE_ROOT=$(cd "$(pwd)/.." && pwd)
SCREENSHOTS_DIR="$WORKSPACE_ROOT/attachments/screenshots"
mkdir -p "$SCREENSHOTS_DIR"
echo "Log file: $LOG_FILE"
echo "Screenshots will be saved to $SCREENSHOTS_DIR"

Note the LOG_FILE and SCREENSHOTS_DIR paths for the next steps.

Why mktemp? Variable expansion like $$ behaves unreliably in background shell execution. Using a separate foreground mktemp call is more robust.

Step 2: Start Storybook as a background process

Use the Bash tool with run_in_background: true, using the log file from Step 1:

{
  "command": "cd sculptor/frontend && npm run storybook:headless 2>&1 | tee <LOG_FILE>",
  "run_in_background": true,
  "description": "Start Storybook dev server in background"
}

This returns a task_id that you need for killing the server later.

Step 3: Wait for readiness and extract the port

Wait 5 seconds, then check the log file for the "ready" message:

tail -10 <LOG_FILE>

Look for output containing the local URL (e.g., http://localhost:6006/). If not ready yet, wait another 5 seconds and check again. Repeat up to 6 times (30 seconds total). Storybook typically starts within 10–15 seconds.

Extract the port from the log output. Storybook defaults to port 6006 but will pick a different port if 6006 is busy. Parse the actual port from the URL in the log (e.g., Local: http://localhost:6007/) and use it as STORYBOOK_PORT in all subsequent steps. Do NOT hardcode port 6006.

If the log shows an error (e.g., compilation failure), stop the background process with TaskStop using the task_id and investigate.

IMPORTANT: Do NOT use TaskOutput for monitoring — it returns all cumulative output and will fill your context. Always use tail to see only recent output.

Step 4: Write a Playwright screenshot script

Save all screenshots and videos to $SCREENSHOTS_DIR (set up in Step 1). This is the attachments/screenshots/ directory inside the workspace root.

Write a Python script to /tmp/storybook_screenshots.py that navigates to story iframe URLs and takes screenshots:

"""Take screenshots of Storybook component stories."""

import time
from playwright.sync_api import sync_playwright

STORYBOOK_URL = "http://localhost:<STORYBOOK_PORT from step 3>"
SCREENSHOTS_DIR = "<SCREENSHOTS_DIR from step 1>"

def story_iframe_url(story_id: str, theme: str = "light") -> str:
    """
    Build the iframe URL for a story.

    story_id format: "{kebab-title}--{kebab-variant}"
    e.g., "custom-askuserquestion--single-question"
         "radix-button--default"
    """
    return f"{STORYBOOK_URL}/iframe.html?id={story_id}&globals=theme:{theme}&viewMode=story"

def main() -> None:
    with sync_playwright() as p:
        browser = p.chromium.launch(headless=True)
        context = browser.new_context(viewport={"width": 1400, "height": 900})
        page = context.new_page()

        page.goto(story_iframe_url("custom-askuserquestion--single-question", theme="dark"))
        page.wait_for_load_state("networkidle")
        time.sleep(1)
        page.screenshot(path=f"{SCREENSHOTS_DIR}/askuserquestion_dark.png")

        browser.close()

if __name__ == "__main__":
    main()

Step 5: Run the Playwright script

Run the script as a foreground command (it completes quickly, unlike the server):

.venv/bin/python3 /tmp/storybook_screenshots.py

The .venv/ is at the repo root (code/.venv/), not under sculptor/.

Step 6: Display results in chat

After taking a screenshot or recording a video, display it inline in the chat by outputting an <img> or <video> tag with the absolute path. Only absolute local file paths (starting with /) are supported — HTTP URLs will not be rendered.

Examples:

<img src="/absolute/path/to/attachments/screenshots/component.png" alt="component screenshot">

<video src="/absolute/path/to/attachments/screenshots/recording.webm" controls></video>

Step 7: Clean up

Kill the Storybook background process using TaskStop with the task_id from Step 2.

Always clean up, even if the screenshot step failed.

Story ID format

Story IDs are derived from the title and export name in the .stories.tsx file. The conversion is: lowercase, slashes and spaces become hyphens, two hyphens separate the story title from the variant name.

Story file title	Export name	Story ID
Custom/AskUserQuestion	SingleQuestion	custom-askuserquestion--single-question
Custom/AskUserQuestion	MultiSelect	custom-askuserquestion--multi-select
Custom/AskUserQuestion	MultipleQuestions	custom-askuserquestion--multiple-questions
Custom/AskUserQuestion	NoDismiss	custom-askuserquestion--no-dismiss
Custom/BranchNameField	Idle	custom-branchnamefield--idle
Custom/Onboarding/DependencyCard	NotInstalled	custom-onboarding-dependencycard--not-installed
Radix/Button	Default	radix-button--default
Radix/Dialog	Default	radix-dialog--default

To discover all available story IDs, fetch the Storybook index (use the port from Step 3):

curl -s http://localhost:<STORYBOOK_PORT>/index.json | python3 -c "
import json, sys
data = json.load(sys.stdin)
for story_id in sorted(data['entries'].keys()):
    entry = data['entries'][story_id]
    if entry['type'] == 'story':
        print(story_id)
"

Common patterns

Screenshot all variants of a component

VARIANTS = [
    "custom-askuserquestion--single-question",
    "custom-askuserquestion--multi-select",
    "custom-askuserquestion--multiple-questions",
    "custom-askuserquestion--minimal",
    "custom-askuserquestion--no-dismiss",
]

for variant in VARIANTS:
    for theme in ["light", "dark"]:
        page.goto(story_iframe_url(variant, theme=theme))
        page.wait_for_load_state("networkidle")
        time.sleep(1)
        name = variant.split("--")[1]
        page.screenshot(path=f"{SCREENSHOTS_DIR}/{name}_{theme}.png")

Clip to just the component (no surrounding padding)

page.goto(story_iframe_url("custom-askuserquestion--single-question"))
page.wait_for_load_state("networkidle")
# Find the story root element and clip to its bounding box
element = page.locator("#storybook-root").first
element.screenshot(path=f"{SCREENSHOTS_DIR}/component_only.png")

Screenshot at a specific viewport size

context = browser.new_context(viewport={"width": 800, "height": 600})

Video recording

context = browser.new_context(
    viewport={"width": 800, "height": 700},
    record_video_dir=SCREENSHOTS_DIR,
    record_video_size={"width": 800, "height": 700},
)
page = context.new_page()
# ... navigate and interact ...
context.close()  # Video is finalized when context closes

Gotchas

• Use the iframe URL, not the full Storybook shell: The iframe URL (/iframe.html?id=...) renders just the component without the Storybook chrome (sidebar, toolbar). This gives cleaner screenshots. The full shell URL is /?path=/story/{id} but it includes the Storybook UI.

• src/api/ must be pre-generated: The Storybook vite config explicitly strips the generate-types plugin to avoid needing the Python backend. If the src/api/ directory is missing, stories that import from ~/api will fail to compile. Run npm run generate-api from sculptor/frontend/.

• Wait after networkidle: Some components use CSS transitions or async rendering. Add a time.sleep(1) after wait_for_load_state("networkidle") to let animations settle before screenshotting.

• Always kill the server when done: The Storybook process runs indefinitely. Always use TaskStop to clean up, even if the script fails.