External Electron Apps

External Electron App Automation

Use this skill for external Electron desktop apps running on the user's machine. Do not default to this for this repository's own Electron app unless the user explicitly asks.

Core workflow

1. Quit the app if it is already running.
2. Relaunch the app with --remote-debugging-port=<port>.
3. Connect with npx libretto connect http://127.0.0.1:<port> --session <session>.
4. Verify targets with npx libretto pages --session <session>.
5. Run interactions with npx libretto exec "<code>" --session <session>.
6. Capture evidence with npx libretto snapshot --session <session>.
7. When a reusable workflow file is ready, execute it with npx libretto run ./workflow.ts --cdp http://127.0.0.1:<port> (optional --page page-N).

Launch examples

macOS

open -a "Slack" --args --remote-debugging-port=9222
open -a "Visual Studio Code" --args --remote-debugging-port=9223
open -a "Discord" --args --remote-debugging-port=9224

Linux

slack --remote-debugging-port=9222
code --remote-debugging-port=9223
discord --remote-debugging-port=9224

Windows

"C:\Users\%USERNAME%\AppData\Local\slack\slack.exe" --remote-debugging-port=9222
"C:\Users\%USERNAME%\AppData\Local\Programs\Microsoft VS Code\Code.exe" --remote-debugging-port=9223

Session pattern

Use one session per app:

npx libretto connect http://127.0.0.1:9222 --session slack-desktop
npx libretto pages --session slack-desktop
npx libretto exec "return await page.title()" --session slack-desktop
npx libretto snapshot --session slack-desktop

Interaction examples

npx libretto exec "await page.locator('button:has-text(\"Search\")').click()" --session slack-desktop
npx libretto exec "await page.keyboard.type('incident-123')" --session slack-desktop
npx libretto exec "await page.keyboard.press('Enter')" --session slack-desktop

When selectors are unstable, inspect first:

npx libretto snapshot --session slack-desktop
npx libretto exec "return await page.content()" --session slack-desktop

Multiple pages

Electron apps often have multiple windows/pages. Use pages to list them and --page to target a specific one:

npx libretto pages --session slack-desktop
npx libretto exec --session slack-desktop --page <page-id> "return await page.url()"
npx libretto snapshot --session slack-desktop --page <page-id>

Scripted workflows

After interactive discovery, run a default-exported workflow() against the same CDP endpoint. Libretto attaches to the selected page without navigating to workflow startUrl, so leave the app on the target screen first (or navigate in the handler). Closing the Libretto session does not quit the Electron app.

npx libretto run ./slack-workflow.ts --cdp http://127.0.0.1:9222
npx libretto run ./slack-workflow.ts --cdp http://127.0.0.1:9222 --page page-1

Troubleshooting

• If connection fails, make sure the app was launched with --remote-debugging-port and relaunch it.
• Prefer 127.0.0.1 over localhost in CDP URLs.
• If no pages are listed right after launch, wait 2-5 seconds and retry pages.
• If a session is stale, run connect again with the same --session.

Use npx libretto close --session <session> to clear the session. This does not terminate the external app — it only removes the session state so Libretto stops tracking it.