locale screenshot agent stuck on date picker cdp timeout

Fix the locale screenshot agent stuck on a date picker CDP timeout

TL;DR

The date picker never settles because it re-renders on locale data load, so wait for network idle plus the picker element instead of a fixed timeout. CDP timeouts fire while the picker is still fetching locale data. Wait for the picker to be visible and stable, then screenshot.

The error

Locale screenshot agent: CDP timeout waiting for date picker
picker opens but dates never render in the target locale

Fix it

Step 1: Watch what the picker does on open

node -e "console.log('open the picker manually, watch network: it fetches locale data after opening')"

Expected: You see the late locale fetch.

Step 2: Wait for the picker content, not a fixed delay

node -e "console.log('pattern: click to open, waitForSelector the day cells in the target locale, then screenshot')"

Expected: The wait targets the real readiness signal.

Step 3: Raise the CDP timeout for locale-heavy widgets

node -e "console.log('date pickers with locale data deserve a longer protocol timeout than plain buttons')"

Expected: Slow locale loads stop timing out.

Step 4: Re-run the screenshot flow

node scripts/locale-shots.js --widget datepicker | tail -3

Expected: The picker renders and the screenshot captures it.

When to use this

• A screenshot agent CDP-times-out on a date picker
• The picker opens but locale dates never render

When NOT to use this

• The picker never opens, that is an interaction bug
• Dates render but wrong, check the locale data

Tool and version compatibility

• Chrome DevTools Protocol, Playwright/Puppeteer
• Locale-aware date picker widgets

Variant phrasings

timeout on other locale widgets

Same pattern. Wait for the widget's rendered content, not a timer.

picker renders but in the wrong locale

The locale data fetch used the default locale. Pass the locale before opening.

Why it happens

Locale-aware pickers fetch month and day names asynchronously after opening. A fixed wait or a short CDP timeout fires during that fetch, so the agent times out on a widget that was about to be ready.

Edge cases

• Cache the locale data between runs, refetching every screenshot is slow
• Some pickers virtualize months, scroll them into view before screenshotting
• CDP timeouts also cover the screenshot itself, keep them generous for big pages

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_bw5nie8hqewdlKDdHvDI8Q