[vishnuv688]

What & why

Closes #564. Part of the #516 follow-ups.

The Selenium screencast called selenium-webdriver's createCDPConnection('page') for every browser. On Safari and Appium there is no CDP endpoint, and selenium-webdriver threw TypeError: debuggerAddress.match is not a function while looking for one. The adapter caught it and fell back to polling, so nothing was lost, but every such run logged CDP screencast unavailable (debuggerAddress.match is not a function) and spent a call that could not succeed (seen in #516 on desktop Safari and Android/iOS native, and in 44 cloud runs of the PR #442 dataset).

The screencast now reads the session capabilities first, with the same rule selenium-webdriver 4.52 uses to find an endpoint: SELENIUM_REMOTE_URL set, or se:cdp, or a string debuggerAddress under goog:chromeOptions (or ms:edgeOptions when that is absent); Firefox is declined. A session with no endpoint goes straight to polling with an info line, no CDP endpoint in the session capabilities; polling. A CDP call that still fails falls back as before.

Type of change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Polish (an improvement to an existing feature)
• Breaking change (existing behavior changes for users)
• Documentation
• Internal (build, CI, dependencies, tooling)

Packages touched

• shared (types and contracts)
• core (framework-agnostic capture/reporting)
• elements (published element/snapshot API — @wdio/elements)
• service (WebdriverIO adapter)
• nightwatch-devtools (Nightwatch adapter)
• selenium-devtools (Selenium adapter)
• selenium-devtools-py (Selenium Python adapter)
• backend (server)
• app (UI)
• script (page-injected runtime)
• trace (Trace mode)

Capability matrix

• packages/conformance/src/features.ts updated, and tables regenerated with pnpm docs:capabilities, if this adds or changes user-facing behaviour

No capability change: the Selenium filmstrip reason ("Chromium streams over CDP; other browsers poll") still holds. The docs site needs no change.

Notes for reviewers

• cdpUnavailableReason (helpers/cdp-endpoint.ts) mirrors selenium-webdriver's createCDPConnection endpoint lookup line for line, including its quirk that a goog:chromeOptions without debuggerAddress does not fall through to ms:edgeOptions. Every case it declines is one where selenium-webdriver 4.52 throws, so no session that used to get CDP push now polls.
• Capabilities come from driver.getCapabilities(), answered from the session selenium-webdriver already holds (no round trip, and an ignored command, so no action row), under the existing handshake ceiling; a driver without it, or a timeout, keeps the old try-then-fall-back path.
• The root README also claimed the screencast went through selenium-webdriver/bidi; it uses createCDPConnection, now stated correctly.
• An independent review found nothing blocking; its wording points (Firefox on older selenium-webdriver, the changeset's log line, the SELENIUM_REMOTE_URL route in the README) are fixed.

Testing

• pnpm build, pnpm typecheck, pnpm test (4073 passed, 1 skipped), pnpm lint, pnpm docs:capabilities --check are green.
• tests/screencast.test.ts: Safari-, Appium native-, Appium Chrome- (goog:chromeOptions: {}, the shape that threw) and Firefox-shaped sessions poll without calling createCDPConnection (these fail without the change); Chrome, Edge, Grid se:cdp and SELENIUM_REMOTE_URL still try CDP; a rejected CDP call still falls back.

Needs checking by hand

1. DEVTOOLS_MODE=trace SELENIUM_BROWSER=safari pnpm --filter @wdio/selenium-devtools example:mocha: the log shows no CDP endpoint in the session capabilities; polling and no debuggerAddress.match line.
2. The same example on Chrome still logs Screencast recording started (CDP mode).

Screenshots / recordings

None.

🤖 Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
devtools	Ready	Preview	Nov 10, 2026 11:44am UTC