Tommy D. Rossi
adc7125b47
When a single-expression code snippet auto-returns a Playwright object (e.g. `await page.goto(url)` returning a Response), the CLI previously called util.inspect() at depth 4 on the handle, producing 400K+ chars that included every process.env variable (API keys, tokens, secrets). Even with the playwright-core util.inspect fix (@xmorse/playwright-core@1.59.7), these handles are useless output — they're programmatic references with no display value. Agents and users get nothing meaningful from seeing: [return value] Response@response@abc123 { request: Channel<...>, ... } Fix: add isPlaywrightChannelOwner() duck-type check in the executor return value path. Handles are silently skipped (duck: _type + _guid + _connection). The existing 'Code executed successfully (no output)' fallback applies when there's no other output. To see data, users must explicitly: return response.url() → prints the URL string return response.status() → prints 200 console.log(response) → prints safe summary via playwright-core Also includes: - Regression test (channel-owner-inspect.test.ts) for inspect handler - isPlaywrightChannelOwner() unit tests (executor.unit.test.ts) - Stale color-scheme snapshot fix (relay-core.test.ts) - MEMORY.md with learnings (Node util.inspect bypass of Proxy traps)
3.3 KiB
Memory
Auto-returned values in playwriter CLI: skip useless Playwright handles (Apr 2026)
The CLI auto-returns single-expression code (e.g. await page.goto(url)).
Playwright methods return handle objects (Response, Page, Browser, Locator)
that are useless to print — they're programmatic references, not display
data. The user does NOT want a hint message either — just silently skip.
Rule: if auto-returned value is a ChannelOwner (duck-type: _type +
_guid + _connection), emit nothing. The Code executed successfully (no output) fallback handles the "nothing else printed" case.
User must explicitly console.log(response) or return specific fields
(return response.url()) to see data. console.log still works safely
via the playwright-core custom inspect handler.
Playwright browsers install is broken locally (Apr 2026)
pnpm exec playwright install fails with Command "playwright" not found
because this repo uses @xmorse/playwright-core not playwright. The core
CLI node playwright/packages/playwright-core/cli.js install chromium also
fails with TypeError: onExit is not a function.
Workaround for pnpm test (which needs chromium-1209): symlink the
already-installed 1208 build to 1209. Tests launchPersistentContext and
work with the slightly older binary:
ln -sf ~/Library/Caches/ms-playwright/chromium-1208 \
~/Library/Caches/ms-playwright/chromium-1209
ln -sf ~/Library/Caches/ms-playwright/chromium_headless_shell-1208 \
~/Library/Caches/ms-playwright/chromium_headless_shell-1209
For standalone integration tests: pass
executablePath: '/Applications/Google Chrome for Testing.app/Contents/MacOS/Google Chrome for Testing'
to chromium.launch({ headless: true, executablePath }).
Node util.inspect bypasses Proxy traps (Apr 2026)
Node's util.inspect does NOT invoke Proxy get traps when looking up
Symbol.for('nodejs.util.inspect.custom'). It reads the symbol property
directly from the proxy target object.
To expose a custom inspect handler on a proxied object, the symbol MUST be
set on the underlying target, not via the proxy's get trap:
// BAD — never fires
new Proxy(target, {
get: (obj, prop) => {
if (prop === Symbol.for('nodejs.util.inspect.custom'))
return () => 'custom output'
return obj[prop]
},
})
// GOOD — works
target[Symbol.for('nodejs.util.inspect.custom')] = function () {
return 'custom output'
}
const proxy = new Proxy(target, { get: (obj, prop) => obj[prop] })
Direct property access proxy[Symbol.for('nodejs.util.inspect.custom')]
DOES go through the proxy get trap — only util.inspect's internal lookup
bypasses it.
Playwright ChannelOwner leaks process.env via util.inspect (issue #82)
Playwright's ChannelOwner._connection._platform.env is set to process.env
on node. At depth 4, util.inspect(response) traverses:
Response → _connection → _platform → env: { ALL_ENV_VARS }
This dumps every environment variable (API keys, tokens, passwords).
Happened whenever a user auto-returned a Playwright object from the CLI,
e.g. playwriter -s 1 -e 'await page.goto(url)'.
Fix: custom [Symbol.for('nodejs.util.inspect.custom')] on ChannelOwner
prototype + on the channel proxy target. See
playwright/packages/playwright-core/src/client/channelOwner.ts.