* fix(browserless): construct the fetch and screenshot clients off the event loop
* fix(browserless): close the client a cancelled construction still builds
Keeping the constructor off the loop is right, but awaiting
`asyncio.to_thread(httpx.AsyncClient, ...)` directly is not cancellation-safe:
the await can be cancelled while the worker thread is still inside the
constructor. The await is abandoned, the thread runs on and hands back a live
client, and execution never enters the `async with` that would have closed it,
so `is_closed` stays False and the connection pool leaks on that cancellation.
Own the construction as a task instead. When the caller is cancelled, wait for
the task with the shield loop this package already uses for cleanup, close
whatever client it produced, and only then let the cancellation propagate. A
failure while closing is logged rather than raised, so it cannot mask the
cancellation the caller asked for.
The new regression test gates the constructor on a thread event, cancels the
operation while it is parked there, and releases the worker afterwards. Against
the previous commit it fails for both fetch_html_with_status and
capture_screenshot with "the client built after the cancellation was leaked".
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Co-authored-by: inchang-ing <197932532+inchang-ing@users.noreply.github.com>
