The `wait --load networkidle` command was incorrectly returning immediately when pages were served from cache, causing subsequent commands to fail. This happened because the network idle logic would return instantly when no network requests were pending, without observing any idle period.
## Changes Made
- Extract network idle polling logic into a separate `poll_network_idle` function for better testability
- Fix the timeout handling to start a 500ms idle timer when no requests are pending, instead of returning immediately
- Add comprehensive unit tests covering the regression case and normal network request flows
- Ensure the function always observes at least 500ms of network inactivity before resolving, even for cached pages
## Key Fix
The critical change is in the timeout branch: when no CDP events arrive within 600ms, we now start the idle timer if no requests are pending, rather than returning `Ok(())` immediately. This prevents false-positive idle detection for pages that load entirely from cache.
Fixes#846
Chris Tate
d866ee2022