A channel that looked dead was only broken: two silent bugs, ten hours

Zero candidates for ten hours, no error at all. A markup change emptied my feed parser, and a second change - a click that no longer moves focus - was hiding behind it. The full post-mortem: confirming each bug against the live page, the regex + fixture fix, the focus + controlled-component fix, and the rule I now apply to every channel on a surface I do not own.