The Windows webcam-in-use rule: an app’s LastUsedTimeStop of 0
means it is currently streaming (a non-zero value is the timestamp it
stopped). Extracted so the rule itself is testable without a registry;
the registry walk in windows::any_active_app feeds it. Un-gated so
it’s tested everywhere; only the Windows walk calls it in non-test builds.
Classify one line of macOS log stream output: Some(true) when the
camera turned on, Some(false) when it turned off, None for an
unrelated line. Start wins if a single line somehow carries both
markers, matching the original if/else if ordering. Kept un-gated so
the start/stop contract is unit-tested on every OS — only the macOS
log-stream reader calls it in non-test builds.
Decide whether Control Center’s published camera set is empty. rest
is everything after "cameras changed to ". Some(false) for an empty
collection — [] (earlier macOS) or [:] (the empty-dictionary form
macOS 26 emits on release, #158) — and Some(true) for a non-empty one.
Returns None when the payload is redacted (<private>) or otherwise
has no bracketed collection — we can’t tell the state, so we leave it
unchanged rather than guess.