The image monitor now reports every settled output (linked or not, also
when linking raised) with its resolved path through set_output_listener.
The API's notify_output_settled hops from the monitor's worker thread onto
the server's loop (call_soon_threadsafe) and does nothing before the loop is
known or after cleanup. mark_root_dirty matches the path against each
walk's resolved_root (normcase(realpath), computed in the executor by
walk_root, now its fourth value) and marks the root dirty.
A dirty root gets one background walk, no sooner than
rewalk_interval = min(15, max(5, 5 x last walk's duration)) after the
previous walk started (last_started_at / last_duration are recorded on
every walk). _schedule_walk is shared with PR 1's delayed stale refresh:
one deferred walk per root, never armed while a walk runs (the walk's end
re-checks dirty: the trailing walk), at least 0.5 s away, the earlier
deadline wins, and every walk start cancels it. A failed walk clears dirty.
Rescan semantics are unchanged.
Vito Sansevero
e84e56aa3b