Implement the approved observer comparison phase: Compare with preselects the current observer, displays both observers on aligned windows and axes, and reuses the retained flood-packet overlap endpoint with clear raw-history limitations. Preserve share links and return context; test swapped selection, invalid/missing observers, non-overlapping/empty histories and rapid range changes. English/French UI. Depends on the observer dashboard; new reach/timing metrics remain later work.
Implement the approved observer comparison phase: Compare with preselects the current observer, displays both observers on aligned windows and axes, and reuses the retained flood-packet overlap endpoint with clear raw-history limitations. Preserve share links and return context; test swapped selection, invalid/missing observers, non-overlapping/empty histories and rapid range changes. English/French UI. Depends on the observer dashboard; new reach/timing metrics remain later work.