The no---from/--to fallback in dispatch_generalize probes EACH listed
symbol's full archive window (same partial bounds threaded through) and
resolves the one shared campaign window as their intersection — latest
start, earliest end — instead of symbols[0]'s window alone, so the
cross-instrument floor is measured over a genuinely common period.
Disjoint archives refuse at runtime (exit 1) naming each symbol's span.
The intersect-or-refuse arithmetic lives in the pure
intersect_shared_window helper (unit-tested: single symbol, overlapping,
disjoint); the explicit --from+--to path stays byte-identical. The
superseded shape test is renamed to
generalize_without_explicit_window_resolves_a_shared_window_and_completes
with its doc comment reworded to the intersection contract.
closes#213
Brummel
d3ad9f4e73