The main /map timeline was rendering each forecast hour twice
('Now 22:00' + '0h 22:00', '+1h 23:00' + '+1h 23:00', …).
Root cause: during the rolling `.ntms` → `.prop` rename window,
both extensions live on NFS for the same valid_time. `list_score_files`
matches either, so `list_valid_times_raw` mapped 2 files → 2 DateTimes
with no dedupe. Propagation.available_valid_times inherited the dup,
push_timeline pushed it to the JS hook, renderTimeline drew one chip
per entry — hence the visible duplicate.
Fix: `Enum.uniq` before the sort. Regression test writes a `.prop`
file, copies it as the same valid_time's `.ntms` legacy twin, and
asserts list_valid_times returns a single DateTime.
Also land a small refactor that was queued behind this: move the three
pure mechanism display helpers (label/1, badge_class/1, explainer/1)
out of the 2500-line contact_live/show.ex into a new
MicrowavepropWeb.ContactLive.Mechanism module. No behavior change — just
shrinks the LiveView and gives the display mapping a testable home.
Graham McIntire
d3ca2e5791