Variant 5 from the findings doc, as GROUND TRUTH for validating the
from-track wind estimate — it does NOT feed kcal/power. Chosen scope
(per user): a toggle button now, binary "in the face" only, voice later.
- rec screen button "Ветер в лицо": tap opens a headwind interval, tap
closes it; the open state is highlighted and survives a screen re-render
- GPS.toggleWindMark()/_closeOpenWindMark(); recording.windMarks =
[{startTs,endTs}] ms, persisted to localStorage, written to the DB on
finish and restored on crash recovery (a dangling interval auto-closes)
- gps_sessions.wind_marks (JSON) + DB.setSessionWindMarks (separate from
finishGpsSession so recompute paths preserve marks); parsed in getGpsSession
- rec-bottom wraps now so the third button never overflows a narrow screen
Analysis (marks vs estimate) stays in tools/track once enough km accumulate.