Create a watch

Free to create. Adds a target to the Watchlist. Where the plan includes the collection section, a watched event’s imagery is then checked automatically at 1 token a day per watch, until before and after scenes are found or 14 days after the first report; a day without enough tokens is skipped and not charged, and on other plans imagery is not checked and nothing is charged. target_type "event": pass the signal’s id (uuid) as event_id — the server resolves and binds the CANONICAL event (never an article URL), so further reporting and even a later cluster merge stay on the same watch. target_type "area": pass a bbox — created as a saved bookmark; to measure something there use POST /api/v1/monitoring, to watch its events use POST /api/v1/standing-orders (both join the same watch automatically). target_type "site": watch a specific place for change — a registry facility (entity_id from GET /api/v1/entities/search) or any point (lat, lon) — at a scale: "facility" (radius 250 m–3 km; measured from imagery by default when the kind of facility has a suggested measurement, e.g. vessel counts for a port), "city" (radius 5–20 km; measured only when you pass a metric) or "country" (followed through reporting only; never measured). Linked events are reported with how they were linked (named / nearby / country). A refused explicit metric creates nothing; a refused default is reported in measurement.reason. Measuring uses a monitored-area slot and costs the same as POST /api/v1/monitoring. Active watches are plan-limited; re-adding an existing target returns the existing watch (200) instead of consuming a slot.