Watch a job intent

Register a standing intent so new matches can be pulled later.

The caller supplies its OWN anonymous fingerprint (e.g. "#a3f9-k2p7-x8q1"; make it 12+ random characters, a four-character tag collides with strangers) — the client generates and owns it; the server stores but can never recover it, so persist it client-side and pass the identical one to check_watches. Only the fingerprint and non-PII filter keys are stored — never a name, email, phone or résumé. Accepted filter keys mirror search_jobs: skills (ANY-overlap), required_skills (ALL/AND — use this to keep sales / solutions-architect roles out), remote (bool), role_family (e.g. "engineering"), min_salary (int), company (one employer, resolved at registration), location (substring of the location text, alias-aware like search_jobs: 广州 also reaches 广东·天河区 rows, Beijing reaches 北京市, "remote" reaches 远程), title (list of title substrings, ANY-of, synonym-expanded for HR terms like search_jobs — the way to watch for recruiting or other roles no skill tag names). Any other key is REFUSED (ERR_UNKNOWN_FILTER) rather than silently dropped, and a role_family outside engineering | data | product | design | marketing | sales | hr | ops | other is refused too (ERR_UNKNOWN_ROLE_FAMILY); "recruiting" and "招聘" resolve to hr.

min_salary keeps rows with NO stated pay (they cannot be ruled out); it only drops rows whose stated pay is below the floor. Pay is stated mostly where law requires it (US postings on Greenhouse/Lever/Ashby), so a watch that needs a number will lean US.

A board watch: pass board_url (a Greenhouse / Lever / Ashby / Moka / 北森 / Workable / SmartRecruiters / Workday careers URL, as for read_board) with optional location and title and nothing else; check_watches then reads that board live on every pull and reports what appeared and what disappeared since the last pull. This is how an employer outside the index is watched. Not combinable with company, skills, remote, min_salary or role_family; a closed portal (Feishu, a job site) is refused with the reason.

Returns { watch_id, status, fingerprint, existing_watches, fingerprint_notice }. existing_watches > 0 means this fingerprint was already in use; if those watches are not yours, pick a longer random fingerprint.