Poll a watch for new changes (priced per delta)

Poll new parcel_deeds / parcel_permits changes matching the watch since its per-source cursor. preview=true returns the pending count + exact price + a masked sample (FREE, no cursor move). A paid poll debits the credit balance PER DELTA (clamp($0.05 x event-strength, $0.02, $0.20), capped $20/poll), advances the cursor, and returns the full deltas. A poll with no new changes is free. Insufficient balance -> 402. Parcel watches match on the full parcel identity; each delta carries canonical_id + match_basis. A watch created before 2026-09-22 whose stored bare ids are ambiguous reports them in identity_issues (not matched) on every poll. Deed parties (grantor / grantee names and addresses, prior / new owner) are people data, delivered to accounts only: a poll paid with a credit token and no account (no API key, no signed-in session) receives the deltas with those fields set to null and a top-level people_fields marker (see PeopleFieldsWithheld). The events themselves (what changed, where, when, for how much) are unchanged.