-- 090: Capture the vector (stroke-path) form of a drawn signature.
--
-- Today esign_records.signature_data holds a base64 PNG of the drawn signature,
-- which is fine as a raster copy, but a resolution-independent vector form of the
-- strokes is more faithful and reusable for downstream rendering.
--
-- We store the captured strokes as JSON so the same signing event yields both:
--   * signature_data       -- base64 PNG  (raster copy, audit trail)
--   * signature_vector     -- stroke paths (high-fidelity vector form)
--
-- Format (normalized into a 0..1 box, origin top-left, matching canvas capture):
--   {
--     "v": 1,
--     "w": <canvas css width px>, "h": <canvas css height px>,
--     "strokes": [ [ {"x":0.12,"y":0.40,"t":12}, ... ], ... ]
--   }
-- x/y are fractions of the capture box (resolution-independent); t is ms since
-- stroke start (optional, for future pressure/speed modeling).

ALTER TABLE esign_records
    ADD COLUMN IF NOT EXISTS signature_vector JSONB;

COMMENT ON COLUMN esign_records.signature_vector IS
    'Stroke-path (vector) form of a drawn signature (normalized 0..1, origin '
    'top-left). NULL for typed signatures or signatures captured before this '
    'column existed.';