WORN Fit

How one to three watches fit a wrist of a given size, checked against WORN's catalogue of 46,000 watches (case, thickness, lug width): how far each watch's lugs stop from the edges of the wrist, whether it wears bigger or smaller than its case, and how it sits under a shirt cuff. Returns the verdicts in words, a link to the watches drawn to scale on the wrist, and the drawing as a card where cards are shown. Names are matched as people say them; case_mm and lug_to_lug_mm, when known, make the answer exact.

{
  "type": "object",
  "properties": {
    "wrist_mm": {
      "type": "number",
      "minimum": 120,
      "maximum": 260,
      "description": "Wrist circumference in mm, measured where a watch sits (17 cm is 170)"
    },
    "watches": {
      "minItems": 1,
      "maxItems": 3,
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "name": {
            "type": "string",
            "minLength": 1,
            "maxLength": 80,
            "description": "The watch's brand and model as the person would say them, e.g. 'Tudor Black Bay 58' or 'Omega Seamaster Diver 300M'. WORN looks it up in its catalogue of 46,000 watches"
          },
          "case_mm": {
            "description": "Case diameter in mm (width, for a square case), if you know it; it picks the right size where the model comes in several. Leave out and WORN uses its catalogue",
            "type": "number",
            "minimum": 20,
            "maximum": 60
          },
          "lug_to_lug_mm": {
            "description": "Lug-to-lug span in mm from the maker's specs, if you know it. WORN's catalogue does not hold it: left out, it is estimated at 1.2 times the case and said to be",
            "type": "number",
            "minimum": 20,
            "maximum": 75
          },
          "thickness_mm": {
            "description": "Case thickness in mm, if you know it; WORN's catalogue fills it where it can",
            "type": "number",
            "minimum": 3,
            "maximum": 30
          },
          "shape": {
            "description": "Case shape, for the drawing",
            "type": "string",
            "enum": [
              "round",
              "square"
            ]
          },
          "note": {
            "description": "One short line on why you suggest this watch, shown under it",
            "type": "string",
            "maxLength": 140
          }
        },
        "required": [
          "name"
        ]
      }
    }
  },
  "required": [
    "wrist_mm",
    "watches"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}

The case diameters and lug-to-lug spans that fit a wrist of a given circumference, and why lug to lug matters more than the case.

{
  "type": "object",
  "properties": {
    "wrist_mm": {
      "type": "number",
      "minimum": 120,
      "maximum": 260,
      "description": "Wrist circumference in mm, measured where a watch sits (17 cm is 170)"
    }
  },
  "required": [
    "wrist_mm"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}

For a person who does not know their wrist size, or wants to see watches on their own wrist. Makes a link, with a QR code for a computer, that opens on their phone: the back camera measures the wrist in a few seconds with no tape or coin, then draws each watch on a photo of their own wrist at true size, to switch between. Nothing of the picture leaves the phone; tapping Send shares only the size and the watch they liked, which get_try_on_result returns with the code. Up to three watches; the link works for an hour. A picture of each watch can come as a link in image_url (a cutout with a transparent background, or the maker's or a shop's product photo on a plain white or grey background, which WORN cuts out) or as an uploaded file in photos; WORN shows it on the wrist at true size in place of its drawing.

{
  "type": "object",
  "properties": {
    "watches": {
      "minItems": 1,
      "maxItems": 3,
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "name": {
            "type": "string",
            "minLength": 1,
            "maxLength": 80,
            "description": "The watch's brand and model as the person would say them, e.g. 'Tudor Black Bay 58' or 'Omega Seamaster Diver 300M'. WORN looks it up in its catalogue of 46,000 watches"
          },
          "case_mm": {
            "description": "Case diameter in mm (width, for a square case), if you know it; it picks the right size where the model comes in several. Leave out and WORN uses its catalogue",
            "type": "number",
            "minimum": 20,
            "maximum": 60
          },
          "lug_to_lug_mm": {
            "description": "Lug-to-lug span in mm from the maker's specs, if you know it. WORN's catalogue does not hold it: left out, it is estimated at 1.2 times the case and said to be",
            "type": "number",
            "minimum": 20,
            "maximum": 75
          },
          "thickness_mm": {
            "description": "Case thickness in mm, if you know it; WORN's catalogue fills it where it can",
            "type": "number",
            "minimum": 3,
            "maximum": 30
          },
          "shape": {
            "description": "Case shape, for the drawing",
            "type": "string",
            "enum": [
              "round",
              "square"
            ]
          },
          "note": {
            "description": "One short line on why you suggest this watch, shown under it",
            "type": "string",
            "maxLength": 140
          },
          "image_url": {
            "description": "https link to the best picture you have of this exact watch, seen from the front, straight on, 12 o'clock up and the crown to the right (PNG, WebP or JPEG). Best is a cutout with a transparent background; a product photo on a plain white or grey background works too, as WORN cuts the watch out of it. WORN draws it on the person's own wrist at true size; a watch shot on a wrist, at an angle or on a busy background is drawn from its sizes instead",
            "type": "string",
            "maxLength": 1000
          },
          "image_case_px": {
            "description": "Width in pixels of the case in that picture, edge to edge without the crown (40 to 4000), if you know it; left out, WORN measures it from the watch's outline",
            "type": "number"
          }
        },
        "required": [
          "name"
        ]
      },
      "description": "The watches to try on"
    },
    "photos": {
      "description": "Pictures of the watches the person uploaded, straight on, to draw on their wrist in place of the drawing: a cutout, or the watch on a plain background, which WORN cuts out",
      "maxItems": 3,
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "download_url": {
            "type": "string",
            "description": "The file's download URL, as ChatGPT gives it"
          },
          "file_id": {
            "type": "string",
            "description": "The file's id, as ChatGPT gives it"
          },
          "mime_type": {
            "type": "string"
          },
          "file_name": {
            "type": "string"
          },
          "watch": {
            "description": "The name of the watch in the picture, as given in watches; left out, the pictures go to the watches in order",
            "type": "string",
            "maxLength": 80
          }
        },
        "required": [
          "download_url",
          "file_id"
        ]
      }
    }
  },
  "required": [
    "watches"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}

The wrist size the person measured with their phone through a try-on link (start_try_on), the watch they liked best, and how each watch fits that wrist. Says when they have not sent it yet, or when the link has expired.

{
  "type": "object",
  "properties": {
    "code": {
      "type": "string",
      "minLength": 4,
      "maxLength": 12,
      "description": "The code start_try_on returned"
    }
  },
  "required": [
    "code"
  ],
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}