diff --git a/.cspell/custom-words.txt b/.cspell/custom-words.txt
index 4bef035a6..e669861e6 100644
--- a/.cspell/custom-words.txt
+++ b/.cspell/custom-words.txt
@@ -170,3 +170,13 @@ punycode
 userinfo
 examplecorp
 zapatillas
+# rich media formats (video / 3D model source types)
+glb
+gltf
+m3u8
+mp4
+mpd
+mpegurl
+usdz
+vnd
+webm
diff --git a/docs/specification/catalog/index.md b/docs/specification/catalog/index.md
index 2964757ac..4d417655b 100644
--- a/docs/specification/catalog/index.md
+++ b/docs/specification/catalog/index.md
@@ -132,8 +132,57 @@ as the first element. Platforms SHOULD treat the first element as featured.
 
 ### Media
 
+A single logical media item on a Product or Variant: an image, a video, or a
+3D model. `url` identifies the item's primary resource, and its interpretation
+depends on `type`. `preview` is a still image the Platform can render before —
+or instead of — loading that resource.
+
+`type` is an open string with three well-known values: `image`, `video`, and
+`model_3d`. A Platform **MUST** ignore a media item whose `type` it does not
+recognize.
+
+When present, `sources` contains the complete set of available renditions or
+encodings. A Business that provides `sources` **SHOULD** include a source whose
+`url` equals the media item's `url`, unless `url` is an externally hosted
+video's watch page rather than a rendition.
+
+For an image, a self-hosted video, or a 3D model, a Platform loads the
+renderable or loadable primary resource at `url`. For an externally hosted
+video with `embed_url`, `url` identifies the watch page and `embed_url`
+identifies third-party active player content. A Platform **MAY** decline to
+embed that content under its security, privacy, or presentation policy and use
+the watch-page `url` instead. For a thumbnail, a Platform can use `preview.url`
+and fall back to `url` for an image, which is directly displayable.
+
 {{ schema_fields('types/media', 'catalog') }}
 
+#### Image
+
+{{ schema_fields('types/media_image', 'catalog') }}
+
+#### Video
+
+A self-hosted video's `url` identifies its directly playable default rendition.
+An externally hosted video is distinguished by `embed_url`, which identifies
+the third-party active player content; its `url` identifies the watch page, not
+a playable rendition.
+
+A Platform that selects a rendition from `sources` **SHOULD** use the `width`
+and `height` of that entry rather than those on the media item, unless the
+entry omits them.
+
+For an externally hosted video, a Business **SHOULD** provide both
+`preview.width` and `preview.height` with a ratio that matches the intended
+player, unless it has no suitable preview. A Platform **SHOULD** reserve the
+initial player layout using that ratio, unless its presentation policy supplies
+another ratio.
+
+{{ schema_fields('types/media_video', 'catalog') }}
+
+#### 3D Model
+
+{{ schema_fields('types/media_model_3d', 'catalog') }}
+
 ### Product Option
 
 {{ schema_fields('types/product_option', 'catalog') }}
diff --git a/docs/specification/catalog/mcp.md b/docs/specification/catalog/mcp.md
index d92fa4ea3..f401de45b 100644
--- a/docs/specification/catalog/mcp.md
+++ b/docs/specification/catalog/mcp.md
@@ -533,7 +533,79 @@ Maps to the [Catalog Lookup](lookup.md#get-product-get_product) capability. Retu
               {
                 "type": "image",
                 "url": "https://cdn.example.com/products/runner-pro-blue.jpg",
-                "alt_text": "Runner Pro in Blue"
+                "alt_text": "Runner Pro in Blue",
+                "width": 1600,
+                "height": 1600
+              },
+              {
+                "type": "video",
+                "url": "https://cdn.example.com/products/runner-pro-demo-720p.mp4",
+                "name": "Runner Pro flex demo",
+                "alt_text": "Runner Pro shoe flexing to show sole cushioning",
+                "duration": 24,
+                "preview": {
+                  "url": "https://cdn.example.com/products/runner-pro-demo-poster.jpg",
+                  "width": 1280,
+                  "height": 720
+                },
+                "sources": [
+                  {
+                    "url": "https://cdn.example.com/products/runner-pro-demo-720p.mp4",
+                    "mime_type": "video/mp4",
+                    "format": "mp4",
+                    "width": 1280,
+                    "height": 720,
+                    "filesize": 4200000
+                  },
+                  {
+                    "url": "https://cdn.example.com/products/runner-pro-demo-1080p.mp4",
+                    "mime_type": "video/mp4",
+                    "format": "mp4",
+                    "width": 1920,
+                    "height": 1080,
+                    "filesize": 8480000
+                  },
+                  {
+                    "url": "https://cdn.example.com/products/runner-pro-demo.m3u8",
+                    "mime_type": "application/vnd.apple.mpegurl",
+                    "format": "m3u8"
+                  }
+                ]
+              },
+              {
+                "type": "model_3d",
+                "url": "https://cdn.example.com/products/runner-pro.glb",
+                "alt_text": "Runner Pro 3D model",
+                "preview": {
+                  "url": "https://cdn.example.com/products/runner-pro-3d-thumb.jpg"
+                },
+                "sources": [
+                  {
+                    "url": "https://cdn.example.com/products/runner-pro.glb",
+                    "mime_type": "model/gltf-binary",
+                    "format": "glb",
+                    "filesize": 4200000
+                  },
+                  {
+                    "url": "https://cdn.example.com/products/runner-pro.usdz",
+                    "mime_type": "model/vnd.usdz+zip",
+                    "format": "usdz",
+                    "filesize": 5100000
+                  }
+                ]
+              },
+              {
+                "type": "video",
+                "url": "https://videos.example.com/watch?v=abc123",
+                "embed_url": "https://videos.example.com/embed/abc123",
+                "name": "Runner Pro trail review",
+                "alt_text": "Reviewer running a trail in the Runner Pro",
+                "duration": 212,
+                "preview": {
+                  "url": "https://cdn.example.com/products/runner-pro-review-poster.jpg",
+                  "width": 1280,
+                  "height": 720
+                }
               }
             ],
             "options": [
diff --git a/docs/specification/catalog/rest.md b/docs/specification/catalog/rest.md
index cd5b2ca31..05518372d 100644
--- a/docs/specification/catalog/rest.md
+++ b/docs/specification/catalog/rest.md
@@ -409,7 +409,79 @@ on option values and returns variants matching the selection.
           {
             "type": "image",
             "url": "https://cdn.example.com/products/runner-pro-blue.jpg",
-            "alt_text": "Runner Pro in Blue"
+            "alt_text": "Runner Pro in Blue",
+            "width": 1600,
+            "height": 1600
+          },
+          {
+            "type": "video",
+            "url": "https://cdn.example.com/products/runner-pro-demo-720p.mp4",
+            "name": "Runner Pro flex demo",
+            "alt_text": "Runner Pro shoe flexing to show sole cushioning",
+            "duration": 24,
+            "preview": {
+              "url": "https://cdn.example.com/products/runner-pro-demo-poster.jpg",
+              "width": 1280,
+              "height": 720
+            },
+            "sources": [
+              {
+                "url": "https://cdn.example.com/products/runner-pro-demo-720p.mp4",
+                "mime_type": "video/mp4",
+                "format": "mp4",
+                "width": 1280,
+                "height": 720,
+                "filesize": 4200000
+              },
+              {
+                "url": "https://cdn.example.com/products/runner-pro-demo-1080p.mp4",
+                "mime_type": "video/mp4",
+                "format": "mp4",
+                "width": 1920,
+                "height": 1080,
+                "filesize": 8480000
+              },
+              {
+                "url": "https://cdn.example.com/products/runner-pro-demo.m3u8",
+                "mime_type": "application/vnd.apple.mpegurl",
+                "format": "m3u8"
+              }
+            ]
+          },
+          {
+            "type": "model_3d",
+            "url": "https://cdn.example.com/products/runner-pro.glb",
+            "alt_text": "Runner Pro 3D model",
+            "preview": {
+              "url": "https://cdn.example.com/products/runner-pro-3d-thumb.jpg"
+            },
+            "sources": [
+              {
+                "url": "https://cdn.example.com/products/runner-pro.glb",
+                "mime_type": "model/gltf-binary",
+                "format": "glb",
+                "filesize": 4200000
+              },
+              {
+                "url": "https://cdn.example.com/products/runner-pro.usdz",
+                "mime_type": "model/vnd.usdz+zip",
+                "format": "usdz",
+                "filesize": 5100000
+              }
+            ]
+          },
+          {
+            "type": "video",
+            "url": "https://videos.example.com/watch?v=abc123",
+            "embed_url": "https://videos.example.com/embed/abc123",
+            "name": "Runner Pro trail review",
+            "alt_text": "Reviewer running a trail in the Runner Pro",
+            "duration": 212,
+            "preview": {
+              "url": "https://cdn.example.com/products/runner-pro-review-poster.jpg",
+              "width": 1280,
+              "height": 720
+            }
           }
         ],
         "options": [
diff --git a/source/schemas/common/types/media.json b/source/schemas/common/types/media.json
index 57e28cfbc..de0bb7150 100644
--- a/source/schemas/common/types/media.json
+++ b/source/schemas/common/types/media.json
@@ -2,7 +2,7 @@
   "$schema": "https://json-schema.org/draft/2020-12/schema",
   "$id": "https://ucp.dev/schemas/common/types/media.json",
   "title": "Media",
-  "description": "Media item (image, video, etc.).",
+  "description": "A single logical media item: an image, video, or 3D model. `url` is the primary resource; when present, `sources` is the complete set of available renditions. When `sources` is present and `url` identifies a rendition, the Business SHOULD include that rendition.",
   "type": "object",
   "required": [
     "type",
@@ -11,12 +11,16 @@
   "properties": {
     "type": {
       "type": "string",
-      "description": "Media type. Well-known values: `image`, `video`, `model_3d`."
+      "description": "Media type. The Platform MUST ignore unknown values. Well-known values: `image`, `video`, `model_3d`."
     },
     "url": {
       "type": "string",
       "format": "uri",
-      "description": "URL to the media resource."
+      "description": "Primary/canonical URL for the item; interpretation depends on `type` (specialized per type)."
+    },
+    "name": {
+      "type": "string",
+      "description": "Human-readable title or label for the media, distinct from `alt_text` (accessibility text). Often present for `video` and `model_3d`."
     },
     "alt_text": {
       "type": "string",
@@ -25,12 +29,65 @@
     "width": {
       "type": "integer",
       "minimum": 1,
-      "description": "Width in pixels (for images/video)."
+      "description": "Pixel width of the media."
     },
     "height": {
       "type": "integer",
       "minimum": 1,
-      "description": "Height in pixels (for images/video)."
+      "description": "Pixel height of the media."
+    },
+    "preview": {
+      "type": "object",
+      "description": "Poster/thumbnail still the Platform renders before or instead of the primary resource. A Business SHOULD provide it for `video` and `model_3d` unless no suitable still exists, and MAY provide it for `image` as a low-resolution placeholder. For externally hosted video, `preview.width` and `preview.height` provide the layout aspect ratio.",
+      "required": [
+        "url"
+      ],
+      "properties": {
+        "url": {
+          "type": "string",
+          "format": "uri",
+          "description": "URL of the preview image."
+        },
+        "width": {
+          "type": "integer",
+          "minimum": 1,
+          "description": "Actual pixel width of the preview image. The ratio of `preview.width` to `preview.height` is used to reserve embedded-video player layout."
+        },
+        "height": {
+          "type": "integer",
+          "minimum": 1,
+          "description": "Actual pixel height of the preview image. The ratio of `preview.width` to `preview.height` is used to reserve embedded-video player layout."
+        }
+      }
+    }
+  },
+  "allOf": [
+    {
+      "if": {
+        "properties": { "type": { "const": "image" } },
+        "required": ["type"]
+      },
+      "then": {
+        "$ref": "media_image.json"
+      }
+    },
+    {
+      "if": {
+        "properties": { "type": { "const": "video" } },
+        "required": ["type"]
+      },
+      "then": {
+        "$ref": "media_video.json"
+      }
+    },
+    {
+      "if": {
+        "properties": { "type": { "const": "model_3d" } },
+        "required": ["type"]
+      },
+      "then": {
+        "$ref": "media_model_3d.json"
+      }
     }
-  }
+  ]
 }
diff --git a/source/schemas/common/types/media_image.json b/source/schemas/common/types/media_image.json
new file mode 100644
index 000000000..1153a468c
--- /dev/null
+++ b/source/schemas/common/types/media_image.json
@@ -0,0 +1,18 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://ucp.dev/schemas/common/types/media_image.json",
+  "title": "Media Image",
+  "description": "Type-specific properties for image media.",
+  "type": "object",
+  "properties": {
+    "url": {
+      "description": "A directly displayable image."
+    },
+    "width": {
+      "description": "Authoritative pixel width of the image."
+    },
+    "height": {
+      "description": "Authoritative pixel height of the image."
+    }
+  }
+}
diff --git a/source/schemas/common/types/media_model_3d.json b/source/schemas/common/types/media_model_3d.json
new file mode 100644
index 000000000..2266dec68
--- /dev/null
+++ b/source/schemas/common/types/media_model_3d.json
@@ -0,0 +1,19 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://ucp.dev/schemas/common/types/media_model_3d.json",
+  "title": "Media Model 3D",
+  "description": "Type-specific properties for 3D model media.",
+  "type": "object",
+  "properties": {
+    "url": {
+      "description": "The primary model file (e.g. GLB)."
+    },
+    "sources": {
+      "type": "array",
+      "description": "The complete set of available model encodings/file formats (glTF/GLB/USDZ). When present, the Business SHOULD include a source whose `url` equals the media `url`.",
+      "items": {
+        "$ref": "media_source.json"
+      }
+    }
+  }
+}
diff --git a/source/schemas/common/types/media_source.json b/source/schemas/common/types/media_source.json
new file mode 100644
index 000000000..f89c7b21d
--- /dev/null
+++ b/source/schemas/common/types/media_source.json
@@ -0,0 +1,40 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://ucp.dev/schemas/common/types/media_source.json",
+  "title": "Media Source",
+  "description": "A single encoded rendition of a parent Media item — one resolution/format of a video, or one file format of a 3D model. The Platform selects the best supported source.",
+  "type": "object",
+  "required": [
+    "url"
+  ],
+  "properties": {
+    "url": {
+      "type": "string",
+      "format": "uri",
+      "description": "URL to this rendition's file or streaming manifest."
+    },
+    "mime_type": {
+      "type": "string",
+      "description": "IANA media type of this source. A Platform MUST NOT reject the parent media item solely because this value is unknown, but MAY skip a source it cannot decode. Examples: `video/mp4`, `video/webm`, `application/vnd.apple.mpegurl` (HLS), `application/dash+xml` (DASH), `model/gltf-binary` (GLB), `model/gltf+json` (glTF), `model/vnd.usdz+zip` (USDZ)."
+    },
+    "format": {
+      "type": "string",
+      "description": "Short format token for display/selection. A Platform MUST NOT reject the parent media item solely because this value is unknown, but MAY skip a source it cannot decode. Examples: `mp4`, `webm`, `m3u8`, `mpd`, `glb`, `gltf`, `usdz`."
+    },
+    "width": {
+      "type": "integer",
+      "minimum": 1,
+      "description": "Pixel width of this rendition (video). Omitted for adaptive manifests and 3D models."
+    },
+    "height": {
+      "type": "integer",
+      "minimum": 1,
+      "description": "Pixel height of this rendition (video). Omitted for adaptive manifests and 3D models."
+    },
+    "filesize": {
+      "type": "integer",
+      "minimum": 1,
+      "description": "File size in bytes. Lets the Platform decide whether to prefetch a large asset (e.g. a multi-megabyte 3D model). Omitted for adaptive-streaming manifests, whose total size is not fixed."
+    }
+  }
+}
diff --git a/source/schemas/common/types/media_video.json b/source/schemas/common/types/media_video.json
new file mode 100644
index 000000000..0c0520139
--- /dev/null
+++ b/source/schemas/common/types/media_video.json
@@ -0,0 +1,35 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://ucp.dev/schemas/common/types/media_video.json",
+  "title": "Media Video",
+  "description": "Type-specific properties for video media.",
+  "type": "object",
+  "properties": {
+    "url": {
+      "description": "The directly playable default rendition for a self-hosted video, or the watch-page URL for an externally hosted video with `embed_url`. When `sources` is present and `url` identifies a rendition, the Business SHOULD include a source whose `url` equals the media `url`; this does not apply when `url` is an external watch-page URL."
+    },
+    "embed_url": {
+      "type": "string",
+      "format": "uri",
+      "description": "Player embed (iframe) URL for an externally hosted video, through which the Platform may play the video; absent for self-hosted video. A Platform MAY decline third-party active content under its security, privacy, or presentation policy and use the watch-page `url` instead."
+    },
+    "duration": {
+      "type": "integer",
+      "minimum": 1,
+      "description": "Duration in seconds."
+    },
+    "width": {
+      "description": "The video's display width in pixels, for layout and aspect ratio. A selected rendition's exact width is in that `sources[]` entry."
+    },
+    "height": {
+      "description": "The video's display height in pixels, for layout and aspect ratio. A selected rendition's exact height is in that `sources[]` entry."
+    },
+    "sources": {
+      "type": "array",
+      "description": "The complete set of available encoded renditions (MP4/WebM, HLS/DASH manifests). A Business that provides `sources` SHOULD include a source whose `url` equals the media `url` when `url` identifies a rendition; an external watch-page `url` does not identify a rendition.",
+      "items": {
+        "$ref": "media_source.json"
+      }
+    }
+  }
+}