Merge branch 'master' into mattmiller/spec-nullable-device-index-essentials-category

The previous description said "null for nodes that don't set
ESSENTIALS_CATEGORY (V1)" — that's wrong. server.py:739-740 uses
`hasattr` and OMITS the key when the V1 attribute isn't defined; null
only happens if the attribute is explicitly set to None. Spell out
all three legal shapes (string / null / absent) and which path
produces which.

openapi.yaml

@@ -2347,7 +2347,12 @@ components:
           description: Device type (cuda, mps, cpu, etc.)
         index:
           type: number
-          description: Device index
+          nullable: true
+          description: |
+            Device index within its type (e.g. CUDA ordinal for `cuda:0`,
+            `cuda:1`). `null` for devices with no index, including the CPU
+            device returned in `--cpu` mode (PyTorch's `torch.device('cpu').index`
+            is `None`).
         vram_total:
           type: number
           description: Total VRAM in bytes
@@ -2503,7 +2508,18 @@ components:
           description: Alternative search terms for finding this node
         essentials_category:
           type: string
-          description: Category override used by the essentials pack
+          nullable: true
+          description: |
+            Category override used by the essentials pack. The
+            `essentials_category` key may be present with a string value,
+            present and `null`, or absent entirely:
+
+            - V1 nodes: `essentials_category` is **omitted** when the node
+              class doesn't define an `ESSENTIALS_CATEGORY` attribute, and
+              **`null`** if the attribute is explicitly set to `None`.
+            - V3 nodes (`comfy_api.latest.io`): `essentials_category` is
+              **always present**, and **`null`** for nodes whose `Schema`
+              doesn't populate it.
 
     # -------------------------------------------------------------------
     # Models