feat(api): typed feature meter reference (#4332)

Author: tothandras

api/spec/packages/aip/src/features/feature.tsp

@@ -7,6 +7,23 @@ using TypeSpec.JsonSchema;
 
 namespace Features;
 
+@friendlyName("FeatureMeterReference")
+model FeatureMeterReference {
+  /**
+   * The ID of the meter to associate with this feature.
+   */
+  @visibility(Lifecycle.Read, Lifecycle.Create)
+  @summary("Meter ID")
+  id: Shared.ULID;
+
+  /**
+   * Filters to apply to the dimensions of the meter.
+   */
+  @maxProperties(10)
+  @summary("Meter dimensions filters")
+  filters?: Record<Shared.QueryFilterStringMapItem>;
+}
+
 /**
  * A capability or billable dimension offered by a provider.
  */
@@ -20,28 +37,15 @@ model Feature {
    */
   @summary("Meter reference")
   @visibility(Lifecycle.Read, Lifecycle.Create)
-  meter?: {
-    /**
-     * The ID of the meter to associate with this feature.
-     */
-    @visibility(Lifecycle.Read, Lifecycle.Create)
-    id: Shared.ULID;
-
-    /**
-     * Filters to apply to the dimensions of the meter.
-     */
-    @maxProperties(10)
-    @summary("Meter dimensions filters")
-    filters?: Record<Shared.QueryFilterStringMapItem>;
-  };
+  meter?: FeatureMeterReference;
 
   /**
    * Optional per-unit cost configuration.
    * Use "manual" for a fixed per-unit cost, or "llm" to look up cost
    * from the LLM cost database based on meter group-by properties.
    */
   @summary("Unit cost")
-  @visibility(Lifecycle.Read, Lifecycle.Create)
+  @visibility(Lifecycle.Read, Lifecycle.Create, Lifecycle.Update)
   unit_cost?: FeatureUnitCost;
 }