added optional web component UI control

docs/CURRENT_SYSTEM_ARCHITECTURE.md

@@ -77,6 +77,7 @@ The checked-in implementation is `ShaderRuntimeContentController`. It wraps `Run
 - build state and message
 - bypass state
 - manifest parameter definitions
+- optional shader-declared custom UI metadata
 - current parameter values
 - render-ready artifacts
 
@@ -111,6 +112,7 @@ The host configuration editor is separate from runtime layer persistence. The UI
 - rescan `shaders/`
 - re-read manifests
 - rebuild the supported shader catalog
+- refresh optional shader custom UI metadata
 - update active layer metadata and parameter definitions from changed manifests
 - preserve compatible parameter values
 - default new or incompatible parameter values
@@ -155,6 +157,7 @@ Screenshot routes are present in the UI/OpenAPI surface but are not implemented
 The HTTP server runs on its own thread. `HttpControlServer` owns socket lifetime, HTTP parsing, static asset helpers, OpenAPI/Swagger helper serving, and WebSocket state transport. `RenderCadenceHttpRoutes` owns this app's current endpoint map:
 
 - UI assets
+- shader package custom UI assets under `/shader-assets/{shaderId}/...`
 - OpenAPI/Swagger docs
 - `GET /api/state`
 - `/ws` state updates

docs/openapi.yaml

@@ -106,6 +106,51 @@ paths:
             text/plain:
               schema:
                 type: string
+  /shader-assets/{shaderId}/{assetPath}:
+    get:
+      tags: [Static]
+      summary: Serve a shader package UI asset
+      description: Serves custom shader UI files declared by `shader.json`. Assets are resolved through the active runtime-content controller and must stay inside that shader package's `ui/` directory.
+      operationId: getShaderPackageAsset
+      parameters:
+        - name: shaderId
+          in: path
+          required: true
+          description: Shader package id.
+          schema:
+            type: string
+        - name: assetPath
+          in: path
+          required: true
+          description: Relative asset path below the shader package, usually `ui/controls.js`.
+          schema:
+            type: string
+      responses:
+        "200":
+          description: Shader package UI asset.
+          content:
+            text/javascript:
+              schema:
+                type: string
+            text/css:
+              schema:
+                type: string
+            image/svg+xml:
+              schema:
+                type: string
+            image/png:
+              schema:
+                type: string
+                format: binary
+            text/plain:
+              schema:
+                type: string
+        "404":
+          description: Asset was not found, the shader did not declare custom UI, or the path was unsafe.
+          content:
+            text/plain:
+              schema:
+                type: string
   /docs:
     get:
       tags: [Docs]
@@ -1200,6 +1245,29 @@ components:
           $ref: "#/components/schemas/TemporalState"
         feedback:
           $ref: "#/components/schemas/FeedbackState"
+        ui:
+          $ref: "#/components/schemas/ShaderUiDefinition"
+          nullable: true
+    ShaderUiDefinition:
+      type: object
+      nullable: true
+      properties:
+        type:
+          type: string
+          enum: [webComponent]
+        entry:
+          type: string
+          description: Package-relative JavaScript module path from the shader manifest.
+          example: ui/controls.js
+        tag:
+          type: string
+          description: Custom element tag registered by the module.
+          example: my-shader-controls
+        assetUrl:
+          type: string
+          description: HTTP URL for loading the JavaScript module from the local control server.
+          example: /shader-assets/my-shader/ui/controls.js
+      additionalProperties: false
     TemporalState:
       type: object
       properties:
@@ -1232,6 +1300,9 @@ components:
           type: boolean
         temporal:
           $ref: "#/components/schemas/TemporalState"
+        ui:
+          $ref: "#/components/schemas/ShaderUiDefinition"
+          nullable: true
         parameters:
           type: array
           items: