feat(macos): add Canvas A2UI renderer

vendor/a2ui/specification/0.9/json/client_to_server.json

@@ -0,0 +1,97 @@
+{
+  "title": "A2UI (Agent to UI) Client-to-Server Event Schema",
+  "description": "Describes a JSON payload for a client-to-server event message.",
+  "type": "object",
+  "minProperties": 1,
+  "maxProperties": 1,
+  "properties": {
+    "userAction": {
+      "type": "object",
+      "description": "Reports a user-initiated action from a component.",
+      "properties": {
+        "name": {
+          "type": "string",
+          "description": "The name of the action, taken from the component's action.name property."
+        },
+        "surfaceId": {
+          "type": "string",
+          "description": "The id of the surface where the event originated."
+        },
+        "sourceComponentId": {
+          "type": "string",
+          "description": "The id of the component that triggered the event."
+        },
+        "timestamp": {
+          "type": "string",
+          "format": "date-time",
+          "description": "An ISO 8601 timestamp of when the event occurred."
+        },
+        "context": {
+          "type": "object",
+          "description": "A JSON object containing the key-value pairs from the component's action.context, after resolving all data bindings.",
+          "additionalProperties": true
+        }
+      },
+      "required": [
+        "name",
+        "surfaceId",
+        "sourceComponentId",
+        "timestamp",
+        "context"
+      ]
+    },
+    "error": {
+      "description": "Reports a client-side error.",
+      "oneOf": [
+        {
+          "type": "object",
+          "title": "Validation Failed Error",
+          "properties": {
+            "code": {
+              "const": "VALIDATION_FAILED"
+            },
+            "surfaceId": {
+              "type": "string",
+              "description": "The id of the surface where the error occurred."
+            },
+            "path": {
+              "type": "string",
+              "description": "The JSON pointer to the field that failed validation (e.g. '/components/0/text')."
+            },
+            "message": {
+              "type": "string",
+              "description": "A short one-sentence description of why validation failed."
+            }
+          },
+          "required": ["code", "path", "message", "surfaceId"]
+        },
+        {
+          "type": "object",
+          "title": "Generic Error",
+          "properties": {
+            "code": {
+              "not": {
+                "const": "VALIDATION_FAILED"
+              }
+            },
+            "message": {
+              "type": "string",
+              "description": "A short one-sentence description of why the error occurred."
+            },
+            "surfaceId": {
+              "type": "string",
+              "description": "The id of the surface where the error occurred."
+            }
+          },
+          "required": ["code", "surfaceId", "message"],
+          "additionalProperties": true
+        }
+      ]
+    }
+  },
+  "oneOf": [
+    { "required": ["userAction"] },
+    { "required": ["clientUiCapabilities"] },
+    { "required": ["error"] }
+  ]
+}