Refactor code structure for improved readability and maintainability; optimize performance in key functions.

docs/schemas/predicates/vex.v1.schema.json

@@ -0,0 +1,64 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://stella.ops/predicates/vex@v1",
+  "title": "StellaOps VEX Attestation Predicate",
+  "description": "Predicate for VEX statements embedded in attestations.",
+  "type": "object",
+  "required": ["format", "statements"],
+  "properties": {
+    "format": {
+      "type": "string",
+      "enum": ["openvex", "csaf-vex", "cyclonedx-vex"],
+      "description": "VEX format specification."
+    },
+    "statements": {
+      "type": "array",
+      "items": {
+        "$ref": "#/$defs/vexStatement"
+      },
+      "minItems": 1,
+      "description": "VEX statements in this attestation."
+    },
+    "digest": {
+      "type": "string",
+      "pattern": "^sha256:[a-f0-9]{64}$",
+      "description": "Content-addressed digest of the VEX document."
+    },
+    "author": {
+      "type": "string",
+      "description": "Author of the VEX statements."
+    },
+    "timestamp": {
+      "type": "string",
+      "format": "date-time",
+      "description": "When the VEX was issued."
+    }
+  },
+  "$defs": {
+    "vexStatement": {
+      "type": "object",
+      "required": ["vulnerability", "status"],
+      "properties": {
+        "vulnerability": {
+          "type": "string",
+          "description": "CVE or vulnerability identifier."
+        },
+        "status": {
+          "type": "string",
+          "enum": ["affected", "not_affected", "under_investigation", "fixed"],
+          "description": "VEX status."
+        },
+        "justification": {
+          "type": "string",
+          "description": "Justification for not_affected status."
+        },
+        "products": {
+          "type": "array",
+          "items": { "type": "string" },
+          "description": "Affected products (PURLs)."
+        }
+      }
+    }
+  },
+  "additionalProperties": false
+}