fix: make Codex hooks transactional

src/plugins/strict-json.ts

@@ -0,0 +1,57 @@
+import {
+  parse,
+  parseTree,
+  printParseErrorCode,
+  type Node,
+  type ParseError,
+} from 'jsonc-parser';
+
+export type JsonObject = Record<string, unknown>;
+
+export function isObject(value: unknown): value is JsonObject {
+  return typeof value === 'object' && value !== null && !Array.isArray(value);
+}
+
+function rejectDuplicateKeys(
+  node: Node | undefined,
+  label: string,
+  location: string[] = [],
+): void {
+  if (!node) return;
+  if (node.type === 'object') {
+    const keys = new Set<string>();
+    for (const property of node.children ?? []) {
+      const key = String(property.children?.[0]?.value);
+      const childLocation = [...location, key];
+      if (keys.has(key)) {
+        throw new Error(`${label} contains duplicate field "${childLocation.join('.')}"`);
+      }
+      keys.add(key);
+      rejectDuplicateKeys(property.children?.[1], label, childLocation);
+    }
+    return;
+  }
+  if (node.type === 'array') {
+    for (const child of node.children ?? []) rejectDuplicateKeys(child, label, location);
+  }
+}
+
+export function parseStrictJsonObject(raw: string, label: string): JsonObject {
+  const errors: ParseError[] = [];
+  const value: unknown = parse(raw, errors, {
+    allowTrailingComma: false,
+    disallowComments: true,
+  });
+  if (errors.length > 0) {
+    const details = errors
+      .map((error) => `${printParseErrorCode(error.error)} at offset ${error.offset}`)
+      .join(', ');
+    throw new Error(`Failed to parse ${label}: ${details}`);
+  }
+  if (!isObject(value)) throw new Error(`${label} must contain a JSON object`);
+  rejectDuplicateKeys(parseTree(raw, [], {
+    allowTrailingComma: false,
+    disallowComments: true,
+  }), label);
+  return value;
+}