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apps/x/packages/shared/src/frontmatter.ts

@@ -0,0 +1,60 @@
+/**
+ * Frontmatter parsing utilities for knowledge base markdown files.
+ * Used by core (get-base-state) to scan knowledge files for available properties.
+ */
+
+/**
+ * Parse a markdown file's YAML frontmatter into key-value pairs.
+ * Handles both scalar values (`key: value`) and list values (`key:\n  - item`).
+ * Returns `{ fields, body }` where fields maps keys to string or string[].
+ */
+export function parseFrontmatter(content: string): { fields: Record<string, string | string[]>; body: string } {
+  if (!content.startsWith('---')) {
+    return { fields: {}, body: content };
+  }
+  const endIndex = content.indexOf('\n---', 3);
+  if (endIndex === -1) {
+    return { fields: {}, body: content };
+  }
+
+  const rawBlock = content.slice(4, endIndex); // skip opening '---\n'
+  const body = content.slice(endIndex + 4).replace(/^\n/, '');
+  const fields: Record<string, string | string[]> = {};
+  let currentKey: string | null = null;
+
+  for (const line of rawBlock.split('\n')) {
+    if (line.trim() === '' || line === '---') {
+      currentKey = null;
+      continue;
+    }
+
+    // Top-level key: value
+    const topMatch = line.match(/^(\w[\w\s]*\w|\w+):\s*(.*)$/);
+    if (topMatch) {
+      const key = topMatch[1];
+      const value = topMatch[2].trim();
+      if (value) {
+        fields[key] = value;
+        currentKey = null;
+      } else {
+        // List will follow
+        currentKey = key;
+        fields[key] = [];
+      }
+      continue;
+    }
+
+    // List item under current key
+    if (currentKey) {
+      const itemMatch = line.match(/^\s+-\s+(.+)$/);
+      if (itemMatch) {
+        const arr = fields[currentKey];
+        if (Array.isArray(arr)) {
+          arr.push(itemMatch[1].trim());
+        }
+      }
+    }
+  }
+
+  return { fields, body };
+}