fix: stabilize runtime follow-up regressions

site/doc/pages/has.txt

@@ -0,0 +1,36 @@
+:sig
+bool DTree::has(String s) const
+
+:params
+s : child key to test
+return value : true when the node is map-shaped and contains the key
+
+:see
+>types
+0_DTree
+get_by_path
+each
+is_array
+
+:content
+Tests whether a map-shaped `DTree` contains a child key, without creating it. This is a read accessor: it is `const`, never creates or modifies nodes, and dereferences internal references automatically.
+
+Returns `false` for scalar nodes and for missing keys.
+
+This matters because `operator[]` creates missing entries, exactly like `std::map`. Use `has()` (or `get_by_path()`) when you only want to look:
+
+```cpp
+if(context.props.has("avatar"))
+	print(component("components/basic/avatar", context.props["avatar"], context));
+```
+
+`has()` only checks one level. For nested checks, combine with `get_by_path()`:
+
+```cpp
+bool configured = context.cfg.get_by_path("mail/smtp").is_array();
+```
+
+## Related Concepts
+
+- PHP: `array_key_exists()` / `isset()`
+- JavaScript: `Object.hasOwn(obj, key)` / `key in obj`