:title
route_path_sanitize

:sig
String route_path_sanitize(String path, String default_path = "index")

:see
route_path_is_safe
route_path_normalize
request_query_path
request_query_route
request_context_params

:content
Normalizes and validates a route path for file-backed routing.

Rules:

- leading and trailing `/` are removed
- an empty path becomes `default_path`
- every path segment must be non-empty
- `.` and `..` segments are rejected
- only ASCII letters, digits, `_`, and `-` are accepted inside a segment
- unsafe input returns an empty string

Use this instead of manually checking app routes before composing file paths.

```cpp
route_path_sanitize("/workspace/projects/"); // "workspace/projects"
route_path_sanitize("../secret");            // ""
route_path_sanitize("");                     // "index"
```

`request_query_path()`, `request_query_route()`, and the runtime-populated `ROUTE_PATH` params already use this sanitizer.
