> The article doesn't show any function lifetime annotations, only @safe and @unsafe.

It does, but it's under the "External Annotations" section:

    // External annotations go in a header file
    // @external: {
    //   strlen: [safe, (const char* str) -> owned]
    //   strcpy: [unsafe, (char* dest, const char* src) -> char*]
    //   strchr: [safe, (const char* str, int c) -> const char* where str: 'a, return: 'a]
    //
    //   // Third-party libraries work the same way
    //   sqlite3_column_text: [safe, (sqlite3_stmt* stmt, int col) -> const char* where stmt: 'a, return: 'a]
    //   nlohmann::json::parse: [safe, (const string& s) -> owned json]
    // }

The GitHub repo also has an annotations guide with some more info [0]. The general syntax appears to be:

    // @lifetime: (parameters) -> return_type where constraints