The various stream lists tied to the circuit structures should use tor_queue.h
Offshoot of #16052 (moved).
Every list that uses edge_connection_t.next_stream, should be converted to a TOR_SLIST for maintainability/sanity. Carved off into a separate ticket because #16052 (moved) will probably get a 0.2.6 backport, while this should not as it is rather intrusive (if mechanical).
To upload designs, you'll need to enable LFS and have admin enable hashed storage. More information