A refinement of our staircase kind which can be climbed.

Presumably all staircase-type connections between rooms should respond when the player says CLIMB STAIRS (or the equivalent). So

"Hayseed"
A staircase is a kind of door. A staircase is usually open. A staircase is seldom openable.
The ladder is a staircase. It is above the Barn and below the Hayloft.
Instead of climbing a staircase:
   try entering the noun.
Test me with "climb ladder / g".
Test me with "climb ladder / g".
Barn
You can see a ladder here.

>(Testing.)

>[1] climb ladder

Hayloft
You can see a ladder here.

>[2] g

Barn
You can see a ladder here.

Attempts to climb other types of door will still be treated as useless.