Boolflow flattens nested circuit blocks into one simulated netlist, with a pin-mapping bug found along the way

Boolflow is a free browser logic simulator in which each block stores its own definition as a nested node, and before simulation every block is replaced by a copy of that definition. The flattening step gives every inner element a path-based id, such as DIV2/D.Q, with a #2 suffix for repeated copies, so simulation state stays distinct. Pins are determined by their position in the definition, and wires crossing a block's edge are rewritten to match, with an output-mapping step restoring block outputs after simulation. The author describes a bug in an early version that tied wires to pin index rather than pin name, causing a renamed-and-reordered output to silently read the wrong pin. The fix keeps wires attached to pins by name, with the editor reporting how many wires were moved or dropped.