This would be appreciated, if it's at all possible.

For example, remembering my current state on the item (quality, buffs, durability) each time a new Step progresses. If a disconnect occurs, dump the mats back to inventory. Log back in, the item has 'Resume Progress' option, which restores the last recorded state the synthesis was in. Choosing to reject 'Resume Progress' warns you that any materials contributed to that synthesis will be forfeited (regardless of what you're trying to craft with them now).