All is not well, at this point.
For the Autumn, the goblins sent a siege, which as far as I can tell prevented the arrival of the dwarven caravan. I was expecting a hefty shipment of leather and cloth to cloth my dwarves. Better luck next year, I suppose.
Unfortunately, the siege did not go as well as it could have if I had been more patient: Despite all three of the goblins' infantry platoons arriving at roughly the same time, I let the marksdwarves engage the goblins before their mounted crossbowman platoon was all the way in the trap hallway. Thusly, a marksdwarf died of a broken heart. After being pierced by a crossbow bolt, her husband, who had been standing right next to her, wandered off to get some ammo, leaving her to bleed to death alone.
After all four goblin platoons were in the grinder and sufficiently shredded, I released the melee squads by stationing them in the bottom of the pit. They rushed across the bridge, slaughtering every goblin on it, before fighting their way down the stairs. During the melee,several injuries were received, and two soldiers were struck down on the spot. Nearly all of the surviving greenskins died on the stairwell, and those who didn't were unconscious at the bottom of the pit when they had their heads smashed in. It was a sad day for the dwarves of Luckystream, but the soldiers who died during the siege will receive special honors in a second memorial hall, attached to the first.
During the siege, I accidentally planespacked a leather shirt by designating civilian burrow restrictions to keep everyone out of harm's way. The farmer who made it was only possessed, and it was a tanning mood, so I suppose getting a very image-heavy leather shirt out of it isn't such a bad deal. I can't provide a screenshot, unfortunately. All the extra stuff he grabbed was leather.