The plasma bolt struck the cabinet above Austin’s head. Hot metal sprayed across the aisle.
Pug leaped from behind the cart and caught the drone in his middle jaws. He crushed it, dropped the sparking shell, and wagged his tail.
“Good boy. Keep them off us,” Austin said. “Xiaoyao, exchanger one goes back into Bay C.”
Another drone fired. Pug bounded after it while Austin and Xiaoyao dragged the first heat exchanger off the cart.
The mounting rails were hot. Xiaoyao wrapped his burned palms in the cloth Austin had given him and guided the unit into place. Austin connected the supply line. The return fitting would not seat.
“Threads are crossed,” Xiaoyao said.
Austin almost forced it, then stopped. “Back it off. We need a clean joint, not a fast one.”
Xiaoyao realigned the collar by hand. This time it turned smoothly. Austin tightened it and opened the isolation valve.
[EXCHANGER 03: ONLINE]
The temperature kept rising.
“Eight minutes,” Xiaoyao read from the wall.
They installed the second exchanger. Then the third. Pug’s game of fetch grew less funny as more drones arrived. He knocked them out of the air, caught their shells against the floor, and placed himself between their weapons and the workers.
When the fourth exchanger was ready, the cart blocked the shortest route to Bay F.
“Over the empty rack?” Xiaoyao asked.
“Too heavy. Around the end.”
A tone sounded overhead.
[CORE PURGE IN FIVE MINUTES]
Xiaoyao looked at his survey notes. He had drawn the aisle spacing while Austin unloaded the servers. “There is a service gap behind Bay D. Narrow, but straight.”
They tilted the exchanger onto its padded edge and slid it through. Austin guided the top; Xiaoyao kept the bottom clear of cable trays. The service gap saved them a full trip around the row.
“Last valve,” Austin said. “Open it slowly.”
Xiaoyao turned the wheel. Pressure knocked once, then settled into a steady rush.
The relief lasted one breath. Six red indicators remained on the control display.
“Cooling’s back, but the core still can’t distribute its calculations,” Austin said. “Those six blades run thermal control. I took the brains along with the radiators.”
They returned to the cart. Austin read each label and separated the six assigned to ordinary workshop jobs from the six the Vault needed. He no longer cared about his planned four hundred percent upgrade.
“These six stay. Mark the empty slots before we seat them.”
Xiaoyao checked the cabinet numbers against his labels. He caught Austin reaching toward Bay 12 with a blade marked 21.
“Wrong rack.”
Austin looked down. “So it is. Good catch.”
They installed the blades one by one. Xiaoyao called out the slot; Austin connected power and coolant; the other confirmed each green light before they moved on. No speeches. No shortcuts.
The final blade clicked home.
Austin leaned against the cabinet and exhaled. “That was too close.”
Xiaoyao sat beside the cart. His hands were shaking now that the work was done. “We still have six blades for Sunset Peak.”
“If the Overseer agrees they’re spare. Ownership doesn’t make it safe to strip a live plant.” Austin wrote the sentence on his clipboard. “And I’m not pretending I knew that five minutes ago.”
Pug crunched the last drone and trotted back with a bent lens in his mouth. Thirty-six damaged spheres lay across the aisles. The repair had taken seven minutes and left them with scorched cabinets, cut cables, and a great deal of work still to do.
Austin collected the cut security cables and capped the coolant ports. “We clean up what we broke. Then we talk to the administrator.”
They pushed the lighter cart toward the central dome. A circular blast door waited at the eastern wall.
Austin rested his wrench on his shoulder. “And this time we ask for the operating limits before we touch anything else.”