The moment the welding torch touched the metal, Nana said, "Stop."

Chen Hao's hand trembled, and the flame was extinguished with a "pop".

"What is it now?" He tilted his head to look at her, his arm still hanging in mid-air, a thin layer of sweat on his forehead that was chilled by the evening breeze.

“The weld temperature is 0.8 degrees higher than the sides,” she said, turning the terminal around to show him. A red line on the screen was slightly raised, like a pencil line that someone had accidentally drawn crookedly.

"This has only just been lit! Don't you understand the concept of thermal expansion and contraction?"

“It’s not expanding, it’s accumulating stress.” She reached out and pressed the edge of the support. “The part you welded yesterday already has micro-cracks. Re-welding it now is like pouring hot water on the crack—it sounds okay, but it’s actually about to collapse underneath.”

Chen Hao sighed and tossed the welding torch aside next to the toolbox. "Why is this thing so delicate? When I was a kid, I could wear slippers tied with wire for three months straight."

"So, do you want to build a waterwheel that can run for three years, or do you want it to fall apart on day one?"

"I want it to at least last through tonight's celebration music system."

"No. Any additional load must be prohibited until the system is stable."

"Not even 'Unforgettable Tonight' is acceptable?"

"I might even call the police if my breathing rate is too high."

Chen Hao rolled his eyes and squatted down to remove the screws. The metal parts were tightly gripped, and it took him a long time to unscrew them until his fingers turned red before he finally removed the third support. As he ground down the original weld points, he muttered, "I should have just bought a ready-made one to take apart."

There are no hardware stores on this desolate planet.

"You can't blame my skills; it's due to incomplete infrastructure."

Nana didn't reply, but instead projected the thermal image onto the terminal, staring at that area like she was guarding a kettle about to boil over.

As darkness fell, there were no lights on this side of the riverbank, only a few yellow lights from the distant base barely illuminating the shadows. Chen Hao turned on his headlamp, the light flickering, and with his welding helmet on, he looked like a lost miner.

"Weld in sections, each section no more than five centimeters long, and let it cool naturally for thirty seconds after welding," Nana announced the parameters. "Don't rush, and don't be lazy."

"When have I ever slacked off? Last time I soldered for forty minutes straight!"

“After that incident, the drive bay shifted by two millimeters, and I adjusted the compensation program six times.”

"That's called passionate dedication."

"That's called a disaster rehearsal."

Sparks flew again, and a tiny spark landed on his sleeve, burning a small hole. He dusted it off and continued working. This time he was much slower, pausing to blow on the weld after each small section, as if soothing a child who couldn't fall asleep.

Nana stared at the temperature curve and finally nodded: "It's okay."

He breathed a sigh of relief, wiped his face, and found his palms covered in dust. "Finally done?"

"The self-inspection hasn't even started yet."

She initiated a full system scan. Data streams scrolled across the console screen: transmission efficiency, shaft alignment, blade stress distribution... lines of green text popped up, occasionally flashing a yellow light before being quickly corrected.

Ten minutes later, a notification sound rang.

Structural safety level: A

Power transmission stability: 91.3%

[Ready to run: Ready]

"Wow, it actually works?" Chen Hao grinned. "I thought we'd have to go through at least one more round."

"Because you didn't close your eyes while welding this time."

"That's because I didn't dare to close it—I was afraid you'd write it in the log and deduct it from my performance record."

"You have no performance."

"Then don't write it in the fault report either."

Nana closed the terminal: "It's ready to start now."

Chen Hao stood up, brushed the debris off his pants, and walked to the inlet control valve. "Let's get it moving. The people of the desolate planet have been waiting for this day for far too long."

"There are only the two of us on this desolate planet right now."

“They are the people too! And I am speaking on behalf of the vast majority of the silent masses.”

He flipped the switch. The diversion valve of the upstream water tank slowly opened, and the water flowed down the newly built irrigation canal, hitting the blades at the bottom of the waterwheel.

The wheel rim jolted violently at first.

The alarm went off immediately.

"Damn it!" Chen Hao jumped back a step. "Is it going to explode?"

"It's just that the startup shock was too great." Nana pulled up the hydrological chart. "The upstream flow fluctuated violently, causing the instantaneous pressure to exceed the limit. We are adjusting the opening of the diversion valve."

On the screen, the valve icon flashed a few times, the value dropped from 75% to 62%, and then slowly rose back to the stable range.

"Adjust the blade angle manually to reduce the water-facing surface," she said.

Chen Hao grabbed a wrench, stepped onto the maintenance ladder, and turned the adjusting bolt on the lowest blade two turns. The blade slightly closed, and the tilt became gentler.

"Are you done yet?"

"Try again."

He pressed the start button again.

This time, when the water hit, the wheel rim only wobbled slightly before starting to rotate slowly. One rotation, two rotations, the speed gradually increased, emitting a deep hum, like the breath coming from the depths of the earth.

The connecting shaft drives the transmission belt, the grinding machine's drum begins to rotate, the water pump piston moves rhythmically, and the conveyor belt moves accordingly.

"All three devices are operating in tandem." Nana looked at the remote feedback. "The operation is stable and the energy consumption is normal."

Chen Hao stood with his hands on his hips, looking up at the enormous machine slowly turning, and couldn't help but laugh out loud: "Hey, it's really turning."

“It’s not ‘hey,’ it’s ‘operating as planned.’”

"I'm talking about feelings, not reports."

"Feelings are feelings, and data is data."

"Then you can at least give me an expression, even just a blink."

"My optical lens does not have a mimicry function."

Are you happy about that?

She paused for a moment, and then a chart suddenly popped up on the terminal screen with the title: "[Project Completion Assessment]". The curve stretched all the way to 100%, and a small star was added at the end.

Chen Hao paused for two seconds, then burst into laughter: "Are you secretly giving yourself an award certificate?"

"This is a project completion identifier automatically generated by the system."

"You're lying, you're clearly happy."

"I'm just confirming the mission is closed."

"Fine, fine, I know even if you don't admit it." He took out his phone, turned on the video recording function, and started snapping photos of the waterwheel. "Dear viewers, welcome to the 'First Power Project Commissioning Ceremony on the Wilderness Star.' I am your host, Chen Hao. Right now behind me, the spark of human civilization has been ignited once again!"

Nana stood aside and did not stop him.

Only after he finished recording, played it back once, and nodded in satisfaction did he speak: "Can we play music now?"

"cannot."

"Can I hum a few lines?"

"As long as it doesn't affect the monitoring accuracy."

He cleared his throat and began to sing softly: "A great river flows wide..."

The singing floated on the river, mixed with the hum of the waterwheel, almost like an accompaniment.

Ten minutes passed, and all indicators remained stable. There was no abnormal vibration, no temperature spike, and no sudden power outage.

"Stable operation confirmed." Nana closed the monitoring interface. "Project accomplished."

"Shouldn't we do something?" Chen Hao put away his phone and rubbed his hands together. "Like grab a drink? Have a nice meal? Or at least take a group photo?"

"You have used up your dinner calorie allowance."

"How about taking a picture?"

"Yes. But you are not allowed to hold a pose for more than three seconds, as it will affect the evacuation efficiency."

"You're truly the king of robots."

He moved closer to her and took a selfie with his phone. In the background, the waterwheel turned slowly, the mechanical arm swung rhythmically, and the lights reflected on the river, creating shimmering patterns.

“Eggplant!” he said.

The photo freezes in time.

The next second, Nana suddenly raised her hand.

"etc."

She pointed to a support rod near the base of the waterwheel.