Chen Hao placed his pen on the corner of the table. The sentence in his notebook, "The defenses are repaired today, but I've also been pricked by thorns," was left unfinished. He stared at the bandage on his forearm; the resin film was a little tight against his skin, and moving it made the area around the wound itchy. He scratched it a couple of times, then withdrew his hand.

The control panel screen was still lit, with rows of green operating lights flashing steadily. After a whole day of troubleshooting yesterday, the system finally stopped alarming. He should have breathed a sigh of relief, but he felt inexplicably empty, like the unease of forgetting to turn off the gas stove.

He flipped through his notebook, trying to find out how the irrigation module had been adjusted that day. The handwriting on the paper was crooked and messy: "Open valve → Check pressure → Adjust frequency," with an arrow next to it pointing to "Don't touch the red button." He himself couldn't understand what it said.

"I remember setting the flow rate first and then turning on the pump... or is it the other way around?" he muttered, getting up and walking to the control panel. He tapped the menu a few times to bring up the irrigation system's operating curve.

The page redirected, and a long list of data appeared. He stared at those numbers for half a minute, but still couldn't find the peak point recorded yesterday. He went back one level, then went back again, then went back again. He did this three times, finally slamming his finger heavily on the screen.

"This thing is even harder to memorize than pi."

Nana stood in the corner, her optical glasses slightly rotating. "Are you trying to replicate yesterday's actions?"

“It’s not an attempt, it’s a recollection.” He sat back in his chair and tugged at his sleeve. “The problem is, I can’t remember the parameters. It seemed pretty simple at the time, so how come everything’s a mess now?”

"Human short-term memory lasts an average of 72 hours, and it is easily lost without reinforcement." After she finished speaking, the robotic arm lifted slightly. "I suggest creating an operation manual."

"Document? You're not going to make one of those densely packed tables again, are you?"

"A template is already available. It includes process logic, safety thresholds, and a fault code lookup table—"

“Stop.” He waved his hand. “What I want is ‘press this button when there’s not enough water,’ not an engineering license test.”

Nana paused for a second. "It can be simplified into step-by-step guidance cards, retaining only key actions and warning prompts."

“I can understand this,” he nodded, “but you have to write it in plain language. For example, don’t write ‘start booster pump P3,’ write ‘turn the blue knob on the left.’”

"Yes. We can use recycled resin plates for recording, which are wear-resistant and easy to hang on-site."

"Okay, shall we start now? We don't have anything else to do anyway."

The two moved to the control panel in the living area. Nana connected to the terminal, retrieved the irrigation system structure diagram from the database, and broke it down into six steps: check the water source, open the main valve, set the flow rate, start the water pump, monitor the pressure, and shut down in case of emergency. Each step was accompanied by a sentence description and an icon.

Chen Hao shook his head as he looked at the first draft. "The icon is too abstract. Who can tell if it's a water pump or a toilet?"

Nana adjusted the image, changing it to a simple line drawing. A square with a spiral represents a water pump; a wavy line with an arrow represents water flow.

"Almost there." He took the carving knife and began to trace the lines onto the resin plate. "First piece: Check the water level before opening the valve. Don't force it open if it's low, or you'll burn out the pump."

He carved each character carefully, beads of sweat forming on his forehead. He dared not exert force with his left arm, relying solely on his right. After finishing a line, he flicked his wrist.

"Second rule: Don't exceed 12 liters per minute. I think I set it to 20 last time? It almost flooded the vegetable seedlings in the west area."

"The actual recorded rate was 18.3 liters per minute, lasting for four minutes and seventeen seconds," Nana added. "The soil moisture once reached 91%, close to saturation."

"No wonder the ground was covered in mud when I came back." He grinned. "Luckily, not all the seedlings died."

They worked until evening, and all six resin boards were finished. Each board was about the size of a palm, strung together with rope, and hung next to the irrigation control box. Chen Hao stepped back to admire the result, like looking at his own child's homework.

"It may be ugly, but it's understandable. That's true pragmatism."

“It has been entered into the knowledge base index, number op-001,” Nana said. “It can be extended to other systems in the future.”

"I'll try it out tomorrow. I'll see if it can really save lives."

It drizzled a little during the night, and the temperature dropped slightly. Chen Hao drank some hot water before bed and fell asleep shortly after lying down. In his dream, he was surrounded by buttons and numbers, running around pressing this and turning that off, until he was finally woken up by a sign that read "Unit Error".

The irrigation system started automatically at six o'clock the next morning.

The alarm sounded at 6:07.

Chen Hao jumped out of bed with a start, grabbed his coat, and rushed out. Nana had already arrived at the control room, where a red warning box on the screen kept flashing: "Over-irrigation, soil moisture exceeds the standard."

"Cut off the water supply." She entered the command, and the valve closed immediately.

The two rushed to the farmland, where the eastern side was a mess. Several newly transplanted tomato seedlings had been washed away, their roots exposed, and they lay sprawled on the ground. The soil was wet and slippery, making it easy to slip and fall.

"Here we go again." Chen Hao squatted down, shoveling away the mud to examine the roots. "No wonder I dreamt about mixing up my workplace last night..."

Nana pulled up the system log. "Last night the flow rate was set to twelve cubic meters per hour, not twelve liters per minute."

"A hundred times worse?" he exclaimed, his eyes wide.

"Exactly."

“But I clearly remember it said ‘twelve liters’…” He turned and ran back.

On the control panel, the string of engraved resin plates hung quietly. He ripped one down and flipped it to the third one: "Set flow rate: 12 L/min".

The characters are correct.

Upon closer inspection, he discovered that the small print below was something he had added later: "Conversion = 0.72 m3/h".

"Damn it!" He slapped his forehead. "I memorized the converted value as the set value!"

Nana scans the panel. "The original record is correct, but the user's memory is flawed. This type of error occurs in 34.6% of non-professional operators."

"So, I'm not the first one to make a stupid mistake?"

"You're the first person to make this mistake using resin boards."

Chen Hao gave a wry smile. He sat in the chair, his hand supporting his forehead. "I always thought that as long as I remembered the general idea, it would be fine, since you were there to back me up. But now it seems that if you were to have a short circuit one day, I wouldn't even know how to turn off the water pump."

"My system stability is above 99.8%".

"But I'm not like that. I can even misunderstand the words I write myself."

After a few seconds of silence, he said, "Let's redo it. This time I'll check it word by word, and you can read it to me sentence by sentence."

Nana nodded and regenerated the document. The two of them went through the process from the beginning, standardized all units, bolded key values, and added a yellow warning bar to the "Set Flow Rate" step: "Note the units! L/min ≠ m3/h".

It was late at night when I finished carving.

Chen Hao hung the new board back in its place and checked it again. He ran his finger over each line of text to make sure there was no ambiguity.

"This time there shouldn't be any problems."

"I suggest adding an auxiliary confirmation mechanism," Nana said.

"for example?"

"When manually entering key parameters, the system announces the set values ​​for the operator to check."

"Voice prompts? Sounds like a driving school instructor."

"The functions are the same, and the purpose is to prevent accidental operation."

"Okay, let's add it then. It's better than flooding."

Nana integrated the voice module and wrote the trigger logic. Whenever the user inputs the flow rate, pressure, or time on the irrigation interface, the system will automatically synthesize a voice announcement: "The irrigation flow rate has been set to twelve liters per minute."

During the test, Chen Hao deliberately entered "120", and the speaker immediately announced: "The irrigation flow rate has been set to 120 liters per minute."

"Too high." He deleted and re-entered.

Enter "12" again, and the voice will sound again: "The irrigation flow rate has been set to twelve liters per minute."

"Now I feel relieved." He nodded.

Nana marked the feature as V1.0 and added it to the list of features to be tested.

At one in the morning, only the low hum of the equipment could be heard in the control room. Chen Hao took off his headphones; the confirmation tone from earlier was still playing on a loop. He rubbed his temples; the edges of the bandage on his left arm were slightly damp.

He stared at the control panel, his finger hovering over the confirmation button.

The next set of instructions hasn't been entered yet.

He didn't press the button immediately.