Chapter 157: Bypass and Bottom Line

The screen’s cold glow fell across his face. In the dorm room, all that remained was the low hum of the computer fan and, now and then, the sound of wind brushing past outside the window. Lin Chen split the Security Compliance Adaptation Checklist into three modules: connection initialization, heartbeat keepalive, and exception retry. Old Zhao’s operations department had rigid rules—every external connection had to go through the proxy whitelist. That meant he had to strip out all the original socket calls in the script that connected directly to the database and API, and replace them with forwarding through the internal HTTP proxy. He created a new proxy_handler.py and used urllib2 to wrap the proxy authentication logic. Every time he finished a section, he spun up a mock proxy server in his local virtual machine and ran it once. The port wouldn’t connect; the logs threw Connection refused. He checked the firewall rules and discovered the proxy server’s authentication header had been sent incorrectly. He added the Basic Auth Base64 encoding and ran it again. This time it went through.

Under the desk, his left foot began twitching again. He stopped typing and nudged the chair back half an inch, letting the foot hang in the air. By two in the morning, the ibuprofen had started to wear off. The swelling around his ankle felt like a layer of soaked cotton wrapped around the bone, and the veins under his skin throbbed in tiny pulses. He unscrewed his thermos. There was only one mouthful of cold water left inside, and when he swallowed it, his throat tightened. He glanced at the time. Three forty. There were still more than four hours before eight-thirty in the morning. He couldn’t stay up all night—his injured foot wouldn’t take it, and his mind would go dull. He set an alarm for four-thirty, tossed the compiled script into the test queue, shut the laptop, and lay down fully dressed on the hard bed. In the darkness, he could hear his own breathing, steady and restrained. There was no excitement in it, only the fatigue that came after one more process had been pushed forward.

When the alarm rang, dawn had not fully broken yet. Outside the window, everything was gray-blue, and every so often came the sound of an early bus rolling over the asphalt. Lin Chen sat up, and the instant his foot touched the floor, a sharp pain shot up his calf. He clenched his teeth and slowly shifted his weight onto his right foot. He washed up, changed clothes, and stuffed the white paper he had printed the night before and the USB drive into his backpack. He had deliberately brought two adhesive bandages and a small roll of elastic wrap; sitting at the edge of the bed, he bound his ankle tight before pulling on the sneakers whose laces he had intentionally tied loose. The man in the mirror had dark shadows under his eyes, but his gaze was calm. He patted the student ID and identification card in his pocket to make sure they were there. His mobile banking balance showed 1220.30. The number ran through his mind once—enough to cover today’s transportation, printing, and emergency expenses, but with no extra margin. He had to clear this in one go.

At seven sharp, he walked out of the dorm building. The late-autumn wind carried a chill that sharpened him as it struck his face. He went to the school gate and waited for the K3 bus. At the stop stood a few other students with backpacks on, holding soy milk and steamed buns. Lin Chen bought nothing. With his stomach empty, he paradoxically didn’t feel hungry. The bus swayed its way up onto the elevated road, and outside the window the city began to wake. Steam from breakfast stalls, the scrape of sanitation workers’ brooms, the clatter of rolling shutters being pulled open at morning shops—all of it mixed together. Leaning against the window, he looked at his own reflection in the glass. In 1992, he had still been chasing chickens down the dirt roads of Qingshi Village. Now he was riding a bus in the provincial capital with a set of code in his bag that was about to enter a production line. The times were like a massive conveyor belt: he had to keep the rhythm, or he would be thrown off. He closed his eyes and went through the rollback plan again in his head. Main system anomaly → threshold triggered → cut off new queue → switch to legacy I/O → manual confirmation. There was no “in theory,” only “if X happens, execute Y.”

At eight twenty, they reached the convention center. The sign for Hall B was impossible to miss, the glass curtain wall reflecting the newly risen sun. Lin Chen followed the flow of people inside. The metal detector at the security checkpoint gave a series of beeps. He had already taken out the USB drive and ID card, and passed through without trouble. Door 3 of Hall B was off to the side, comparatively quiet. Professor Zhou was already waiting there, wearing a dark gray jacket and holding a thermos.

“You’re here.” Professor Zhou glanced at his watch. “How’s the foot?”

“I can walk.” Lin Chen hitched his backpack higher on his shoulder.

Professor Zhou asked no more. He pointed to the bench beside him. “Sit. The factory representatives come in at nine. Eight-thirty is the internal briefing. How many hard copies did you bring?”

“Two. One bound, one loose-leaf.”

“Give me the loose-leaf.” Professor Zhou took the booklet and flipped quickly to the implementation risk assessment page. “You wrote the downtime window as fifteen minutes. Too idealistic. The old electricians in the factory take twenty minutes just to swap out a contactor. Increase the buffer time to twenty, and add ‘manual bypass switching’ to the rollback steps. They’re not afraid your code isn’t elegant. They’re afraid that when something goes wrong, no one can hold the line.”

Lin Chen nodded and took out a pen, rapidly revising the loose-leaf copy. The pen tip scratched softly across the paper. When he finished, Professor Zhou gave it one glance and handed it back. “Remember this: today you’re not here to defend a thesis. You’re here to solve problems. If they ask about cost, give them the total account. If they ask about schedule, give them the bottom line. Don’t bury them in technical terms. Speak like a human being.”

“Understood.”

At eight forty, the sound of leather shoes striking tile came from the far end of the corridor. Three men approached. The one in front was around fifty, wearing a dark blue work jacket, his hair graying, a black briefcase in hand. Behind him came two younger men, one with glasses, the other carrying a tablet computer. Professor Zhou stood and greeted them. “Director Li, long time no see.”

“Professor Zhou.” Director Li shook his hand. His gaze swept over Lin Chen, paused on the slightly tightened laces over his injured foot, then moved away. “This is the student who wrote the proposal?”

“Lin Chen. Third-year, computer science,” Professor Zhou introduced him.

Director Li nodded. No pleasantries. He pulled out a chair and sat down at once. “I had the technical department look over the proposal last night. The logic is fine, but you people have never been on the shop floor. Our PLC is a Siemens S7-200, and the communication protocol is the old PPI. Your script specifies Modbus TCP. It won’t interface. Also, there’s heavy dust in the workshop. The server can’t be placed beside the control room—we’ll have to use a wireless bridge. Have you calculated the signal attenuation?”

Lin Chen’s heart sank. He had checked the equipment model the night before, but he had not expected the protocol version to be this old. And the wireless bridge attenuation issue was indeed not written into the white paper. He drew a slow breath and spread the loose-leaf booklet open on the table.

“Director Li,” Lin Chen said, his voice not loud but very steady, “I reserved an interface for protocol conversion in the V3.1 adaptation layer. PPI-to-Modbus mapping can be done through middleware, and the latency will stay within a controllable range. As for the wireless bridge attenuation, I added a link budget table last night.” He flipped to the appendix of the white paper and pointed to a hand-drawn topology diagram. “If signal strength drops below -75dBm, the script will automatically throttle down to polling mode to make sure no packets are lost. Performance will drop by eight percent, but production won’t stop.”

Director Li did not look at the drawing. He stared straight into Lin Chen’s eyes. “An eight percent drop means forty fewer units per hour. Over a month, that loss in capacity is enough to buy ten of your servers. You students write code and think in math problems. We think in livelihoods.”

The air went still for two seconds. Professor Zhou said nothing. He merely unscrewed the cap of his thermos.

Lin Chen knew that the theoretically optimal solution became wastepaper on the shop floor. He closed the booklet and took out another sheet of paper from his backpack, handwritten in the dorm room the night before. There was no code on it, only three lines: 1. Hardwired bypass plan (cost: 800 yuan) 2. Temporary wired fiber deployment (requires 4 hours of production halt) 3. Reduced-frequency polling fallback (accept output loss).

“Director Li,” Lin Chen said, sliding the paper over, “math problems calculate limits. But on the shop floor, I secure the bottom line first. Pick whichever path you want, and I’ll write the corresponding script branch tonight.”

Director Li picked up the paper and looked at it for a long time. His finger paused over the line that read “4 hours of production halt,” then moved to “reduced-frequency polling.” He raised his head. There was less scrutiny in his eyes now, and something else in its place.

“Nine o’clock sharp. Into the meeting room.” Director Li folded the paper and slipped it into the pocket of his jacket. “Bring your computer. I want to see it run on-site.”

Lin Chen nodded. He pulled open his backpack, his fingers brushing the cold metal shell inside. His left foot throbbed faintly in the shoe, but he straightened his body. The corridor lights fell across the cover of the white paper, making the grain of the matte paper stand out with perfect clarity. He followed Director Li toward the meeting room, their footsteps echoing through the empty hallway. Before the door opened, he checked the directory structure on the USB drive one last time.

Inside the folder, branch_fallback.py lay there quietly. He knew that the real test was only beginning now.