Chapter 231: Validation and Margin

The progress bar in the terminal window was stuck at 73 percent. The chassis fans had been pushed to full speed, giving off a dull, continuous drone, like an old tractor climbing a slope. Lin Chen stared at the memory-usage curve in the lower-right corner of the screen. The peak was already pressing toward 92 percent. He reached out and touched the side panel of the case; the metal shell was hot enough to numb his fingertips. This server had been picked up from the secondhand market. The thermal paste had long ago dried and cracked into powder. Running a full hash verification—a heavy job that ate through compute—was like walking on a knife edge.

He got up and went to the kitchen for half a basin of cold water. He soaked an old towel that had been washed stiff, wrung it out, and laid it over the side panel of the case. Steam rose at once, carrying the smell of rust and dust. The swelling in his left ankle crawled up along the muscles of his calf, the tendons feeling as if they had been tightened by fine threads. He leaned against the edge of the desk, shifted all his weight onto his right leg, and leveled his breathing. He could not panic. Hash verification was a hard order from the testing institute. The original training set contained 120,000 images, and every one of them had to be calculated with SHA-256. One wrong byte, and the report would be sent straight back. The time window had less than eight hours left.

He sat back down and opened another terminal window. He typed htop and checked the process priority. Then he suspended the background log synchronization and model fine-tuning tasks, freeing CPU resources. The progress bar on the screen began moving again: 74 percent, 75 percent. He opened his mistake notebook, the tip of his pen drawing several short, sharp lines across the paper.

"Compute bottleneck. Countermeasure: chunked verification, memory-mapped files instead of full loading. Risk: after chunking, hash stitching must be strictly aligned, or verification fails. Execution: write middleware script, slice by 5,000 images, write each segment to disk after it finishes."

The code logic ran through his mind once. He created a new Python file and imported hashlib and mmap. His fingers struck the keyboard in a steady rhythm. There were no wasted movements; every line existed to resolve the blockage in front of him. Outside the window, night was thick as ink. Distant streetlights formed a dim yellow line. From time to time a night-shift truck passed by, the sound of its tires rubbing over asphalt drifting into the room before being swallowed by the roar of the server fans.

Su Man’s profile picture flashed on WeChat.

"I'm downstairs. The access control is broken and the guard won't let me in. Also, I pulled the Health Commission’s spot-inspection checklist. The focus is data desensitization and permission auditing. How's your side going?"

Lin Chen replied:

"Batch running. Memory is tight; I'm changing the chunking logic. Bring the access card up, and package the test-environment access logs while you're at it. A spot inspection doesn't care how advanced the algorithm is. It only checks whether the process is compliant."

Ten minutes later, the lock clicked. Su Man pushed the door open, carrying two plastic bags with hot buns and soy milk inside. She set them at the corner of the desk without speaking, first walking to the server case to take a look. She reached out and tested the temperature. "The thermal paste needs replacing. If it keeps baking like this, the motherboard capacitors won't last the month."

"After this payment comes in. Finish the run first." Lin Chen did not look up. His eyes stayed fixed on the screen.

Su Man pulled over the folding chair beside him and sat down, opening her own laptop. The cold light from the screen lit her face, revealing faint bluish shadows under her eyes. She did not complain and went straight to the point. "I've exported the permission logs. Administrator login frequency is normal, but two external IPs tried to access the desensitization interface at three in the morning. The firewall blocked them, but the spot-inspection experts will definitely ask. I need to write an explanation that separates test traces from malicious scanning."

Lin Chen typed the last line of code, saved, and ran it. "Make the timestamps, IP segments, and blocking strategy clear. Don't use 'suspected.' Use 'confirmed.' Inspectors only look for a closed loop. They don't listen to explanations."

Su Man nodded, her fingers moving rapidly over the keyboard. The room held only the sound of typing and the panting of the chassis fans. The buns gradually cooled. A thin skin formed on the surface of the soy milk. Neither of them had time to eat. The ledger lay open on the desk. On the newest page was written: "Server monthly rent - 2,800; Xiaoman's medical expenses - 1,200; expedited testing fee - 3,500. Final payment pending: 17,500." Numbers did not speak, but they could hold up the floor. He knew how to fill in the blanks, and he also knew that whatever could not be filled in could only be endured over time.

The progress bar jumped to 89 percent. Suddenly, a red line appeared in the terminal:

MemoryError: Unable to allocate array with shape (5000, 256, 256) and data type float32

The chunking logic had still slammed into the memory wall.

Lin Chen's fingers stopped in midair. The pause did not last more than two seconds. He quickly commented out the current script and brought up the backup plan.

"Don't load it into memory. Read it directly as a stream. Use a generator to read one image at a time, calculate it, and release it. Slower, but it won't crash."

He rewrote the core loop, added yield and gc.collect(), and ran it again. The progress bar resumed from 89 percent. The speed was clearly slower, but the curve was steady, and memory usage stabilized around 65 percent.

He glanced at the wall clock. 2:47 a.m. Seven hours and thirteen minutes remained before the delivery deadline. He lifted the now-cold soy milk and took a sip. The cloying sweetness slid down his throat, pressing down the emptiness in his stomach. His left foot began cramping again. He stood, braced himself against the wall, and walked two slow steps, putting all his weight on his right leg until the ache passed. Then he sat back down.

Su Man looked up at him. "If your leg can't take it, lie down for a while. I'll check the logs."

"No need." Lin Chen's voice was very calm. "The script is running; the people can't stop. For the spot-inspection reference directory, arrange it along a timeline. Put the original data-desensitization logs, the cleaning script version records, and the scanned ethics approval into one folder. Name them by 'date_module_version number.' When the experts sample-check, we have to locate any file within ten seconds."

Su Man did not try to persuade him again. She continued organizing the documents. She knew Lin Chen's rhythm. He did not need comfort; he needed confirmation that every link was still on track.

At 5:20 a.m., the terminal printed its final log line:

Hash verification complete. Total files: 120,000. Mismatch: 0. Report generated.

Lin Chen let out a long breath. He opened the generated PDF and quickly scanned the list of verification codes. Everything aligned. He packaged the files, encrypted them, and uploaded them through the testing institute's designated port. The progress bar finished and displayed "received successfully." He took a screenshot and saved it into "delivery records." Once the compliance seal went down, the gate on the final payment would loosen by a crack.

Su Man closed her laptop and rubbed the space between her brows. "I listed twenty mock questions and answers for the spot inspection. We'll go through them tomorrow afternoon. Also, Old Zhao messaged this morning asking whether the hospital's procurement process can be timed to follow the testing institute's approval. I told him we'd push after the hash report was submitted."

Lin Chen nodded. "Push it. But don't rush them. Hospital procurement goes through collective decision-making. Pressing too hard only makes them suspicious. Prepare our clinical indicators and compliance materials, then wait for them to finish their own process."

He stood up, ready to wash his face. His phone suddenly vibrated. It was not WeChat; it was a call. The screen showed an unfamiliar number with a provincial-capital location. He answered.

"Lin Chen? This is the Equipment Department of the Provincial People's Hospital. We've reviewed the ethics approval and hash report for the imaging analysis system you submitted for testing. But during next Monday's spot inspection, the Health Commission specifically wants to sample-check your 'data traceability module.' Does your current version support real-time auditing?"

Lin Chen tightened his grip on the phone. Real-time auditing. That meant adding a layer of log interception and tamper-proof storage to the underlying architecture. The existing system had not reserved an interface for it. If they changed it, they would have to touch core code, and there was not enough time. If they did not, the spot inspection would veto them outright.

He looked at Su Man. She had heard it too; her eyes instantly drew taut.

Lin Chen was silent for two seconds. His voice remained steady. "It supports it. But we need to push the audit middleware as a hot update tonight. It won't affect existing operations. We'll send over the audit-log integration document before eight tomorrow morning."

He hung up. The room was quiet enough for him to hear his own heartbeat.

Su Man looked at him. "A hot update? That's too risky. If it crashes, we won't even keep the first version."

Lin Chen walked back to the desk and opened the mistake notebook. The pen tip came down.

"Item 232: temporary architecture refactor. Risk: hot update may cause service interruption. Countermeasure: gray release, dual-write logs, retain rollback snapshot. Execution: switch traffic tonight, deliver documentation tomorrow morning. No retreat."

He closed the notebook. Outside the window, the sky was beginning to pale. Morning fog pressed against the glass, and the halos of the streetlights slowly faded inside it. The chassis fans gradually quieted, like an old beast that had finally caught its breath. He knew the buffer period was over. The next round of dismantling began now.