Chapter 230: Graduations and Gaps

At 7:40 in the morning, the alarm did not ring. Lin Chen was already awake.

The sky outside the window was gray-blue. From the corridor came the muffled sounds of a neighbor closing a door and an electric scooter backing up. He threw back the quilt. When his left foot touched the floor, numbness wrapped around his ankle like a layer of thick cotton batting, followed by the familiar dull pain. Holding the edge of the bed, he straightened himself, adjusted his crutch to the right height, and took an ironed white shirt and dark trousers from the wardrobe. The collar of the shirt was a little worn. He buttoned the top button, then placed the legal representative authorization letter, the duplicate business license, the desensitized data list, and the ethics-approval application form into a hard-shell folder in order. The edges of the folder were already fraying, so he wrapped them once more with clear tape.

8:20. He went out. The subway car in the morning rush was packed. He leaned in a corner, bearing his weight on his right leg, the crutch tucked under his arm. The folder was pressed against his chest; its hard edge dug into his ribs. He closed his eyes and went through the testing center's process in his head: take a number, preliminary review, submit originals, book the fast-track channel, sign. Every step had a clear time node. He did not need to imagine the result; he only needed to confirm whether each action was in place.

9:00 sharp. The lobby on the first floor of the municipal medical-device testing center. Red numbers rolled across the queue screen. He sat on a plastic bench and set the folder on his knees. His left foot began to swell. Beneath the trouser leg, the skin faintly burned. He adjusted his posture, shifted his center of gravity to the right, and unconsciously rubbed the plastic cover of the folder with his fingers.

"Lin Chen?" The clerk behind the counter looked up, her voice muffled through the glass.

He stood, walked over with his crutch, and handed in the materials. The clerk turned the pages very slowly, her fingernails making a faint rustle across the paper. "Where is the original ID card of the legal representative?"

"Su Man is on a business trip. The original is at headquarters. This is the notarized authorization letter and a copy, both stamped with the company seal." Lin Chen handed over another document. The paper edges were aligned, without a crease.

The clerk glanced at it and frowned slightly. "The fast-track channel requires the legal representative to be present or complete video verification. In your situation, it has to go through special approval. Next Wednesday at the earliest."

"The Municipal Health Commission has a surprise inspection next Wednesday." Lin Chen's tone stayed steady. He was not urging her, only stating a fact. "The testing schedule is already stuck in February. Clinical reorder cannot wait. We can submit the materials first and run internal validation in parallel during approval. If the approval cannot come through before Wednesday, we will bear the responsibility for the delay. Procedurally, we will cooperate with any supplementary documents."

The clerk looked at him without speaking, then picked up the internal phone and dialed a number. After a few low-voiced exchanges, she hung up. "We'll take the materials first. Leave your contact information. I'll notify you once the approval result comes back. But the original has to be supplemented, otherwise the report can't be stamped."

"Understood." Lin Chen wrote down her employee number and turned to leave.

When he walked out of the lobby, cold wind poured into his collar. He looked at his phone: 9:45. Fifteen minutes slower than planned. But the materials had been submitted. The process was stuck at the approval stage, not in his hands. He walked to the bus stop and waited. The pain in his left foot intensified. He swallowed half an ibuprofen tablet with warm water from his thermos. The pill scraped down his throat with a faint bitterness.

Noon. The machinery factory. The workshop was filled with the smell of machine oil and metal-cutting fluid. The noise was loud. An overhead crane moved slowly above him, its chains scraping with an ear-piercing sound. Lin Chen connected his laptop to the industrial camera and adjusted the angle of the light source. The interface documentation Su Man had sent remotely was already running, but site lighting differed from the laboratory. The model's confidence on tiny scratches was dropping. The parts on the conveyor belt carried reflections that interfered with edge detection.

"Engineer Lin, can it see them?" Workshop Director Old Zhou walked over with a safety helmet in his hand, black oil stains on the soles of his shoes.

"Five more minutes." Lin Chen's fingers tapped quickly across the keyboard. He adjusted the contrast threshold, added dynamic white-balance compensation, and raised the filtering weight for background noise. The detection boxes on the screen stabilized again, and the false-positive rate dropped from 12% to 4.3%. He switched to the backend log and pulled up historical test data.

"It's ready." He nodded.

Old Zhou leaned closer to the screen, watching the parts pass one by one through the recognition zone on the conveyor belt. "What about this oil stain? Last time you said it couldn't tell the difference."

"We've added a feature-filtering layer. Oil-stain texture is diffuse; scratches are linear. The algorithm can distinguish them now." Lin Chen opened the backend log and brought up the historical test data. "This is last week's score: accuracy 89.1%. After the on-site lighting changed, we ran adaptive calibration. It is currently stable above 87%. Samples with confidence below 0.75 enter the manual-review queue and do not directly stop the production line."

Old Zhou watched for several minutes without speaking. The only sound in the workshop was the rumble of machinery. At last he patted Lin Chen on the shoulder, smearing machine oil from his glove onto Lin Chen's sleeve. "All right. Trial use for one month first. The final payment follows the contract."

Lin Chen handed over the acceptance form. Old Zhou signed. His phone vibrated. A bank-app notification: "Account ending in 8842 has received a transfer of 17,500.00 yuan."

He took a screenshot and saved it into the "Cash Flow" folder. The gap in the ledger shrank by another notch. Numbers did not speak, but they could hold the bottom up.

4:00 in the afternoon. Back at the rented room. His leg had swollen so badly it no longer fit into the original trouser leg. He filled a basin with cold water and applied a cold compress for twenty minutes. When the water warmed, he dried himself and opened the computer. The screen lit up; the draft ethics report was still stopped at last night's edits. He checked "model F1 value 0.89" again and changed it to "assisted film-reading efficiency improved by 28%, false-negative rate reduced to 4.2%." He changed "convolutional-layer parameter optimization" to "reduces the risk of radiation exposure from repeated scans." Technical language had to be translated into indicators clinicians could understand. That was Director Li's requirement and the key to passing review. Doctors did not read code. They read the risk-benefit ratio. He weighed each word, deleting every modifier and leaving only verbs and nouns.

7:00 in the evening. Su Man sent a message: "The log-backup script has finished running. Access records are normal, but two abnormal IPs were found. They were old servers used for previous tests. Already blocked."

Lin Chen replied: "Received. Export the blocking records and attach them to the report for inspection. The surprise inspection only checks whether the permission loop is closed; it won't pursue historical test traces. Also pull the login frequency for administrator accounts. Mark anything over three times as routine inspection."

He opened the terminal and ran the final round of data validation. The progress bar on the screen advanced slowly. His left foot twitched from time to time. He stood, held the edge of the desk, walked two steps to loosen the stiff joint, then sat back down. The only sounds in the room were the hum of the computer fan and the tapping of the keyboard. He exported the ethics report as a PDF, checked the page numbers and signature positions, confirmed there were no errors, then printed it. Bound it.

9:30. All materials were back in place. He leaned against the back of the chair and closed his eyes. The numbers in the ledger arranged themselves automatically in his mind: ninety thousand in advance payment, seventeen thousand five hundred in final payment, monthly server rent, his younger brother's medical expenses, testing fast-track fees. The gap was still there, but water was seeping into it. He knew how to fill it, and he also knew the parts that could not be filled could only be endured through time.

The phone screen suddenly lit up. It was a text from an unfamiliar number: "Engineer Lin, this is the Quality Control Section of the testing center. The fast-track approval has passed, but we require the complete hash-value verification report for the original training set before ten o'clock tomorrow morning. In addition, the Health Commission's surprise inspection has been moved up to next Monday. Please prepare accordingly."

Lin Chen opened his eyes and stared at the line of text.

Hash-value verification. Two days earlier.

He picked up his pen and opened the error notebook. The pen tip paused on the paper for one second, then fell.

"Entry 231: Time window compressed. Testing center requires hash verification of the original data; full-batch processing must be completed tonight. Surprise inspection moved up; permission logs require a second review. Risk: insufficient server computing power; batch process may time out. Countermeasure: cut off nonessential processes, prioritize verification of the core data set. Deliver before eight tomorrow morning. Every action, by the stopwatch."

He closed the notebook, got up, and went to the kitchen to boil water. The kettle gave a low hum. Outside the window, the night was heavy; distant streetlights joined into a dim yellow line. He knew tomorrow had no buffer, only execution.

The water boiled. He brewed a cup of strong tea. Tea stems floated on the surface, then slowly sank. The cursor on the screen began to blink. Logs scrolled through the terminal window. He checked the filtering logic line by line, tightened tolerances, and aligned the mapping table.

His left foot was still numb. But his breathing was steady.

The tapping of the keyboard sounded in the quiet room, once, then again. Like a second hand, and like a heartbeat.