Chapter 283: Local and Boundaries

Thursday morning, nine o'clock. Lin Chen went through the materials in his canvas bag once more. The comparison charts for the ten desensitized cases had been arranged along a timeline, their edges secured with paper clips, the page corners pressed flat. He sat at his desk, his left foot propped on a low stool. The red marks left by the elastic bandage had already turned purplish, and the skin around his ankle was stretched glossy and taut. There was a box of ibuprofen in the drawer. He shook out two tablets and swallowed them with the half bottle of mineral water left from last night. The pills scraped down his throat with a faint bitterness. He glanced at the wall clock, got up, and changed his shoes. The shoelaces were tied only through the top two eyelets, leaving enough room for his swollen instep. His movements were slow, but every step landed solidly.

Metro Line 4, transferring to Line 2. The morning-rush carriage was packed with people. The smell of sweat, the oily aroma of breakfast buns, and the scent of disinfectant mingled together, clinging to the carriage walls and condensing into a thin haze. Lin Chen gripped the handrail, subtly shifting his center of gravity with the sway of the train, trying to keep as much weight as possible on his right leg. He closed his eyes and ran through what he would say later. No beating around the bush. No grand promises. He would talk about only three things: how the missed-diagnosis rate had been brought down, how the review process saved time, and how responsibility would be divided when something went wrong. Old Zhao was right: clinical experts did not buy empty talk. What they faced every day were living, breathing people, not curves on a PPT. To them, time meant duty rosters, bed turnover rates, and whether they could get home on schedule after work for a hot meal.

The outpatient building of City First Hospital. The electronic display in the registration hall scrolled through call numbers, its voice mechanical and urgent. Following the route Old Zhao had given him, Lin Chen passed through the inpatient department corridor and arrived at the neurology ward. A faint smell of iodophor hung in the hallway. The call bell at the nurses' station rang now and then, short and clear. He found a plastic chair in a corner and sat down, placing the canvas bag on his lap. Ten minutes before two, footsteps came from the end of the corridor. White coat, name badge, a stack of medical records tucked in one hand, walking fast. Director Zhou.

Director Zhou did not invite him into the office. He sat down directly at an empty desk beside the nurses' station. "Mr. Lin, right? Old Zhao already spoke to me. I only have fifteen minutes. I have three more consultations after this." Lin Chen nodded and pushed the bound booklet over to him. Director Zhou opened it, his gaze sweeping quickly over the line charts and scatter plots. His finger paused at the column reading "missed-diagnosis rate 0.03%." "The data looks very pretty. But clinical practice is not a laboratory. Your 4.1 minutes is 1.6 minutes longer than full automation. Can patients afford to wait?"

"They can." Lin Chen's voice was steady. "A fully automated system produces a report in 2.5 minutes, but the false-positive rate is high. Once doctors receive the report, they have to spend extra time reviewing abnormal waveforms. Add communication and secondary confirmation, and the actual time exceeds 6 minutes. Our process moves review to the front end: the machine filters out 90% of normal waveforms, and doctors only look at the remaining 10%. The total time is shorter instead. And every step has logs. Who judged it, why it was changed—the system records it all clearly."

Director Zhou looked up at him. "You're not afraid of taking the responsibility onto yourselves?"

"We are." Lin Chen did not evade the question. "That is why we wrote an 'explainability boundary' into the white paper. The algorithm only performs preliminary screening and feature marking. The final diagnostic authority remains with the doctor. What we sell is a tool, not a scapegoat. If the system gives an incorrect prompt, responsibility is traced according to the logs. If the code needs to be fixed, we fix it. If the clinical threshold needs adjustment, the clinicians adjust it. Only when the boundaries are drawn clearly can everyone sleep at night."

Director Zhou said nothing. His fingers tapped lightly twice on the tabletop. He turned to the last page of the booklet, where a blank evaluation opinion form was attached. "This logic of yours sounds very practical. But practical things are often the hardest to implement." He picked up a pen, wrote several lines on the opinion form in a thin, firm hand, and pushed it back. "I can sign it. But on one condition. For next Monday's demonstration, you don't use the desensitized data you've prepared. I will use the department's real archived waveforms from the past three months, mixed with interference artifacts and electrode detachment records. You run it once on site. If you can produce results, I will endorse you for this 15% weighting. If you can't run it, or if the logs don't match, the signature is void."

Lin Chen took the form. The paper was light, but it carried weight. "Understood. We'll bring the complete environment over."

"Don't bring an environment." Director Zhou stood up, tucking the medical records under his arm. "Bring your original code and a debugging terminal. There is no network at the clinical site, and no time to wait for you to connect to a server. It only counts if it runs locally."

When Lin Chen walked out of the inpatient department building, the afternoon sunlight slanted across the glass curtain wall, dazzling enough to make him narrow his eyes. His left foot was already so numb it had lost sensation. Every step felt like treading on cotton, but the stabbing pain in his ankle reminded him that his center of gravity was still there. He went to the small convenience stand by the hospital's back gate and bought a bottle of ice water and two tea eggs. Sitting beside a flower bed, he peeled off the eggshells and ate slowly. His phone vibrated. Su Man had sent a message: "The bidding system format validation passed. Mr. Zhao is asking about progress on the clinical endorsement."

Lin Chen took a photo of the signed evaluation opinion form and sent it over. He added: "Obtained. Condition: next Monday on site, use real archived waveforms and run locally. Need to prepare an offline debugging terminal and complete code repository."

Su Man replied within seconds: "Received. I'll coordinate with operations right away to package the local image. How's your foot?"

"It's fine." Lin Chen replied. He tilted his head back and finished the water, crushed the plastic bottle, and tossed it into the trash can.

By the time he returned to the company, it was already evening. The office lights were on. Su Man and two engineers were checking the dependency packages for local deployment. Lin Chen did not disturb them and walked straight to his own workstation. He opened the terminal and pulled the latest code branch. Director Zhou's requirement was very clear: offline, local, resistant to interference. That meant the modules they had previously relied on cloud computing power to preprocess had to be refactored, all pushed down into local CPU/GPU hybrid inference. Only four days remained.

He created a new script and began writing fault-tolerant logic for the data loader. Real waveforms were not as neat as desensitized data. Electrode detachment, electromyographic interference, power-frequency noise—these pieces of "dirty data" filtered out in the laboratory were the norm in clinical practice. His fingers struck the keyboard in a steady rhythm. His left foot rested on the low stool, twitching occasionally. He reached down to press his calf, then kept writing.

At eleven that night, Su Man brought over a bowl of instant noodles and set it on the corner of his desk. "The local image is packaged. But the real data packet Director Zhou sent just came through. You'd better take a look."

Lin Chen opened the compressed file. The decompression progress bar crawled upward slowly. When the file list expanded, his brows furrowed slightly. The format was not standard EDF, but a custom binary stream exported from an old EEG machine. The header file was missing, and the sampling-rate markers were chaotic. More troublesome still, it was mixed with large numbers of unlabeled sleep-stage and wake-stage segments, with severe baseline drift in the waveforms.

"This doesn't look like clinically archived data." Su Man stood behind him and lowered her voice. "It looks more like raw logs from failed test runs on a testing machine."

Lin Chen said nothing. He dragged the mouse and opened a file at random. The waveform chart unfolded on the screen, chaotic and formless, like a ball of crumpled thread. He stared at it for several seconds, his fingers suspended above the keyboard. This was not making things difficult for the sake of it. It was a probe. Director Zhou was testing their bottom line. Clinical sites never provided clean data. They only wanted results.

"Switch the parser to the underlying logic from V2.0," Lin Chen said, his voice a little hoarse. "Don't use the ready-made EDF library. Manually write byte-offset parsing. Infer the sampling rate from the hidden fields in the header file. Use sliding-window adaptive filtering for the baseline drift."

"That means rewriting the entire data pipeline." Su Man frowned. "There definitely won't be any sleep tonight."

"Then don't sleep." Lin Chen had already typed the first line of code. "Before eight tomorrow morning, I want to see the parser output clean CSV. The remaining time goes to running the model."

Su Man looked at him and did not try to persuade him again. She turned and pulled over another chair. The server room fans began to sound again, drowning out the traffic beyond the window. Lin Chen's gaze settled on the characters flickering across the screen. His left foot ached faintly, but he did not move. He knew the real hard battle had only just begun.

The phone screen lit up on the corner of the desk. A new text message, from Zhao Qiming: "Zhinao Technology just obtained City Second Hospital's joint testing report. For next Monday's demonstration, the review panel may temporarily add a comparison segment. How confident are you that you can run locally?"

Lin Chen did not reply. He pressed Enter, and the terminal began compiling. The progress bar inched forward slowly. He picked up the instant noodles, now completely cold, and took a sip of soup. The flavor was very thin, but he could swallow it.