Chapter 313: Grace Period

In the early morning corridors of the Third Municipal Hospital, fluorescent tubes hummed at a low frequency. Lin Chen pushed open the glass door to the neurology ward, and the smell of disinfectant mixed with old floor wax hit him in the face. As he stepped over the threshold, his left foot struck hard against it. A numb, sharp pain shot up his shinbone. He paused for half a second, shifted his center of gravity, put his full weight on his right leg, and kept walking. His gait was slightly uneven, but his rhythm never faltered.

His mother, Wang Guiying, sat on a bench, hands folded over her knees. She wore a deep blue jacket washed pale, its cuffs frayed. Seeing Lin Chen, she stood up immediately, her movement slightly hurried before she forced herself to calm down. "You're here." Her voice was soft, raspy from a sleepless night.

Lin Chen nodded. His gaze fell on Xiaoman in the adjacent bed. Xiaoman had already changed into a hospital gown, eyes closed, breathing steadily. The sedative hadn't been administered yet, but he was already drowsy. On the bedside table sat a half-empty bottle of mineral water and a dog-eared sketchbook. On the cover, a few crooked stars were drawn in pencil.

"The attending physician is in the office," Wang Guiying said. "He needs a family member's signature. He said a video authorization would work, but I was worried about the signal, so I waited for you."

"I'll sign it." Lin Chen walked to the nurses' station and took the electronic signature pad. The screen lit up, requiring a handwritten signature and a fingerprint. Holding the pen in his left hand, his strokes trembled slightly but remained clear. When pressing his fingerprint, the machine prompted, "Please press harder." He applied more pressure until the green light came on.

The doctor emerged from the office, a man in his forties wearing black-framed glasses, speaking quickly. "The sedative dosage is calculated by weight. The EEG cap needs to stay on for a full two hours. There might be slight electromyographic interference during the process; family members don't need to worry. After it's done, observe for half an hour before leaving. Has he missed any medication recently?"

"No," Lin Chen said. "Twice a day, morning and evening, after meals."

The doctor nodded and turned to prepare. Wang Guiying looked at Lin Chen's left foot, her lips parting slightly, but she didn't ask if it hurt. She knew asking was pointless. Instead, she pulled a thermos from her cloth bag and handed it to him. "Rice porridge I simmered. Take a few sips."

Lin Chen took it. The sides of the cup were warm. He unscrewed the lid and took a sip. The porridge was thin, with a faint scorched taste. He swallowed it and handed the cup back. "Mom, go stay with Xiaoman. I'll wait outside."

The stairwell at the end of the corridor had no surveillance cameras, only the green glow of the emergency exit sign. Lin Chen leaned against the fire door and pulled a slim laptop from his backpack. The screen lit up, its cold light illuminating the dark circles under his eyes. He connected to the hospital's public Wi-Fi; the signal was full, but the latency was unstable. He switched to his phone's hotspot and plugged in an Ethernet adapter.

He opened the terminal. SSH connected back to the company's jump server. The authentication service's configuration file lay under /etc/nginx/conf.d/. A fifteen-minute token refresh interval meant one-sixth of the requests every minute required origin validation. Zhao Qiming's probes were stress-testing at exactly this frequency, burning through bandwidth and CPU cycles. Capital didn't care how elegant the architecture was; it only cared about the numbers on the bill.

Lin Chen created a new branch. auth-cache-v2.

The logic was straightforward: cache token states in local memory, with a TTL set to thirty minutes. After the first validation hit, write it to a local LRU queue. Subsequent requests read directly from local cache, bypassing remote RPC calls. On a cache miss, degrade to asynchronous refresh, synchronously returning the old token with a five-second grace period. Trade consistency for cost. Trade space for time.

He typed out the code. Variable names. Boundary conditions. Concurrency locks. Protection against cache breakdown. No comments, only the most essential logical branches. His fingers moved across the keyboard; his left foot twitched slightly inside his shoe. He ignored it. His breathing remained steady. Characters on the screen multiplied line by line, like laying bricks. Every brick had to fit perfectly.

Twenty minutes later, the core logic was complete. He ran a unit test. Simulating one hundred thousand requests. Hit rate: ninety-two percent. Origin fallback rate dropped to eight percent. Expected CPU usage decrease: fifteen percent.

"Ready to deploy," he murmured.

Commit. Push to the test environment. Trigger CI/CD. The progress bar crawled upward. Compile. Package. Deploy.

His phone vibrated. A WeChat message from Su Man: Canary nodes ready. Routing ten percent of traffic.

Lin Chen replied: Switch it. Monitor error rates and P99 latency.

He closed the laptop. Leaning against the door, he closed his eyes. The stairwell was quiet, save for the faint hum of a distant elevator. He knew this move would survive tonight's cost audit, but it was only a stopgap. Zhao Qiming wasn't after a technical flaw; he was targeting the fragility of their business model. Once capital confirmed the burn rate was controllable, the next step would be to suppress the valuation or force the early triggering of the VAM clauses.

He opened the mistake notebook he always carried. The pages were already dog-eared. On a fresh page, he wrote: Local cache reduces authentication costs. Trade-off: eventual consistency for session states. Grace period: five seconds. Risk: clock drift on edge nodes causing premature token expiration. Requires monitoring.

The pen tip paused. He added a line: Capital tests the bottom line, not the limit. Only by holding the bottom line do you earn a seat at the negotiation table.

The EEG room door opened. A nurse wheeled out an equipment cart. Xiaoman lay on a mobile hospital bed, wearing a net cap studded with electrodes, like a strange metal helmet. His eyes were closed, eyelashes trembling slightly, but he showed no fear. Wang Guiying walked beside him, one hand resting lightly on the bed rail.

Lin Chen stood up and made way. As Xiaoman passed him, he suddenly opened his eyes. Their gazes met. Xiaoman's lips moved, making no sound, but the mouth shape was clear: Brother.

Lin Chen nodded. He reached out and pressed lightly on Xiaoman's shoulder. Very light. Just for a second.

The bed was wheeled into the examination room. The door closed. Behind the glass window, Xiaoman lay quietly. EEG waveforms began to jump across the monitor. Green, red, blue. Like some silent tide.

Wang Guiying stood outside the glass, hands clutching the hem of her jacket. Lin Chen stood half a step beside her. Neither spoke. Time ticked by. The fluorescent tubes in the corridor flickered occasionally. His phone vibrated in his pocket. Su Man: Traffic switched to fifty percent. Authentication latency down forty percent. CPU usage dropping. But session drift detected on edge nodes. Some users are being kicked out and forced to re-login.

Lin Chen frowned. Clock drift. He had anticipated it, but it was happening faster than expected. He switched back to the terminal and checked the logs. Sure enough, two CDN edge nodes in South China had system times lagging the master server by 0.8 seconds. At the thirty-minute TTL threshold, they were being prematurely marked as expired.

His fingers flew across the keyboard. Modifying configurations. Injecting forced NTP synchronization commands into the edge nodes. Simultaneously, adding a timestamp tolerance layer to the authentication gateway, allowing a deviation of plus or minus two seconds.

Commit. Hot update.

The log stream resumed scrolling. Session drift errors stopped. The error rate curve fell back.

Su Man: Stabilized.

Lin Chen didn't reply. He stared at the screen. Time synchronization on the edge nodes was just the surface. The real issue was that Zhao Qiming's probes were deliberately inducing clock skew. They were testing the system's fault-tolerance boundaries, and the team's response speed.

The EEG finished. The nurse wheeled Xiaoman out. The sedative was still in effect; he was very quiet. Wang Guiying took the medical record, her fingers trembling slightly before steadying. "The doctor said the waveforms are more stable than last time. The current dosage can be maintained."

"Good," Lin Chen said. "Make sure he takes it on schedule when you get back. Don't miss a dose."

He helped his mother get Xiaoman into a taxi. Closed the door. Watched the taillights disappear around the corner.

He turned, hailed a cab. Back to the office.

The air in the server room was still dry. Su Man sat at the monitoring console, bloodshot eyes visible. Seeing him enter, she handed him a cup of black coffee. "Zhao Qiming's team pulled the probes. But they left a backdoor."

"What backdoor?"

"The data sync queue." Su Man pulled up the monitoring dashboard. "They didn't touch authentication; they changed the priority for data fetching. Our real-time inference relies on incremental sync of training data. Now, the sync queue has been pushed to a low-priority channel. If long-tail requests continue, data latency will accumulate to the minute level. The model will start inferring with stale data."

Lin Chen walked to the screen. The curve was indeed climbing slowly. Latency: 12 seconds. 15 seconds. 18 seconds.

This wasn't a technical attack. It was a commercial chokehold. Forcing product degradation through data timeliness. Inaccurate inference leads to user churn, and the VAM metrics get breached outright.

He pulled out a chair and sat down. His left foot hit the floor, a sharp pain clearly registering. He opened his notebook and wrote on a new page: Data sync priority downgraded. Model inference timeliness compromised.

The pen tip hovered. He knew the next step couldn't rely on tweaking parameters alone. They had to change the architecture. Or, change the contract.

His phone screen lit up. A new email notification. Sender: Zhao Qiming. Subject: Supplementary Notice on Q3 VAM Clauses and Data Compliance Review.

Lin Chen opened it. The body contained only one line: Please submit the full data traceability report by 18:00 tomorrow. Failure to do so will trigger the audit clause.

He put down his phone. Stared at the latency curve jumping continuously on the monitoring dashboard.

The next step was traceability. The seventy-two hours were far from over.