I'm doing engineering in the instance.

The control room was smaller than he had expected.

The room, approximately fifteen square meters, had three walls entirely composed of control panels—most of which were now powered off, their metal panels rusted, and several pieces of the instrument panel's glass shattered into a spiderweb pattern. The only remaining piece of life was the panel in the center of the west side: a round button, about fifteen centimeters in diameter, red, surrounded by a ring of indicator lights, all currently glowing a faint red light. This was the main switch.

Xie Chengzhou stood at the door, not going in immediately, but letting his eyes scan the area first.

On the east side: four iron filing cabinets, lined up in a row, their surfaces rusted. There was a slight disturbance of dust around the leg of the rightmost cabinet—his "structural perspective" automatically marked this location with a yellow anomaly warning, low priority, not a structural problem, but a sign of displacement. He noted this on the edge of his consciousness, without immediately processing it.

North side: A window, the glass intact, cracked but not broken. A thin layer of dust covered the surface, but it could still be used as a mirror. He walked sideways to the window, adjusted the angle, and observed the first floor through the oblique reflection in the glass—

The factory supervisor is in the northeast corner, moving at a steady pace, taking one step every two seconds.

He took the testing hammer out of his waist bag, pointed it downwards, and gently touched the ground to feel the vibration. The glass reflection provided orientation, while the testing hammer provided distance perception—two sources of information, with an error margin of less than five meters, corroborating each other.

Northeast corner. Normal condition.

Xie Chengzhou retreated to the center of the control room, updated the current coordinates of the plant supervisor in the memo, and then began to calculate the timing of the compression.

It has been approximately seven minutes since the last route change, and the factory supervisor is currently in the northeast corner—this is not the optimal time. If you press the button now, the supervisor's route will begin to contract towards the control room after 15 seconds. At that point, the supervisor's starting point will be in the northeast corner, and the contracting route will move from northeast to northwest, passing through the north staircase area, with the closest point to the control room being approximately twelve meters. If the supervisor triggers an alert state during their patrol after 15 seconds, the thermal sensor will activate, and body temperature within a four-meter radius can be directly detected.

Twelve meters. That's safe enough with alert status off. But he doesn't know if that twelve meters includes errors due to route deviation.

It's not the best time.

He wrote the calculation results into his memo: "Current timing: suboptimal. Wait for the next route change. Start pressing the button the instant the change is made. The plant supervisor will complete the change within 30 seconds. The new route direction is unknown, but statistically, it is more likely to deviate from the control room."

He sat down against the west wall of the control room, his back against the wall, and kept lightly tapping the test hammer on the ground while waiting.

The player was still outside the crack in the door, his hand pressed against the wall of the corridor, his eyes fixed on Xie Chengzhou. He didn't speak, and neither did Xie Chengzhou.

Waiting is the most exhausting part of engineering—not because it's boring, but because all possibilities hang in the balance. You know variables are evolving, but you can't see them; you can only keep waiting until the next data point appears. He waited 72 hours for a geological survey report in Africa, 48 hours for the floodwaters to recede in Bangladesh, and over 20 days for the final opinion of the acceptance committee in China. Waiting never made him anxious; it was simply part of the engineering process.

About six minutes later, the detection hammer transmitted a familiar signal.

"Pre-compression".

A subtle force appeared before the uniform rhythm of a two-second step—not the footstep itself, but the signal about 0.31 seconds before the footstep, but this time, the amplitude of the signal was about 20% higher than the previous average. He had recorded this in Chapter 4 when verifying implicit rule D: the increased amplitude meant that a route change was about to occur.

He stood up, walked to the main switch panel, held the test hammer in his left hand, and hovered his right hand above the button.

and so on.

The rhythm of the low-frequency vibrations was briefly interrupted—a change of course was taking place.

The interruption lasted for about two seconds, then the vibration resumed. The direction shifted, moving from the northeast corner to due east, meaning the new route's coverage center was on the east side of the factory, significantly reducing coverage to the north and west.

This is the best possible outcome for any changes at present.

Xie Chengzhou pressed his right palm onto the main switch button.

The button was more resistant than he had expected. It wasn't spring resistance, but the entire button panel felt taut—like pressing down on a disc supported by elastic pads, requiring a steady pressure of three to four kilograms, and it couldn't be loosened, or it would reset the progress. He placed his right palm completely over the button, his forearm suspended in the air, steadily transmitting the pressure through the weight of his arm and muscle control.

In the third second, nothing happened.

At the seventh second, the red indicator light began to change slightly, as if there was a gradual change that was not yet fully determined, tentatively testing the edge between red and orange.

At the tenth second, the indicator light turned orange, and at the same time, the entire panel emitted a low-frequency vibration that lasted for about two seconds—not a sound, but a vibration transmitted directly through the palm of the hand, with a frequency of about thirty hertz. Xie Chengzhou mentally categorized it: "Activation of mid-range signal. Normal."

The testing hammer in his left hand kept lightly touching the ground.

The vibrations detected by the factory monitoring system were on the due east side, with a uniform rhythm, occurring every two seconds, and remained unchanged during the patrol.

The fifteenth second.

The indicator light was still orange, but the signal from the detection hammer had changed.

It wasn't a major change, but a slight directional shift—the vibration source drifted slightly northward from due east, the amplitude was small, but stable and directional, not random noise. Xie Chengzhou continuously tracked this shift for the next three seconds, converting the rate of shift into the direction of movement of the plant monitoring equipment:

Northwest.

Towards the control room.

Hidden rule B is being triggered.

He didn't let go. His right hand maintained pressure, while his left hand continued tracking. In his mind, he had created a real-time coordinate system: the factory monitor was currently about thirty meters to the east, with a shift rate equivalent to about six meters per minute. There were still about fifteen seconds left to press, which meant that before activation was complete, the factory monitor's closest point was about twenty-four meters away.

Twenty-four meters.

The thermal sensor's alert activation range is four meters, and its tracking range is six meters.

If the plant monitor maintains the current rate, it will not enter the heat-sensing range. However, the "current rate" is an assumption, not a confirmation.

He continued pressing.

At the eighteenth second, the offset signal from the detection hammer paused once—the rhythm of the factory supervisor's footsteps did not change, but the directional offset paused for about three seconds, as if a judgment had been made at some point: continue to approach or turn around.

Xie Chengzhou wasn't breathing. It wasn't intentional; it was a state closer to that of engineering testing—all his attention was focused on the tactile sensation of the tools and the transmission through his feet, while other bodily reactions automatically faded into the background.

three seconds.

The direction of the vibration began to change.

Instead of continuing north, it began to veer eastward, at a rate almost twice as fast as when it was approaching—the plant monitoring was accelerating, its direction was moving away from the control room, and it was resuming its normal patrol rhythm.

It did not come close to the heat-sensing range.

The reason is unknown. Perhaps this change of route deviated its patrol direction at some turning point; perhaps it judged something and decided there was no target worth approaching. Xie Chengzhou marked this location in his mind: about twenty-two meters away, the factory supervisor paused for three seconds, then left. He wrote an incomplete entry in his memo, leaving it for later: "Hidden Rule E - Suspected: The factory supervisor approached after 15 seconds, paused for 3 seconds at about 22 meters away, and turned away before entering the heat-sensing range. Reason—"

At the twentieth second, the indicator light turned yellow.

At the 25th second, the detection hammer sensed that the vibration direction of the plant monitoring system had completely stabilized at due east-southeast, and the distance from the control room was increasing, no longer getting closer.

The thirtieth second.

The indicator light turned green.

The entire panel vibrated more strongly than it had at ten seconds, lasting for about four seconds before stopping. Xie Chengzhou removed his right hand from the button, leaving a light red, circular indentation about fifteen centimeters in diameter on his palm.

The main switch is activated.

He wrote in his memo: "Activation complete. Time taken: exactly 30 seconds. Hidden rule B has been triggered. The factory monitor approached to approximately 22 meters, did not enter the heat detection range, and turned around on its own. Assessment: The timing of this activation was effective."

Xie Chengzhou stood up and turned his gaze to the filing cabinet on the east side.

The yellow "structural perspective" markings are still there—the displacement marks at the bottom of the cabinet on the far right, the shallow marks left by the cabinet legs on the ground, pointing towards the corner of the wall, not outwards, but inwards, as if someone pushed the cabinet out of the corner of the wall, took something from the bottom, and then pushed it back, but did not push it completely back to its original position, leaving this scratch mark.

He walked over, squatted down, and shone the flashlight beam close to the ground—the scratch was about 0.5 millimeters deep, and its width matched the cross-section of the cabinet leg. It wasn't caused by dragging, but by a single push, with concentrated force and a clear purpose.

He stood up, placed his hands on the sides of the cabinet, and slowly applied force, moving the cabinet about thirty centimeters away from the corner of the wall.

bottom layer.

There were four compartments, three of which were empty. The innermost compartment contained a folded document, placed in a brittle kraft paper envelope.

He took it out and unfolded it.

The feel of the paper made him realize something was wrong immediately—it wasn't the texture of any construction paper he had ever encountered. It was thicker, finer, and had extremely fine lines on the surface, as if it were the result of some kind of pressing process rather than ordinary mechanical papermaking.

He began to read.

The title is "Consciousness Protocol · World · Abandoned Chemical Plant | Structural Safety Assessment Report | No.: LC-001-α". The format is similar to the structural survey reports he is familiar with, but the precision far exceeds any similar reports he has ever seen from any era - the load calculations are accurate to four decimal places, the stress analysis diagrams use a symbol system he does not recognize, but he understands the logic of the diagrams, and that logic is correct.

He paused on the north staircase: "Cantilever structure, aging coefficient of support node is 0.73, static load safety factor is 1.24. It is recommended that one person pass through at a time, on the inner side, with the center of gravity close to the support side."

That's what he did when he went upstairs. He thought it was his own judgment.

He continued reading. The section on "Chemical Residue Area" stated: "The ground coating has a noticeable grainy texture; mid-frequency acoustic amplification factor is 2.1-2.3 times." In Chapter Two, he measured "approximately twice," using reverse extrapolation, with an error margin of about 15%. Here, it reads 2.1-2.3.

Cracks in the second-floor corridor: "The cracks are bent and deformed, pointing eastward, perpendicular to the direction of the floor slab's stress, with a height difference of less than 1mm. The structure is now stable. Avoid walking around it; the noise from footsteps is a high risk."

He turned to the third page.

The third page contains an additional handwritten section outside the main text format. The handwriting differs from the printed text of the first two pages; it is handwritten, with strokes more neat than a signature, but it reveals a clear personal habit—like someone adding a personal note at the end of a formal report.

"The acoustic characteristics of this structure exceed the scope of conventional evaluation, hence this note. This report is intended for readers with structural awareness; ordinary evaluations are invalid."

Recommended activation timing for the main switch in the third-floor control room: activate immediately after the route change. Within a 30-second window, based on the thermal sensing radius, the route can be narrowed to approximately 22 meters away.

This is archived here for future reference.

After reading this passage, Xie Chengzhou laid the report flat against his thigh and remained still for about five seconds.

Take action immediately after the route changes.

That's exactly what he just did. He used the detection hammer to sense the "pre-compression" signal, and when the route changed, he pressed down—he thought he had calculated it himself, spending nearly forty minutes and revising it six times in his memo before confirming the timing.

The report was already here before he arrived; the answers were already written on the paper.

He turned to the last page.

In the bottom right corner of the last page was an engineer's signature, handwritten, the characters unfamiliar to him, not from this world, but the strokes possessed a precise and restrained quality—not artistic, but professional, the handwriting of someone who wrote their name in engineering symbols. Next to the signature was only a small note, but he could make it out under his flashlight:

"——G"

Just these two characters. Not a name, but a code, or an abbreviation, or some kind of label that has no corresponding representation in this world's character system.

Xie Chengzhou looked at the signature for about ten seconds, then folded the report again and put it into the inner bag.

In his memo, he wrote: "File cabinet: Hidden document. Paper quality and precision are abnormal. Report title: Constitutive Protocol · World · Abandoned Chemical Plant, Structural Safety Assessment Report LC-001-α. Constitutive Protocol—this term also appears in the header of Chapter 1 Rule Text. Meaning: The rule system behind the historical realm? Report content: #001 Plant Structural Analysis, correct, with a level of detail exceeding the current world's engineering standards. The notes include a suggestion for activation timing—completely consistent with the actual execution. Signature: Non-world character, code G. Source: To be verified."

He paused, then wrote two more lines below that line:

"This report is not what this copy should contain."

"He figured it out. Even earlier than me."

He returned to the doorway and gestured to the player in the corridor.

"You can go now," he said. "Head east, don't take the stairs, take the freight elevator shaft."

"Freight elevator?"

"At the end of the eastern section of the third-floor corridor," Xie Chengzhou said, "the freight elevator is no longer usable, but the metal ladder in the shaft is still there, allowing you to climb directly to the first floor." He had noticed the location of the freight elevator shaft entrance during the first phase of the factory inspection, where it was marked as a "backup evacuation route," and now it was needed. "It's faster than taking the stairs, and since the factory supervisor is currently on the southeast side, while the freight elevator shaft is in the eastern section, the routes will intersect. We need to complete the descent before the factory supervisor patrols to the eastern section, which will take about six minutes."

The person nodded.

Xie Chengzhou held the testing hammer in his hand, slipped out through the crack in the door, and walked east along the corridor. The cone of the testing hammer lightly touched the ground, the "pre-compression" signal was clear, the plant supervisor was located slightly south of due east, about thirty-five meters from the control room, still patrolling, and still in normal condition.

A six-minute window is enough.

He controlled his pace to be about one-third slower than normal walking, and he had chosen his footing in advance—the floor of the third-floor corridor was of better quality than that of the second floor, but there were two places where slight bow-shaped deformations had begun to appear. Stepping on the edge of the deformed area would produce a noticeable sound, so he had to go around it.

The person followed behind him, their footsteps perfectly aligned with his.

At the end of the eastern corridor, Xie Chengzhou saw the metal gate of the freight elevator shaft. It was rusted, but the hinges were intact. Pushing it open manually would not make a sound. He had confirmed this in the first chapter, when he used the touch point judgment of "structural perspective": the stress point of the hinge is near the hinge axis. The rust at that position is uniform and surface-level, not deep into the metal, so it will not cause jamming when pushed.

He pushed open the gate, revealing the freight elevator shaft.

The vibrations in the factory building on the first floor were still even, occurring every two seconds, calm and as if nothing had happened.

Xie Chengzhou tucked the testing hammer into his waistband and began to lower it.