Chương 4
He was in his early fifties, wore scuffed brown shoes, and carried two hard cases that looked as if they had survived several airports and one war.
Before touching the X9, he photographed the machine from every side.
He photographed the serial number.
He photographed the ports.
He photographed the seals over the actuator housing.
Then he asked Nathan to sign a form acknowledging that opening certain diagnostic interfaces might give StrideCore grounds to claim warranty interference.
Nathan read all three pages.
"Will opening them alter the device?"
"No."
"Will they know?"
"Possibly."
Nathan signed.
Sam looked at me.
"You were present for all four events?"
"Yes."
"Same movement phase?"
"Not exactly."
"Explain."
I pulled my notes from the binder.
"The first happened during assisted forward progression after left heel strike."
He held up a hand.
"Slow down."
I did.
He made notes in a battered yellow legal pad despite having two laptops open.
I liked him immediately for that.
People who wrote things down by hand generally understood that software was a tool, not a religion.
When I finished, Sam leaned back.
"Anybody else see all four?"
"Only me."
"That matters."
Nathan frowned.
"Why?"
"Because if this becomes adversarial, they'll ask whether the incidents share an observer rather than a defect."
Nathan's jaw hardened.
Sam noticed.
"I'm not saying she's wrong."
"I'm saying that's what their lawyers will say."
"I know how lawyers work."
"Then you know anger doesn't make inconvenient questions disappear."
For a second I thought Nathan might throw him out.
Instead, he looked away.
"Do your job."
"Trying to."
Sam connected a write-blocking device between his laptop and the X9 service port.
He explained the process to us only when necessary, which I appreciated.
The room filled with ordinary sounds.
A ceiling vent rattled.
A lawn service started two houses down.
Owen rolled past the doorway once, saw three adults staring at a powered-off robot, and kept going.
After forty minutes, Sam asked, "Who had administrative access?"
"StrideCore," Nathan said.
"Anyone local?"
"No."
"The clinical portal?"
"I had clinician permissions," I said.
"Could you change event status?"
"Not service events."
Sam nodded.
"That's consistent with the permissions table."
Nathan stepped closer.
"What are you seeing?"
"Give me a minute."
He compared two timestamps.
Then three.
His eyebrows drew together.
"What?"
I asked.
"Maybe nothing."
I almost laughed.
"That's becoming my least favorite sentence."
Sam looked up.
"Good instinct."
He rotated the laptop toward us.
The service history showed remote connections originating from StrideCore's support environment.
That part wasn't unusual.
The unusual part was when they occurred.
The first remote session began twenty-seven minutes after my first incident report.
The second began eleven minutes after the second.
The third began nine minutes after the third.
Each session ended with the corresponding fault marked resolved.
Nathan leaned over the screen.
"Who logged in?"
"Credential is masked here."
"Can you unmask it?"
"Not from this image."
"But StrideCore can."
"Almost certainly."
"Then Miriam can subpoena it."
Sam gave him a patient look.
"Eventually, maybe."
Nathan straightened.
"I don't like maybe."
"Then you're going to hate evidence."
That shut him up.
Sam clicked into another table.
The fourth lock event, the one from yesterday, was different.
A remote session had been initiated after the fault.
It had failed.
"Because Nathan disabled access," I said.
"Looks that way."
Sam nodded.
"Which is useful."
"Why?"
"Because the local unit retained something the earlier sessions may have overwritten."
He opened a buffer record.
Most of it meant nothing to me.
Raw sensor values.
Motor current.
Load estimates.
Joint-angle commands.
Then Sam froze the display.
"Here."
"What?"
Nathan said.
"This command."
Sam pointed to a line of data.
"The controller requested continued flexion."
I leaned closer.
"But the actuator didn't respond."
"Right."
"Why?"
"Protection state."
"Triggered by what?"
Sam scrolled one line up.
A torque limit.
My pulse picked up.
"That's the same threshold."
"Nearly."
"Is that threshold too low?"
"I don't know yet."
Nathan gave an irritated breath.
Sam looked at him.
"I can tell you what happened."
"I cannot tell you yet whether what happened was caused by a defective actuator, incorrect configuration, corrupted calibration, a sensor error, an inappropriate safety setting, or some interaction among them."
"But it locked."
"Yes."
"Under normal use."
"I haven't established normal use."
Nathan turned toward me.
I felt the accusation before he spoke.
"I followed the protocol."
Sam glanced between us.
"Nobody said you didn't."
Nathan ran a hand over his face.
"Sorry."
I looked down at the machine.
"Don't apologize because he's in the room."
Nathan's hand stopped.
Sam pretended to study his screen.
That was one of the uglier things about fear.
It made old resentments suddenly feel useful.
Nathan had questioned my judgment four times in the past month, always gently enough to deny he was doing it.
I had stored every one.
He nodded once.
"Fair."
I regretted the comment immediately and did not take it back.
Sam continued working.
An hour later, he found a second discrepancy.
The firmware configuration file on the X9 had been updated three weeks before Owen's first lock event.
Nathan looked at me.
"Did you approve an update?"
"No."
"Could it install automatically?"
I checked my notes.
"StrideCore pushed a maintenance package."
"When?"
"March fourteenth."
Sam looked at the system.
"That's the date."
"What changed?"
Nathan asked.
"Configuration tables were refreshed."
"Which tables?"
"That's what I'm trying to determine."
The current file did not preserve a visible change log.
Sam had to compare its checksums against whatever StrideCore had published or provided to regulators, assuming he could obtain those files.
Nathan's phone buzzed.
He looked down.
His face changed.
"What?"
I asked.
He turned the screen toward me.
It was an email from Victor.
The subject line read: URGENT DEVICE SAFETY NOTICE.
Nathan opened it.
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The message stated that StrideCore had detected "possible unauthorized diagnostic access" to Owen's unit and was suspending remote support pending a compliance review.
It also warned that operation of the device after third-party access could create safety risks and might void service obligations.
