The integrated model became a formal early deliverable.
That was the point of bringing him back, Eleanor realized. Not because he possessed secret technical intuition no one else could learn. Because he had experienced what happened when organizations allowed system boundaries to become excuses.
The harder test came on Thursday.
A young controls engineer named Melanie Shaw raised an objection during a review of a valve-actuation concept. She believed a redundancy scheme could create a rare common-mode response under a specific failure sequence.
The probability estimate was low.
The schedule cost of redesigning around it would be real.
The room became uncomfortable in a way Isaac recognized instantly.
Not hostile.
Worse.
Polite.
People began saying things like low likelihood, acceptable development risk, and capture for later maturation.
Isaac watched Melanie's posture change as the room translated her concern into a future task.
He did not rescue her.
That mattered.
Instead, he asked, "What would prove you wrong?"
Melanie blinked.
"Excuse me?"
"Give us the test. What result makes you withdraw the objection?"
She looked at the whiteboard.
"A coupled fault simulation across both channels with the timing offsets randomized. If the common-mode response stays below threshold across the full uncertainty band, I'm wrong."
"How long?"
"Two days to build. One to run."
The program manager started to speak.
Isaac held up one finger.
"Three days to turn disagreement into data. Do it."
"We have a design freeze Monday."
"Then the design freeze moves or the objection stays open."
The room quieted.
Eleanor, seated near the wall, said nothing.
She wanted to see whether Isaac would become the kind of authority he had once fought.
He did not.
Melanie's test showed the fault was less severe than she feared but not imaginary. A minor logic change eliminated the common-mode response with one week of schedule impact.
At the next review, Isaac made her present the result.
"You were partly wrong," he told her beforehand.
"I know."
"Good. Say that first."
She looked at him. "Won't that weaken the argument?"
"No. It strengthens your credibility. Engineers who never admit what changed their mind eventually stop knowing when their mind should change."
Melanie presented the full result, including where her original estimate had been too pessimistic.
The team approved the logic change.
After the meeting, Eleanor caught Isaac near the coffee station.
"You enjoyed that."
"What?"
"Making the schedule move."
"A little."
"Vindictive."
"Therapeutic."
She laughed.
The more time Isaac spent in Houston, the more complicated his feelings became.
There were people here he liked.
That was inconvenient.
Grace invited him to dinner with her family. Adrian started leaving terrible coffee on his desk as retaliation for years of remote criticism. Priya argued with him about material assumptions so aggressively that other engineers occasionally stopped in the hallway to listen.
Isaac had forgotten that professional disagreement could be pleasurable when no one was secretly calculating whether dissent should cost someone employment.