The Throat

The thermal schedule was already in breach when Marek Solyani arrived at Relay Control, and from the color of the status wall—amber shading toward a red that nobody in the room wanted to acknowledge—it had been in breach for some time. He set his coffee bulb against the magnetized strip on the console edge, where it joined three others in various states of cooling, and pulled up the corridor extension queue without sitting down.

"When did the Halcyon packet cross the handoff threshold?" he asked.

Jun Meiwei, the routing coordinator on shift, didn't look up from her display. "Eleven hours ago. Proxima Relay Four confirmed acquisition and began primary braking sequence at 0340." She paused, and the pause was its own kind of answer. "They also confirmed they're holding the beam for the full deceleration window."

Marek sat down. "The full window. Not the abbreviated."

"The full window."

He stared at the numbers. The Halcyon was a Class II packet—fragile technical cargo, precision braking required—inbound from Sol on the Proxima corridor and scheduled for redirect to Alpha Centauri after partial deceleration. The system had been doing this for decades. Sol pushed packets down the corridor to Proxima. Proxima's outer arrays caught them, bled off the first tranche of velocity, and then the inner relays kicked them across the 0.19 light-years to Alpha's own capture envelope, where Alpha's arrays completed the job. It was elegant, in the way that things designed by committees across decades-long communication delays could be elegant, which is to say it functioned until it didn't.

The problem was not Relay Four itself. Relay Four pointed along the Proxima-Alpha beam path and did exactly one thing well: catch packets coming from Proxima's direction. Alpha's Tau-facing outbound array—the one that would accelerate the Durance toward Tau Ceti—pointed in a completely different direction, 13.25 light-years away along a vector that had nothing to do with the Proxima corridor. The two arrays could not physically interfere with each other's beam geometry. But they shared something more fundamental than geometry: they shared Junction Seven.

Junction Seven was the power-routing and thermal-management hub that sat at the center of Alpha's outer infrastructure cluster, roughly 1,800 AU from Alpha Station. It distributed power from Alpha's solar collectors to whatever arrays needed it, and it absorbed and radiated the waste heat that those arrays generated during operations. Every major beam operation in Alpha's outer system drew power through Junction Seven and dumped thermal load into Junction Seven's radiator complex. The junction's thermal capacity was the ceiling on what Alpha could do—not because the arrays lacked beam power, but because the shared cooling infrastructure could only reject so much waste heat before it saturated.

And right now, Junction Seven was feeding Relay Four's full-window braking campaign for the Halcyon, a sustained 11.2-terawatt thermal load that would continue for another thirty-one days and leave the junction's thermal buffers completely saturated. After cooldown—mandatory, non-negotiable, governed by material fatigue curves that no amount of institutional pressure could bend—the junction would need nine days before it could support another high-power tasking. Only then could the Tau-facing array draw the power it needed for the Durance injection.

Thirty-one plus nine was forty. The Durance window closed in nineteen.

"Show me the thermal stack for Junction Seven," Marek said.

Jun pulled it up. The numbers told the story the way numbers always did in Centauri: with the flat indifference of physics to human planning. Junction Seven was a shared asset—technically joint infrastructure, maintained by Alpha-based crews but power-fed through the corridor extension's distribution grid, politically claimed by neither system in any way that could survive a formal challenge. Its radiator array was rated for 14 terawatts of sustained waste heat rejection. The Halcyon braking campaign held it at 11.2 terawatts, leaving no margin for a simultaneous Tau-facing injection that would demand another 8 to 10 terawatts of thermal throughput.

"They know," Jun said quietly, and Marek understood that she was not referring to anyone in this room, or on this station, or in the Alpha Centauri system at all.

The thing about the Centauri corridor extension was that it had never been designed. It had accreted, the way infrastructure does when you cannot afford to build from scratch and cannot afford not to build at all. Proxima had been first—Sol's initial corridor terminus, the proof of concept, the system that demonstrated that human civilization could reach across 4.25 light-years and catch what it threw. Alpha Centauri, 0.19 light-years farther out, had been an afterthought that became a dependency that became a rival.

The corridor extension—the set of relay arrays, beam paths, and shared infrastructure nodes that connected Proxima's inner capture system to Alpha's outer envelope—was the throat through which everything flowed and was simply called as such by everyone who mattered. Every Sol packet destined for Alpha passed through Proxima first. Every Alpha packet destined for Sol or Tau Ceti needed power routed through the extension's shared grid. The arrays pointed in different directions—Relay Four toward Proxima, the Tau-facing array toward Tau Ceti, the Sol-return array along a third vector entirely—but they all drew from the same thermal well. Junction Seven could support one major beam operation at a time with comfortable margins, or two minor ones if the scheduling was precise and the duty cycles were respected and neither side pushed for priority at the expense of the other.

In practice, the junction was always contested. Not violently—the Centauri systems had never quite managed that particular stupidity, though they had come close during the Relay Three incident—but in the grinding, procedural, half-invisible way that infrastructure disputes always unfold. Scheduling conflicts. Maintenance windows that conveniently expanded. Calibration requirements that mysteriously intensified when the other side needed thermal margin. The throat was shared the way a single road through a mountain pass is shared by two towns on opposite sides: with grudging cooperation underlaid by the constant awareness that cooperation is a choice, and choices can be revised.

Marek Solyani was Alpha Centauri's Corridor Extension Coordinator, a title that sounded administrative and was in fact one of the most politically fraught positions in either system. His job was to negotiate Alpha's access to the shared infrastructure of the throat—particularly Junction Seven, the node where every scheduling conflict eventually landed. His primary counterpart was Lien Oshiro, Proxima Corridor Authority's resident liaison at Alpha—stationed on Alpha Station itself, sharing the same air and the same local time, but representing an institution whose actual decision-makers sat 0.19 light-years away, a distance that light crossed in roughly sixty-nine days. The Corridor Authority had posted Lien here precisely because the throat demanded faster coordination than a four-and-a-half-month round-trip could provide. She had delegated authority for routine scheduling, maintenance coordination, and standard capture operations. What she did not have—what no liaison could have—was the authority to make precedent-setting decisions on behalf of a government that could not be consulted within any operationally relevant timeframe.

Every conversation Marek had with her was shaped by that boundary — what she could decide, and what she had to refer.

He called her office. She picked up in two rings.

"Lien. I'm looking at the Halcyon braking schedule and the Junction Seven thermal stack. I need to understand the decision logic behind running the full deceleration window rather than the abbreviated profile. The abbreviated profile was in the shared schedule as of last quarter's corridor review. The full window saturates Junction Seven for the entire braking campaign and forecloses our Durance injection. You know this."

A pause—the smaller, human pause of someone choosing words carefully in something close to real time. "The deceleration profile change was made at the recommendation of our capture systems team based on updated sail degradation models for long-transit Class II packets. The Halcyon has been in transit for eighteen years. Sail reflectivity projections indicate potential degradation from R-0.999 to R-0.993 or lower. At that reflectivity, the abbreviated profile would impose absorbed thermal loads exceeding the brake sail's design envelope. We are not willing to accept the risk of a sail failure during final braking."

"That recommendation came from Proxima proper?"

Another pause, slightly longer. "It came through the standard technical advisory channel. I endorsed it and authorized the profile change under my operational safety mandate."

"You authorized it." Marek kept his voice level. "Under your safety mandate. Not under scheduling authority."

"The safety mandate takes precedence over scheduling when there's a credible risk of capture failure, Marek. You know that."

He did know that. It was written into the corridor extension protocols—safety override authority was the one area where Lien's delegated powers were essentially unlimited. If she determined, based on available technical data, that a capture operation posed a risk to shared infrastructure, she could unilaterally modify the deceleration profile, adjust beam parameters, even abort a capture entirely. The provision existed because the sixty-nine-day delay to Proxima proper meant that safety decisions could not wait for institutional approval.

It also meant that safety authority was the one lever Lien could pull without exceeding her mandate. And she had pulled it in a way that just happened to saturate Junction Seven through the entire Durance launch window.

"I'm not asking you to change it," Marek said, echoing the careful phrasing he'd rehearsed in his head on the walk to Relay Control. "I'm asking whether the degradation model supports the full window specifically, or whether the abbreviated profile with enhanced thermal monitoring might be sufficient."

"I'll share the model parameters. But Marek—I need to tell you something else, and I'm telling you now because you should hear it from me before it comes through official channels."

She told him about the manifest amendment. The Mandate Group advisory attachment. Two Sol personnel in torpor. Class III insertion requirements.

The room changed temperature.

The Durance packet was not merely cargo. It was Alpha Centauri's first fully independent contribution to the Tau Ceti corridor—industrial seed modules, fabrication templates, and control architectures designed and built entirely within the Alpha system, representing a manufacturing capability that Alpha had spent three decades developing. If it reached Tau Ceti, it would establish Alpha as a legitimate node in the inter-colony network, a system that could build things other systems needed. If it missed its window, the next viable alignment wouldn't occur for another four years, and the political implications of a four-year delay—the narrative that Alpha couldn't manage its own corridor access, that it remained dependent on Proxima's goodwill for anything beyond basic survival—would compound in ways that no amount of engineering could repair.

Marek understood this not because anyone had explained it to him but because he had lived the last fifteen years inside the constraint network that made it true. Alpha's beam infrastructure was younger, smaller, and less thermally mature than Proxima's. The Tau-facing array itself was capable—Alpha had built it specifically for the Tau Ceti corridor, and its beam geometry and power handling were designed for payloads in the Durance's class. But the array could not operate without Junction Seven's thermal support, and Junction Seven was currently saturated by a braking campaign that Proxima's local representative had authorized on technically defensible but strategically convenient grounds.

The question was not whether Lien's safety rationale was legitimate. Sail degradation was real. Eighteen years of interstellar medium exposure, cosmic ray bombardment, and micrometeoroid impacts could absolutely reduce reflectivity from the factory-fresh 0.999 to 0.993 or lower. At R-0.993, the absorbed fraction of beam energy rose from 0.1% to 0.7%—a sevenfold increase. On a sail absorbing a multi-terawatt beam, that was the difference between manageable thermal load and catastrophic heating.

The question was whether the degradation models were projections or measurements. Nobody could measure the Halcyon's actual sail reflectivity until the packet was close enough for active interrogation, and that wouldn't happen for another twelve days. Lien had authorized the full window based on a model, not a reading, and the model's assumptions—validated against the last three long-transit arrivals, she'd said, all of which showed degradation consistent with or exceeding projections—were conservative by design.

And then there was the timing. The manifest amendment revealing the Mandate advisory attachment had arrived on the last Sol relay burst—a wide-beam from the Sol corridor terminus that reached Alpha and Proxima simultaneously, crossing the 0.19 light-years in sixty-nine days from the relay's transmission point. But Lien had authorized the full window before the amendment arrived. She'd told Marek about it as a courtesy, as something he should hear from her first—but the profile change had already been made.

Either Lien had known about the advisory attachment through a channel that predated the official relay burst—a tight-beam from Proxima proper to their liaison, perhaps, sent weeks ago and only now becoming relevant—or she had made the safety call independently and the Mandate attachment was coincidence.

Marek did not believe in coincidence in Centauri. But he also did not believe that Lien was simply Proxima's instrument. She had lived on Alpha Station for nine years. She maintained the throat's operational schedules, attended Alpha's infrastructure reviews, ate in Alpha's commissary. She was embedded in both systems in a way that nobody on Proxima proper could be, and that embedding informed her judgment in ways that pure institutional loyalty could not. But judgment and authority were not the same thing, and Lien's authority had limits that the next few days would test.

He called a meeting with Alpha's Corridor Planning Board.

The Board met in a room that had been designed for eight people and now held fourteen, because the Durance situation had drawn in representatives from Alpha's manufacturing directorate, its emerging Tau Ceti liaison office, and—significantly—two officers from Alpha's system defense coordination group, who attended with the particular alertness of military personnel who sensed that their domain was about to become relevant.

Marek laid out the situation in the precise, layered way that infrastructure people communicated: the thermal stack, the scheduling conflict, the degradation model question, the Mandate advisory attachment. He did not editorialize. The numbers did that for him.

"Options," said Director Yeun, who ran the manufacturing directorate and had spent eleven years shepherding the Durance payload from concept to completion. She was not a person who asked for options lightly; she was a person who wanted to know which options existed so she could begin eliminating the ones that involved accepting failure.

"Three that I can see," Marek said. "First, we accept the delay. Durance misses this window, we wait four years for the next Tau alignment, we absorb the political cost. Second, we propose a compromise: Lien agrees to shift to the abbreviated braking profile when active reflectivity data comes in at the twelve-day mark, assuming the numbers support it. The abbreviated profile draws less sustained power through Junction Seven—lower peak thermal load, shorter campaign. If the sail's in good shape, the junction cools down in time for a compressed Durance injection, though the margins will be thin. Third—" He paused, because the third option was the one that would change the room's atmosphere, and he wanted to mark the transition. "Third, we attempt to run the Durance injection without Junction Seven entirely. Direct power feed from Alpha's inner-system solar arrays to the Tau-facing outbound array, bypassing the junction."

The silence that followed was the silence of people doing math in their heads and not liking the results.

"The direct feed path doesn't have the transmission capacity," said Coordinator Voss from the defense group. "We'd be limited to roughly forty percent of the Tau array's rated beam power. For 400 tonnes to 0.05c, the beam-on time extends to—" He ran it. "Over a year. And the Tau array's own radiators can't handle sustained operations at that power level without junction support. We'd need to reduce payload mass, accept a lower cruise speed, or both."

"Both," Marek said. "If we cut the Durance to 200 tonnes and target 0.03c, the direct feed path can manage it. Beam-on time is still roughly 260 days, and the transit time to Tau nearly doubles. And we'd be running the Tau array at maximum rated capacity on its own thermal budget for the entire campaign, which means no other major operations for most of a year. No inbound capture support, no defense operations beyond passive monitoring. The array would be thermally committed."

"Cutting the payload in half defeats the purpose," Director Yeun said, her voice flat in the way that signaled not calm but a controlled decision to remain calm. "The Durance was designed as an integrated industrial package. You can't remove half the modules and still have a functional seed kit at the other end."

"You could send the other half on the next window," Jun offered from the corner where she'd been quietly running numbers on her portable display.

"In four years. After the first half has been sitting in Tau's capture queue for—" Yeun calculated. "Roughly 440 years of cruise at 0.03c, plus deceleration. Versus 265 years at 0.05c through the junction. That's 175 years of additional transit. The fabrication templates in the first shipment will be obsolete before the second shipment arrives."

The room sat with that number for a while.

"There's a fourth option," said the other defense coordinator, Lieutenant Commander Aran Tesh, who had been so still during the discussion that Marek had almost forgotten she was present. "We don't comply with the Mandate advisory group's implied authority. We inform Lien that we consider the full deceleration window a unilateral breach of the shared scheduling agreement. We demand reversion to the abbreviated profile. And we prepare to assert direct scheduling authority over Junction Seven if she refuses."

"Assert authority how?" Marek asked, though he already knew.

"Junction Seven is shared infrastructure with shared access credentials. If we lock Proxima out of the junction's scheduling system, Relay Four loses its power feed and has to shut down. The Halcyon braking stops. The junction's thermal load drops to near zero on an accelerated timeline. We redirect power to the Tau-facing array and launch the Durance."

The room was very quiet.

"And the Halcyon," Marek said. "A packet currently under active deceleration. With two Sol advisory personnel in torpor."

"Would need to be recaptured on a secondary array. Proxima has the capacity on their inner systems. It adds time and thermal cost to their schedule, but it's not a loss-of-packet scenario."

"It's a seizure-of-shared-infrastructure scenario. In the presence of Sol Mandate authority."

"Sol Mandate authority that's eighteen years out of date and hasn't been validated by any current institutional framework in either system."

Marek looked at Tesh with the careful attention he reserved for people who were technically correct in ways that could be catastrophic. She was right that the advisory group's authority was legally ambiguous—Centauri's governance frameworks had evolved significantly in the eighteen years since those orders were written, and there was no established protocol for validating Mandate authority that arrived under changed political conditions. She was also right that Junction Seven was technically shared infrastructure with dual-access credentials. Everything she was proposing was, in the most clinical sense, within the space of actions that Alpha could take.

But clinical analysis existed in a frictionless universe, and Centauri did not.

"If we lock Proxima out of Junction Seven," Marek said slowly, "we establish a precedent that shared infrastructure can be unilaterally seized when scheduling disputes reach an impasse. Proxima will remember this. They control seventy percent of the relay infrastructure between here and Sol. They maintain the primary capture arrays that every Sol-origin packet depends on for initial deceleration. If they decide to reciprocate—not now, not next month, but in three years or ten—they can deny us access to incoming Sol packets. Medical supplies. Data archives. Personnel transfers." He paused. "The throat works because both sides agree that it works. The moment one side demonstrates that it can be selectively choked, the other side starts building alternatives. And alternatives, in Centauri, take decades."

"We should already be building alternatives," Tesh said, and she was not wrong about that either.

"There's another problem," Marek added. "Lien authorized the full window under her safety mandate. That mandate is delegated authority from the Corridor Authority on Proxima proper—and Proxima proper is sixty-nine days away by lightspeed. If we challenge her safety call, she can refer the dispute to the Authority. The referral itself is the weapon: it takes the decision out of her hands and places it with people who cannot respond within our timeline. The Durance window closes in nineteen days. A referral to Proxima proper wouldn't even arrive before the window is gone, let alone produce a ruling."

The room absorbed this—the structural trap that the delay created. Lien's authority was limited, but the mechanism for challenging it was even more limited, because the institution behind her was unreachable.

Marek walked to Lien's office after the Board meeting, because some conversations required the kind of presence that voice channels could not provide—the ability to read posture, to register hesitation in a shift of weight rather than a pause in speech, to occupy the same space as the person whose decisions were reshaping your future.

Lien's office was on the administrative level of Alpha Station, three corridors from his own—close enough that the physical proximity had always felt like a kind of institutional irony, given the distance between the systems they represented. Her door was open. She was reading something on her display, and she didn't look up immediately when he entered, which was its own kind of message: she had been expecting him.

"The degradation model," she said without preamble. "I'll send you the full parameter set within the hour. You'll find it's conservative. That's by design—our capture systems people build in margin because the cost of a failed capture is asymmetric. A successful abbreviated profile saves scheduling time. A failed one contaminates the throat with debris and thermal bloom that could take months to clear."

"I'm not here about the degradation model," Marek said. He sat down, uninvited, because standing across a desk from someone created a geometry of confrontation that he wanted to avoid. "I'm here about the Mandate attachment, and about the scope of your authority to do what I'm about to propose."

He told her about the entropy barges.

The idea was ugly. Ugly in the way that solutions born from constraint always were—not elegant, not efficient, but possible.

Junction Seven sat roughly 1,800 AU from Alpha Station, at the hub of the outer infrastructure cluster where the throat's relay arrays, power distribution grid, and thermal management systems converged. It was not a single structure but a constellation of platforms: power routers, thermal buffer masses, radiator arrays, and the control systems that coordinated them all. At that distance, Alpha's relay tugs—chemical-thermal workhorses rated for about 40 km/s of delta-v per fueled sortie—could make the transit in eleven days on a high-thrust brachistochrone profile, burning hard at departure and flipping for deceleration at the midpoint. It was the kind of trajectory that shortened the mission but doubled the propellant expenditure and imposed thermal stress on engine bells that were already past their recommended service interval. The tugs would arrive capable of unloading cargo and not much else; they'd limp back on fume-economy thrust over the following weeks, and the maintenance crews would spend months rebuilding what the sprint had cost.

But Junction Seven's nine-day cooldown was driven by its radiator capacity: 14 terawatts of sustained waste heat rejection at 1500 kelvin across roughly 54 square kilometers of radiator surface. After a full-window braking campaign—thirty-one days of feeding Relay Four's beam at 11.2 terawatts of thermal throughput—the junction's thermal storage buffers would be saturated. Somewhere in the range of 600 to 900 terajoules of stored energy, depending on how much the buffer management system had been able to bleed off during operations. The radiators needed time to bring the system back to operational baseline. Nine days. Immovable.

Unless you moved the heat somewhere else.

Expendable heat rejection—entropy barges, in the operational vernacular—was the brute-force option. You loaded the excess thermal energy into sacrificial mass, heated it to tolerance, and ejected it. The mass requirement was punishing: roughly a thousand kilograms per second per gigawatt of waste heat, which at the terawatt scale meant tens of thousands of tonnes per day. But you didn't need to cool the entire junction. You only needed to dump the stored buffer energy—the residual heat trapped in the thermal mass after the radiators had done what they could during operations. For an estimated 750 terajoules of buffer overhang, at a heat capacity of roughly a megajoule per kilogram across a thousand-kelvin temperature rise, you needed approximately 750 tonnes of expendable mass. Call it 800 for margin, because margin was the only currency that mattered when the alternative was a collapsed timeline.

That would cut the cooldown from nine days to roughly four—the time needed for the radiators to handle the remaining steady-state thermal load without the buffer overhang. Maybe three days, if the slag quality was good and the thermal coupling was efficient. Once Junction Seven was back to operational baseline, it could route power to the Tau-facing array, and the Durance injection could begin—on margins thin enough to be measured in hours rather than days, with no room for slippage anywhere in the chain.

Lien listened without interrupting, which was unusual for her. When Marek finished, she was quiet for a long moment, and he could see her running the same calculation he had already run: not the thermal math, which was straightforward, but the authority math, which was not.

"This falls within my operational coordination mandate," she said slowly, as if testing the words for structural integrity. "Thermal management of shared infrastructure. Integration of external resources into cooldown cycles. It's not a scheduling override—it's a scheduling optimization that works within the existing deceleration profile." She looked at him. "I don't have to change the full window. I don't have to alter Relay Four's braking campaign at all. I just have to accept your mass delivery at Junction Seven and integrate it into the post-braking cooldown."

"Yes."

"But the Corridor Authority will know that the practical effect is to free Junction Seven for the Durance launch. They'll understand that I've used my operational mandate to work around a thermal constraint that the safety override created."

"Will they object?"

Another pause—longer this time, weighted with the particular density of a person calculating institutional risk across a sixty-nine-day communication gap. If Lien approved the thermal dump and the Corridor Authority later determined she had exceeded her mandate, the ruling would arrive months after the Durance had already launched. The precedent would be set. The Authority could censure her, recall her, replace her—but they could not undo the launch. And if they did recall her, Alpha would lose the one Proxima representative who understood the throat's operational reality from the inside, and the next liaison would arrive cold, uninformed, and months behind the political landscape.

"They'll object," Lien said. "But not immediately, and not in a way that reverses what's already been done. The question is what they'll want in return."

"Terms."

"Terms. And I can tell you what they'll want, because I know the people involved, even if I can't consult them. They'll want Alpha to acknowledge that the full deceleration window was a legitimate safety decision, not a scheduling intervention—because it was, Marek, whatever else it also was. And they'll want a framework for handling future Mandate-related traffic that preserves Sol's institutional standing on shared infrastructure."

"Default priority for Mandate packets?"

Lien's expression shifted—not quite a wince, but a tightening around the eyes that suggested the phrasing hit close to something she'd been thinking about. "That's what the hardliners would push for, if I referred this to them. Default priority, formalized in the corridor protocols, applicable to all future scheduling conflicts." She paused. "I am not going to refer this to them."

Marek let that settle. She was choosing not to escalate to Proxima proper — choosing to handle this within her own mandate, accepting the political risk of acting without her principals' explicit approval, on the theory that acting within the sixty-nine-day gap was better than waiting for guidance that would arrive after the crisis was over.

It was, Marek recognized, exactly the kind of decision that the liaison model was designed to enable. It was also exactly the kind of decision that the liaison model's designers had feared.

"What terms can you offer?" he asked. "Within your mandate."

"Acknowledgment of the safety rationale—formal, documented, referenceable. A joint scheduling protocol for future Mandate-related packets: not default priority, but a priority-weighted system where Mandate traffic receives a scheduling advantage that can be offset by demonstrated operational necessity. The weighting formula gets developed jointly over the next year." She held up a hand before he could respond. "I know what you're going to say. You're going to say that any priority weighting is a concession that disadvantages Alpha's autonomous operations. And you're right. But the alternative is that I refer this dispute to Proxima, the referral takes sixty-nine days to arrive, another sixty-nine for the response, and by then your Durance window has been closed for four months and the Corridor Authority has had five months to formalize exactly the default-priority framework I'm trying to avoid."

Marek sat with it. She was right—the delay was the weapon, and Lien was, in effect, shielding Alpha from the worst version of the outcome by preempting it with a less damaging version that she could authorize locally. The compromise was real, and it cost Alpha something real, but it cost less than the alternative that the sixty-nine-day gap would produce if the decision was kicked upward.

"There's another dimension," he said. "And I want to put it on the table because we're both going to need it when the Authority reviews what we've done." He described the maintenance dependency—Relay nodes Two, Five, and Six, jointly maintained but serviced by Alpha-based thermal conditioning crews. Relay Six handling thirty percent of Proxima's own inbound Sol traffic during peak scheduling periods. The structural fact that Proxima needed Alpha's maintenance infrastructure as much as Alpha needed the throat's thermal capacity.

Lien listened with the careful stillness of someone filing information for future use. "You're telling me this so I have an argument when the Authority questions my judgment."

"I'm telling you this because it's true, and because the throat survives only if both sides understand that breaking it hurts everyone. Not equally—nothing in Centauri is equal—but enough."

"Send me the maintenance dependency analysis. Formally. I want it in the record."

"You'll have it within the hour."

The tugs launched the next morning—three vehicles, each carrying roughly 270 tonnes of processed slag and spent shielding material from the Belanger processing platform, pushing hard on brachistochrone trajectories that would burn 38 of their 40 km/s delta-v budget on the outbound leg alone. Marek watched the launch from Relay Control, where the tracking displays showed the tugs as three bright points pulling away from Alpha's inner stations and arcing toward the distant position of Junction Seven—invisible at this distance, but its thermal signature showed up as a diffuse warm bloom on the infrared monitors, the waste heat of a hub feeding an eleven-terawatt braking campaign into the dark.

Jun stood beside him. "Lien signed the integration authorization twenty minutes ago. Junction Seven's operations team is preparing the thermal coupling infrastructure."

"Before the Authority knows."

"Before the Authority can possibly know. Her authorization, the tug launches, the Durance prep—all of it will be accomplished fact by the time a lightspeed message even reaches Proxima, let alone generates a response."

Marek considered this—the strange, vertiginous quality of acting in a gap between local authority and distant oversight. Everything they were doing was legitimate under the protocols as written. Lien's operational mandate covered thermal management coordination. Alpha's tugs were Alpha's assets, deployed at Alpha's discretion. The Durance injection, once Junction Seven was available, was a scheduling action that fell within normal corridor operations. Each piece, examined individually, was within bounds.

But the whole—the pattern of actions, the cumulative effect, the way local authority was being used to create infrastructure facts that distant authority could not reverse—that was something else. That was what the throat had always been: a system that only functioned because the people closest to it made decisions the people farthest from it would have to live with.

"That's the thing about the sixty-nine-day gap," Marek said. "It doesn't just delay information. It delegates authority, whether anyone intended to delegate it or not. The gap is where the actual decisions get made, by the people who happen to be standing in it."

"Is that a justification or a warning?"

"Both. Intent doesn't survive transit. Only actions do. And actions get interpreted by whoever receives them, in whatever present they're living in. Proxima's Authority will see what we've done. They'll see what Lien authorized. They'll interpret it in a context we can't predict, months from now, and they'll respond in a context we can't imagine. All we can control is whether the actions we take now are the ones we can defend when the interpretation arrives."

They watched the tracking displays in silence for a while. Three bright points crawling toward a thermal smudge, across the 1,800 AU that separated Alpha's stations from the infrastructure that made Alpha possible.

Director Yeun rescheduled the Durance deployment sequence around the tug fleet's absence. The tugs wouldn't return for weeks—limping back on fume-economy thrust after burning their delta-v on the outbound sprint—so the Durance payload modules would need to be pre-positioned using Alpha's two remaining light-duty shuttles, which had never handled loads of that mass class and whose thermal ratings were, in Jun's precise assessment, "aspirational." The entire deployment chain was now contingent on platforms that had been designed for crew transfer and light maintenance runs, operating at the edge of their design envelope, with no margin for error and no backup if anything failed.

This was not a normal operational context.

Eleven days later, the tugs reached Junction Seven and began offloading 780 tonnes of thermal dump mass. The junction's operations crew—a mixed team of Proxima Corridor Authority personnel and Alpha-based thermal conditioning technicians, taking direction from Lien's integration authorization—coupled the slag into the thermal buffer system and began the accelerated cooldown sequence. The junction's radiators continued their steady work, rejecting waste heat at 14 terawatts into the black, while the expendable mass absorbed the buffer overhang and was ejected in controlled thermal dumps—superheated slugs of processed regolith tumbling away from the hub in slow, glowing arcs, carrying stolen heat into trajectories that would never intersect anything important.

Junction Seven's cooldown dropped from nine days to three and a half. Its thermal baseline restored, the hub began routing power to the Tau-facing array.

The Durance window held. Barely.

The Durance launched seventeen days after the crisis began, on margins so thin that Marek didn't sleep for the final forty-eight hours of the injection sequence. The Tau-facing array, fed at full power through a Junction Seven that had been cooled by brute force and institutional improvisation, engaged its beam along the vector toward Tau Ceti—a direction that had nothing to do with Proxima, nothing to do with the corridor extension, everything to do with a future that Alpha was building for itself. The Durance's launch sail caught the beam and began to accelerate, slowly at first, then with the steady, building momentum of an object that would not stop until another beam, at another star, caught it and slowed it down decades from now.

Marek watched from Relay Control until the Durance's tracking signature had stabilized on its corridor trajectory, and then he turned to the other display—the one showing the Halcyon, still decelerating on Relay Four's beam, fed through that same Junction Seven that was now simultaneously supporting the opening phase of the Durance injection on a carefully partitioned thermal budget. Two beams, two directions, one thermal well—the junction managing both loads only because the Durance's early-phase power draw was still ramping up while Relay Four's campaign was winding down, the thermal curves crossing in a window that lasted exactly long enough, and not a day more.

The Halcyon carried its two sleeping Sol advisors toward a system that had changed since they'd closed their eyes, and would change again before they opened them.

Lien was standing in the doorway. He hadn't heard her arrive—or perhaps he had, and had filed it away the way you file away familiar sounds in a space you've occupied too long.

"The Authority will receive my operational report in sixty-two days," she said. "Along with the maintenance dependency analysis, the thermal dump integration logs, and the scheduling protocol framework. They'll have the full picture—or at least, the picture as it existed when I sent it. By the time they respond, the Durance will be months into its transit and the weighted scheduling protocol will have been in operational use long enough to have generated its own precedents."

"And the advisory group?"

"Revival is scheduled for eight days after the Halcyon reaches Proxima's inner system. Estimated time to operational awareness: two to three weeks after that. They'll wake up, observe, evaluate, compose recommendations, and load them onto a Sol-bound comm packet. Four years to reach Sol. Four more for Sol to respond." She paused. "By then we'll all be living in a different reality."

"By then the protocol will be infrastructure," Marek said. "Not policy. Infrastructure. The kind of thing that's harder to change than to maintain, because changing it requires understanding how it works. And understanding how it works requires being here."

"Is that a comment about the advisory group or about the Corridor Authority?"

"Both."

The advisory group would wake up. They would observe. They would evaluate. They would send their recommendations to Sol, which would describe a system that no longer existed by the time anyone read them, proposing solutions to problems that had already been solved or transformed or replaced by new problems that the recommendations could not have anticipated. This was the fundamental condition of authority in Centauri—not that it was wrong, but that it was always describing a past that the present had already outgrown.

And the Corridor Authority on Proxima proper would receive Lien's report and have to decide whether she had acted within her mandate or beyond it, and their decision would be shaped not by what she had done but by its consequences—consequences that would be, by then, accomplished facts woven into the operational fabric of the throat. If the Durance succeeded and the scheduling protocol functioned and the throat continued to operate, her judgment would be validated by the infrastructure itself. If anything failed—if the thermal dump had damaged Junction Seven's buffer systems, if the Durance injection had gone wrong, if the protocol had generated a scheduling conflict that neither side could resolve—then her judgment would be second-guessed by people who had not been present and could not have acted faster.

This was how power worked in Centauri. Not through force or fiat but through the patient accumulation of infrastructure facts—beam time used, thermal margins spent, scheduling precedents established, authority exercised in the gap between local presence and distant oversight—that became, over time, indistinguishable from the physics that governed them. The throat would continue to be shared, and the sharing would continue to be contested, and the contestation would continue to be shaped by the fundamental asymmetry of two systems bound together by a corridor that neither could afford to lose and neither could fully control.

Jun appeared at his shoulder with a fresh coffee bulb. Marek took it. It was neither hot enough nor strong enough, but it was here, which was more than could be said for most things that mattered in Centauri.

"The throat holds," he said, to no one in particular, or perhaps to the corridor extension itself, that fragile chain of relays and beam paths and shared infrastructure stretched across 0.19 light-years of nothing.

The throat holds. For now.