Lung Index Door

The throat opened onto breath that was not hers.

Eris stopped one pace short of the door because courtesy still mattered underground, even when the symposium had filed its honesty late. The slab was not a slab. It rose and fell—a slow tidal lung cut from mirrored salt and factory glass, each exhale tasting of temper and sealed-lab permission. The seam bore no chisel mark she recognized. Instead, condensation wrote and erased catalog numbers in the exhale: MS-11.6 / OFFSET / WITNESS PENDING.

Her witness statement was still wet on the flats behind her.

The Violet Compass hung grey at her belt—spent honesty, not broken instrument. Eris had walked margin long enough to know the difference. Without violet bearing she would have to navigate by receipt, not needle.

She fanned the tide pack. Salt Signal lay face-up, still warm from the fork. Mirror Stratum answered the lung-door's exhale with a faint double image, as if the card insisted the door breathed for two indexes at once. The blank that had taken ripple-ink at the overlay still showed: OFFSET / BOTH WALKED / MS-11.6.

"I already witnessed," Eris said. "You are asking for a second signature."

The lung-door exhaled. Warmth, then cold—the symposium stumble she had felt as pressure above, now rendered as temperature debt. Someone in a sealed laboratory had opened a listening fork and the flats were billing the expedition for the echo.

Eris pressed her symposium capsule to the breathing seam. Wax from clause seven softened. The door did not open on charter alone—it opened on amendment. Revision B-as-correction-to-A, the throat she had forced the overlay to admit.

She spoke the receipt aloud, because archives underground were as vain as archives in glass towers:

"Revision B is not contraband. It is correction. I witness both indexes walked the same day. Publish that or publish me as perjury."

The lung stilled mid-inhale.

Condensation on the salt wrote a single line beneath the catalog numbers: WITNESS ACCEPTED / LUNG INDEX / MS-11.8.

The door exhaled open.

Beyond lay not a chamber but a duct—glass-throat honest, narrow enough that Eris had to turn sideways and trust the walls not to breathe closed. Mirrored salt faced her on both sides, each reflection a half-beat out of phase: revision A's boots behind her, revision B's boots one pace ahead, the same gait filed on different pages.

Footsteps resumed in phase behind her—Syndicate rhythm, almost courteous—and did not close the distance. Whoever followed had decided witnessing was cheaper than seizure.

Eris walked the duct without lantern. Offset constellations pooled in the glasswork exhale, starlight that was not ratified triad—bearing debt the symposium would have to show its work to explain. At each pool she scratched a tally mark parallel to her margin line, building a chain of witness scratches the lung index could not erase without admitting it had breathed for two catalogs.

The duct ended at a listening fork set in salt like a meridian nail—twin tines of mirrored glass humming at a frequency her gauge-card gutter recognized as unlicensed filament memory, the same stress-line language the card had spoken at the filed-late throat.

Eris set the spent compass against the fork.

Grey needle. No violet left.

But the fork answered anyway—not with bearing, with index. A pulse traveled up the duct, through the lung-door's exhale, back toward the overlay where she had knelt and scratched parallel to both margin lines. The flats were forwarding her witness statement along the amendment throat, the way sealed labs forwarded triad failure when pride finally cost more than correction.

She understood, then, what the lung index was for: not entry, but distribution. The door breathed symposium air so revision B could reach auditors who still pretended revision A was the only chart that had ever walked these flats.

Eris capped her tide pack. She had no compass bearing left and did not need one. The receipt was traveling on its own lung.

Ahead, past the listening fork, the duct opened onto a wider breath—factory temper remembered sideways, the exhale of glassworks she had never visited and did not need to visit to recognize as someone else's parallel index, filed where harbor rumors and salt archives could finally argue in the same room.

She intended to be standing in that room when the symposium answered.

She kept walking.