These terms place the [Encounter And Mechanism Placement Inventory](/Hold%20The%20Flood/Encounter%20And%20Mechanism%20Placement%20Inventory)'s crowds in physical rooms; scale figures are that page's. "Widened" below reserves space.

- **Source volume.** A backing space that physically holds bodies: a ward wing, duct, loft or store. It is geometry owned by its host, not a room: the astronaut never enters it and it carries no action. If later layout makes one enterable with its own action, it counts as a room under the rule above and the room count rises.

- **Closing early or late.** Closing a source's access before its release commits prevents that release and gives lasting safety and access. The closure preview counts that source's actual unpaid marks in still-uncommitted bands, rather than promising a fixed loss for every seal. Earned marks, queued Tunes and partial progress remain until home; sealing is not itself a growth award. Combat Rules owns the detailed growth and milestone rules. A physical seal completed after commitment resolves the stage at once, without waiting for the peak. Either way, bodies already through still need clearing or separation. P01's held shutter and P03's dogged-open shutter follow their own rows.

- **Reuse.** A module shape carries no population. Only the hosts in the first table below carry sources. Another room may receive a conserved group only through an explicitly mapped walking route; reuse alone never populates refuge or evidence space.

- **Population placement.** Before an expedition begins, a mapped finite group may already have walked from its named unsealed source to its standing positions along an open route. Those bodies are deducted from the source, never copied. Its approach warning and commitment occur when the band wakes into the player's route. During play, further arrivals physically emerge from shown apertures or cross visible neighbouring thresholds after warning. Load, re-entry, retreat, waiting and efficient fighting never repeat initialization.

| **R02 Cargo Turn** (E01; with R03) | From R01's threshold: the entry lane, the board and part cradle at the inside corner, the waist-high rack at the bend and, past it, the second lane ending at the patient-bay shutter with P01's floor frame and preview lamps in front. Both lanes are widened for a standing crowd (20–40); the bend stays the choke. | **Patient-bay ward**, a backing volume on the rigid R02/R03 assembly. The noisy final fastener or a completed Caller call releases its stage (40–60) through the shutter, across the frame and round the bend. **Seal:** P01's completed manual dog hand-cycle with the shutter across that lane; the dog sits beside the frame, reachable before it. A shutter held by the board or by the Fork Relay (the splitter) only suppresses the stage while held, and an undogged shutter returns neutral on withdrawal or death. | Hold the bend with the rack breaking one lane; install Fork so the board holds rack and shutter together, or carry it and fight the open lane. R03's fastener work is visible across the fixed throat. **Retreat:** R03→throat→entry lane→R01, never crossing the frame or the shutter lane and never depending on shutter state. | Fixed throat and conduit, releases in both rooms, the no-Fork selector path, R03's fasteners and bridge identity. The standing crowd is not a stage. |

| **R08 First Local Latch Hall** (E03, later variant only) | First lesson: one Clampcrawler in a quiet hall, count lamp empty. Later-expedition variant: the count silhouette of the occupied holding volume behind the opaque alarm-only shutter at the end of the branch P03's frame intersects. A side holding apron between that shutter and the centre island is widened for the later crowd (20–40). | **Holding volume**, reached only through the closed opaque shutter, with no mutual sight. A completed P03 alert opens the route; cutting the exposed lead before commitment prevents the stage; a cut after commitment neither closes the route nor recalls the crowd. **No seal:** P03's persistent commit dogs the shutter open, so this stage resolves only by clearing. A dogged-open shutter stays open and excludes the closed-holding variant; it is never closed again to stage a crowd. | Island cover and opposed-face sightlines; the latch work position sits inside the Crawler's arc while the side step and R09 retreat lie outside it. The apron's lane never takes the side step or blocks the network-side release. **Retreat:** R08→R09. | Introduction-seen bit set on entry to the first lesson; no creature on a retry within the same expedition; both-side releases; no second shutter or latch. |

| **R17 Jammed Pressure Approach** (E06; with R20) | From the near threshold: the long lane, both offset pillars, the far threshold into R20, the marked blank panel under the far lamp, the side gallery along one wall with the Flanker pack in it and, between the pillars, two ward doors, one in each wall, with their locks. The lane is widened around the second pillar between the doors. | **Open-local-source pass: two side wards.** The Flanker-only approach comes first, down the visible gallery, before the wards are disturbed; it is standing opposition, not a release stage. Once the player is mid-hall the wards release one physical stage (40–80 through the hall). For ordinary growth, the standing Flankers and the two ward portions are three visible pressure bands, with a Break Mark preview at the gallery approach and each ward door. Fresh expeditions renew these local groups only through their viable approach and still-unsealed doors. With both wards sealed, Trace A2 instead places two R35-owned standing bands of 20–30 each in the long lane; the local groups do not renew. The locks are mid-hall too, so throwing them seals the stage after its release commits rather than preventing it. **Seal:** throw both ward-door locks as completed acts; each sits on the entry side of its door, reachable from pillar cover. | Meet the Flankers from the first pillar; move pillar to pillar; use the long lane as a firing line. Completed cutter work at the marked panel opens a narrow two-way local service passage from R17's near side to its existing far threshold into R20. Take the long lane outward for its bands, or use the passage as a bypass and safer return. **Work beyond:** R20's valve and caps, with Siphon a special pressure at the valve rather than another stage. **Retreat:** the near threshold, visible from the far end. | R17's long route and permanent local passage remain, with no added room, source, objective or station-joining face and no short-rescue qualification. R20 has no source: creatures use the shown walking thresholds under the relevant route mapping, two pillars stay between tether line and valve, and caps stay on different quarters with the dry outer arc. |

| **R24 Transfer Service Gallery** (E07 apertures) | From the R15 leg in Arrangement B: the bollard, R22's booth and its pair down one leg, the approach to R23's bay down the other, the closable service recess, three feeding hatches in the ceiling above the legs near their mouths and three dog wheels on the bollard apron. R21 cannot be seen from here. | **Transfer-gallery loft**, one backing volume over the gallery. Its stage releases through all three hatches when R23's corrective pair is operated or a capture of it is committed (30–60 through the placement); looking at or recording R21's or R22's clean pair releases nothing. Arrivals walk the legs toward the work. **Closure:** dog each hatch from the apron. With all three dogged before the release commits, nothing comes; growth and milestone consequences follow Combat Rules; after commitment, dogging the last open hatch seals and resolves the stage at once. | Bollard cover; each leg is a funnel; dog the retreat leg's hatch first. **Work:** framing angles. **Retreat:** the leg the astronaut entered by. | All three legs stay walkable for records and continuation. The abort recess lies under no hatch, and its door is separate from the dogs, Aster's outside lock at R22 and the transfer machinery. |

| **R28 Regulator Gallery** (E09) | From the approach at the panel end: panel and reply socket, four rack aisles with plates and tells, the fan flank, the Grid rail between pull face and fan flank with ceramic bypass and clamps visible from the protected mark, the grille at the far end of the fourth aisle and the ceiling hatch above the socket. The cross-aisle before the panel and the rear service walk are widened for circulation. | **Rear rack store** behind the fourth-aisle grille: 30–60 enter, cross the rear walk and come down all four aisles. **Ceiling maintenance space** above the socket: a completed Caller call releases a second stage through its hatch; cutting the alarm first prevents it but does not recall bodies already moving. **Seals:** the grille by a pull rod at the fourth aisle's panel end; the hatch by a chain beside the socket; both independent of the alarm lead and the reply. | Aisles as firing lines; fan shelter and flank; lure a rail impact; walk ceramic. **Work:** pull R4, observe the line and test the matching R3 B plate from the protected marks. **Retreat:** the approach threshold. | Nothing depends on R29 or R30; neither volume stores a plate; closures never replace pulling or testing; A face and releases. |

| **R27 Thermal Exchange Room** | Mara's clean abort apron with its local tell, core release and R face. M10's gantry fitting belongs to R14 only. |

| **M02 Bent Freight Turn — R02** | L-shaped cargo aisle with two lanes wide enough for a standing crowd. The entry lane runs from the threshold past the service board and part cradle at the inside corner; a waist-high rack at the bend obscures but does not hide the second lane, which ends at a feeding shutter from a host-owned backing volume. Board, removable part cradle and shutter view share one exposed work position, and the retreat runs back along the entry lane without crossing the second lane or depending on the shutter. | Makes installing/reclaiming Fork compete with holding two cued lanes and a released crowd. Its only placement is the opening Freight Split/Cargo Turn; later freight decoration must not be called this module unless it preserves the two-lane board choice, the separate retreat and recovery access. |

| **M04 Split Service Junction — R06, R10, R11, R24, R38** | Three-leg T junction with a central fixed bollard, two visible branch mouths and one shallow service recess. A worker at the recess yields the centre and can be approached from either branch. The base form has no feeding aperture. A host adds a source only where its row says so—a side-wall grille (R11) or hatches above its legs (R24)—and then keeps all three legs walkable, widens only the bollard apron and puts the closure controls on that apron. | R06 supplies the pace-bay approach and Ivo abort recess without containing the belt, R10 supplies a controlled signature refusal, R11 makes the R-3 side lane one leg rather than a long escort, R24 gives transfer records distinct viewing angles, and R38 is the second-clamp flank. R06, R10 and R38 carry no source. The module supplies a readable choice of lanes, not a permanent relationship among whatever rooms currently occupy its branches, and reuse creates no population. |

| **M08 Refuge/Recovery Vestibule — R12, R16, R37** | Small two-door pressure space with a closable inner door, visible gauge and a control reachable from both sides. It has standing room for recovery but no hidden continuation. | R12 is the stocked R-3 abort refuge, R16 is the `TAAN` stair-only comparison, and R37 contains the first iris clamp and a recoverable retreat. These uses differ by rescue, language and mechanism work. A vestibule is counted here; no attached panel or cupboard becomes another room. |

| **M11 Cable Junction — R15** | Cross-shaped cable room with the heavy cable main terminating at a labelled bank while a pump main continues through. An open wall panel reveals a crawl edge; a transparent rail separates one visible pressure lane from the record position. A cable-duct grille sits in the same wall as the crawl panel, on the pressure-lane side of the rail post, and feeds that lane behind the rail gate; its closure lever is on the record side of the post, and closing it leaves the crawl open. | Hosts builder-run comparison, wall-access case, Thermal Lens, visitor continuation mark, A/B/address evidence and the placement-5 Veil/Bolt relation. Removing Lens chills only its exchanger. The crawl may block and never promises its historical far bay is currently reachable; the grille is never a route. |

| **M15 Balance Gallery — R25** | Broad gallery centered on a neutral line, fixed rib and occupied maintenance stirrup. Breath Bank draw lane, Phase-Balance chamber and cap control are visible from the entry; waiting Pressers are visible before commitment. Two feeding mouths in the outer walls, away from both walking thresholds, open onto a widened outer floor; the paired plates stay flush with it and open along their outer edge, so bodies crossing toward the astronaut can walk onto them. | Hosts placement 8/setpiece A and one exchanger-core checkpoint. Durable cap/pin work changes later traversal. The gallery can be overpowered or crossed with cover/timing; it adds no reactive population and is not a generic arena shell. Widening the floor does not enlarge the plates. |

| **M19 Clinical Comparison Bay — R19** | Shielded two-tray treatment fixture faces a pressure-annex refuge. Active and physical-bypass feeds are simultaneously visible; the commissioning-card sleeve and tissue-record viewer are outside the exposure shield. | Hosts the controlled equivalent culture patches, profile card, active/bypass capture, later Yeva refuge variant and mechanism slot 11. Its cultures are not Mara's rack or Cycler sample. Interruption preserves only completed tray observations; isolation cannot reconstruct a missed live comparison. |

| **M22 Pressure-Receiver Vault — R36** | Central iris and empty vessel face the entry; two side openings lead to separately counted clamp rooms. Gauge, inward/outward selectors, reply face and retreat boundary are visible before commit. | Hosts objective 11, mechanism slot 10, language convergence, trapped strip and setpiece B's final work. Direct selector or two-clamp equalisation reaches the same hand-cycle. The closed iris never hides its only recovery control. It has no feeding aperture; its side openings are walking passages only. |

| **M24 Synchronization Gallery — R34** | Three-face gallery around a test plinth. Each face accepts a local test pulse; one reversible machine state visibly maps its input family to a different output while a separate roster display reports joined/discovered/anonymous counts. | Hosts mechanism slot 12 and the late converter insight. It diagnoses only current local transformations and join membership; it does not import journal records, reveal unseen names/routes or latch anything. Mode persists; walking latches remain separate. |

| **R04 Intake Marked Wall — M06 — O1/chain L2** | Builder-cut wall-access string beside a pressure door and matching blank panel. Record mark, material and closed condition without assuming a duct. | Compare with R15's open crawl and R26's standing passage; later choose R17's marked bypass test. | **A/R** faces with interior releases. Capture persists; panel/door work is separate. No mark reveals the current neighbour behind the wall. No feeding aperture; the panel is never a crowd hatch. |

| **R08 First Local Latch Hall — M06 — O3, encounter 3, mechanism 3** | Two observed faces, wall-fixed charged diagnostic cradle, Triage Relay and Clampcrawler operator arc. Attempt one valid or refused join, then walk to the network-side release. The first lesson is quiet; only a later-expedition variant fills the holding volume behind its opaque alarm-only shutter. | A later wrong occupied bridge face can be recovered using this learned mechanical pattern. The record also helps reinterpret R40's separated walk/junction and isolation controls. | **A/B** faces. Join/checkpoints persist; cradle charge does not, and population follows the encounter rule. Both-side releases are mandatory and mismatch spends no pulse. |

| **R10 Collar Service Spur — M04 — O3** | Quiet third leg exposes one incompatible outward/outward signature and a safe inspection angle; it is the objective's controlled refused case, not another mechanism. | Later Foundry/Archive opposition gives the old refusal larger network meaning. | **R** face, interior release and no hidden source or M04 source variant. Capture persists; compatibility with a future neighbour must be observed anew. |

| **R11 R-3 Approach — M04 — O4, encounter 4** | Central bollard and three walking legs—ship, rescue and onward exploration—form the single contested junction on an eligible R-3 route. A Flanker pack comes along the exploration leg while a Presser river pours from the quarantine wing through a grille in that leg's side wall. Rescue begins only once the walked, prepared route is quiet or separated. Closing the grille stops arrivals but leaves what already came through. | A later visit with Arc removed changes local counterplay while leaving route/refuge work intact. The same module's other branch never becomes a hidden second junction. | **A** face. A completed grille closure persists; population follows the encounter rule. Closing the grille removes no leg. Only an actually walked current route can qualify. |

| **R16 TAAN Stair Vestibule — M08 — O5** | Stair-only terminating space under the single run `TAAN`; player records that a third builder string can name a different primary end. | Corrects a two-case overfit without proving translation; its pressure vestibule geometry later contrasts with rescue use of M08. | **R** face and reachable release. Capture persists. Stair ends here and hides no free upper room. |

| **R18 Sealed Receiving Section — M18 — O6** | Dorn refuge; verified side route, committed direct-hoist alternative, far-bay `OSH·b` receiving fitting, destination drawer/card and exposed non-reversing ratchet. | Comparing ratchet/card with R13 wall impression narrows one transfer order and changes testimony without naming a passenger. | **B/R** faces. Direct opening persists even if its route fails verification; side checkpoints persist. Rescue waits for a walked short route. Fork carries control only; hoist supply provides motion. |

| **R22 Receiving Supply Booth — M17 — O7** | Second complete transfer pair, receiving-fitting token in the utterance body slot, and Aster's later refuge variant. After Sent she may request the reachable personnel lock. | Narrows pair direction and later shows why a ledger is not a passenger list. Locking changes one convenience without closing the other objective threshold. | **A/R** faces outside the refuge door; one current short route and abort point required. Lock/record/survivor states persist separately. |

| **R25 Balance Gallery — M15 — O8, encounter 8/setpiece A, mechanisms 7–8** | Bellback preview, visible Pressers, Breath Bank, Phase-Balance neutral line, fixed rib/stirrup, persistent cap/pin, two feeding mouths in the outer walls and a widened outer floor from which bodies can walk onto the plates. One checkpoint helps free the thermal exchanger core. | With Nozzle/advanced rig the same pressure can be overpowered; low-power timing remains. Completed cap removes one draw side, changing revisit geometry. | **A/B** faces, protected control and retreat. Cap/pin/core state persists; mechanism phase does not; mouth closures persist and population follows the encounter rule. The sealed-mouth variant uses the R35 allocation through R26 in Trace A2. No reactive success wave. |

| **R27 Thermal Exchange Room — M10 — O8/O10** | Exchanger core release and local cooling fixture show the fourth ship assembly as separate from portable Nozzle. Its pressure apron can be Mara's counted clean abort place only when stocked and on the verified R26 route. A proposed second ordinary walking threshold, away from the exchanger release, cooling fixture, R face and clean abort apron, meets R35's existing entry only in Trace A2's arrangement. Live pressure through it must be cleared or separated before the apron qualifies as a clean abort. Optional A/B plate is redundancy. | Empty housing on revisit confirms installation did not duplicate the core; pump-room similarity gains a different service meaning. | **R** face, reachable release and no hidden room. The added walking threshold supplies no network signal or rescue shortcut; its unjoined external relation becomes historical after a shift. Core, plate and stocked checkpoint persist under their owners. This room hosts retrieval, not the ship-side readiness report. No source: M10's gantry fitting belongs to R14. |

| **R29 Plate Service Stack — M20 — O9** | Optional current adjacency to R28 offers empty labelled sleeves and a wider safe staging surface for a plate already removed from its rack; it neither creates nor stores an indispensable plate by default. | Supports recovery/organisation after an invalid reply and distinguishes exact object location from “known plate.” If not adjacent, the player uses R28's own surfaces and R29 waits as a separate lead. | **B/R** faces with lower network release. Any deliberately placed plate identity/location persists; shelf labels are not translation. No duplicate appears and no control crosses rooms. |

| **R31 Foundry Block — M10 — O12** | Familiar terminating-machine geometry emits blue-double outward at its free service face; local work demonstrates direction without declaring this a language token. | Earlier pump/cable evidence encourages inspecting which main actually ends; the result reinterprets M10 as geometry, not purpose. Current B-output adjacency to R32's distinct B-output face produces the named failed join. | **B-output** face and interior release. Direction capture persists, current adjacency does not. No extra power or death makes two outputs compatible. No source. |

| **R33 Imaging Exchange — M21 — O12, special connection challenge 1** | Immutable A-input and R-output faces are simultaneously inspectable; the fixed exchanger is **A→R**, with no reverse or selectable mode, as linked in [Mechanical Interfaces And Opening Quantities](/Hold%20The%20Flood/Mechanical%20Interfaces%20And%20Opening%20Quantities). | Old captures distinguish this fixed transform from R34's reversible mode and from merely carrying two static families. A wrong occupied face can be released, but a physical join alone does not prove signal flow. | **A-input/R-output** plus walking release faces. Join state persists; an actual diagnostic pulse still requires current power and compatible oriented inputs. |

| **R35 Receiver Vault Approach — M07 — O11, encounter 10/setpiece B entry** | Widened central span, two pillars, Siphon radius, Shutterback shelter angle, Caller, two sealable side-wall mouths and a far-wall hatch for a second stage are visible before commit. Choose selector lane, fan flank or clamp route. Trace A2 allocates a new proposed 220–370 finite total from the existing side-mouth volumes, preserving 80–150 at once here after 140–220 migrate along the route. | Earlier O6/O9 lessons turn the same threats into a combined work decision; cutting alarm creates a known quiet window. | **B** face and visible retreat. Cut lead and mouth/hatch closures persist; fan/tether state follows encounter rules. The far-wall hatch sits beside R36's opening, and closing it never blocks that opening. The long approach is not rescue geometry. |

| **R37 East Clamp Refuge — M08 — O11** | First mechanical equalisation clamp, gauge and hard retreat space outside the closed iris. Complete one clamp and withdraw. | A later reachable visit resumes at the second clamp without regenerating the first; familiar refuge geometry becomes mechanical recovery, not survivor shelter. | **A** face and two-side release. Clamp checkpoint persists, pressure reading is current. This counted room is one of the two side alcoves, not a free fixture. |

| **R40 Isolation Coupling Hall — M06 — O11/O12/story 2/4, mechanism 13** | Separated walking-latch controls, profile coupling, live tell and approach-side isolation release occupy one room within the compact core assembly. Re-seat, leave, reopen or postpone while the game runs. | R08's two-face lesson distinguishes latch from signal state; if R40 is seen first, later R08 makes recovery geometry interpretable on return. Isolation breaks the live mixed-profile signal but not joins or ordinary revival. | **A/B** assembly-external faces outside the coupling. Isolation/live-feed/captures/joins persist independently. R36-side release is always reachable once the iris opens; no isolation state may maroon R39 or exempt either room from inclusion. No source. |

| **8 later part sources** | Fork R02; Stride R05; Arc R13; Thermal Lens R15; Impact Dynamo R20; Salvage Cycler R23; Vector Nozzle R26; Capacitor R28. The four starter parts begin aboard. Each source is one object identity with a stated removal consequence. |

| **13 placed mechanisms** | 1 Triage Relay R02; 2 Carousel R05; 3 Triage Relay R08; 4 Carousel R15; 5 Breath Bank R20; 6 Resuscitation Grid R23; 7 Breath Bank R25; 8 Phase-Balance R25; 9 Resuscitation Grid R28; 10 iris/two-clamp assembly R36–R38; **11 clinical profile comparator R19**; **12 reversible converter/roster R34**; **13 reversible core-isolation coupling R40**. The SMALL band's sample has 12 mechanism slots; core isolation is a thirteenth. Iris, comparator, converter and isolation are objective mechanisms distinct from the five reusable trap families. |

| **Language II chain 3** | Three complete transfer cases R21, R22, R23; `OSH·a` continuation R15 and far-bay `OSH·b` receiver R18. A traversal result is an evidence state, not another site. |

In any later eligible arrangement for Dorn, R18's side route must be walked while the direct boundary remains sealed. Choosing the direct hoist opens it persistently; only after the astronaut walks the newly exposed route and finds it short may rescue proceed. Finding an extra junction leaves the opening committed and Dorn waiting; a separately verified current side route is the alternative.

R01's outer threshold meets **R14**, whose floor threshold meets **R15**. R15's arms lead back to R14, on to R11 and on to **R24**; its crawl is a test, not a route. R24's other two legs reach **R22** and **R23**, and R23's second external face, a plain B threshold, meets **R21**'s B face, so R21 is reached only through R23. The player records builder mains and visitor transfer pairs, visits R08 for the first latch, and uses gauges plus those predictions at R17/R20. In this arrangement R-3 is reachable only through **R14→R15→R11→R12→R13**: two exposed junctions lie between airlock and refuge, and R12's ship-side abort path is not current. The R-3 person remains waiting. A bearing, a photographed wall string and knowledge of the old route cannot compress it, and no staged refuge chain appears. The player pursues other objectives until a later arrangement yields a genuinely short walked route.

The first objective-12 lesson can be a direct failed adjacency: R31's **B-output** meets R32's separate **B-output**, so the opposed arrows refuse before latching; R32's R-input is visible elsewhere on that same room and does not rescue this face mismatch. R34 later demonstrates only its own reversible A↔B mode. Comparing that local behavior with R26's recorded Decontamination forward/reverse observation supports a possible converter sequence, not an automatic route.

Both traces follow a living return without a room shift. Temporary upgrades and unchosen offers ended aboard; carried property, permanent work and knowledge remain. The new expedition renews combat populations and regular-growth opportunities through viable sources and routes. A **mouth** is a feeding aperture; a **release stage** is a finite sourced crowd whose resolution changes pressure; a **work stage** is a physical step on a mechanism or objective, with its own checkpoint and warning rules. Major-milestone rewards follow Combat Rules rather than automatically attaching to every resolved release.

**Route.** R01→R11→R17→R20→R25. R11's rescue leg remains R12→R13; R17's existing far threshold meets R20's B face, and R20's A face meets R25. There is no extra ship exit.

**Checks.** *Walking:* each step uses one current threshold: R01→R11's ship leg; R11's exploration leg→R17's near threshold; R17's far threshold→R20's B face; R20's A face→R25's approach threshold at its A face. *Rescue:* R01→R11→R12→R13 is unchanged, with one contested junction. Mara's route to R26 crosses R11, R17, R20 and R25, so her rescue waits in this arrangement; Dorn and later Yeva stay unclaimed. *Discovery orders:* the build-first player uses R17's long route and R20's gauges before any language; a player holding R04's marked-wall capture can choose the cutter panel instead; R14/R15 records reinterpret R20's destinations whenever they arrive. Breath Bank is met at R20 before R25, matching the Encounter inventory's assumption that its warning is learned at P05. *Boundary:* E08's withdrawal crossing is R25's threshold toward R20.

**Checkpoint.** The rescue expedition closed R11's quarantine-wing grille and cleared the bodies already inside, stocked R12, captured R13's wall log, and brought the R-3 survivor aboard with the airlock closed: Sent. On the earlier ward-hall visit, the astronaut fought through R17 without permanently locking its wards. R04's marked-wall capture made the panel an informed cutter test. Completed cutter work opened R17's narrow two-way service passage from its near side to its existing far threshold into R20. Returning alive kept this arrangement and every permanent change, while ending temporary power.

**Fresh pressure.** R11's closed grille sends no new bodies. Sound and movement on the exploration leg warn of the fresh Flanker band in R17's visible side gallery; alerted Flankers can follow through the shown near threshold. Both still-unsealed wards hold fresh Pressers and release through their own doors. The gallery approach and each ward door show one band preview. The long lane retains two pillars, its two hall-side locks and one physical ward-release stage of 40–80; the standing pack plus two ward portions are three growth bands, not three new releases.

**Outward choice.** With the starting rig, meet the Flankers from the first pillar, then move along the long lane. Breaking the pack and both ward bands banks one ordinary Tune before R25. A queued Tune and partial progress survive taking another choice or retreating within this expedition; [Combat Rules](/Hold%20The%20Flood/Combat%20Rules) owns the detailed queue and thresholds. The player can take a choice during the journal's full pause or keep fighting. Throwing the ward locks stops their access, not bodies already through; each seal previews the actual uncommitted marks it would prevent. The local passage is also available outward, forgoing these bands rather than granting their growth. R25 retains its no-upgrade baseline.

**Work and climax.** Earn quiet by clearing or separating the arrived bodies, then inspect the panel and its lamp/crew-name sightline. R20 has no source: only real, visible followers from R17 plus the existing Glass Siphon can apply creature pressure there. Its Bank caps, regulator-core assembly, Dynamo and source counter retain their own work and property rules. At R25, the two unsealed mouths announce finite bands. The mouth commitment and Bellback answer are remembered in either order, and the gallery shows which fact has occurred. Leaving the locked cone, sheltering at the rib through its wave, catching it with a faced Barrier, interrupting the unfinished brace by displacement, or defeating Bellback can supply the answer. When both facts exist, transformation ready appears once while later crowd remains. No immunity or replacement creature protects the milestone. Caps and rib pins remain physical work; Nozzle and the exchanger core remain in R26–R27.

**Return and next visit.** The completed R17 passage provides the local return shortcut; it does not automatically qualify any survivor route. Going home ends the temporary climb again. R11's seal and the passage remain, and fresh bands can return through R17/R25 sources that are still viable. R20's Bank phases warn again from neutral unless a cap was closed. This trace covers that explicit open-ward/open-mouth configuration. Trace A2 covers one all-local-seals variant below; neither trace establishes renewal for arbitrary seal combinations or changed external neighbours.

**Checkpoint.** A living return after E05. R14's gantry hatch was dropped and R15's rail group cleared during that expedition. Both builder runs and the A/B/address plates are captured, the Boltspitter was defeated, and the Lens was carried home. P04's first clamp is cut but its final detent is not locked.

**The next expedition.** R01→R14 across its floor: the stair landing is quiet and the hatch is closed. R14→R15: the rail gate stands open, and P04 warns from neutral again because its detent is unlocked. The player crosses between sweeps using the cool bays. New-expedition population placement must respect the closed R14 hatch and use the still-available approaches; the previous clearance does not preserve an empty R15 forever. R15's R11 arm leads towards R-3 by a route with two exposed junctions, so that rescue still waits. R15's third arm opens onto R24.

**Next sourced encounter.** From R24's entry leg the player sees the bollard, three closed hatches above the legs with dust sifting from the occupied **transfer-gallery loft**, three dog wheels on the apron, the closable recess, R22's booth down one leg and the approach to R23's bay down the other. The loft supplies E07's release stage. It releases only when R23's corrective pair is operated or a capture of it is committed; looking at or recording a clean pair releases nothing. *Knowledge-led choice:* R14 and R15's address plates point to R23's third workstation as the test that matters. The player can first slip along R23's receiving floor past its Veilbearer and Boltspitter to R21 and read the clean pair, then come back to the corrective test knowing which direction to expect. At the apron they choose: dog all three hatches before starting to prevent the release, or leave them open and clear the released crowd or dog the hatches afterward. These choices change pressure and access; their growth and milestone consequences follow Combat Rules rather than a guaranteed choice for stage resolution.

**Baseline without upgrades.** Walk the ceramic strips; use the Boltspitter's locked line to lure one rail impact; wait out the discharge; frame from cover, since R15 showed that a veil invalidates targets. Dog the hatches first, or step back to the apron to dog them once the release has come, and clear or slip past what landed. The retreat runs R23→R24→R15.

**Beyond.** R21 is a dead end in this arrangement: its one face is the threshold from R23, and its clean pair has no stage. R22's booth is next to the apron. A later Aster rescue there would need her to be the non-first host, R24 stocked, E07 quiet or separated and a walked one-junction route. Further crowd sources in this arrangement lie off this branch: R17's side wards, R28's rack store and ceiling space, and R35's mouths. On another expedition, renewed crowds must fit the surviving open routes and permanent hatch states. P04 still warns unless locked. The full renewal mapping for this branch remains to be designed.

No playable room may be permanently isolated. Each room has at least one threshold face with an inside/network-side release. A growing connection must extend from the ship-rooted network or merge a fully walkable island through a release reachable after the merge. A join occupies two specific placed faces and persists without power; converter mode and diagnostic reach are separate states. Releasing one mistaken seam leaves other joins, machine modes, room work and current adjacency intact until the next shift.

R13, R19, R22, R18, R26 and R05 keep rescue refuge doors separate from join faces: connecting their room exterior does not open the refuge, move a survivor or certify a rescue route. **One further clearance is required at each eligible rescue host (pending owner decision):** a survivor-operable retreat line must physically exist from every committed segment to the scene's counted abort room — R06, R12, R24 or R27, the four already allocated — with two-sided or survivor-side controls, and that abort room must carry a local closure tell readable only at its own control. Nothing is transmitted to the ship. A host that cannot supply this is not eligible to begin a crossing. This adds no room, module or refuge to the counts. R39 behind the iris becomes eligible only through the physically opened R36 passage, and R40's isolation never removes its walking threshold. Optional evidence, removed part sources and rooms behind intervention remain included even if their live signal or fixture function is absent. A room's only release may never sit behind its own closed boundary, a critical face may never be buried with no network-side control, and a story choice may never delete a room from the roster.

The Synchronization roster may state 40 anonymous total identities, discovered versus joined, but exposes no unseen names, routes or faces. A physically joined room remains counted when diagnostic power is lost. The inventory therefore makes completion inspectable while accepting the spoiler that hidden rooms exist. The final shift algorithm must preserve stable identities and joins, respect compact mechanism boundaries, make every unjoined room eligible for some arrangement and never promise the next arrangement.

Reduce the sample to **22 modules / 36 rooms** by removing **M21 Fixed Conversion Exchange**, merging **M03 Glazed Control Cell** into an expanded M02 opening/control module, and deleting **R07 Navigation Service Room, R30 Reply Observation Niche, R33 Imaging Exchange and R37 East Clamp Refuge**. R03 becomes the second M02 placement rather than referring to a deleted definition.

- Move R33's required fixed A→R exchanger into a separately labelled channel on R34 while retaining R34's reversible A↔B mode. The network remains potentially connectable, but one room now carries two transformation behaviors and loses the clearest fixed-versus-reversible comparison.

Every essential part, assembly, language/story record, rescue and objective retains a named host, and all 13 placed mechanisms remain, but the reduction sacrifices recovery-space variety, one strong reusable control-room contrast and the late network's fixed-versus-reversible transformation discovery. It requires re-review of setpiece B geometry, R34 cue density and the connection graph.

**Accepted costs.** Forty room identities still require forty distinct state/revisit briefs and later layout work. Multi-room encounters and the iris need careful boundary ownership. Seven rescue-host variants across six rooms increase arrangement constraints. Publishing a 40-room roster exposes a known hidden count. Twelve rooms first designed for small fights now reserve receiving floors, apertures and closures; that is real layout work, and it risks making discovery rooms look alike. Renewed populations and growth must fit routes altered by permanent seals; the R17 passage and both representative routes still need later geometry and experience validation. The sealed route also costs a proposed second R27 threshold and a larger finite 220–370 R35 source allocation. R20 and R23 each need a second face. Three signature families, a reversible converter, Decontamination mode and one fixed converter may still be too much network notation—or too little late-puzzle depth. Zero added rooms depends on future geometry fitting every named refuge, fixture and release inside these counted rooms.

- Placement of the selected regular fighting growth and larger horde milestones, following the current Combat Rules proposal.

- Renewal across other permanent-seal and joined-room configurations; the two mapped R17 routes do not establish every source capacity or shifted layout.