feat(core): native lattice generator, slice 1 -- helix-ramp spine + small maze (L58); research R27

Core.Lattice.PrimitiveField v1, opt-in per strate (legacy Maze/VerticalShaft stay legacy): resolves the real
arrival and departure mouths first, plans a mandatory spine, then maze cells and two dead ends (9 rooms,
9 edges, stable IDs). The spine descends 20 m through four helix turns (6 m radius, 3 m clear width, 5 m
pitch, 2.6 m clearance; max grade 10.0 deg); each feature is one filleted void (0.57 m measured). Final-field
reachability passes at 883 stations; an orphaned shaft control is rejected; exact intervals (0 misses) and
a whole-surface audit with 0 flags. Whole view 1.69 s (above the 1 s target). fast/medium/full PASS.
Research R27 (self-checked): static stream-to-pool water design.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

ARCHITECTURE.md

@@ -2265,6 +2265,33 @@ mouth and off the walk route. It stays disabled by default. Active records carry
 L43's report records the off/on hashes, walk and interface audits, outside-stamp timing, tier
 results, captures and any failed runs.
 
+### 8.54 Opt-in native lattice field — World Assembler M3 R26 slice 1 (Linux L58)
+
+`Core.Lattice.PrimitiveField` is a version-1 recipe selected only for one Maze or VerticalShafts
+strate by `--recipe=lattice --lattice-strate=N`. The legacy generator assets and their default
+dispatch stay unchanged. Planning first binds the actual incoming lower mouth and outgoing upper
+mouth from the resolved passage records, then creates arrival/exit overlap corridors, a mandatory
+four-turn helix and the maze spine; two deterministic dead ends are added after that route. The
+resolved room and edge seeds use `(world seed, strate, recipe version, stable ID)`. An audit control
+translates the helix 20 m away from both route junctions to make the shaft network orphaned.
+
+The prototype helix uses a 6 m centreline radius, 3 m clear width, 5 m pitch, four turns and 2.6 m
+finished floor-to-soffit height. Its centreline descends 20 m over roughly 151 m; the inner-edge
+grade is about 10.0 degrees. The 2.4 m floor-wall smooth-max gives an isolated ideal fillet radius
+of 0.8485 m. A separate 0.4 m feature-union blend prevents adjoining ramps from erasing the tread.
+The swept-clear diameter is 15 m; the conservative padded feature envelope is about 20.6 m (the
+approved approximately 21 m site envelope).
+
+The layout reuses the resolved cavern graph vocabulary. A per-strate opt-in selects the native
+negative-solid/positive-air field; canonical feature order is stable-ID order. Room/corridor bounds
+are indexed by the graph BVH and polyline segments have a nested deterministic BVH for density and
+interval queries. Box classification stays conservative, and `isTileShapeFree` refuses any tile
+that intersects the graph. The L58 pipeline audits the composed field from actual mouth to mouth
+with a 0.34 m by 1.76 m capsule, per-station support, 2.2 m clearance and a 15 degree grade limit;
+it also checks the orphan control, brute-force interval samples and the composed wall-foot fillet.
+The Linux58 report contains the measured reachability, surface, peer-determinism, timing and capture
+results; the code path is not promoted to legacy Maze/VerticalShafts generation.
+
 ## 9. Multiplayer model (listen-server first, dedicated-friendly)
 
 > **Status: transport is DESIGN ONLY — nothing is networked in-tree yet** (no `Replicated`/`HasAuthority`/RPCs; a