feat: unify zero-thickness walls

Issue: #306
User-Visible: yes

scripts/config-field-registry.mjs

@@ -203,6 +203,20 @@ export const CONFIG_FIELD_REGISTRY = Object.freeze([
     migration: 'remove the fill token and materialize effective room glow on room edit or explicit optimization',
     compatibility: 'backend and frontend accept the legacy token indefinitely',
   },
+  {
+    id: 'spaces[].open_spans',
+    selector: { path: ['spaces', '*', 'open_spans'] },
+    storage: 'House Plan server config',
+    type: 'Array<{ a: Point; b: Point }>',
+    default: 'unset',
+    level: 'space',
+    ui: 'removed',
+    runtime: 'read-only compatibility projection to cm:0 contour atoms',
+    introduced: 'legacy virtual-boundary model',
+    status: 'migrate-on-write',
+    migration: 'convert covered wall_segments to cm:0 and remove after a structural write, Optimize or import',
+    compatibility: 'accepted only below model v9; canonical v9 rejects it',
+  },
   {
     id: 'spaces[].rooms[].open_to',
     selector: { path: ['spaces', '*', 'rooms', '*', 'open_to'] },
@@ -210,22 +224,36 @@ export const CONFIG_FIELD_REGISTRY = Object.freeze([
     type: 'string[] | null',
     default: 'unset',
     level: 'room',
-    ui: 'replaced by boundary spans',
-    runtime: 'read fallback when explicit open_spans are absent',
+    ui: 'removed',
+    runtime: 'read-only fallback projected to cm:0 when explicit open_spans are absent',
     introduced: 'legacy virtual-boundary model',
     status: 'deprecated-read',
-    migration: 'materialize exact open_spans before geometry changes',
-    compatibility: 'keep reading until every supported config can represent the same geometry losslessly',
+    migration: 'convert the proven shared wall_segments to cm:0 and remove after a structural write, Optimize or import',
+    compatibility: 'accepted only below model v9; canonical v9 rejects it',
+  },
+  {
+    id: 'spaces[].zero_wall_style',
+    selector: { path: ['spaces', '*', 'zero_wall_style'] },
+    storage: 'House Plan server config',
+    type: "'dashed' | 'solid'",
+    default: 'dashed',
+    level: 'space',
+    ui: 'space settings: zero-thickness walls',
+    runtime: 'dashed transmits Glow/sun; solid blocks both without adding a wall body',
+    introduced: 'model v9 / issue #306',
+    status: 'current',
+    migration: 'never materialized implicitly; missing and unknown values read as dashed',
+    compatibility: 'older clients ignore the field and do not understand the unified cm:0 light contract',
   },
   {
     id: 'spaces[].wall_segments',
     selector: { path: ['spaces', '*', 'wall_segments'] },
     storage: 'House Plan server config',
     type: 'Array<{ id: string; a: Point; b: Point; cm: number }>',
-    default: '[] after the first v8 structural write',
+    default: '[] after the first v8 structural write; required in model v9',
     level: 'space',
     ui: 'internal canonical wall identity',
-    runtime: 'authoritative contour-wall identity and thickness in model v8',
+    runtime: 'authoritative contour-wall identity and thickness; cm:0 is a zero-thickness wall in model v9',
     introduced: 'model v8 / issue #282',
     status: 'current',
     migration: 'materialize atomically on a structural write, Optimize or import',

scripts/dev/styles-split.mjs

@@ -14,8 +14,8 @@ const assign = (zone, tokens) => { for (const t of tokens.split(/\s+/)) T[t] = z
 assign('base', ':host .sr-only ha-card .bootveil .toast .empty .spacer');
 assign('plan', `.stage .plan-svg .hp-paper .hp-static-stage .hp-day-cycle-bg .hp-day-cycle-sun .hp-day-cycle-env
   .seg .vertex .pathline .preview .active-axis .active-vertex .physical-hit .physical-chrome .physical-drag
-  .drawwall .drawwall-preview .drawwall-preview-fill .openwall .openwall-preview .wall-repair-preview
-  .wallbody .wallbody-fill .wallthick-hover .griddot .boundary-point
+  .drawwall .drawwall-preview .drawwall-preview-fill .zero-wall .wall-repair-preview
+  .wallbody .wallbody-fill .wallthick-hover .griddot
   .plan-snap-node .plan-snap-line .plan-snap-overlay .hidden-wall-line .hidden-wall-node .hidden-wall-diagnostic
   .room .room-outline .room-hover-fill .room-hover-halo .room-hover-outline .roomlabel
   .rlhandle .rlgear .rlgearbtn .rlname .rlgo

scripts/mutation-gate.mjs

@@ -1494,21 +1494,6 @@ export const MUTANTS = [
         + '    if not _known_optimize_partition(old_partition):',
     }],
   },
-  {
-    id: 'hidden-diagnostic-under-virtual-walls',
-    guard: 'node demo/smoke_plan_snap_overlay.mjs',
-    because: 'hidden wall axes and source endpoints must remain visible above every real and '
-      + 'virtual wall body while staying below transient tool previews (#296)',
-    patches: [{
-      file: 'src/houseplan-card.ts',
-      find: '            ${this._editing ? this._renderOpenWalls(disp) : nothing}\n'
-        + '            ${this._markup ? svg`<g class="hp-editor-only-layer"\n'
-        + '              opacity="${modeVisual?.editorWeight ?? 1}">${this._renderHiddenWallDiagnosticOverlay()}</g>` : nothing}',
-      replace: '            ${this._markup ? svg`<g class="hp-editor-only-layer"\n'
-        + '              opacity="${modeVisual?.editorWeight ?? 1}">${this._renderHiddenWallDiagnosticOverlay()}</g>` : nothing}\n'
-        + '            ${this._editing ? this._renderOpenWalls(disp) : nothing}',
-    }],
-  },
   {
     id: 'atomic-child-thickness-parent-fallback',
     guard: 'npx tsc -p tsconfig.test.json && node scripts/fix-test-build.mjs '
@@ -1640,10 +1625,10 @@ export const MUTANTS = [
   },
   {
     id: 'barrier-cache-never-invalidated',
-    guard: 'node demo/smoke_openwall.mjs',
+    guard: 'node demo/smoke_zero_walls.mjs',
     because: 'кэш барьеров, который не инвалидируется по содержимому, — это свет '
-      + 'сквозь стену, которая уже существует; смок переключает виртуальную границу '
-      + 'и обязан увидеть смену освещённости соседней комнаты',
+      + 'сквозь стену, которая уже существует; смок переключает пунктирную нулевую '
+      + 'стену в сплошную и обязан увидеть смену освещённости соседней комнаты',
     patches: [{
       file: 'src/houseplan-card.ts',
       find: 'if (this._lightBarrierCache?.key === cacheKey) return this._lightBarrierCache.value;',