fix: inherit parent thickness for atomic walls

Issue: #201
User-Visible: yes

demo/smoke_resize_virtual_thick.mjs

@@ -195,6 +195,40 @@ const res = await page.evaluate(async () => {
   out.virtualTJunctionMitred = values.some((x, i) => i % 2 === 0
     && Math.abs(x - (500 + half)) < 1e-6
     && Math.abs(values[i + 1] - (500 - half)) < 1e-6);
+
+  // #201: a fully virtual stretch has no own cm to restore.  Its nearest
+  // solid continuation is one exact 22 cm parent run, atomised at x=600 by a
+  // third room.  Close must read the parent through either child instead of
+  // falling back to the 15 cm draw default.
+  sp().rooms = [
+    { id: 'parent', name: 'Parent', poly: [[0.1, 0.1], [0.9, 0.1], [0.9, 0.5], [0.1, 0.5]], open_to: ['left'] },
+    { id: 'left', name: 'Left', poly: [[0.1, 0.5], [0.3, 0.5], [0.3, 0.9], [0.1, 0.9]], open_to: ['parent'] },
+    { id: 'middle', name: 'Middle', poly: [[0.3, 0.5], [0.6, 0.5], [0.6, 0.9], [0.3, 0.9]] },
+    { id: 'right', name: 'Right', poly: [[0.6, 0.5], [0.9, 0.5], [0.9, 0.9], [0.6, 0.9]] },
+  ];
+  sp().walls = [{
+    key: '0.600000,0.500000@0.0000', cm: 22,
+    a: [0.3, 0.5], b: [0.9, 0.5],
+  }];
+  sp().open_spans = [{ a: [0.1, 0.5], b: [0.3, 0.5] }];
+  delete sp().openings;
+  c._tool = 'boundary';
+  await upd();
+  const atomicParentBefore = JSON.stringify({
+    rooms: sp().rooms, walls: sp().walls, open_spans: sp().open_spans,
+  });
+  const atomicParentCut = c._openCuts()[0];
+  const atomicParentPlan = atomicParentCut && c._planClosedOpenSpan(atomicParentCut);
+  out.atomicParentClosePreviewInherits = atomicParentPlan?.cm === 22;
+  if (atomicParentCut) c._closeOpenSpan(atomicParentCut);
+  await upd();
+  out.atomicParentClosePersistsNeighbourCm = !sp().open_spans
+    && c._intervalCm([100, 500, 300, 500]) === 22;
+  c._undoGeometry();
+  await upd();
+  out.atomicParentCloseUndo = JSON.stringify({
+    rooms: sp().rooms, walls: sp().walls, open_spans: sp().open_spans,
+  }) === atomicParentBefore;
   return out;
 });
 

docs/CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## v1.65.0-beta.4 — 2026-08-19
 
+- Closing a virtual room boundary now inherits the real thickness of an
+  adjacent wall even when another room splits that saved wall into smaller
+  atomic stretches. A 20/22 cm wall therefore no longer receives an accidental
+  15 cm step, while partial thickness spans remain isolated
+  ([#201](https://github.com/Matysh/houseplan-card/issues/201)).
 - Room labels in the Plan editor now keep the same name, Home Assistant Area
   icon and state-row geometry as View, so switching modes no longer shifts a
   carefully positioned label. The icon still opens the Area only in View; in

docs/CHANGELOG.ru.md

@@ -8,6 +8,12 @@
 
 ## v1.65.0-beta.4 — 2026-08-19
 
+- При закрытии виртуальной границы теперь наследуется реальная толщина соседней
+  стены, даже если другая комната разделила сохранённую стену на несколько
+  атомарных участков. Поэтому на стене 20/22 см больше не появляется случайная
+  ступень 15 см, а частичные участки толщины по-прежнему не распространяются
+  дальше своих границ
+  ([#201](https://github.com/Matysh/houseplan-card/issues/201)).
 - Подписи комнат в редакторе Плана теперь сохраняют ту же геометрию имени,
   иконки зоны Home Assistant и строк состояний, что и в Просмотре, поэтому при
   переключении режимов аккуратно выставленная подпись больше не сдвигается.

docs/TESTING.md

@@ -2217,6 +2217,14 @@ require hands on real hardware — they remain for the human pass.
       across a Split boundary: spans owned by different room pairs must stay separate
       [auto: test/open-spans.test.mjs + test/wall-thickness.test.mjs +
       smoke_resize_virtual_thick]
+- [ ] **Atomic child inherits its exact parent on Close (#201)**: let a third
+      room split a non-default exact wall run into atomic solid children, then
+      close a fully virtual collinear neighbour. Preview and persisted masonry
+      inherit the nearest parent's real thickness instead of the 15 cm draw
+      default; Undo restores the virtual span. A partial exact span never leaks
+      onto a longer query, and scale/direction/row order do not change the
+      resolver [auto: test/wall-thickness.test.mjs + test/open-spans.test.mjs +
+      smoke_resize_virtual_thick + mutation-gate].
 - [ ] **Unit + backend**: inset/mitre/bevel, key from either end, degrade,
       rekey, cm↔inches; `walls` schema bounds
       [auto: test/wall-thickness.test.mjs + tests_backend/test_validation.py]

docs/WALL-THICKNESS.md

@@ -185,7 +185,8 @@ atomic rekey after edge/scale; corner Split exterior equality across
 production-scale `0 ↔ 10`, `10 ↔ 20` and `1 ↔ 100` collinear transitions at
 their exact endpoint; full 8-room/25-wall/3-cut virtual-junction resilience,
 ULP-equivalent patch vertices, per-patch failure isolation and record-order
-invariance (#197).
+invariance (#197); exact parent-run thickness inherited by atomic children when
+closing a virtual neighbour, without partial-span leakage (#201).
 Browser: seamless frame; fill not in hatch; m² drops with thickness; a partial
 virtual stretch, its solid thick remainders and Undo move as one real resize;
 the virtual rubber band paints above the real body; sun starts at the room-side

docs/images/screenshots.json

@@ -1,7 +1,7 @@
 {
   "version": 1,
   "fixture": "synthetic-only",
-  "sourceFingerprint": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+  "sourceFingerprint": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
   "captureScriptSha256": "34f2219790d46efd8250e7a1bd829cb8fc0b0547e1260635fefa52407551b41b",
   "command": "npm run build && node demo/docs/capture.mjs",
   "scenarios": {
@@ -13,7 +13,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+      "sourceSha256": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
       "imageSha256": "d36b6f9f8139f31ef73a780c6511a640a26055efd9d7a24c24fd48b1d8379bf0"
     },
     "view-touch": {
@@ -24,7 +24,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+      "sourceSha256": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
       "imageSha256": "358e25ff9984d0fb0c03cfbb848df40c425fdfe64cd5f4f613b1e754ca9d4249"
     },
     "space-create": {
@@ -35,7 +35,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+      "sourceSha256": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
       "imageSha256": "c53db2e5c642a5549c13f3c93a5b359fed69bdb2621bf71a243a877ffcb95e6b"
     },
     "room-contour-close": {
@@ -46,7 +46,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+      "sourceSha256": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
       "imageSha256": "2f13ea645af306eee9cc7c52699c928377b72f412b08c1a3db6beb848ace1b51"
     },
     "plan-context-tray": {
@@ -57,7 +57,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+      "sourceSha256": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
       "imageSha256": "a6c526fede11bc3503fd2384bd4a3f6afa008f481c5c47578f06cae6c81c6f9b"
     },
     "device-editor": {
@@ -68,7 +68,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+      "sourceSha256": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
       "imageSha256": "7c3e25534fc819c45431907616c3d523961505859ee68af27cce2daec9f04fb0"
     },
     "device-display-preview": {
@@ -79,7 +79,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+      "sourceSha256": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
       "imageSha256": "df3a54395c83bffd7a161f1fb3de0143e12e76567535aedf9883873ead74df91"
     },
     "background-editor": {
@@ -90,7 +90,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+      "sourceSha256": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
       "imageSha256": "d7cfe70551d9260169df8efd832e32ed7df99c7f60b55d1fd4a8322bd4c47175"
     },
     "room-card": {
@@ -101,7 +101,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+      "sourceSha256": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
       "imageSha256": "176abba71d41cfb045a33f82a794d9fbb2a5d3c48e6df66e6ec3a8e448311b11"
     },
     "device-info": {
@@ -112,7 +112,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "3425175abf2903733116e8846a9ea0003da0ea7a7a83db5eb85594f789e7c9ed",
+      "sourceSha256": "51c4bdb005b2539779085578bcce5ee1b4b3e3137542ef1aeb440232344c3105",
       "imageSha256": "2199ed88b215bf2bff63bf665028f78b2aa6a92c3032b803931790f2ef071893"
     }
   }

scripts/mutation-gate.mjs

@@ -40,6 +40,19 @@ import { fileURLToPath } from 'node:url';
 // `find` обязан встречаться в файле ровно один раз: патч, который ложится «куда
 // попало», проверяет не то, что объявлен проверять. Это контролирует --check.
 export const MUTANTS = [
+  {
+    id: 'atomic-child-thickness-parent-fallback',
+    guard: 'npx tsc -p tsconfig.test.json && node scripts/fix-test-build.mjs '
+      + '&& node --test --test-name-pattern="exact parent|atomic solid children" '
+      + 'test/wall-thickness.test.mjs test/open-spans.test.mjs',
+    because: 'closing a fully virtual stretch beside an atomised exact parent run must inherit '
+      + 'the real neighbouring thickness instead of silently writing the 15 cm default',
+    patches: [{
+      file: 'src/wall-thickness.ts',
+      find: '  const exact = exactCoveringWall(walls, a, b, pitch, coordScale);',
+      replace: '  const exact = false ? exactCoveringWall(walls, a, b, pitch, coordScale) : null;',
+    }],
+  },
   {
     id: 'stale-space-position-guard-removed',
     guard: 'npx tsc -p tsconfig.test.json && node scripts/fix-test-build.mjs '

src/wall-thickness.ts

@@ -215,7 +215,52 @@ export function thicknessCmAt(
   coordScale = 1,
 ): number {
   const e = lookupWall(walls, a, b, pitch, coordScale);
-  return e && e.cm > 0 ? clampWallCm(e.cm) : 0;
+  if (e && e.cm > 0) return clampWallCm(e.cm);
+  const exact = exactCoveringWall(walls, a, b, pitch, coordScale);
+  return exact ? clampWallCm(exact.cm) : 0;
+}
+
+/**
+ * Lossless parent-run fallback for an atomic child query.
+ *
+ * `lookupWall` intentionally keeps the narrow "one key = one stretch"
+ * contract (AUD-159B6-01).  Closing a virtual span, however, asks about the
+ * atomic solid children around it while persisted exact endpoints may describe
+ * their longer parent run.  Exact endpoints can prove containment without
+ * broadening the ambiguous legacy key-only fallback.
+ */
+function exactCoveringWall(
+  walls: WallEntry[] | null | undefined,
+  a: number[], b: number[],
+  pitch: number,
+  coordScale: number,
+): WallEntry | null {
+  if (!walls?.length) return null;
+  const scale = coordScale > 0 ? coordScale : 1;
+  const queryLen = Math.hypot(b[0] - a[0], b[1] - a[1]);
+  if (queryLen < 1e-12) return null;
+  const queryAngle = segAngle(a, b);
+  const tol = Math.max(pitch * 0.5, 1e-9) * scale;
+  let best: { wall: WallEntry; extra: number; stable: string } | null = null;
+  for (const wall of walls) {
+    if (!(wall.cm > 0)) continue;
+    const span = entrySpan(wall, scale);
+    if (!span) continue;
+    const spanLen = Math.hypot(span[1][0] - span[0][0], span[1][1] - span[0][1]);
+    if (spanLen < 1e-12 || !angleClose(segAngle(span[0], span[1]), queryAngle)) continue;
+    if (distToSeg(a[0], a[1], span[0][0], span[0][1], span[1][0], span[1][1]) > tol
+        || distToSeg(b[0], b[1], span[0][0], span[0][1], span[1][0], span[1][1]) > tol) continue;
+    // A shorter span may sit within endpoint tolerance but cannot prove that
+    // it covers the query.  Keep that tolerance scale-relative, like lookup.
+    if (spanLen + tol < queryLen) continue;
+    const extra = Math.max(0, spanLen - queryLen);
+    const stable = `${wall.key}|${clampWallCm(wall.cm)}|${span.flat().join(',')}`;
+    if (!best || extra < best.extra - 1e-12
+        || (Math.abs(extra - best.extra) <= 1e-12 && stable < best.stable)) {
+      best = { wall, extra, stable };
+    }
+  }
+  return best?.wall || null;
 }
 
 /**

test/open-spans.test.mjs

@@ -95,6 +95,16 @@ describe('open-spans', () => {
     assert.equal(def, DRAW_WALL_DEFAULT_CM);
   });
 
+  it('thicknessOnClose inherits an exact parent run through atomic solid children', () => {
+    const walls = setWallThickness([], [5, 0], [5, 10], 22, pitch);
+    const cm = thicknessOnClose(
+      walls, [5, 4, 5, 6],
+      [[5, 0, 5, 4], [5, 6, 5, 10]],
+      pitch, 1, DRAW_WALL_DEFAULT_CM,
+    );
+    assert.equal(cm, 22);
+  });
+
   it('purgeOpeningsOnSpan removes openings on the stretch', () => {
     const openings = [
       { id: '1', x: 0.005, y: 0.002, angle: 90 }, // on x=5 if scale=1000 → wait normalised

test/wall-thickness.test.mjs

@@ -146,6 +146,35 @@ test('lookupWall finds an entry and thicknessCmAt reads it', () => {
   assert.equal(thicknessCmAt(walls, [0, 0], [1, 1], pitch), 0);
 });
 
+test('thicknessCmAt inherits the narrowest exact parent that covers an atomic child', () => {
+  const parent = setWallThickness([], [0, 0], [10, 0], 20, pitch);
+  assert.equal(thicknessCmAt(parent, [0, 0], [4, 0], pitch), 20);
+  assert.equal(thicknessCmAt(parent, [10, 0], [4, 0], pitch), 20);
+
+  const production = setWallThickness([], [0, 0], [10000, 0], 20, pitch, 1000);
+  assert.equal(thicknessCmAt(production, [0, 0], [4000, 0], pitch, 1000), 20);
+  assert.equal(thicknessCmAt(production, [10000, 0], [4000, 0], pitch, 1000), 20);
+
+  const nested = [
+    ...parent,
+    ...setWallThickness([], [4, 0], [6, 0], 30, pitch),
+  ];
+  for (const walls of [nested, [...nested].reverse()]) {
+    assert.equal(thicknessCmAt(walls, [4, 0], [5, 0], pitch), 30);
+  }
+});
+
+test('thicknessCmAt exact-parent fallback does not leak from partial or unrelated spans', () => {
+  const partial = setWallThickness([], [0, 0], [4, 0], 20, pitch);
+  assert.equal(thicknessCmAt(partial, [0, 0], [10, 0], pitch), 0);
+  assert.equal(thicknessCmAt(partial, [0, 1], [4, 1], pitch), 0);
+  assert.equal(thicknessCmAt(partial, [0, 0], [0, 4], pitch), 0);
+  assert.equal(thicknessCmAt([
+    { key: wallKey([0, 0], [4, 0], pitch), cm: 20, a: ['bad', 0], b: [4, 0] },
+    { key: 'broken', cm: 20, a: [0, 0], b: [0, 0] },
+  ], [0, 0], [2, 0], pitch), 0);
+});
+
 // ------------------------------- units --------------------------------------
 
 test('cm ↔ field: metric stays cm, imperial is inches', () => {