fix: junction limits are honest at the boundaries (#331)

Six normative cuts, both mirrors symmetric (spec revision 3):

- §2.1 node keys quantise to 1e-7 with the repository's canonicalisation
  formula (sign·floor(|v|·1e7+0.5)/1e7, -0 normalised) — toFixed(6) keys
  split one node into two on floating debris and produced two false П4
  refusals on a legitimate resize (reproduced: -1e-8 vs 0). Node pairs
  within 2e-7 of each other (raw coordinates) are ONE node, and the
  node-to-wall incidence uses the same quantum.
- §2.2 a ~0° wedge IS a violation: two rays leaving a node the same way are
  a duplicated or overlaid wall (a butt joint yields 180°, never 0°) — the
  worst degenerate case was invisible while 0.5° was refused.
- §2.3/§2.4 the wall run is an iterative edge walk over the collinear
  component: no recursion (10 000 atoms answered, not RangeError), no
  silently dropped fork (the old .find lost every branch but the first),
  O(E) by construction, and collinearity is measured against the BASE
  segment's axis so an arc of 0.9°-per-atom pieces cannot pose as one wall.
- §2.5 an exception while judging the CANDIDATE refuses the write with the
  junction.limit_check_failed toast (fail-closed, as the #278 guard); the
  baseline branch stays fail-open by design and the smoke proves the
  asymmetry by breaking only the second call of the deterministic pair.
- §2.6 the python mirror narrows its except on the candidate side only:
  a genuine migration bug (TypeError) surfaces as an honest WS error, while
  a previous-side bug keeps the wide "no baseline" fallback — the two AC6
  cases pin the asymmetry so swapped sides turn a unit red.

Parity fixtures gain the new boundary classes (debris node, duplicate wall,
collinear fork); four new mutants pin the filter, the key precision, the
dropped branch and the fail-open hole.

Issue: #331
User-Visible: yes

docs/CHANGELOG.md

@@ -2,6 +2,12 @@
 
 ## Unreleased
 
+- The wall-junction checks are honest at the boundaries: false refusals on
+  microscopic coordinate noise are gone, a wall duplicated along one line is
+  now visible, very long walls no longer crash the check, and an internal
+  check error refuses the write instead of waving it through
+  ([#331](https://github.com/Matysh/houseplan-card/issues/331)).
+
 - Saving and resizing large plans no longer freezes Home Assistant: the
   junction-limit checks (#329) are orders of magnitude faster — the heavy
   part left the server's main loop, repeated work is cached

docs/CHANGELOG.ru.md

@@ -8,6 +8,12 @@
 
 ## Не выпущено
 
+- Проверки стыков стен стали честными на границах: ложные отказы на
+  микроскопических погрешностях координат устранены, дубль стены по одной
+  линии теперь виден, очень длинные стены не роняют проверку, а внутренняя
+  ошибка проверки больше не пропускает запись
+  ([#331](https://github.com/Matysh/houseplan-card/issues/331)).
+
 - Сохранение и изменение размеров на больших планах больше не подвешивают
   Home Assistant: проверка ограничений стыков (#329) ускорена на порядки —
   тяжёлая часть ушла из основного цикла сервера, повторные вычисления

docs/USER-GUIDE.md

@@ -401,6 +401,10 @@ filler segment that compensates a thickness step is legal as long as the whole
 wall is longer than 20 cm. A T-joint (a wall end landing on the middle of
 another wall) is not forbidden by the distance rule.
 
+If the check itself cannot run (an internal error), the change is not saved
+either — a "The junction check could not run" toast appears: the editor
+never waves a write through on faith.
+
 The check runs on writes only. An already saved plan is never re-judged:
 migration, import and backup restore are never blocked, and an edit that does
 not touch the offending element passes as usual. The refusal appears where you

docs/USER-GUIDE.ru.md

@@ -436,6 +436,10 @@ Undo оптимизации.
 стена целиком длиннее 20 см. Т-стык (конец стены упирается в середину чужой)
 правилом дистанции не запрещён.
 
+Если проверку выполнить не удалось (внутренняя ошибка), изменение тоже не
+сохраняется — появляется тост «Проверку стыков выполнить не удалось»:
+редактор никогда не пропускает запись «на авось».
+
 Проверка работает только на записи. Уже сохранённый план не переоценивается:
 миграция, импорт и восстановление из бэкапа не блокируются никогда, а правка,
 не трогающая нарушающий элемент, проходит как обычно. Отказ виден там, где вы

docs/images/screenshots.json

@@ -2,7 +2,7 @@
   "version": 1,
   "fixture": "synthetic-only",
   "chromium": "151.0.7922.34",
-  "sourceFingerprint": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+  "sourceFingerprint": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
   "captureScriptSha256": "ce2e9542fed9dade3085be87d16f69adb2ac8262893ad78ad966b1b9673f2983",
   "command": "npm run build && node demo/docs/capture.mjs",
   "scenarios": {
@@ -14,7 +14,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+      "sourceSha256": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
       "imageSha256": "0ca982495a7749907c48ebbddfd089c54385a4347f79f64e94af2c5a8d5c03eb"
     },
     "view-touch": {
@@ -25,7 +25,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+      "sourceSha256": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
       "imageSha256": "1c8e28ff34736b936ba7c9ec047d1da27aaf6fbb01411155f2d5c05282c02c41"
     },
     "space-create": {
@@ -36,7 +36,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+      "sourceSha256": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
       "imageSha256": "a55b463055a565892ca139014e314a8f63fb5301c87fff2e48d7e69210fe9b6c"
     },
     "room-contour-close": {
@@ -47,7 +47,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+      "sourceSha256": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
       "imageSha256": "dfad9a27371cfa397a3fd8dce7005f42d24649743f5322105ee894067d3a9f16"
     },
     "plan-context-tray": {
@@ -58,7 +58,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+      "sourceSha256": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
       "imageSha256": "b75f348c632296da5c2fc142d53df613f757e1516acac315be50f5b4557729cc"
     },
     "device-editor": {
@@ -69,7 +69,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+      "sourceSha256": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
       "imageSha256": "6b9cd281450e7782cff292f11efc58d227bedd0df86afc3be987feb2edec9dc3"
     },
     "device-display-preview": {
@@ -80,7 +80,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+      "sourceSha256": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
       "imageSha256": "6f628abe6b89d7c4b352e6d73ac0b126526f6fdba5927bb774c5b884e484ca19"
     },
     "background-editor": {
@@ -91,7 +91,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+      "sourceSha256": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
       "imageSha256": "a1d1a905f1410f73231d2ea5d1dfbd8ae79c2fe8b0a79cff87ebb977ac7a3103"
     },
     "room-card": {
@@ -102,7 +102,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+      "sourceSha256": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
       "imageSha256": "48a5685039a5e0de2a28190d857b193c86e2e63606e3c7a8c40fc9d2b190da4e"
     },
     "device-info": {
@@ -113,7 +113,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "dbac4a84d0eb558e66066f5072363977ff4a78c0a032e6f2b9a5d0848cd20f0f",
+      "sourceSha256": "7143ec154b3a4340ba7c23c47bc6f72fa68b81a03980a44b0eedc3f043f7305b",
       "imageSha256": "29a342811aaedaebc54ba337792d60cb454a7cf4c3063b210f6c4bafe0a4d87b"
     }
   }

docs/specs/329-junction-limits.md

@@ -56,6 +56,11 @@
   чужой стены остаётся T-стыком и валидно — правило про «почти-касание» без
   инцидентности). Порог абсолютный, в сантиметрах, и НЕ зависит от
   `cell_cm` пространства.
+- **Точность границ (#331):** ключ узла квантуется к 1e-7 формулой
+  канонизации (`sign·floor(|v|·1e7+0.5)/1e7`, −0 → 0); пары точек ближе
+  2e-7 (сырые координаты) — один узел, а не «почти-касание»; клин ровно 0°
+  (дубль/наложение стены) — нарушение П1 с actual≈0; длина П3 меряется по
+  коллинеарной (±1° к БАЗЕ прогона) компоненте связности одной толщины.
 - **П5. Просвет комнаты:** после вычета тел стен внутренняя область комнаты
   непуста и её площадь ≥ **25 см²**. Порог абсолютный и не зависит от
   `cell_cm`.