feat(mnemosyne): entity resolution lines (#1167)

Draw translucent lines between related crystals in 3D:
- Same entity: thin blue line (opacity 0.35)
- Related entities: thin purple dashed line (opacity 0.25)
- LOD: lines hidden when camera > 50 units from midpoint
- Distance-based opacity fade
- Deduplication (lower ID → higher ID only)
- Cleanup on memory removal

Closes #1167

nexus/components/spatial-memory.js

@@ -133,6 +133,9 @@ const SpatialMemory = (() => {
   let _regionMarkers = {};
   let _memoryObjects = {};
   let _connectionLines = [];
+  let _entityLines = [];      // entity resolution lines (issue #1167)
+  let _camera = null;         // set by setCamera() for LOD culling
+  const ENTITY_LOD_DIST = 50; // hide entity lines when camera > this from midpoint
   let _initialized = false;
 
   // ─── CRYSTAL GEOMETRY (persistent memories) ───────────
@@ -252,6 +255,10 @@ const SpatialMemory = (() => {
       _drawConnections(mem.id, mem.connections);
     }
 
+    if (mem.entity) {
+      _drawEntityLines(mem.id, mem);
+    }
+
     _dirty = true;
     saveToStorage();
     console.info('[Mnemosyne] Spatial memory placed:', mem.id, 'in', region.label);
@@ -298,6 +305,77 @@ const SpatialMemory = (() => {
     });
   }
 
+  // ─── ENTITY RESOLUTION LINES (#1167) ──────────────────
+  // Draw lines between crystals that share an entity or are related entities.
+  // Same entity → thin blue line. Related entities → thin purple dashed line.
+  function _drawEntityLines(memId, mem) {
+    if (!mem.entity) return;
+    const src = _memoryObjects[memId];
+    if (!src) return;
+
+    Object.entries(_memoryObjects).forEach(([otherId, other]) => {
+      if (otherId === memId) return;
+      const otherData = other.data;
+      if (!otherData.entity) return;
+
+      let lineType = null;
+      if (otherData.entity === mem.entity) {
+        lineType = 'same_entity';
+      } else if (mem.related_entities && mem.related_entities.includes(otherData.entity)) {
+        lineType = 'related';
+      } else if (otherData.related_entities && otherData.related_entities.includes(mem.entity)) {
+        lineType = 'related';
+      }
+      if (!lineType) return;
+
+      // Deduplicate — only draw from lower ID to higher
+      if (memId > otherId) return;
+
+      const points = [src.mesh.position.clone(), other.mesh.position.clone()];
+      const geo = new THREE.BufferGeometry().setFromPoints(points);
+      let mat;
+      if (lineType === 'same_entity') {
+        mat = new THREE.LineBasicMaterial({ color: 0x4488ff, transparent: true, opacity: 0.35 });
+      } else {
+        mat = new THREE.LineDashedMaterial({ color: 0x9966ff, dashSize: 0.3, gapSize: 0.2, transparent: true, opacity: 0.25 });
+        const line = new THREE.Line(geo, mat);
+        line.computeLineDistances();
+        line.userData = { type: 'entity_line', from: memId, to: otherId, lineType };
+        _scene.add(line);
+        _entityLines.push(line);
+        return;
+      }
+      const line = new THREE.Line(geo, mat);
+      line.userData = { type: 'entity_line', from: memId, to: otherId, lineType };
+      _scene.add(line);
+      _entityLines.push(line);
+    });
+  }
+
+  function _updateEntityLines() {
+    if (!_camera) return;
+    const camPos = _camera.position;
+
+    _entityLines.forEach(line => {
+      // Compute midpoint of line
+      const posArr = line.geometry.attributes.position.array;
+      const mx = (posArr[0] + posArr[3]) / 2;
+      const my = (posArr[1] + posArr[4]) / 2;
+      const mz = (posArr[2] + posArr[5]) / 2;
+      const dist = camPos.distanceTo(new THREE.Vector3(mx, my, mz));
+
+      if (dist > ENTITY_LOD_DIST) {
+        line.visible = false;
+      } else {
+        line.visible = true;
+        // Fade based on distance
+        const fade = Math.max(0, 1 - (dist / ENTITY_LOD_DIST));
+        const baseOpacity = line.userData.lineType === 'same_entity' ? 0.35 : 0.25;
+        line.material.opacity = baseOpacity * fade;
+      }
+    });
+  }
+
   // ─── REMOVE A MEMORY ─────────────────────────────────
   function removeMemory(memId) {
     const obj = _memoryObjects[memId];
@@ -317,6 +395,16 @@ const SpatialMemory = (() => {
       }
     }
 
+    for (let i = _entityLines.length - 1; i >= 0; i--) {
+      const line = _entityLines[i];
+      if (line.userData.from === memId || line.userData.to === memId) {
+        if (line.parent) line.parent.remove(line);
+        line.geometry.dispose();
+        line.material.dispose();
+        _entityLines.splice(i, 1);
+      }
+    }
+
     delete _memoryObjects[memId];
     _dirty = true;
     saveToStorage();
@@ -342,6 +430,8 @@ const SpatialMemory = (() => {
       }
     });
 
+      _updateEntityLines();
+
     Object.values(_regionMarkers).forEach(marker => {
       if (marker.ring && marker.ring.material) {
         marker.ring.material.opacity = 0.1 + Math.sin(now * 0.001) * 0.05;
@@ -652,6 +742,11 @@ const SpatialMemory = (() => {
     return _selectedId;
   }
 
+  // ─── CAMERA REFERENCE (for entity line LOD) ─────────
+  function setCamera(camera) {
+    _camera = camera;
+  }
+
   return {
     init, placeMemory, removeMemory, update,
     getMemoryAtPosition, getRegionAtPosition, getMemoriesInRegion, getAllMemories,