feat(mnemosyne): constellation-aware connection lines

- Strength-encoded opacity: line brightness proportional to blended
  source/target memory strength (0.15-0.7 range instead of flat 0.2)
- Color blending: lines use lerped colors from source/target region colors
- LOD culling: connection lines fade/hide when camera is far (>60 units)
- Toggle API: toggleConstellation() / isConstellationVisible() for UI
- Fix: replaced undefined _createConnectionLine with _drawSingleConnection
  (dedup-aware, constellation-styled single-connection renderer)

Part of #1215

nexus/components/spatial-memory.js

@@ -173,7 +173,9 @@ const SpatialMemory = (() => {
   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
+  const CONNECTION_LOD_DIST = 60; // hide connection lines when camera > this from midpoint
   let _initialized = false;
+  let _constellationVisible = true; // toggle for constellation view
 
   // ─── CRYSTAL GEOMETRY (persistent memories) ───────────
   function createCrystalGeometry(size) {
@@ -318,10 +320,43 @@ const SpatialMemory = (() => {
     if (!obj || !obj.data.connections) return;
     obj.data.connections.forEach(targetId => {
       const target = _memoryObjects[targetId];
-      if (target) _createConnectionLine(obj, target);
+      if (target) _drawSingleConnection(obj, target);
     });
   }
 
+  function _drawSingleConnection(src, tgt) {
+    const srcId = src.data.id;
+    const tgtId = tgt.data.id;
+    // Deduplicate — only draw from lower ID to higher
+    if (srcId > tgtId) return;
+    // Skip if already exists
+    const exists = _connectionLines.some(l =>
+      (l.userData.from === srcId && l.userData.to === tgtId) ||
+      (l.userData.from === tgtId && l.userData.to === srcId)
+    );
+    if (exists) return;
+
+    const points = [src.mesh.position.clone(), tgt.mesh.position.clone()];
+    const geo = new THREE.BufferGeometry().setFromPoints(points);
+    const srcStrength = src.mesh.userData.strength || 0.7;
+    const tgtStrength = tgt.mesh.userData.strength || 0.7;
+    const blendedStrength = (srcStrength + tgtStrength) / 2;
+    const lineOpacity = 0.15 + blendedStrength * 0.55;
+    const srcColor = new THREE.Color(REGIONS[src.region]?.color || 0x334455);
+    const tgtColor = new THREE.Color(REGIONS[tgt.region]?.color || 0x334455);
+    const lineColor = new THREE.Color().lerpColors(srcColor, tgtColor, 0.5);
+    const mat = new THREE.LineBasicMaterial({
+      color: lineColor,
+      transparent: true,
+      opacity: lineOpacity
+    });
+    const line = new THREE.Line(geo, mat);
+    line.userData = { type: 'connection', from: srcId, to: tgtId, baseOpacity: lineOpacity };
+    line.visible = _constellationVisible;
+    _scene.add(line);
+    _connectionLines.push(line);
+  }
+
   return { ring, disc, glowDisc, sprite };
   }
 
@@ -399,7 +434,7 @@ const SpatialMemory = (() => {
     return [cx + Math.cos(angle) * dist, cy + height, cz + Math.sin(angle) * dist];
   }
 
-  // ─── CONNECTIONS ─────────────────────────────────────
+  // ─── CONNECTIONS (constellation-aware) ───────────────
   function _drawConnections(memId, connections) {
     const src = _memoryObjects[memId];
     if (!src) return;
@@ -410,9 +445,23 @@ const SpatialMemory = (() => {
 
       const points = [src.mesh.position.clone(), tgt.mesh.position.clone()];
       const geo = new THREE.BufferGeometry().setFromPoints(points);
-      const mat = new THREE.LineBasicMaterial({ color: 0x334455, transparent: true, opacity: 0.2 });
+      // Strength-encoded opacity: blend source/target strengths, min 0.15, max 0.7
+      const srcStrength = src.mesh.userData.strength || 0.7;
+      const tgtStrength = tgt.mesh.userData.strength || 0.7;
+      const blendedStrength = (srcStrength + tgtStrength) / 2;
+      const lineOpacity = 0.15 + blendedStrength * 0.55;
+      // Blend source/target region colors for the line
+      const srcColor = new THREE.Color(REGIONS[src.region]?.color || 0x334455);
+      const tgtColor = new THREE.Color(REGIONS[tgt.region]?.color || 0x334455);
+      const lineColor = new THREE.Color().lerpColors(srcColor, tgtColor, 0.5);
+      const mat = new THREE.LineBasicMaterial({
+        color: lineColor,
+        transparent: true,
+        opacity: lineOpacity
+      });
       const line = new THREE.Line(geo, mat);
-      line.userData = { type: 'connection', from: memId, to: targetId };
+      line.userData = { type: 'connection', from: memId, to: targetId, baseOpacity: lineOpacity };
+      line.visible = _constellationVisible;
       _scene.add(line);
       _connectionLines.push(line);
     });
@@ -489,6 +538,43 @@ const SpatialMemory = (() => {
     });
   }
 
+  function _updateConnectionLines() {
+    if (!_constellationVisible) return;
+    if (!_camera) return;
+    const camPos = _camera.position;
+
+    _connectionLines.forEach(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 > CONNECTION_LOD_DIST) {
+        line.visible = false;
+      } else {
+        line.visible = true;
+        const fade = Math.max(0, 1 - (dist / CONNECTION_LOD_DIST));
+        // Restore base opacity from userData if stored, else use material default
+        const base = line.userData.baseOpacity || line.material.opacity || 0.4;
+        line.material.opacity = base * fade;
+      }
+    });
+  }
+
+  function toggleConstellation() {
+    _constellationVisible = !_constellationVisible;
+    _connectionLines.forEach(line => {
+      line.visible = _constellationVisible;
+    });
+    console.info('[Mnemosyne] Constellation', _constellationVisible ? 'shown' : 'hidden');
+    return _constellationVisible;
+  }
+
+  function isConstellationVisible() {
+    return _constellationVisible;
+  }
+
   // ─── REMOVE A MEMORY ─────────────────────────────────
   function removeMemory(memId) {
     const obj = _memoryObjects[memId];
@@ -544,6 +630,7 @@ const SpatialMemory = (() => {
     });
 
       _updateEntityLines();
+      _updateConnectionLines();
 
     Object.values(_regionMarkers).forEach(marker => {
       if (marker.ring && marker.ring.material) {
@@ -866,7 +953,7 @@ const SpatialMemory = (() => {
     getCrystalMeshes, getMemoryFromMesh, highlightMemory, clearHighlight, getSelectedId,
     exportIndex, importIndex, searchNearby, REGIONS,
     saveToStorage, loadFromStorage, clearStorage,
-    runGravityLayout, setCamera
+    runGravityLayout, setCamera, toggleConstellation, isConstellationVisible
   };
 })();
 

nexus/mnemosyne/resonance_linker.py

@@ -0,0 +1,22 @@
+
+"""Resonance Linker — Finds second-degree connections in the holographic graph."""
+
+class ResonanceLinker:
+    def __init__(self, archive):
+        self.archive = archive
+
+    def find_resonance(self, entry_id, depth=2):
+        """Find entries that are connected via shared neighbors."""
+        if entry_id not in self.archive._entries: return []
+        
+        entry = self.archive._entries[entry_id]
+        neighbors = set(entry.links)
+        resonance = {}
+
+        for neighbor_id in neighbors:
+            if neighbor_id in self.archive._entries:
+                for second_neighbor in self.archive._entries[neighbor_id].links:
+                    if second_neighbor != entry_id and second_neighbor not in neighbors:
+                        resonance[second_neighbor] = resonance.get(second_neighbor, 0) + 1
+        
+        return sorted(resonance.items(), key=lambda x: x[1], reverse=True)