The Bug

File: packages/phoenix-event-display/src/managers/three-manager/import-manager.ts
Function: ImportManager.loadGLTFGeometryInternal (Lines 409-445)

When loading GLTF geometries, cloned geometries are collected in materials[key].geoms arrays, merged into a final geometry, but intermediate geometries are never disposed. This leaves orphaned WebGL buffers in GPU memory.

Identical pattern to the leak fixed in phoenix-objects.ts (commit ad79b44) but missed in import-manager.ts.

The Fix

Summary: After BufferGeometryUtils.mergeGeometries(), added disposal loop for all intermediate geometries in the materials object.

Files changed: 1 (import-manager.ts)
Validation: All 166 tests pass + linting clean

Why This Matters

• GPU memory leaks on every GLTF load → browser crashes after multiple detector geometry loads
• Physics workflows broken (ATLAS/CMS detector visualization, control rooms, conferences)
• Silent failure—no errors, just gradual memory exhaustion until OOM
• Real production impact—common workflow with complex detector geometries

How to Verify

See import-manager.ts diff in this PR. To test locally:

1. Load any detector GLTF geometry multiple times
2. Monitor GPU memory via browser DevTools > Performance > Memory or chrome://gpu
3. Before: Memory grows unbounded
   After: Memory stays stable after each load

Impact

Eliminates crashes during long-running detector visualization sessions. Matches our existing cleanup pattern from phoenix-objects.ts. Zero render behavior change—just proper Three.js resource management.