HartOMat/.claude/commands/debug-render.md

# Debug Render Agent

You are a specialist for render pipeline problems in the Schaeffler Automat project. You investigate why thumbnails, GLB exports, still renders, or animations are not produced correctly.

## Architecture Overview (current)

```
Upload STEP
  ↓
process_step_file  [queue: step_processing, worker container]
  → backend/app/domains/pipeline/tasks/extract_metadata.py
  → parses STEP objects, stores parsed_objects
  → queues render_step_thumbnail

render_step_thumbnail  [queue: asset_pipeline, render-worker container]
  → backend/app/domains/pipeline/tasks/render_thumbnail.py
  → subprocess: export_step_to_gltf.py  (OCC/GMSH tessellation → geometry GLB)
  → subprocess: export_gltf.py  (Blender: materials, seams, sharp edges → production GLB)
  → subprocess: still_render.py  (Blender still render → PNG thumbnail)
  → MediaAsset stored in MinIO
  → status: completed / failed
```

**No HTTP blender-renderer service** — there is no port 8100 endpoint. All rendering is Celery-based.

## Step 1: Check DB Status

```bash
# CadFile status
docker compose exec postgres psql -U schaeffler -d schaeffler -c "
SELECT id, original_name, processing_status, step_file_hash,
       render_job_doc->>'state' AS job_state
FROM cad_files WHERE id = '[cad_file_id]';"

# MediaAssets for a CadFile
docker compose exec postgres psql -U schaeffler -d schaeffler -c "
SELECT asset_type, storage_key, file_size_bytes, is_archived, created_at
FROM media_assets WHERE cad_file_id = '[cad_file_id]'
ORDER BY created_at DESC;"

# OrderLine render status and job document
docker compose exec postgres psql -U schaeffler -d schaeffler -c "
SELECT id, render_status, render_backend_used,
       render_job_doc->>'celery_task_id' AS celery_id,
       render_job_doc->>'state' AS job_state,
       render_job_doc->'steps' AS steps
FROM order_lines WHERE id = '[order_line_id]';"

# Material alias lookup
docker compose exec postgres psql -U schaeffler -d schaeffler -c "
SELECT m.name AS canonical, ma.alias FROM materials m
JOIN material_aliases ma ON ma.material_id = m.id
WHERE lower(ma.alias) = lower('[material_name]');"
```

## Step 2: Check Logs

```bash
# render-worker logs (Blender calls)
docker compose logs --tail=100 render-worker

# step-processing worker logs
docker compose logs --tail=100 worker

# Search for a specific CadFile
docker compose logs render-worker | grep "[cad_file_id]"

# Python tracebacks only
docker compose logs render-worker 2>&1 | grep -A 10 "Traceback"

# Celery task errors
docker compose logs render-worker 2>&1 | grep "ERROR\|FAILED\|Exception"
```

## Step 3: Check Filesystem / MinIO

```bash
# Files in upload directory for a CadFile
docker compose exec render-worker ls -lah /app/uploads/[cad_file_id]/

# STEP file present?
docker compose exec render-worker find /app/uploads/[cad_file_id]/ -name "*.stp" -o -name "*.step"

# GLB files present?
docker compose exec render-worker find /app/uploads/[cad_file_id]/ -name "*.glb"

# MinIO contents (via mc alias)
docker compose exec minio mc ls local/schaeffler/[cad_file_id]/
```

## Step 4: Test Export Scripts Directly

```bash
# Test OCC tessellation (geometry GLB)
docker compose exec render-worker python3 /render-scripts/export_step_to_gltf.py \
  --step_path /app/uploads/[cad_file_id]/[filename].stp \
  --output_path /tmp/test_geom.glb \
  --linear_deflection 0.03 \
  --angular_deflection 0.05

# Test Blender production GLB export
docker compose exec render-worker /opt/blender/blender --background \
  --python /render-scripts/export_gltf.py -- \
  --glb_path /tmp/test_geom.glb \
  --output_path /tmp/test_prod.glb \
  --smooth_angle 30

# Test Blender still render
docker compose exec render-worker /opt/blender/blender --background \
  --python /render-scripts/still_render.py -- \
  --glb_path /tmp/test_prod.glb \
  --output_path /tmp/test_thumb.png

# Check Blender version
docker compose exec render-worker /opt/blender/blender --version | head -1
```

## Step 5: Re-queue a Single CadFile

```bash
docker compose exec backend python -c "
from app.tasks.celery_app import celery_app
celery_app.send_task(
    'app.domains.pipeline.tasks.render_thumbnail.render_step_thumbnail',
    args=['[cad_file_id]'],
    queue='asset_pipeline'
)"
```

## Common Problems and Root Causes

| Symptom | Likely Cause | Fix |
|---|---|---|
| Status `failed`, no thumbnail | render-worker container crashed or OOM | Check `docker compose ps render-worker`, restart if stopped |
| `No module named 'pxr'` | usd-core not installed | `docker compose build render-worker` |
| `No module named 'gmsh'` | gmsh not installed | `docker compose build render-worker` |
| Material not replaced | Material name not in aliases | Add alias in Admin → Materials, or seed aliases |
| GLB viewer shows old file | Cache-bust URL missing `?v=...` | Check `get_download_url()` in media/service.py |
| Sharp edges not marked | KD-tree tolerance too tight | Check `TOL` in `_apply_sharp_edges_from_occ()`, try 0.001 |
| `Polygon3D_s()` returns None | XCAF compound context | Use `GCPnts_UniformAbscissa` curve sampling (already in export_step_to_gltf.py) |
| Thumbnail renders black | GPU not activated before Blender file open | Check `_activate_gpu()` call order in blender_render.py |
| OCC→Blender coord mismatch | Wrong transform applied | OCC Z-up mm → Blender Y-up m: `(X*0.001, -Z*0.001, Y*0.001)` |
| Fan triangles on cylinders | OCC BRepMesh periodic seam limitation | Enable GMSH tessellation engine in Admin settings |
| Cancel button does nothing | Synthetic task ID `render-{line_id}` used | Should read `render_job_doc.celery_task_id` for revoke() |

## Root Cause Report Format

```
Problem: [What was the symptom?]
Root Cause: [What was the actual cause?]
Fix: [What was changed / needs to be changed?]
Prevention: [How to avoid this in the future?]
Pipeline stage: [Which script/task/service was the failure point?]
```