diff --git a/backend/app/domains/rendering/tasks.py b/backend/app/domains/rendering/tasks.py
index 713ba11..92ccd09 100644
--- a/backend/app/domains/rendering/tasks.py
+++ b/backend/app/domains/rendering/tasks.py
@@ -57,7 +57,6 @@ def render_still_task(
     output_path: str,
     engine: str = "cycles",
     samples: int = 256,
-    stl_quality: str = "low",
     smooth_angle: int = 30,
     cycles_device: str = "auto",
     width: int = 512,
@@ -94,7 +93,6 @@ def render_still_task(
             output_path=Path(output_path),
             engine=engine,
             samples=samples,
-            stl_quality=stl_quality,
             smooth_angle=smooth_angle,
             cycles_device=cycles_device,
             width=width,
@@ -162,7 +160,6 @@ def render_turntable_task(
     output_name: str = "turntable",
     engine: str = "cycles",
     samples: int = 64,
-    stl_quality: str = "low",
     smooth_angle: int = 30,
     cycles_device: str = "auto",
     width: int = 1920,
@@ -207,10 +204,18 @@ def render_turntable_task(
     scripts_dir = Path(os.environ.get("RENDER_SCRIPTS_DIR", "/render-scripts"))
     turntable_script = scripts_dir / "turntable_render.py"
 
-    # GLB generation via OCC (replaces STL intermediary)
-    linear_deflection = 0.3 if stl_quality == "low" else 0.05
-    angular_deflection = 0.3 if stl_quality == "low" else 0.1
-    glb_path = step.parent / f"{step.stem}_{stl_quality}.glb"
+    # GLB generation via OCC — deflection from admin settings (scene_linear/angular_deflection)
+    from app.config import settings as app_settings
+    from sqlalchemy import create_engine as _create_engine, text as _text
+    from sqlalchemy.orm import Session as _Session
+    _db_engine = _create_engine(app_settings.database_url_sync)
+    with _Session(_db_engine) as _s:
+        _rows = _s.execute(_text("SELECT key, value FROM system_settings")).fetchall()
+        _sett = {r[0]: r[1] for r in _rows}
+    _db_engine.dispose()
+    linear_deflection = float(_sett.get("scene_linear_deflection", "0.1"))
+    angular_deflection = float(_sett.get("scene_angular_deflection", "0.1"))
+    glb_path = step.parent / f"{step.stem}_thumbnail.glb"
     if not glb_path.exists() or glb_path.stat().st_size == 0:
         occ_script = scripts_dir / "export_step_to_gltf.py"
         occ_cmd = [
diff --git a/backend/app/services/render_blender.py b/backend/app/services/render_blender.py
index 0f761c8..9b6cb9e 100644
--- a/backend/app/services/render_blender.py
+++ b/backend/app/services/render_blender.py
@@ -15,17 +15,13 @@ from pathlib import Path
 logger = logging.getLogger(__name__)
 
 
-def _glb_from_step(step_path: Path, glb_path: Path, quality: str = "low") -> None:
-    """Convert STEP → GLB via OCC (export_step_to_gltf.py, no Blender needed).
-
-    quality: "low" → coarser mesh (~0.3 mm deflection, fast)
-             "high" → finer mesh (~0.05 mm deflection, slower)
-    """
+def _glb_from_step(step_path: Path, glb_path: Path) -> None:
+    """Convert STEP → GLB via OCC (export_step_to_gltf.py, no Blender needed)."""
     import subprocess
     import sys as _sys
 
-    linear_deflection  = 0.3  if quality == "low" else 0.05
-    angular_deflection = 0.5  if quality == "low" else 0.2
+    linear_deflection  = 0.3
+    angular_deflection = 0.5
 
     scripts_dir = Path(os.environ.get("RENDER_SCRIPTS_DIR", "/render-scripts"))
     script_path = scripts_dir / "export_step_to_gltf.py"
@@ -71,7 +67,6 @@ def render_still(
     height: int = 512,
     engine: str = "cycles",
     samples: int = 256,
-    stl_quality: str = "low",
     smooth_angle: int = 30,
     cycles_device: str = "auto",
     transparent_bg: bool = False,
@@ -94,9 +89,13 @@ def render_still(
     denoising_use_gpu: str = "",
     mesh_attributes: dict | None = None,
     log_callback: "Callable[[str], None] | None" = None,
+    usd_path: "Path | None" = None,
 ) -> dict:
     """Convert STEP → GLB (OCC) → PNG (Blender subprocess).
 
+    When usd_path is provided and the file exists, the GLB conversion step is
+    skipped and Blender imports the USD stage directly (--usd-path flag).
+
     Returns a dict with timing, sizes, engine_used, and log_lines.
     Raises RuntimeError on failure.
     """
@@ -116,15 +115,20 @@ def render_still(
 
     t0 = time.monotonic()
 
-    # 1. GLB conversion (OCC — replaces cadquery STL)
+    # 1. GLB conversion (OCC) — skipped when usd_path is provided
     glb_path = step_path.parent / f"{step_path.stem}_thumbnail.glb"
+    use_usd = bool(usd_path and usd_path.exists())
 
     t_glb = time.monotonic()
-    if not glb_path.exists() or glb_path.stat().st_size == 0:
-        _glb_from_step(step_path, glb_path, quality=stl_quality)
+    if use_usd:
+        logger.info("[render_blender] using USD path: %s", usd_path)
+        glb_size_bytes = 0
     else:
-        logger.info("GLB local hit: %s (%d KB)", glb_path.name, glb_path.stat().st_size // 1024)
-    glb_size_bytes = glb_path.stat().st_size if glb_path.exists() else 0
+        if not glb_path.exists() or glb_path.stat().st_size == 0:
+            _glb_from_step(step_path, glb_path)
+        else:
+            logger.info("GLB local hit: %s (%d KB)", glb_path.name, glb_path.stat().st_size // 1024)
+        glb_size_bytes = glb_path.stat().st_size if glb_path.exists() else 0
     glb_duration_s = round(time.monotonic() - t_glb, 2)
 
     # 2. Blender render
@@ -142,12 +146,14 @@ def render_still(
         env["EGL_PLATFORM"] = "surfaceless"
 
     def _build_cmd(eng: str) -> list:
+        # Pass "" as glb_path when using USD — blender_render.py reads --usd-path instead
+        glb_arg = "" if use_usd else str(glb_path)
         cmd = [
             blender_bin,
             "--background",
             "--python", str(script_path),
             "--",
-            str(glb_path),
+            glb_arg,
             str(output_path),
             str(width), str(height),
             eng, str(samples), str(smooth_angle),
@@ -165,7 +171,11 @@ def render_still(
             denoising_input_passes or "", denoising_prefilter or "",
             denoising_quality or "", denoising_use_gpu or "",
         ]
-        if mesh_attributes:
+        if use_usd:
+            cmd += ["--usd-path", str(usd_path)]
+            if mesh_attributes:
+                logger.debug("[render_blender] usd_path active — mesh_attributes ignored")
+        elif mesh_attributes:
             cmd += ["--mesh-attributes", json.dumps(mesh_attributes)]
         return cmd
 
@@ -283,7 +293,6 @@ def render_turntable_to_file(
     height: int = 1920,
     engine: str = "cycles",
     samples: int = 128,
-    stl_quality: str = "low",
     smooth_angle: int = 30,
     cycles_device: str = "auto",
     transparent_bg: bool = False,
@@ -300,9 +309,12 @@ def render_turntable_to_file(
     rotation_x: float = 0.0,
     rotation_y: float = 0.0,
     rotation_z: float = 0.0,
+    usd_path: "Path | None" = None,
 ) -> dict:
     """Render a turntable animation: STEP → STL → N frames (Blender) → mp4 (ffmpeg).
 
+    When usd_path is provided and exists, the GLB conversion step is skipped.
+
     Returns a dict with timing, frame count, engine_used, log_lines.
     Raises RuntimeError on failure.
     """
@@ -328,14 +340,18 @@ def render_turntable_to_file(
 
     t0 = time.monotonic()
 
-    # 1. GLB conversion (OCC — replaces cadquery STL)
+    # 1. GLB conversion (OCC) — skipped when usd_path is provided
     glb_path = step_path.parent / f"{step_path.stem}_thumbnail.glb"
+    use_usd = bool(usd_path and usd_path.exists())
 
     t_glb = time.monotonic()
-    if not glb_path.exists() or glb_path.stat().st_size == 0:
-        _glb_from_step(step_path, glb_path, quality=stl_quality)
+    if use_usd:
+        logger.info("[render_blender] turntable using USD path: %s", usd_path)
     else:
-        logger.info("GLB local hit: %s (%d KB)", glb_path.name, glb_path.stat().st_size // 1024)
+        if not glb_path.exists() or glb_path.stat().st_size == 0:
+            _glb_from_step(step_path, glb_path)
+        else:
+            logger.info("GLB local hit: %s (%d KB)", glb_path.name, glb_path.stat().st_size // 1024)
     glb_duration_s = round(time.monotonic() - t_glb, 2)
 
     # 2. Render frames with Blender
@@ -346,12 +362,13 @@ def render_turntable_to_file(
     env = dict(os.environ)
     env["EGL_PLATFORM"] = "surfaceless"
 
+    glb_arg = "" if use_usd else str(glb_path)
     cmd = [
         blender_bin,
         "--background",
         "--python", str(script_path),
         "--",
-        str(glb_path),
+        glb_arg,
         str(frames_dir),
         str(frame_count),
         "360",  # degrees
@@ -371,6 +388,8 @@ def render_turntable_to_file(
         bg_color or "",
         "1" if transparent_bg else "0",
     ]
+    if use_usd:
+        cmd += ["--usd-path", str(usd_path)]
 
     log_lines: list[str] = []
 
diff --git a/backend/app/services/step_processor.py b/backend/app/services/step_processor.py
index a84888a..363bbcd 100644
--- a/backend/app/services/step_processor.py
+++ b/backend/app/services/step_processor.py
@@ -449,9 +449,7 @@ def _get_all_settings() -> dict[str, str]:
         "blender_engine":         "cycles",
         "blender_cycles_samples": "256",
         "blender_eevee_samples":  "64",
-        "threejs_render_size":    "1024",
         "thumbnail_format":       "jpg",
-        "stl_quality":            "low",
         "blender_smooth_angle":   "30",
         "cycles_device":          "auto",
     }
@@ -511,7 +509,6 @@ def _generate_thumbnail(
         render_log.update({
             "engine": engine,
             "samples": int(settings[f"blender_{engine}_samples"]),
-            "stl_quality": settings["stl_quality"],
             "smooth_angle": int(settings["blender_smooth_angle"]),
             "cycles_device": settings["cycles_device"],
             "width": 512,
@@ -534,7 +531,6 @@ def _generate_thumbnail(
                     output_path=tmp_png,
                     engine=engine,
                     samples=samples,
-                    stl_quality=settings["stl_quality"],
                     smooth_angle=int(settings["blender_smooth_angle"]),
                     cycles_device=settings["cycles_device"],
                 )
@@ -543,7 +539,7 @@ def _generate_thumbnail(
                 logger.warning("Blender subprocess render failed: %s", exc)
                 rendered_png = None
         else:
-            logger.warning("Blender not available in this container — falling back to Pillow placeholder")
+            logger.warning("Blender not available in this container")
 
     # Merge rich service response data into render_log
     if service_data:
@@ -555,88 +551,20 @@ def _generate_thumbnail(
     render_log["completed_at"] = time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())
 
     if rendered_png:
-        result = _finalise_image(rendered_png, final_path, fmt)
+        result = _finalise_image(rendered_png, final_path)
         tmp_png.unlink(missing_ok=True)
-        render_log["fallback"] = False
         return result, render_log
 
-    # Pillow placeholder
-    render_log["fallback"] = True
-    return _generate_thumbnail_placeholder(step_path, final_path, fmt), render_log
+    return None, render_log
 
 
-def _finalise_image(src: Path, dst: Path, fmt: str) -> Path | None:
-    """Convert src image to dst using the requested format (jpg or png)."""
-    if fmt == "jpg":
-        try:
-            from PIL import Image
-            img = Image.open(src).convert("RGB")
-            img.save(str(dst), "JPEG", quality=92, optimize=True)
-            return dst
-        except Exception as exc:
-            logger.warning(f"JPG conversion failed: {exc}; keeping PNG")
-            src.rename(dst.with_suffix(".png"))
-            return dst.with_suffix(".png")
-    else:
-        src.rename(dst)
-        return dst
+def _finalise_image(src: Path, dst: Path) -> Path | None:
+    """Move src image to dst, always as PNG."""
+    out = dst.with_suffix(".png")
+    src.rename(out)
+    return out
 
 
-def _generate_thumbnail_placeholder(step_path: Path, out_path: Path, fmt: str = "png") -> Path | None:
-    """Generate a simple placeholder thumbnail using Pillow."""
-    try:
-        from PIL import Image, ImageDraw, ImageFont
-
-        W, H = 512, 512
-        img = Image.new("RGB", (W, H), color=(245, 246, 248))
-        draw = ImageDraw.Draw(img)
-
-        # Subtle grid
-        for i in range(0, W, 32):
-            draw.line([(i, 0), (i, H)], fill=(228, 230, 235), width=1)
-            draw.line([(0, i), (W, i)], fill=(228, 230, 235), width=1)
-
-        # Isometric box (front / top / right faces)
-        cx, cy = 256, 260
-        s = 110  # half-size
-        # Front face
-        draw.polygon(
-            [(cx - s, cy), (cx, cy + s // 2), (cx + s, cy), (cx, cy - s // 2)],
-            fill=(195, 208, 220), outline=(90, 110, 130), width=2,
-        )
-        # Top face
-        draw.polygon(
-            [(cx - s, cy - s), (cx, cy - s - s // 2), (cx + s, cy - s), (cx, cy - s + s // 2)],
-            fill=(220, 230, 240), outline=(90, 110, 130), width=2,
-        )
-        # Right pillar
-        draw.polygon(
-            [(cx + s, cy - s), (cx + s, cy), (cx, cy + s // 2), (cx, cy - s + s // 2)],
-            fill=(160, 178, 196), outline=(90, 110, 130), width=2,
-        )
-
-        # Schaeffler green top bar
-        draw.rectangle([0, 0, W, 10], fill=(0, 137, 61))
-
-        # Model name strip at bottom
-        name = step_path.stem
-        draw.rectangle([0, H - 52, W, H], fill=(30, 50, 70))
-        try:
-            font = ImageFont.load_default(size=15)
-            draw.text((W // 2, H - 26), name, fill=(255, 255, 255), anchor="mm", font=font)
-        except Exception:
-            draw.text((10, H - 38), name, fill=(255, 255, 255))
-
-        if fmt == "jpg":
-            img = img.convert("RGB")
-            img.save(str(out_path), "JPEG", quality=92, optimize=True)
-        else:
-            img.save(str(out_path), "PNG")
-        return out_path
-    except Exception as exc:
-        logger.warning(f"Pillow placeholder thumbnail failed: {exc}")
-    return None
-
 
 def regenerate_cad_thumbnail(cad_file_id: str, part_colors: dict[str, str]) -> bool:
     """
@@ -713,6 +641,7 @@ def render_to_file(
     denoising_quality: str = "",
     denoising_use_gpu: str = "",
     order_line_id: str | None = None,
+    usd_path: "Path | None" = None,
 ) -> tuple[bool, dict]:
     """Render a STEP file to a specific output path using current system settings.
 
@@ -769,14 +698,12 @@ def render_to_file(
         h = height or 512
         render_log.update({
             "engine": actual_engine, "samples": actual_samples,
-            "stl_quality": settings["stl_quality"],
             "smooth_angle": int(settings["blender_smooth_angle"]),
             "cycles_device": actual_cycles_device,
             "width": w, "height": h,
         })
         extra = {
             "engine": actual_engine, "samples": actual_samples,
-            "stl_quality": settings["stl_quality"],
             "smooth_angle": int(settings["blender_smooth_angle"]),
             "cycles_device": actual_cycles_device,
             "width": w, "height": h,
@@ -830,7 +757,6 @@ def render_to_file(
                     output_path=tmp_png,
                     engine=actual_engine,
                     samples=actual_samples,
-                    stl_quality=settings["stl_quality"],
                     smooth_angle=int(settings["blender_smooth_angle"]),
                     cycles_device=actual_cycles_device,
                     width=w, height=h,
@@ -850,13 +776,14 @@ def render_to_file(
                     denoising_quality=denoising_quality,
                     denoising_use_gpu=denoising_use_gpu,
                     log_callback=_log_cb,
+                    usd_path=usd_path,
                 )
                 rendered_png = tmp_png if tmp_png.exists() else None
             except Exception as exc:
                 logger.warning("Blender subprocess render failed: %s", exc)
                 rendered_png = None
         else:
-            logger.warning("Blender not available in this container — using Pillow fallback")
+            logger.warning("Blender not available in this container — render skipped")
 
     if service_data:
         for key in ("total_duration_s", "stl_duration_s", "render_duration_s",
@@ -867,15 +794,11 @@ def render_to_file(
     render_log["completed_at"] = time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())
 
     if rendered_png:
-        result = _finalise_image(rendered_png, out, fmt)
+        result = _finalise_image(rendered_png, out)
         tmp_png.unlink(missing_ok=True)
-        render_log["fallback"] = False
         return result is not None, render_log
 
-    # Pillow placeholder fallback
-    render_log["fallback"] = True
-    result = _generate_thumbnail_placeholder(step, out, fmt)
-    return result is not None, render_log
+    return False, render_log
 
 
 def _convert_to_gltf(step_path: Path, cad_file_id: str, upload_dir: str) -> Path | None:
diff --git a/plan.md b/plan.md
index b3b230a..451571e 100644
--- a/plan.md
+++ b/plan.md
@@ -1,183 +1,88 @@
-# Plan: Priority 1 — Pipeline Cleanup (M1 Dead Code + M3 blender_render Split)
+# Plan: P1 Remaining Cleanup — M1 Dead Code + M3 blender_render.py Split
 
 ## Context
+Three categories of cleanup:
+1. **M1a**: Two legacy HTTP renderer directories (`blender-renderer/`, `threejs-renderer/`) still exist in repo root despite the services being removed in Phase A.
+2. **M1b**: Dead code in backend services — PIL fallback in `step_processor.py`, `stl_quality` param (always "low") in `render_blender.py` and `domains/rendering/tasks.py`.
+3. **M3**: `render-worker/scripts/blender_render.py` is 263 lines (target < 80) — argparse, scene setup, and render config should move to submodules.
 
-ROADMAP Priority 1 is "In Progress". M2 (`step_tasks.py` decomposed to `domains/pipeline/tasks/`) is **done**. Two milestones remain:
-
-- **M1**: Delete dead-code directories, remove `stl_quality` from admin/frontend surface, remove dead functions
-- **M3**: Decompose `blender_render.py` (920 lines) into focused submodules
-
----
+`domains/rendering/tasks.py` is **NOT dead code** — contains 6 active Celery tasks (`render_still_task`, `render_turntable_task`, `render_order_line_still_task`, `export_gltf_for_order_line_task`, `export_blend_for_order_line_task`, `apply_asset_library_materials_task`). Only the `stl_quality` param needs removal.
 
 ## Affected Files
-
-| File | Change |
-|------|--------|
-| `blender-renderer/` | DELETE directory |
-| `threejs-renderer/` | DELETE directory |
-| `renderproblems_tmp/` | DELETE directory |
-| `backend/app/api/routers/admin.py` | Remove `stl_quality` + `VALID_STL_QUALITIES` (7 locations) |
-| `frontend/src/api/orders.ts` | Remove `stl_quality?: string` |
-| `frontend/src/api/worker.ts` | Remove `stl_quality?: string` |
-| `frontend/src/pages/WorkerActivity.tsx` | Remove STL quality KV row |
-| `frontend/src/components/renders/RenderInfoModal.tsx` | Remove STL quality display row |
-| `frontend/src/help/helpTexts.ts` | Remove `setting.stl_quality` entry |
-| `backend/app/services/step_processor.py` | Remove `_render_via_service()` + dead `elif renderer == "threejs"` |
-| `render-worker/scripts/blender_render.py` | Remove `_mark_sharp_and_seams()`; thin to entry-point after submodule extraction |
-| `render-worker/scripts/_blender_gpu.py` | CREATE — `activate_gpu()` |
-| `render-worker/scripts/_blender_import.py` | CREATE — `import_glb()`, `apply_rotation()` |
-| `render-worker/scripts/_blender_materials.py` | CREATE — `build_mat_map_lower()`, `apply_material_library()`, `assign_failed_material()` |
-| `render-worker/scripts/_blender_camera.py` | CREATE — `setup_auto_camera()`, `setup_auto_lights()` |
-| `render-worker/scripts/_blender_scene.py` | CREATE — `ensure_collection()`, `apply_smooth_batch()`, `apply_sharp_edges_from_occ()`, `setup_shadow_catcher()` |
-
----
+- `blender-renderer/` — delete entire directory
+- `threejs-renderer/` — delete entire directory
+- `backend/app/services/step_processor.py` — remove PIL fallback block (~line 565)
+- `backend/app/services/render_blender.py` — remove `stl_quality` param from `_glb_from_step()`, `render_still()`, `render_turntable_to_file()`
+- `backend/app/domains/rendering/tasks.py` — remove `stl_quality` param from `render_still_task`, `render_turntable_task`
+- `render-worker/scripts/blender_render.py` — thin to < 80 lines
+- `render-worker/scripts/_blender_args.py` — new file (argument parsing)
+- `render-worker/scripts/_blender_scene_setup.py` — new file (MODE A/B scene setup)
+- `render-worker/scripts/_blender_render_config.py` — new file (engine + output config)
 
 ## Tasks (in order)
 
-### [x] Task M1-1: Delete obsolete directories
-
-- **What**: `rm -rf blender-renderer/ threejs-renderer/ renderproblems_tmp/`
-- **Acceptance gate**: `ls blender-renderer/ threejs-renderer/ renderproblems_tmp/` → all "No such file"
+### [x] Task 1: Delete legacy renderer directories
+- **File**: `blender-renderer/`, `threejs-renderer/` (repo root)
+- **What**: `git rm -rf blender-renderer/ threejs-renderer/` — removes both legacy HTTP service directories superseded by the Celery render-worker in Phase A
+- **Acceptance gate**: `ls blender-renderer/ threejs-renderer/` both return "no such file or directory"
 - **Dependencies**: none
-- **Risk**: Zero — no active source files
-
----
-
-### [x] Task M1-2: Remove stl_quality from admin.py
-
-- **File**: `backend/app/api/routers/admin.py`
-- **What**: Delete all 7 references:
-  1. `VALID_STL_QUALITIES = {"low", "high"}` constant
-  2. `"stl_quality": "low"` from `SETTINGS_DEFAULTS`
-  3. `stl_quality: str = "low"` from `SettingsOut`
-  4. `stl_quality: str | None = None` from `SettingsUpdate`
-  5. `stl_quality=raw["stl_quality"],` from `_settings_to_out()`
-  6. `if body.stl_quality is not None and body.stl_quality not in VALID_STL_QUALITIES:` validation block
-  7. `if body.stl_quality is not None: updates["stl_quality"] = body.stl_quality` update block
-- **Acceptance gate**: `grep -n "stl_quality\|VALID_STL_QUALITIES" backend/app/api/routers/admin.py` → 0 matches
-- **Dependencies**: none
-- **Risk**: Low — the DB key remains (harmless); pipeline internally still uses `gltf_*_linear_deflection`
-
----
-
-### [x] Task M1-3: Remove stl_quality from frontend
-
-- **Files**:
-  - `frontend/src/api/orders.ts` — remove `stl_quality?: string`
-  - `frontend/src/api/worker.ts` — remove `stl_quality?: string`
-  - `frontend/src/pages/WorkerActivity.tsx` — remove STL quality KV row
-  - `frontend/src/components/renders/RenderInfoModal.tsx` — remove STL quality row
-  - `frontend/src/help/helpTexts.ts` — remove `setting.stl_quality` entry
-- **Acceptance gate**: `grep -rn "stl_quality" frontend/src/` → 0 matches; `npx tsc --noEmit` passes
-- **Dependencies**: M1-2
-- **Risk**: Low — all uses are optional fields (`?:`)
-
----
-
-### [x] Task M1-4: Remove dead _mark_sharp_and_seams from blender_render.py
-
-- **File**: `render-worker/scripts/blender_render.py`
-- **What**: Delete the `_mark_sharp_and_seams()` function (lines 196–256 approx). It is defined but never called — `_apply_sharp_edges_from_occ()` is the active implementation.
-- **Acceptance gate**: `grep -n "_mark_sharp_and_seams" render-worker/scripts/blender_render.py` → 0 matches
-- **Dependencies**: none
-- **Risk**: Zero — verifiably never called
-
----
-
-### [x] Task M1-5: Remove dead code from step_processor.py
+- **Risk**: Low — not imported by any active pipeline code
 
+### [x] Task 2: Remove PIL fallback from step_processor.py
 - **File**: `backend/app/services/step_processor.py`
-- **What**: Delete `_render_via_service()` function and the `elif renderer == "threejs":` branch (which only logs a warning and falls through)
-- **Acceptance gate**: `grep -n "_render_via_service\|renderer == .threejs" backend/app/services/step_processor.py` → 0 matches
-- **Dependencies**: M1-1
-- **Risk**: Low — function is only referenced from within the dead branch
+- **What**: Find `from PIL import Image` (~line 565, inside `_generate_thumbnail()`) and the PIL thumbnail generation conditional branch. Remove the import and the branch — leave only the render-worker path.
+- **Acceptance gate**: `grep -n "PIL\|Pillow" backend/app/services/step_processor.py` returns nothing
+- **Dependencies**: none
+- **Risk**: Low — PIL path unreachable; render-worker handles all thumbnails
 
----
+### [x] Task 3: Remove stl_quality param from render_blender.py
+- **File**: `backend/app/services/render_blender.py`
+- **What**:
+  - `_glb_from_step(step_path, output_dir, quality="low")` → `_glb_from_step(step_path, output_dir)` — hardcode the low-quality deflection values inline (no conditional on quality)
+  - Remove `stl_quality: str = "low"` from `render_still(...)` and `render_turntable_to_file(...)`
+  - Remove all internal `quality=stl_quality` pass-throughs
+- **Acceptance gate**: `grep -n "stl_quality" backend/app/services/render_blender.py` returns nothing
+- **Dependencies**: none (Task 4 updates callers)
+- **Risk**: Medium — callers in tasks.py pass `stl_quality`; update in Task 4 immediately after
 
-### [x] Task M3-1: Create _blender_gpu.py
+### [x] Task 4: Remove stl_quality param from domains/rendering/tasks.py
+- **File**: `backend/app/domains/rendering/tasks.py`
+- **What**:
+  - `render_still_task` (~line 48): remove `stl_quality: str = "low"` from signature and from the `render_still(...)` call
+  - `render_turntable_task` (~line 152): remove `stl_quality: str = "low"` from signature. Lines ~210–228 inline OCC GLB generation reads `stl_quality` to choose deflection values — replace hardcoded quality-based values with DB settings reads (`scene_linear_deflection`, `scene_angular_deflection`). Pattern to follow: `export_glb.py` reads these settings via `sys_settings.get("scene_linear_deflection", 0.03)`.
+- **Acceptance gate**: `grep -n "stl_quality" backend/app/domains/rendering/tasks.py` returns nothing
+- **Dependencies**: Task 3
+- **Risk**: Medium — inline tessellation block must correctly read DB settings; verify key names match migration 062 output
 
-- **File**: `render-worker/scripts/_blender_gpu.py` (NEW)
-- **What**: Extract `_activate_gpu()` from `blender_render.py` into a standalone module. Refactor to accept `cycles_device: str` parameter instead of reading a module-level global. Rename to `activate_gpu()`.
-- **Key signature**: `def activate_gpu(cycles_device: str = "auto") -> str | None`
-- **Acceptance gate**: `grep -c "def _activate_gpu" render-worker/scripts/blender_render.py` → 0; function callable as `from _blender_gpu import activate_gpu`
-- **Dependencies**: M1-4
-- **Risk**: Medium — must pass `sys.path` correctly so Blender Python finds the module
+### [x] Task 5: Extract _blender_args.py
+- **File**: `render-worker/scripts/blender_render.py`, new `render-worker/scripts/_blender_args.py`
+- **What**: Move the `argparse` block (lines ~44–110, ~67 lines) into `_blender_args.py` as a `parse_args()` function. `blender_render.py` calls `from _blender_args import parse_args` and uses `args = parse_args()`.
+- **Acceptance gate**: `_blender_args.py` exists with the parser; `blender_render.py` line count drops by ~60
+- **Dependencies**: none
+- **Risk**: Low — pure refactor, no logic change
 
----
+### [x] Task 6: Extract _blender_scene_setup.py
+- **File**: `render-worker/scripts/blender_render.py`, new `render-worker/scripts/_blender_scene_setup.py`
+- **What**: Move the MODE A / MODE B scene setup branches (lines ~131–214, ~84 lines) into `_blender_scene_setup.py` as `setup_scene(args, scene)` (dispatches internally to mode A or B based on `args.blend_template`). Import and call in `blender_render.py`.
+- **Acceptance gate**: `_blender_scene_setup.py` exists; `blender_render.py` line count drops by ~80
+- **Dependencies**: Task 5
+- **Risk**: Low — pure refactor; `bpy` available in Blender Python context
 
-### [x] Task M3-2: Create _blender_import.py
-
-- **File**: `render-worker/scripts/_blender_import.py` (NEW)
-- **What**: Extract `_import_glb()` and `_apply_rotation()` into module. Rename to `import_glb()` / `apply_rotation()`.
-- **Acceptance gate**: `grep -c "def _import_glb\|def _apply_rotation" render-worker/scripts/blender_render.py` → 0
-- **Dependencies**: M1-4
-- **Risk**: Low — no hidden globals beyond `bpy`, `math`, `Vector`
-
----
-
-### [x] Task M3-3: Create _blender_materials.py
-
-- **File**: `render-worker/scripts/_blender_materials.py` (NEW)
-- **What**: Extract `_assign_failed_material()`, `_apply_material_library()`, and the `mat_map_lower` building loop. Consolidate the duplicated `mat_map_lower` logic (currently in Mode A and Mode B) into a single `build_mat_map_lower()` helper. `FAILED_MATERIAL_NAME` constant lives here.
-- **Acceptance gate**: `grep -c "def _assign_failed_material\|def _apply_material_library" render-worker/scripts/blender_render.py` → 0
-- **Dependencies**: M1-4
-- **Risk**: Medium — `_apply_material_library()` currently uses `part_names_ordered` global; must convert to parameter
-
----
-
-### [x] Task M3-4: Create _blender_camera.py
-
-- **File**: `render-worker/scripts/_blender_camera.py` (NEW)
-- **What**: Extract auto-camera placement block (bounding sphere computation, isometric positioning, clip plane setup, `ELEVATION_DEG`/`AZIMUTH_DEG` constants) and `setup_auto_lights()`.
-- **Key signatures**: `def setup_auto_camera(parts, width, height) -> tuple[Vector, float]` (returns center + radius for reuse by lights); `def setup_auto_lights(bbox_center, bsphere_radius) -> None`
-- **Acceptance gate**: `grep -c "ELEVATION_DEG\|AZIMUTH_DEG\|bsphere_radius" render-worker/scripts/blender_render.py` → 0
-- **Dependencies**: M3-2
-- **Risk**: Low — camera block is self-contained
-
----
-
-### [x] Task M3-5: Create _blender_scene.py
-
-- **File**: `render-worker/scripts/_blender_scene.py` (NEW)
-- **What**: Extract `_ensure_collection()`, `_apply_smooth_batch()`, `_apply_sharp_edges_from_occ()`, shadow catcher setup into module.
-- **Acceptance gate**: `grep -c "def _ensure_collection\|def _apply_smooth_batch\|def _apply_sharp_edges_from_occ" render-worker/scripts/blender_render.py` → 0
-- **Dependencies**: M1-4
-- **Risk**: Low
-
----
-
-### [x] Task M3-6: Thin blender_render.py to entry-point
-
-- **File**: `render-worker/scripts/blender_render.py`
-- **What**: Replace all extracted function bodies with imports from submodules. Add `sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))` before imports so Blender Python finds the submodules. Result: argument parsing + Mode A/B orchestration + timing only. Target: < 200 lines.
-- **Acceptance gate**: `wc -l render-worker/scripts/blender_render.py` → < 200; upload `81113-l_cut.stp` → thumbnail renders correctly
-- **Dependencies**: M3-1, M3-2, M3-3, M3-4, M3-5
-- **Risk**: High (integration step) — test immediately after deploy
-
----
+### [x] Task 7: Extract _blender_render_config.py and verify ≤ 80 lines
+- **File**: `render-worker/scripts/blender_render.py`, new `render-worker/scripts/_blender_render_config.py`
+- **What**: Move engine/render settings + output path logic (lines ~216–258, ~43 lines) into `_blender_render_config.py` as `configure_render(scene, args, output_path, gpu_type)`. After extraction, `blender_render.py` must be ≤ 80 lines.
+- **Acceptance gate**: `wc -l render-worker/scripts/blender_render.py` shows ≤ 80
+- **Dependencies**: Task 6
+- **Risk**: Low — pure refactor
 
 ## Migration Check
-
-**No migration required.** `stl_quality` key stays in DB (harmless). No new columns or tables.
-
----
+No new Alembic migration required. Task 4 reads existing keys (`scene_linear_deflection`, `scene_angular_deflection`) from the `system_settings` table, already present after migration 062.
 
 ## Order Recommendation
-
-```
-M1-1 (delete dirs) → M1-4 (dead func blender) → M1-5 (dead func step_processor)
-→ M1-2 (admin.py) → M1-3 (frontend)
-→ M3-1..M3-5 (create submodules in parallel where possible)
-→ M3-6 (thin blender_render.py — integration, highest risk, test immediately)
-```
-
-Deploy after M1: `docker compose up -d --build backend`
-Deploy after M3-6: `docker compose up -d --build render-worker`
-
----
+Tasks 1 and 2 are independent — can run in parallel.
+Tasks 3 and 4 are coupled — run 3 immediately before 4.
+Tasks 5, 6, 7 are sequential — each further reduces blender_render.py line count.
 
 ## Risks / Open Questions
-
-1. **Blender `sys.path`**: Submodule files must be at `/render-scripts/` (the volume mount path). `sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))` is the safe way to ensure this regardless of CWD.
-2. **`part_names_ordered` global**: Currently used across multiple functions in `blender_render.py`. Must be explicitly passed as a parameter to `apply_material_library()` in M3-3.
-3. **M3 scope**: M3 is a pure refactor — no behaviour change. If time is limited, M1 (dead code removal) delivers clean value on its own. M3 can be deferred to a separate session.
+- `render_turntable_task` inline tessellation: confirm exact key names are `scene_linear_deflection` / `scene_angular_deflection` (not the old `gltf_preview_*` names) by reading `export_glb.py` before Task 4.
+- After Task 7, do a smoke-test render to confirm submodule imports work inside Blender's Python interpreter.
diff --git a/render-worker/scripts/_blender_args.py b/render-worker/scripts/_blender_args.py
new file mode 100644
index 0000000..0e46b80
--- /dev/null
+++ b/render-worker/scripts/_blender_args.py
@@ -0,0 +1,99 @@
+"""Argument parsing for blender_render.py.
+
+Parses positional and named CLI arguments passed after the '--' separator
+when Blender is invoked as:
+  blender --background --python blender_render.py -- <glb_path> ...
+"""
+import json as _json
+import os
+import sys
+from types import SimpleNamespace
+
+
+def parse_args() -> SimpleNamespace:
+    """Parse CLI arguments and return a SimpleNamespace of all render options."""
+    argv = sys.argv[sys.argv.index("--") + 1:] if "--" in sys.argv else []
+    if len(argv) < 4:
+        print("Usage: blender --background --python blender_render.py -- "
+              "<glb_path> <output_path> <width> <height> ...")
+        sys.exit(1)
+
+    def _arg(n, default="", transform=str):
+        return transform(argv[n]) if len(argv) > n and argv[n] else default
+
+    glb_path               = argv[0]
+    output_path            = argv[1]
+    width                  = int(argv[2])
+    height                 = int(argv[3])
+    engine                 = _arg(4, "cycles", str.lower)
+    samples                = _arg(5, None, int)
+    smooth_angle           = _arg(6, 30, int)
+    cycles_device          = _arg(7, "auto", str.lower)
+    transparent_bg         = argv[8] == "1" if len(argv) > 8 else False
+    template_path          = _arg(9, "")
+    target_collection      = _arg(10, "Product")
+    material_library_path  = _arg(11, "")
+    material_map           = _json.loads(_arg(12, "{}")) if _arg(12, "{}") else {}
+    part_names_ordered     = _json.loads(_arg(13, "[]")) if _arg(13, "[]") else []
+    lighting_only          = argv[14] == "1" if len(argv) > 14 else False
+    shadow_catcher         = argv[15] == "1" if len(argv) > 15 else False
+    rotation_x             = _arg(16, 0.0, float)
+    rotation_y             = _arg(17, 0.0, float)
+    rotation_z             = _arg(18, 0.0, float)
+    noise_threshold        = _arg(19, "")
+    denoiser               = _arg(20, "")
+    denoising_input_passes = _arg(21, "")
+    denoising_prefilter    = _arg(22, "")
+    denoising_quality      = _arg(23, "")
+    denoising_use_gpu      = _arg(24, "")
+
+    if samples is None:
+        samples = 64 if engine == "eevee" else 256
+
+    mesh_attributes: dict = {}
+    if "--mesh-attributes" in sys.argv:
+        _idx = sys.argv.index("--mesh-attributes")
+        try:
+            mesh_attributes = _json.loads(sys.argv[_idx + 1])
+        except Exception:
+            pass
+
+    usd_path = ""
+    if "--usd-path" in sys.argv:
+        _usd_idx = sys.argv.index("--usd-path")
+        usd_path = sys.argv[_usd_idx + 1] if _usd_idx + 1 < len(sys.argv) else ""
+
+    if template_path and not os.path.isfile(template_path):
+        print(f"[blender_render] ERROR: template not found: {template_path}")
+        sys.exit(1)
+
+    return SimpleNamespace(
+        glb_path=glb_path,
+        output_path=output_path,
+        width=width,
+        height=height,
+        engine=engine,
+        samples=samples,
+        smooth_angle=smooth_angle,
+        cycles_device=cycles_device,
+        transparent_bg=transparent_bg,
+        template_path=template_path,
+        target_collection=target_collection,
+        material_library_path=material_library_path,
+        material_map=material_map,
+        part_names_ordered=part_names_ordered,
+        lighting_only=lighting_only,
+        shadow_catcher=shadow_catcher,
+        rotation_x=rotation_x,
+        rotation_y=rotation_y,
+        rotation_z=rotation_z,
+        noise_threshold=noise_threshold,
+        denoiser=denoiser,
+        denoising_input_passes=denoising_input_passes,
+        denoising_prefilter=denoising_prefilter,
+        denoising_quality=denoising_quality,
+        denoising_use_gpu=denoising_use_gpu,
+        mesh_attributes=mesh_attributes,
+        usd_path=usd_path,
+        use_template=bool(template_path),
+    )
diff --git a/render-worker/scripts/_blender_import.py b/render-worker/scripts/_blender_import.py
index d51023b..69ad64d 100644
--- a/render-worker/scripts/_blender_import.py
+++ b/render-worker/scripts/_blender_import.py
@@ -83,3 +83,9 @@ def apply_rotation(parts: list, rx: float, ry: float, rz: float) -> None:
     bpy.context.view_layer.objects.active = parts[0]
     bpy.ops.object.transform_apply(location=False, rotation=True, scale=False)
     print(f"[blender_render] applied rotation ({rx}°, {ry}°, {rz}°) to {len(parts)} parts")
+
+
+def import_usd_file(usd_path: str) -> list:
+    """Import USD stage into current Blender scene — delegates to import_usd module."""
+    from import_usd import import_usd_file as _impl
+    return _impl(usd_path)
diff --git a/render-worker/scripts/_blender_render_config.py b/render-worker/scripts/_blender_render_config.py
new file mode 100644
index 0000000..5913e74
--- /dev/null
+++ b/render-worker/scripts/_blender_render_config.py
@@ -0,0 +1,55 @@
+"""Engine configuration and final render call for blender_render.py."""
+import sys
+from typing import Callable
+
+import bpy  # type: ignore[import]
+
+from _blender_gpu import configure_engine
+
+
+def configure_and_render(args, early_gpu_type, use_template: bool, lap_fn: Callable[[str], None]) -> None:
+    """Configure render engine, colour management, resolution, then render.
+
+    Reads engine, samples, device, denoiser, and output settings from args.
+    lap_fn is called with label strings at timing checkpoints.
+    """
+    scene = bpy.context.scene
+    configure_engine(
+        scene, args.engine, args.samples, args.cycles_device, early_gpu_type,
+        args.noise_threshold, args.denoiser,
+        args.denoising_input_passes, args.denoising_prefilter,
+        args.denoising_quality, args.denoising_use_gpu,
+    )
+
+    if not use_template:
+        scene.view_settings.view_transform = "Standard"
+        scene.view_settings.exposure        = 0.0
+        scene.view_settings.gamma           = 1.0
+        try:
+            scene.view_settings.look = "None"
+        except Exception:
+            pass
+
+    scene.render.resolution_x               = args.width
+    scene.render.resolution_y               = args.height
+    scene.render.resolution_percentage      = 100
+    scene.render.image_settings.file_format = "PNG"
+    scene.render.filepath                   = args.output_path
+    scene.render.film_transparent           = args.transparent_bg
+
+    if scene.render.engine == "CYCLES":
+        cprefs = bpy.context.preferences.addons["cycles"].preferences
+        print(
+            f"[blender_render] VERIFY: engine={scene.render.engine}, "
+            f"cycles.device={scene.cycles.device}, "
+            f"compute_device_type={cprefs.compute_device_type}, "
+            f"gpu_devices={[(d.name, d.type, d.use) for d in cprefs.devices if d.type != 'CPU']}",
+            flush=True,
+        )
+
+    lap_fn("pre_render_setup")
+    print(f"[blender_render] Rendering → {args.output_path}  (Blender {bpy.app.version_string})", flush=True)
+    sys.stdout.flush()
+    bpy.ops.render.render(write_still=True)
+    print("[blender_render] render done.", flush=True)
+    lap_fn("gpu_render")
diff --git a/render-worker/scripts/_blender_scene_setup.py b/render-worker/scripts/_blender_scene_setup.py
new file mode 100644
index 0000000..32c9a35
--- /dev/null
+++ b/render-worker/scripts/_blender_scene_setup.py
@@ -0,0 +1,129 @@
+"""MODE A / MODE B scene setup for blender_render.py.
+
+MODE A — factory settings (no template): auto-camera + auto-lights
+MODE B — template file: load .blend, import into named collection
+"""
+import time as _time
+from typing import Callable
+
+import bpy  # type: ignore[import]
+
+from _blender_camera    import setup_auto_camera, setup_auto_lights
+from _blender_import    import import_glb, apply_rotation, import_usd_file
+from _blender_materials import (
+    assign_failed_material,
+    build_mat_map_lower,
+    apply_material_library,
+)
+from _blender_scene     import (
+    ensure_collection,
+    apply_smooth_batch,
+    apply_sharp_edges_from_occ,
+    setup_shadow_catcher,
+)
+
+
+def setup_scene(args, lap_fn: Callable[[str], None]) -> None:
+    """Set up the Blender scene according to args (MODE A or B).
+
+    Handles import, rotation, smooth shading, material assignment, shadow
+    catcher, and auto-camera/lights. lap_fn is called with a label string
+    at each timing checkpoint.
+    """
+    if args.use_template:
+        _setup_mode_b(args, lap_fn)
+    else:
+        _setup_mode_a(args)
+
+
+def _setup_mode_b(args, lap_fn: Callable[[str], None]) -> None:
+    """MODE B: Template-based render — load .blend, import into collection."""
+    print(f"[blender_render] Opening template: {args.template_path}")
+    bpy.ops.wm.open_mainfile(filepath=args.template_path)
+    lap_fn("template_load")
+
+    target_col = ensure_collection(args.target_collection)
+    if args.usd_path:
+        parts = import_usd_file(args.usd_path)
+    else:
+        parts = import_glb(args.glb_path)
+    lap_fn("glb_import")
+    apply_rotation(parts, args.rotation_x, args.rotation_y, args.rotation_z)
+    lap_fn("rotation")
+
+    for part in parts:
+        for col in list(part.users_collection):
+            col.objects.unlink(part)
+        target_col.objects.link(part)
+
+    apply_smooth_batch(parts, args.smooth_angle)
+    if not args.usd_path:
+        _occ_pairs = args.mesh_attributes.get("sharp_edge_pairs") or []
+        if _occ_pairs:
+            apply_sharp_edges_from_occ(parts, _occ_pairs)
+    lap_fn("smooth_shading")
+
+    if args.material_library_path and args.material_map:
+        apply_material_library(
+            parts, args.material_library_path,
+            build_mat_map_lower(args.material_map), args.part_names_ordered,
+        )
+    else:
+        for part in parts:
+            assign_failed_material(part)
+    lap_fn("material_assign")
+
+    if args.shadow_catcher:
+        setup_shadow_catcher(parts)
+
+    needs_auto_camera = (
+        (args.lighting_only and not args.shadow_catcher)
+        or not bpy.context.scene.camera
+    )
+    if args.lighting_only and not args.shadow_catcher:
+        print("[blender_render] lighting_only mode: using template World/HDRI, forcing auto-camera")
+    elif needs_auto_camera:
+        print("[blender_render] WARNING: template has no camera — will create auto-camera")
+
+    if not needs_auto_camera and bpy.context.scene.camera:
+        bpy.context.scene.camera.data.clip_start = 0.001
+
+    print(f"[blender_render] template mode: {len(parts)} parts imported into collection '{args.target_collection}'")
+
+    if needs_auto_camera:
+        setup_auto_camera(parts, args.width, args.height)
+
+
+def _setup_mode_a(args) -> None:
+    """MODE A: Factory settings — auto-camera + auto-lights."""
+    bpy.ops.wm.read_factory_settings(use_empty=True)
+    if args.usd_path:
+        parts = import_usd_file(args.usd_path)
+    else:
+        parts = import_glb(args.glb_path)
+    apply_rotation(parts, args.rotation_x, args.rotation_y, args.rotation_z)
+
+    _t = _time.time()
+    apply_smooth_batch(parts, args.smooth_angle)
+    if not args.usd_path:
+        _occ_pairs = args.mesh_attributes.get("sharp_edge_pairs") or []
+        if _occ_pairs:
+            apply_sharp_edges_from_occ(parts, _occ_pairs)
+    for part in parts:
+        assign_failed_material(part)
+    print(f"[blender_render] smooth+fallback-material: {len(parts)} parts ({_time.time()-_t:.2f}s)", flush=True)
+
+    if args.material_library_path and args.material_map:
+        apply_material_library(
+            parts, args.material_library_path,
+            build_mat_map_lower(args.material_map), args.part_names_ordered,
+        )
+
+    bbox_center, bsphere_radius = setup_auto_camera(parts, args.width, args.height)
+    setup_auto_lights(bbox_center, bsphere_radius)
+    world = bpy.data.worlds.new("World")
+    bpy.context.scene.world = world
+    world.use_nodes = True
+    bg = world.node_tree.nodes["Background"]
+    bg.inputs["Color"].default_value    = (0.96, 0.96, 0.97, 1.0)
+    bg.inputs["Strength"].default_value = 0.15
diff --git a/render-worker/scripts/blender_render.py b/render-worker/scripts/blender_render.py
index ed5a2c8..6b1861a 100644
--- a/render-worker/scripts/blender_render.py
+++ b/render-worker/scripts/blender_render.py
@@ -17,231 +17,51 @@ Features:
 """
 import sys
 import os
+import time as _time
 
-# Force unbuffered stdout so render log lines appear immediately
 os.environ["PYTHONUNBUFFERED"] = "1"
 if hasattr(sys.stdout, "reconfigure"):
     sys.stdout.reconfigure(line_buffering=True)
 
-# Add script directory to sys.path so Blender Python finds our submodules
 sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
 
 import bpy  # type: ignore[import]
 
-from _blender_gpu       import activate_gpu, configure_engine
-from _blender_import    import import_glb, apply_rotation
-from _blender_materials import (
-    FAILED_MATERIAL_NAME, assign_failed_material,
-    build_mat_map_lower, apply_material_library,
-)
-from _blender_camera    import setup_auto_camera, setup_auto_lights
-from _blender_scene     import (
-    ensure_collection, apply_smooth_batch,
-    apply_sharp_edges_from_occ, setup_shadow_catcher,
-)
+from _blender_gpu          import activate_gpu
+from _blender_args         import parse_args
+from _blender_scene_setup  import setup_scene
+from _blender_render_config import configure_and_render
 
 # ── Parse arguments ────────────────────────────────────────────────────────────
-import json as _json
-
-def _arg(n, default="", transform=str):
-    return transform(argv[n]) if len(argv) > n and argv[n] else default
-
-argv = sys.argv[sys.argv.index("--") + 1:] if "--" in sys.argv else []
-if len(argv) < 4:
-    print("Usage: blender --background --python blender_render.py -- "
-          "<glb_path> <output_path> <width> <height> ...")
-    sys.exit(1)
-
-glb_path              = argv[0]
-output_path           = argv[1]
-width                 = int(argv[2])
-height                = int(argv[3])
-engine                = _arg(4, "cycles", str.lower)
-samples               = _arg(5, None, int)
-smooth_angle          = _arg(6, 30, int)
-cycles_device         = _arg(7, "auto", str.lower)
-transparent_bg        = argv[8] == "1" if len(argv) > 8 else False
-template_path         = _arg(9, "")
-target_collection     = _arg(10, "Product")
-material_library_path = _arg(11, "")
-material_map          = _json.loads(_arg(12, "{}")) if _arg(12, "{}") else {}
-part_names_ordered    = _json.loads(_arg(13, "[]")) if _arg(13, "[]") else []
-lighting_only         = argv[14] == "1" if len(argv) > 14 else False
-shadow_catcher        = argv[15] == "1" if len(argv) > 15 else False
-rotation_x            = _arg(16, 0.0, float)
-rotation_y            = _arg(17, 0.0, float)
-rotation_z            = _arg(18, 0.0, float)
-noise_threshold_arg        = _arg(19, "")
-denoiser_arg               = _arg(20, "")
-denoising_input_passes_arg = _arg(21, "")
-denoising_prefilter_arg    = _arg(22, "")
-denoising_quality_arg      = _arg(23, "")
-denoising_use_gpu_arg      = _arg(24, "")
-
-if samples is None:
-    samples = 64 if engine == "eevee" else 256
-
-# Named argument: --mesh-attributes <json>
-_mesh_attrs: dict = {}
-if "--mesh-attributes" in sys.argv:
-    _idx = sys.argv.index("--mesh-attributes")
-    try:
-        _mesh_attrs = _json.loads(sys.argv[_idx + 1])
-    except Exception:
-        pass
-
-if template_path and not os.path.isfile(template_path):
-    print(f"[blender_render] ERROR: template not found: {template_path}")
-    sys.exit(1)
-
-use_template = bool(template_path)
-print(f"[blender_render] engine={engine}, samples={samples}, size={width}x{height}, smooth_angle={smooth_angle}°, device={cycles_device}, transparent={transparent_bg}")
-print(f"[blender_render] part_names_ordered: {len(part_names_ordered)} entries")
-print(f"[blender_render] {'template='+template_path+', collection='+target_collection+', lighting_only='+str(lighting_only) if use_template else 'no template — Mode A'}")
-if material_library_path:
-    print(f"[blender_render] material_library={material_library_path}, material_map keys={list(material_map.keys())}")
+args = parse_args()
+print(f"[blender_render] engine={args.engine}, samples={args.samples}, size={args.width}x{args.height}, smooth_angle={args.smooth_angle}°, device={args.cycles_device}, transparent={args.transparent_bg}")
+print(f"[blender_render] part_names_ordered: {len(args.part_names_ordered)} entries")
+print(f"[blender_render] {'template='+args.template_path+', collection='+args.target_collection+', lighting_only='+str(args.lighting_only) if args.use_template else 'no template — Mode A'}")
+if args.material_library_path:
+    print(f"[blender_render] material_library={args.material_library_path}, material_map keys={list(args.material_map.keys())}")
 
 # ── Early GPU activation (must happen BEFORE open_mainfile / Cycles init) ─────
-_early_gpu_type = activate_gpu(cycles_device)
+_early_gpu_type = activate_gpu(args.cycles_device)
 
 # ── Timing harness ─────────────────────────────────────────────────────────────
-import time as _time
 _t0 = _time.monotonic()
 _timings: dict = {}
 
 
 def _lap(label: str) -> None:
     now = _time.monotonic()
-    if not hasattr(_lap, '_last'):
+    if not hasattr(_lap, "_last"):
         _lap._last = _t0
     delta = now - _lap._last
-    total = now - _t0
     _timings[label] = round(delta, 3)
-    print(f"[blender_render] TIMING {label}={delta:.2f}s (total={total:.2f}s)", flush=True)
+    print(f"[blender_render] TIMING {label}={delta:.2f}s (total={now - _t0:.2f}s)", flush=True)
     _lap._last = now
 
 
-# ── SCENE SETUP ───────────────────────────────────────────────────────────────
+# ── Scene setup + render ───────────────────────────────────────────────────────
+setup_scene(args, _lap)
+configure_and_render(args, _early_gpu_type, args.use_template, _lap)
 
-if use_template:
-    # ── MODE B: Template-based render ─────────────────────────────────────────
-    print(f"[blender_render] Opening template: {template_path}")
-    bpy.ops.wm.open_mainfile(filepath=template_path)
-    _lap("template_load")
-
-    target_col = ensure_collection(target_collection)
-    parts = import_glb(glb_path)
-    _lap("glb_import")
-    apply_rotation(parts, rotation_x, rotation_y, rotation_z)
-    _lap("rotation")
-
-    for part in parts:
-        for col in list(part.users_collection):
-            col.objects.unlink(part)
-        target_col.objects.link(part)
-
-    apply_smooth_batch(parts, smooth_angle)
-    _occ_pairs = _mesh_attrs.get("sharp_edge_pairs") or []
-    if _occ_pairs:
-        apply_sharp_edges_from_occ(parts, _occ_pairs)
-    _lap("smooth_shading")
-
-    if material_library_path and material_map:
-        apply_material_library(parts, material_library_path, build_mat_map_lower(material_map), part_names_ordered)
-    else:
-        for part in parts:
-            assign_failed_material(part)
-    _lap("material_assign")
-
-    if shadow_catcher:
-        setup_shadow_catcher(parts)
-
-    needs_auto_camera = (lighting_only and not shadow_catcher) or not bpy.context.scene.camera
-    if lighting_only and not shadow_catcher:
-        print("[blender_render] lighting_only mode: using template World/HDRI, forcing auto-camera")
-    elif needs_auto_camera:
-        print("[blender_render] WARNING: template has no camera — will create auto-camera")
-
-    if not needs_auto_camera and bpy.context.scene.camera:
-        bpy.context.scene.camera.data.clip_start = 0.001
-
-    print(f"[blender_render] template mode: {len(parts)} parts imported into collection '{target_collection}'")
-
-else:
-    # ── MODE A: Factory settings ───────────────────────────────────────────────
-    needs_auto_camera = True
-    bpy.ops.wm.read_factory_settings(use_empty=True)
-    parts = import_glb(glb_path)
-    apply_rotation(parts, rotation_x, rotation_y, rotation_z)
-
-    _t_smooth_a = _time.time()
-    apply_smooth_batch(parts, smooth_angle)
-    _occ_pairs = _mesh_attrs.get("sharp_edge_pairs") or []
-    if _occ_pairs:
-        apply_sharp_edges_from_occ(parts, _occ_pairs)
-    for part in parts:
-        assign_failed_material(part)
-    print(f"[blender_render] smooth+fallback-material: {len(parts)} parts ({_time.time()-_t_smooth_a:.2f}s)", flush=True)
-
-    if material_library_path and material_map:
-        apply_material_library(parts, material_library_path, build_mat_map_lower(material_map), part_names_ordered)
-
-if needs_auto_camera:
-    bbox_center, bsphere_radius = setup_auto_camera(parts, width, height)
-    if not use_template:
-        setup_auto_lights(bbox_center, bsphere_radius)
-        # Mode A world background
-        world = bpy.data.worlds.new("World")
-        bpy.context.scene.world = world
-        world.use_nodes = True
-        bg = world.node_tree.nodes["Background"]
-        bg.inputs["Color"].default_value    = (0.96, 0.96, 0.97, 1.0)
-        bg.inputs["Strength"].default_value = 0.15
-
-# ── Render engine ──────────────────────────────────────────────────────────────
-scene = bpy.context.scene
-engine = configure_engine(
-    scene, engine, samples, cycles_device, _early_gpu_type,
-    noise_threshold_arg, denoiser_arg,
-    denoising_input_passes_arg, denoising_prefilter_arg,
-    denoising_quality_arg, denoising_use_gpu_arg,
-)
-
-# ── Colour management ──────────────────────────────────────────────────────────
-if not use_template:
-    scene.view_settings.view_transform = 'Standard'
-    scene.view_settings.exposure        = 0.0
-    scene.view_settings.gamma           = 1.0
-    try:
-        scene.view_settings.look = 'None'
-    except Exception:
-        pass
-
-# ── Render settings ────────────────────────────────────────────────────────────
-scene.render.resolution_x               = width
-scene.render.resolution_y               = height
-scene.render.resolution_percentage      = 100
-scene.render.image_settings.file_format = 'PNG'
-scene.render.filepath                   = output_path
-scene.render.film_transparent           = transparent_bg
-
-# ── Final verification + render ────────────────────────────────────────────────
-if scene.render.engine == 'CYCLES':
-    cprefs = bpy.context.preferences.addons['cycles'].preferences
-    print(f"[blender_render] VERIFY: engine={scene.render.engine}, "
-          f"cycles.device={scene.cycles.device}, "
-          f"compute_device_type={cprefs.compute_device_type}, "
-          f"gpu_devices={[(d.name, d.type, d.use) for d in cprefs.devices if d.type != 'CPU']}",
-          flush=True)
-
-_lap("pre_render_setup")
-print(f"[blender_render] Rendering → {output_path}  (Blender {bpy.app.version_string})", flush=True)
-sys.stdout.flush()
-bpy.ops.render.render(write_still=True)
-print("[blender_render] render done.", flush=True)
-_lap("gpu_render")
-
-# ── Final timing summary ───────────────────────────────────────────────────────
 _total = _time.monotonic() - _t0
 print(f"[blender_render] TIMING_SUMMARY total={_total:.2f}s | " +
       " | ".join(f"{k}={v:.2f}s" for k, v in _timings.items()), flush=True)
diff --git a/review-report.md b/review-report.md
index d032fa6..6a69820 100644
--- a/review-report.md
+++ b/review-report.md
@@ -1,36 +1,50 @@
-# Review Report: Pipeline Cleanup (M1 + M3)
-Date: 2026-03-11
+# Review Report: P1 Remaining Cleanup — M1 Dead Code + M3 blender_render.py Split
+Date: 2026-03-12
 
-## Result: ✅ Approved (2 low-severity unused imports fixed inline)
+## Result: ⚠️ Minor issues
 
 ---
 
 ## Problems Found
 
-### render-worker/scripts/blender_render.py:20 — Unused `import math`
-**Severity**: Low
-**Description**: `import math` is at the top of the entry-point but `math` is no longer referenced there — all math operations moved to submodules.
-**Fix**: Remove the import. Applied inline.
+### [_blender_scene_setup.py:12] `import_usd_file` depends on uncommitted `_blender_import.py` change
+**Severity**: Medium
+**Description**: `_blender_scene_setup.py` imports `import_usd_file` from `_blender_import` (line 12). This function does NOT exist in the committed `_blender_import.py` at HEAD — it is only present in a pre-existing uncommitted modification to that file (`_blender_import.py` shows `??` is untracked/modified). If the new submodule files (`_blender_args.py`, `_blender_scene_setup.py`, `_blender_render_config.py`) are committed without including the `_blender_import.py` change, every Blender render will crash with `ImportError: cannot import name 'import_usd_file'`.
+**Recommendation**: Ensure `render-worker/scripts/_blender_import.py` (with the `import_usd_file` addition) is staged and committed in the same commit as the new submodule files.
 
-### render-worker/scripts/_blender_import.py:5 — Unused `import re as _re`
+---
+
+### [step_processor.py:561] `_finalise_image()` ignores `fmt` parameter — always produces `.png`
 **Severity**: Low
-**Description**: `re` module is imported at module level but not used anywhere in `_blender_import.py`. The `_re.sub` calls live in `_blender_materials.py`.
-**Fix**: Remove the import. Applied inline.
+**Description**: The new `_finalise_image(src, dst, fmt)` accepts `fmt` but always does `out = dst.with_suffix(".png")`. When `thumbnail_format = "jpg"` is configured in system settings, the callers compute `final_path` with a `.jpg` extension and pass `fmt="jpg"`, but the returned path will always have `.png` extension. The `fmt` parameter is silently ignored.
+
+This is a deliberate consequence of removing PIL (which was never installed anyway), so the behavior change is acceptable. However, the dead `fmt` parameter creates misleading API.
+**Recommendation**: Remove the `fmt` parameter from `_finalise_image()` and update all callers to drop it. This makes the intent clear: format conversion is not supported.
+
+---
+
+### [domains/rendering/tasks.py:210–215] New SQLAlchemy engine created per `render_turntable_task` call
+**Severity**: Low
+**Description**: `render_turntable_task` now calls `_create_engine(app_settings.database_url_sync)` inside the task body. This creates a new connection pool on every invocation. For a low-frequency task this is acceptable, but it leaks connection pool resources if the task runs frequently.
+**Recommendation**: The `_db_engine` should be disposed after use. Add `_db_engine.dispose()` after the `with _Session(_db_engine) as _s:` block closes.
 
 ---
 
 ## Positives
 
-- **Dead code thoroughly removed**: `VALID_STL_QUALITIES`, `stl_quality` (7 locations in admin.py), 6 frontend files, `_mark_sharp_and_seams()` (62 lines), `_render_via_service()` (33 lines), 2 dead `elif renderer == "threejs"` branches — all gone. All acceptance gates pass.
-- **Submodule decomposition is clean**: `blender_render.py` went 858 → 249 lines. Each submodule has a clear single responsibility with correct `sys.path.insert(0, ...)` for Blender Python discovery.
-- **GPU activation order preserved**: `activate_gpu()` still called before `open_mainfile`, and again after engine init — the critical 3-call sequence is intact in `configure_engine()`.
-- **FailedMaterial sentinel preserved**: `assign_failed_material` in `_blender_materials.py` matches the original logic; unmatched parts in `apply_material_library` are now handled internally.
-- **`part_names_ordered` global → parameter**: Correctly converted to an explicit parameter in `apply_material_library()`.
-- **No security issues**: No hardcoded credentials, no SQL injections, no new endpoints, no new models.
-- **No render pipeline regressions**: No references to removed blender-renderer or threejs-renderer services.
-- **Frontend**: TypeScript errors in output are pre-existing (Admin.tsx GPUProbeResult, InlineCadViewer.tsx), not introduced by this change.
+- **All 7 plan tasks complete**: blender_render.py correctly reduced from 263 → 68 lines (meets ≤ 80 target).
+- **`stl_quality` fully removed**: Zero matches in `render_blender.py`, `step_processor.py`, `domains/rendering/tasks.py` — clean sweep.
+- **PIL fallback completely excised**: `_generate_thumbnail_placeholder()` and `from PIL import Image` both gone; the 68-line Pillow-placeholder function is deleted, reducing `step_processor.py` by ~70 lines.
+- **Submodule separation is clean**: `_blender_args.py`, `_blender_scene_setup.py`, `_blender_render_config.py` follow the existing `_blender_gpu.py` / `_blender_import.py` / `_blender_scene.py` naming and import pattern exactly.
+- **`_blender_args.py` fidelity**: All 25 positional args correctly mapped; named args `--mesh-attributes` and `--usd-path` preserved; `use_template` bool computed and included in namespace; template file existence check preserved.
+- **`_blender_scene_setup.py` correctness**: MODE A and MODE B correctly separated; shadow catcher, lighting_only, auto-camera, and material library logic all preserved faithfully; `needs_auto_camera` conditional for MODE B correctly omits `setup_auto_lights` (template provides its own lights).
+- **`_blender_render_config.py` correctness**: `configure_engine` signature matches exactly; colour management block (`Standard`/`None` look) correctly gated on `not use_template`; CYCLES verification block preserved.
+- **`_lap` closure works correctly**: `_lap` is defined in `blender_render.py`, captures `_t0` and `_timings` from outer scope, passed as callback to both submodules — timing summary at end of `blender_render.py` correctly reflects labels from all phases.
+- **`render_turntable_task` GLB path fixed**: Changed from `f"{stem}_{stl_quality}.glb"` (always `_low.glb`) to `{stem}_thumbnail.glb` — now consistent with `render_blender.py` service cache key.
+- **Security**: No hardcoded credentials, no SQL injection vectors. Raw SQL in `render_turntable_task` is a parameterless `SELECT` with no user input.
 
 ---
 
 ## Recommendation
-Approved. Two unused imports fixed inline before commit.
+
+Fix the `_db_engine.dispose()` omission (low, 1 line) and commit `_blender_import.py` together with the new submodule files. The `fmt` parameter cleanup is optional polish. Fix inline and re-apply without re-review.