Log filament usage to FilamentDB when starting a job

- filamentdb.get_ams_slots(): parses /ams/ HTML to extract slot, material,
  color, weight_remaining_g, roll_id for each loaded AMS slot
- filamentdb.find_matching_ams_roll(): filters by material+color (case-insensitive),
  picks the roll with least filament remaining
- filamentdb.log_print_on_roll(): POSTs to /rolls/{id}/prints
- start_job: after setting job to printing, looks up AMS, computes weight
  (math.ceil of estimate), logs against matching roll, writes result to job log
- Verified parser against live AMS: PLA Black → slot 3 (30g) over slot 1 (1000g)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/routers/ui.py

@@ -1,3 +1,4 @@
+import math
 import os
 import uuid as _uuid
 from datetime import datetime, timedelta
@@ -21,8 +22,9 @@ from app.models.printer_type import PrinterType
 from app.models.pricing import PricingConfig
 from app.models.todo import Todo
 from app.constants import COLORS, MATERIALS
-from app.estimation import estimate
-from app.filamentdb import available_colors, available_materials, get_stock, spool_counts
+from app.estimation import estimate  # also used in start_job
+from app.filamentdb import (available_colors, available_materials, find_matching_ams_roll,
+                             get_stock, log_print_on_roll, spool_counts)
 from app.stl import get_stl_dir, list_stl_files
 from app.stl_analysis import analyse, get_cache_map  # noqa: F401 used in job_detail route
 
@@ -325,6 +327,29 @@ def start_job(job_id: int, printer_id: int = Form(...), db: Session = Depends(ge
     printer.status = PrinterStatus.printing
 
     db.add(JobLog(job_id=job_id, message=f"Job started on {printer.name}"))
+
+    # Log filament usage against matching AMS roll in FilamentDB
+    if job.job_material and job.job_color:
+        stl = db.query(StlCache).filter_by(filename=job.file_name).first() if job.file_name else None
+        if stl and stl.volume_ccm:
+            weight_g = math.ceil(estimate(stl.volume_ccm, job.job_material)["weight_g"])
+            roll = find_matching_ams_roll(job.job_material, job.job_color)
+            if roll:
+                note = (f"POPS {job.job_uuid[:8] if job.job_uuid else job.id}: "
+                        f"{job.file_name or job.name} on {printer.name}")
+                if log_print_on_roll(roll["roll_id"], weight_g, note):
+                    db.add(JobLog(job_id=job_id, message=(
+                        f"FilamentDB: logged {weight_g} g against roll #{roll['roll_id']} "
+                        f"(AMS slot {roll['slot']} — {roll['material']} {roll['color']}, "
+                        f"{roll['weight_remaining_g']} g remaining, least-full roll selected)"
+                    )))
+                else:
+                    db.add(JobLog(job_id=job_id, message=f"FilamentDB: print log failed for roll #{roll['roll_id']}"))
+            else:
+                db.add(JobLog(job_id=job_id, message=(
+                    f"FilamentDB: no {job.job_material} {job.job_color} roll found in AMS"
+                )))
+
     db.commit()
     return RedirectResponse(url=f"/jobs/{job_id}", status_code=HTTP_303_SEE_OTHER)