Backend: UTC nel DB, +00:00 nelle API, ora italiana solo in presentazione (#42)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/backend/services/auth_service.py

@@ -1,7 +1,8 @@
 """Authentication service - password hashing, API key management."""
 import hashlib
 import secrets
-from datetime import datetime, timedelta, timezone
+from datetime import datetime, timedelta
+from src.backend.utils.tempo import utcnow
 
 import bcrypt
 from fastapi import HTTPException, status
@@ -78,11 +79,6 @@ async def authorise_supervisor(db: AsyncSession, username: str, password: str) -
     return supervisor
 
 
-def utcnow() -> datetime:
-    """Naive UTC now (the whole DB moves to naive UTC, #42)."""
-    return datetime.now(timezone.utc).replace(tzinfo=None)
-
-
 def hash_api_key(key: str) -> str:
     """SHA-256 hex digest of an API key; this is all the DB ever stores."""
     return hashlib.sha256(key.encode("utf-8")).hexdigest()

src/backend/services/measurement_service.py

@@ -1,6 +1,7 @@
 """Measurement service - pass/fail calculation, data storage."""
 import math
 from datetime import datetime
+from src.backend.utils.tempo import utcnow
 from decimal import Decimal
 from typing import TYPE_CHECKING
 
@@ -343,7 +344,7 @@ async def authorise_measurement(
 ) -> Measurement:
     """Let an out-of-tolerance value stand, on the supervisor's name."""
     measurement.supervisor_id = supervisor.id
-    measurement.authorised_at = datetime.now()
+    measurement.authorised_at = utcnow()
     await db.flush()
     await db.refresh(measurement)
     return measurement

src/backend/services/production_export_service.py

@@ -14,6 +14,7 @@ import csv
 import io
 import logging
 from datetime import datetime
+from src.backend.utils.tempo import iso_utc, to_local, utcnow
 from pathlib import Path
 
 from sqlalchemy import select, update
@@ -169,9 +170,9 @@ async def build_statistics_csv(db: AsyncSession, run: ProductionRun) -> str:
             measurement.input_method,
             "" if measurement.input_duration_ms is None else measurement.input_duration_ms,
             measurement.measured_by,
-            measurement.measured_at.isoformat() if measurement.measured_at else "",
+            iso_utc(measurement.measured_at),
             measurement.supervisor_id or "",
-            measurement.authorised_at.isoformat() if measurement.authorised_at else "",
+            iso_utc(measurement.authorised_at),
         ])
 
     return output.getvalue()
@@ -191,7 +192,7 @@ async def export_run_statistics(db: AsyncSession, run: ProductionRun) -> str | N
     directory = Path(settings.upload_path) / EXPORT_SUBDIR
     directory.mkdir(parents=True, exist_ok=True)
 
-    stamp = (run.closed_at or datetime.now()).strftime("%Y%m%d_%H%M%S")
+    stamp = to_local(run.closed_at or utcnow()).strftime("%Y%m%d_%H%M%S")
     filename = f"production_{run.id}_{stamp}.csv"
     # A large run's file can take a moment to write: off the event loop, so
     # closing one run does not stall every other request being served.

src/backend/services/production_service.py

@@ -14,6 +14,7 @@ the countdown would be off by the UTC offset. The number is the contract; the
 timestamp is only there for the audit trail.
 """
 from datetime import datetime, timedelta
+from src.backend.utils.tempo import utcnow
 from typing import Optional
 
 from fastapi import HTTPException, status
@@ -34,10 +35,10 @@ from src.backend.services import (
 def _now() -> datetime:
     """Single source of time for runs.
 
-    Naive local time, matching what the database writes for ``func.now()`` defaults,
+    Naive UTC, matching what the database writes for ``func.now()`` defaults,
     so a run's started_at and its deadline are comparable.
     """
-    return datetime.now()
+    return utcnow()
 
 
 # ---------------------------------------------------------------------------

src/backend/services/report_service.py

@@ -2,6 +2,7 @@
 import asyncio
 import base64
 from datetime import datetime
+from src.backend.utils.tempo import to_local, utcnow
 from pathlib import Path
 
 import plotly.graph_objects as go
@@ -342,7 +343,7 @@ async def generate_spc_report(
         control_chart_svg=control_chart_svg,
         histogram_svg=histogram_svg,
         filters_desc=filters_desc,
-        generated_at=datetime.now(),
+        generated_at=to_local(utcnow()),
         n_measurements=len(measurements),
     )
 
@@ -395,7 +396,7 @@ async def generate_measurement_report(
             "value": f"{float(m.value):.4f}",
             "unit": st_info.get("unit", "mm"),
             "pass_fail": m.pass_fail,
-            "measured_at": m.measured_at.strftime("%Y-%m-%d %H:%M"),
+            "measured_at": to_local(m.measured_at).strftime("%Y-%m-%d %H:%M"),
             "operator": operator_map.get(m.measured_by, f"ID {m.measured_by}"),
             "lot_number": m.lot_number or "—",
             "serial_number": m.serial_number or "—",
@@ -430,7 +431,7 @@ async def generate_measurement_report(
         rows=rows,
         summary=summary,
         filters_desc=filters_desc,
-        generated_at=datetime.now(),
+        generated_at=to_local(utcnow()),
         n_measurements=len(measurements),
     )