fix(vision): NaN/inf/bool di uno strumento non diventano più una quota (#16)

runner.run_graph esclude bool e NaN/inf dagli output numerici, con il
motivo in RunOutcome.invalid_outputs. vision_service tratta una quota
mappata con valore None/assente/non finito come "non prodotta" (422),
invece di arrivare a float(None) e sollevare TypeError.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/backend/services/vision_service.py

@@ -6,6 +6,7 @@ to the worker over HTTP and stays ignorant of how a number was produced.
 from __future__ import annotations
 
 import json
+import math
 from pathlib import Path
 from uuid import uuid4
 
@@ -21,6 +22,21 @@ from src.backend.models.orm.vision import VisionReferenceImage, VisionResult
 from src.backend.services import measurement_service
 
 
+def _is_measurable(value: object) -> bool:
+    """A worker output counts as a quote only if it is a finite, non-bool number.
+
+    None (absent, or explicitly null in a malformed response), a bool (a
+    subclass of int), and NaN/inf all fail this - each one would otherwise
+    reach `float()` and either crash with a bare TypeError or silently save a
+    value nobody could have measured.
+    """
+    return (
+        isinstance(value, (int, float))
+        and not isinstance(value, bool)
+        and math.isfinite(value)
+    )
+
+
 async def _call_worker(image_bytes: bytes, graph: dict) -> dict:
     """The one place that talks to the worker; the tests replace it.
 
@@ -159,8 +175,13 @@ async def execute_task(
     outputs = report["outputs"]
 
     # Every quote or none. A half-measured piece read as a whole one is worse
-    # than a piece not measured at all.
-    missing = [q.vision_output for q in quotes if q.vision_output not in outputs]
+    # than a piece not measured at all. A quote counts as produced only if its
+    # output is present *and* a finite, non-bool number: the in-process runner
+    # already drops NaN/inf itself (see src/vision/runner.py), but the worker
+    # is reached over HTTP - a different implementation of it, or a malformed
+    # response, could still hand back None or a non-finite float for a mapped
+    # key instead of omitting it outright.
+    missing = [q.vision_output for q in quotes if not _is_measurable(outputs.get(q.vision_output))]
     if missing:
         failed = ", ".join(f["tool_name"] for f in report["failures"])
         raise HTTPException(