feat(meals): enforce three lower-calorie dinners with media

backend/tests/test_image_generation.py

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+import base64
+from types import SimpleNamespace
+from unittest.mock import Mock
+from uuid import UUID
+
+from app.services import image_generation
+
+
+def test_generate_image_persists_local_url_and_openai_provenance(tmp_path, monkeypatch):
+    recipe = SimpleNamespace(
+        id=UUID("12345678-1234-5678-1234-567812345678"),
+        name="Spiced Chickpea Bowl",
+        ingredients=[{"name": "chickpeas"}],
+        cuisine_tags=["Mediterranean"],
+        image_url=None,
+        image_source=None,
+    )
+    db = Mock()
+    image_bytes = b"mock-png-bytes"
+    response = Mock(status_code=200)
+    response.json.return_value = {
+        "data": [{"b64_json": base64.b64encode(image_bytes).decode()}]
+    }
+    post = Mock(return_value=response)
+
+    monkeypatch.setattr(image_generation.settings, "AI_IMAGE_ENABLED", True)
+    monkeypatch.setattr(image_generation, "_openai_api_key", lambda: "test-key")
+    monkeypatch.setattr(image_generation, "STATIC_IMAGES_DIR", tmp_path)
+    monkeypatch.setattr(image_generation.httpx, "post", post)
+    monkeypatch.setenv("AI_IMAGE_MODEL", "gpt-image-1")
+
+    image_url = image_generation.generate_image_for_recipe(recipe, db=db)
+
+    assert image_url is not None
+    assert image_url.startswith("/static/images/")
+    assert (tmp_path / image_url.removeprefix("/static/images/")).read_bytes() == image_bytes
+    assert recipe.image_url == image_url
+    db.add.assert_called_once_with(recipe)
+    db.commit.assert_called_once_with()
+    assert recipe.image_source
+    assert "openai" in recipe.image_source.lower()
+    assert "gpt-image-1" in recipe.image_source.lower()