Use full-bleed photos with a single-line bottom watermark

tests/test_photo_watermark.py

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+from io import BytesIO
+
+import pytest
+from PIL import Image
+
+from pigway_frame_flow.renderers.photo_caption import render_captioned_photo
+from pigway_frame_flow.renderers.photo_layout import PhotoLayout, WatermarkLayout
+
+
+@pytest.mark.parametrize("size", [(1600, 1200), (1200, 1600)])
+@pytest.mark.parametrize("fit", ["contain", "cover", "smart"])
+def test_watermark_has_no_letterboxing(service, size, fit):
+    stream = BytesIO()
+    Image.new("RGB", (400, 100), "blue").save(stream, "JPEG")
+    data = render_captioned_photo(
+        stream.getvalue(),
+        {"title": "Family", "date": "2026-10-06", "place": "Shanghai"},
+        service.renderer.font,
+        fit=fit,
+        size=size,
+    )
+    with Image.open(BytesIO(data)) as image:
+        assert image.size == size
+        layout = WatermarkLayout().layout(size, {})
+        for point in [
+            (10, 10),
+            (size[0] - 10, 10),
+            (10, size[1] - layout.footer_height - 10),
+        ]:
+            assert image.getpixel(point)[2] > image.getpixel(point)[0] + 100
+        assert image.getpixel((size[0] - 10, size[1] - 10))[0] > 240
+        assert layout.footer_height / min(size) <= 0.06
+
+
+def test_layout_provider_is_injectable(service):
+    class Custom:
+        def layout(self, size, caption):
+            return PhotoLayout(100, 30, 40)
+
+    stream = BytesIO()
+    Image.new("RGB", (160, 120), "blue").save(stream, "JPEG")
+    data = render_captioned_photo(
+        stream.getvalue(),
+        {"title": "Custom", "date": "2026-10-06"},
+        service.renderer.font,
+        size=(1600, 1200),
+        layout_provider=Custom(),
+    )
+    with Image.open(BytesIO(data)) as image:
+        assert image.getpixel((1500, 1120))[0] > 240
+
+
+def test_long_multiline_caption_does_not_wrap_or_hang(service):
+    stream = BytesIO()
+    Image.new("RGB", (160, 120), "blue").save(stream, "JPEG")
+    data = render_captioned_photo(
+        stream.getvalue(),
+        {"title": "Long title\n" * 100, "date": "2026-10-06", "place": "Place " * 100},
+        service.renderer.font,
+    )
+    assert Image.open(BytesIO(data)).size == (1200, 1600)