Test final template output validation

tests/test_templates.py

@@ -9,7 +9,7 @@ from fastapi.testclient import TestClient
 from app.container import build_container
 from app.core.exceptions import TemplateValidationError
 from app.models.media import InputMedia, MediaSource, ResolvedRequest
-from app.templates.executor import OPERATION_BINDINGS
+from app.templates.executor import OPERATION_BINDINGS, TemplateExecutor
 from app.templates.loader import TemplateLoader
 from app.templates.registry import TemplateRegistry
 from app.templates.validator import TemplateValidator
@@ -289,3 +289,47 @@ def test_voiceover_music_ducking_template_uses_two_original_inputs(settings) ->
     assert prepared.pipeline[0].inputs == ["original", "original:1"]
     assert prepared.pipeline[0].parameters["music_volume"] == 0.22
     assert prepared.output.format == "mp4"
+
+
+def test_final_output_validation_reports_media_metadata(settings, tmp_path: Path) -> None:
+    output = tmp_path / "final.mp3"
+    output.write_bytes(b"non-empty-output")
+    media = InputMedia(
+        source=MediaSource.LOCAL_PATH,
+        filename=output.name,
+        mime_type="audio/mpeg",
+        temp_path=output,
+        size=output.stat().st_size,
+        duration=12.5,
+        metadata={
+            "duration": 12.5,
+            "container": "mp3",
+            "audio_streams": [{"codec": "mp3"}],
+            "video_streams": [],
+            "resolution": None,
+        },
+    )
+
+    report = TemplateExecutor._output_validation(media)
+
+    assert report["valid"] is True
+    assert report["size_bytes"] == output.stat().st_size
+    assert report["duration_seconds"] == 12.5
+    assert report["audio_stream_count"] == 1
+    assert report["video_stream_count"] == 0
+
+
+def test_final_output_validation_rejects_empty_artifact(settings, tmp_path: Path) -> None:
+    output = tmp_path / "empty.mp3"
+    output.write_bytes(b"")
+    media = InputMedia(
+        source=MediaSource.LOCAL_PATH,
+        filename=output.name,
+        mime_type="audio/mpeg",
+        temp_path=output,
+        size=0,
+    )
+    prepared = build_container(settings).template_registry.prepare("mp3@1", {})
+
+    with pytest.raises(Exception, match="empty"):
+        TemplateExecutor._validate_output(prepared, media)