Fix edge cases and consistency issues

pixstrip-core/src/pipeline.rs

@@ -21,7 +21,7 @@ pub struct ProcessingJob {
     pub metadata: Option<MetadataConfig>,
     pub watermark: Option<WatermarkConfig>,
     pub rename: Option<RenameConfig>,
-    pub overwrite_behavior: OverwriteBehavior,
+    pub overwrite_behavior: OverwriteAction,
     pub preserve_directory_structure: bool,
     pub progressive_jpeg: bool,
     pub avif_speed: u8,
@@ -44,11 +44,11 @@ impl ProcessingJob {
             metadata: None,
             watermark: None,
             rename: None,
-            overwrite_behavior: OverwriteBehavior::default(),
+            overwrite_behavior: OverwriteAction::default(),
             preserve_directory_structure: false,
             progressive_jpeg: false,
             avif_speed: 6,
-            output_dpi: 72,
+            output_dpi: 0,
         }
     }
 
@@ -70,6 +70,18 @@ impl ProcessingJob {
         count
     }
 
+    /// Returns true if the job requires decoding/encoding pixel data.
+    /// When false, we can use a fast copy-and-rename path.
+    pub fn needs_pixel_processing(&self) -> bool {
+        self.resize.is_some()
+            || matches!(self.rotation, Some(r) if !matches!(r, Rotation::None))
+            || matches!(self.flip, Some(f) if !matches!(f, Flip::None))
+            || self.adjustments.as_ref().is_some_and(|a| !a.is_noop())
+            || self.convert.is_some()
+            || self.compress.is_some()
+            || self.watermark.is_some()
+    }
+
     pub fn output_path_for(
         &self,
         source: &ImageSource,