runner/live: add some docs to pipeline

runner/app/live/pipelines/interface.py

@@ -2,13 +2,47 @@
 from PIL import Image
 
 class Pipeline(ABC):
+    """Abstract base class for image processing pipelines.
+
+    Processes frames sequentially and supports dynamic parameter updates.
+
+    Notes:
+    - Methods are only called one at a time in a separate process, so no need
+      for any locking.
+    - Error handling is done by the caller, so the implementation can let
+      exceptions propagate for optimal error reporting.
+    """
+
     def __init__(self, **params):
+        """Initialize pipeline with optional parameters.
+
+        Args:
+            **params: Parameters to initalize the pipeline with.
+        """
         pass
 
     @abstractmethod
     def process_frame(self, frame: Image.Image) -> Image.Image:
+        """Process a single frame through the pipeline.
+
+        Called sequentially with each frame from the stream.
+
+        Args:
+            frame: Input PIL Image
+
+        Returns:
+            Processed PIL Image
+        """
         pass
 
     @abstractmethod
     def update_params(self, **params):
+        """Update pipeline parameters.
+
+        Must maintain valid state on success or restore previous state on failure.
+        Called sequentially with process_frame so concurrency is not an issue.
+
+        Args:
+            **params: Implementation-specific parameters
+        """
         pass