Refactoring: table based branching

src/app/endpoints/streaming_query.py

@@ -134,12 +134,14 @@ def stream_end_event(metadata_map: dict) -> str:
 def stream_build_event(chunk: Any, chunk_id: int, metadata_map: dict) -> Iterator[str]:
     """Build a streaming event from a chunk response.
 
-    This function processes chunks from the Llama Stack streaming response and formats
-    them into Server-Sent Events (SSE) format for the client. It handles two main
-    event types:
+    This function processes chunks from the Llama Stack streaming response and
+    formats them into Server-Sent Events (SSE) format for the client. It
+    dispatches on (event_type, step_type):
 
-    1. step_progress: Contains text deltas from the model inference process
-    2. step_complete: Contains information about completed tool execution steps
+    1. turn_start, turn_awaiting_input -> start token
+    2. turn_complete -> final output message
+    3. step_* with step_type in {"shield_call", "inference", "tool_execution"} -> delegated handlers
+    4. anything else -> heartbeat
 
     Args:
         chunk: The streaming chunk from Llama Stack containing event data
@@ -154,18 +156,24 @@ def stream_build_event(chunk: Any, chunk_id: int, metadata_map: dict) -> Iterato
     event_type = chunk.event.payload.event_type
     step_type = getattr(chunk.event.payload, "step_type", None)
 
-    if event_type in {"turn_start", "turn_awaiting_input"}:
-        yield from _handle_turn_start_event(chunk_id)
-    elif event_type == "turn_complete":
-        yield from _handle_turn_complete_event(chunk, chunk_id)
-    elif step_type == "shield_call":
-        yield from _handle_shield_event(chunk, chunk_id)
-    elif step_type == "inference":
-        yield from _handle_inference_event(chunk, chunk_id)
-    elif step_type == "tool_execution":
-        yield from _handle_tool_execution_event(chunk, chunk_id, metadata_map)
-    else:
-        yield from _handle_heartbeat_event(chunk_id)
+    match (event_type, step_type):
+        case (("turn_start" | "turn_awaiting_input"), _):
+            yield from _handle_turn_start_event(chunk_id)
+        case ("turn_complete", _):
+            yield from _handle_turn_complete_event(chunk, chunk_id)
+        case (_, "shield_call"):
+            yield from _handle_shield_event(chunk, chunk_id)
+        case (_, "inference"):
+            yield from _handle_inference_event(chunk, chunk_id)
+        case (_, "tool_execution"):
+            yield from _handle_tool_execution_event(chunk, chunk_id, metadata_map)
+        case _:
+            logger.debug(
+                "Unhandled event combo: event_type=%s, step_type=%s",
+                event_type,
+                step_type,
+            )
+            yield from _handle_heartbeat_event(chunk_id)
 
 
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