Refactor emit_metric to use structured payload dict

Pass a single dict payload instead of positional args to avoid
arg-order bugs and ensure temporal fields (fiscal_year, end_date,
form) are not dropped. Adds debug logging of the JSON payload.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app.py

@@ -238,11 +238,18 @@ async def handle_message_send(params: dict, request_id: Any) -> dict:
 
 
 def create_progress_callback(task_id: str):
-    """Create a progress callback that adds partial metrics to the task."""
-    def callback(source: str, metric: str, value: Any,
-                 end_date: str = None, fiscal_year: int = None, form: str = None):
+    """Create a progress callback that receives structured metric payloads."""
+    def callback(payload: dict):
         task = TASK_STORE.get(task_id)
         if task and task.status == TaskStatus.WORKING:
+            # Extract fields from structured payload
+            source = payload.get("source", "unknown")
+            metric = payload.get("metric", "unknown")
+            value = payload.get("value")
+            end_date = payload.get("end_date")
+            fiscal_year = payload.get("fiscal_year")
+            form = payload.get("form")
+
             entry = MetricEntry(
                 source=source,
                 metric=metric,

mcp_client.py

@@ -35,11 +35,18 @@ async def emit_metric(
     fiscal_year: int = None,
     form: str = None
 ):
-    """Emit a metric event with optional temporal data and configurable delay."""
+    """Emit a metric event as a structured payload with optional temporal data."""
     if progress_callback:
-        temporal_info = f" ({form} {fiscal_year})" if fiscal_year else ""
-        logger.debug(f"emit_metric: {source}/{metric}={value}{temporal_info}")
-        progress_callback(source, metric, value, end_date, fiscal_year, form)
+        payload = {
+            "source": source,
+            "metric": metric,
+            "value": value,
+            "end_date": end_date,
+            "fiscal_year": fiscal_year,
+            "form": form,
+        }
+        logger.debug(f"emit_metric payload: {json.dumps(payload, default=str)}")
+        progress_callback(payload)
         await asyncio.sleep(METRIC_DELAY_MS / 1000)