only allow plots tool when there is a session and there are plots

Author: sharon-wang

extensions/positron-assistant/package.json

@@ -357,7 +357,8 @@
         "modelDescription": "View the current active plot if one exists. Don't invoke this tool if there are no plots in the session.",
         "canBeReferencedInPrompt": false,
         "tags": [
-          "positron-assistant"
+          "positron-assistant",
+          "requires-session"
         ]
       },
       {
@@ -390,7 +391,8 @@
           ]
         },
         "tags": [
-          "positron-assistant"
+          "positron-assistant",
+          "requires-session"
         ]
       },
       {

extensions/positron-assistant/src/participants.ts

@@ -277,6 +277,10 @@ abstract class PositronAssistantParticipant implements IPositronAssistantPartici
 						// TODO: Remove this restriction when the tool is supported in R https://github.com/posit-dev/positron/issues/8343
 						// The logic above with TOOL_TAG_REQUIRES_ACTIVE_SESSION will handle checking for active sessions once this is removed.
 						return activeSessions.has('python');
+					case PositronAssistantToolName.GetPlot:
+						return positronContext.plots?.hasPlots === true;
+					// case PositronAssistantToolName.InspectVariables:
+					// TODO: only allow this tool when there are variables to inspect
 					// Otherwise, include the tool if it is tagged for use with Positron Assistant.
 					// Allow all tools in Agent mode.
 					default: