Add an icon to clear the copilot chat (#2236)

This add a "Clear chat" icon (see below on the right) to the Quantum
Copilot chat panel, and wires up the pre-existing clear chat
functioality to it

<img width="396" alt="image"
src="https://github.com/user-attachments/assets/a22dfa83-d613-42d0-9b64-13c3d213e824"
/>

Author: billti

Diff for: vscode/package.json

@@ -240,6 +240,11 @@
           "command": "qsharp-vscode.workspacesAdd",
           "when": "view == quantum-workspaces",
           "group": "navigation"
+        },
+        {
+          "command": "qsharp-vscode.copilotClear",
+          "when": "view == quantum-copilot",
+          "group": "navigation"
         }
       ],
       "view/item/context": [
@@ -386,6 +391,13 @@
         "title": "Remove workspace connection",
         "icon": "$(remove)"
       },
+      {
+        "command": "qsharp-vscode.copilotClear",
+        "category": "Q#",
+        "title": "Clear Quantum Copilot chat",
+        "enablement": "!qdkCopilotIsBusy",
+        "icon": "$(clear-all)"
+      },
       {
         "command": "qsharp-vscode.workspacePythonCode",
         "category": "Q#",

Diff for: vscode/src/copilot/copilot.ts

@@ -21,6 +21,7 @@ import { OpenAIChatService } from "./openAiChatService";
 import { getRandomGuid } from "../utils";
 import { EventType, sendTelemetryEvent, UserFlowStatus } from "../telemetry";
 import { knownToolNameOrDefault } from "./azqTools";
+import { commands } from "vscode";
 
 export class Copilot {
   private service: IChatService;
@@ -59,7 +60,14 @@ export class Copilot {
     }
     this.messages.push({ role: "user", content: userMessage });
 
-    await this.completeChat();
+    // Set the context so the 'clear' command is disabled when processing a response.
+    await commands.executeCommand("setContext", `qdkCopilotIsBusy`, true);
+    try {
+      await this.completeChat();
+    } finally {
+      // Reset the busy context when the chat is done.
+      await commands.executeCommand("setContext", `qdkCopilotIsBusy`, false);
+    }
   }
 
   /**

Diff for: vscode/src/copilot/webviewViewProvider.ts

@@ -3,6 +3,7 @@
 
 import { log } from "qsharp-lang";
 import {
+  commands,
   CancellationToken,
   ExtensionContext,
   Uri,
@@ -13,6 +14,7 @@ import {
 } from "vscode";
 import { Copilot, CopilotUpdateHandler } from "./copilot";
 import { CopilotCommand } from "./shared";
+import { qsharpExtensionId } from "../common";
 
 export function registerCopilotPanel(context: ExtensionContext): void {
   const provider = new CopilotWebviewViewProvider(context.extensionUri);
@@ -25,6 +27,11 @@ export function registerCopilotPanel(context: ExtensionContext): void {
       },
     ),
   );
+  context.subscriptions.push(
+    commands.registerCommand(`${qsharpExtensionId}.copilotClear`, async () => {
+      provider.clearChat();
+    }),
+  );
 }
 
 class CopilotWebviewViewProvider implements WebviewViewProvider {
@@ -99,6 +106,10 @@ class CopilotWebviewViewProvider implements WebviewViewProvider {
     }
   }
 
+  clearChat() {
+    this.copilot?.restartChat([]);
+  }
+
   handleMessageFromWebview(message: CopilotCommand) {
     if (!this.copilot) {
       return;