From 3492bebe44960899c05d076a057c091729121d49 Mon Sep 17 00:00:00 2001
From: luca cappa <lucappa@microsoft.com>
Date: Fri, 27 Mar 2026 17:40:34 -0700
Subject: [PATCH] minimize the calls to lm.selectChatModels

---
 .../Providers/CopilotHoverProvider.ts         | 44 ++++++++++++++++---
 Extension/src/LanguageServer/extension.ts     | 10 +++--
 2 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/Extension/src/LanguageServer/Providers/CopilotHoverProvider.ts b/Extension/src/LanguageServer/Providers/CopilotHoverProvider.ts
index b04b8e302..b04e17cd3 100644
--- a/Extension/src/LanguageServer/Providers/CopilotHoverProvider.ts
+++ b/Extension/src/LanguageServer/Providers/CopilotHoverProvider.ts
@@ -26,10 +26,45 @@ export class CopilotHoverProvider implements vscode.HoverProvider {
     private cancelledDocument: vscode.TextDocument | undefined;
     private cancelledPosition: vscode.Position | undefined;
     private content: string | undefined;
+    private chatModel: vscode.LanguageModelChat | undefined;
+    // Flag to avoid querying the LanguageModelChat repeatedly if no model is found
+    private checkedChatModel: boolean = false;
     constructor(client: DefaultClient) {
         this.client = client;
     }
 
+    public async getCachedChatModel(): Promise<vscode.LanguageModelChat | undefined> {
+        if (this.checkedChatModel) {
+            return this.chatModel;
+        }
+
+        const vscodelm = getVSCodeLanguageModel();
+        if (vscodelm) {
+            try {
+                const [model] = await vscodelm.selectChatModels(modelSelector);
+                if (!model) {
+                    telemetry.logLanguageServerEvent('CopilotHoverNoModelSelected', { remoteName: vscode.env.remoteName || 'local' });
+                } else {
+                    this.chatModel = model;
+                }
+            } catch (e: any) {
+                const exceptionType = e?.name || e?.constructor?.name || typeof e;
+                telemetry.logLanguageServerEvent('CopilotHoverSelectModelFailed', {
+                    remoteName: vscode.env.remoteName || 'local',
+                    exceptionType: String(exceptionType)
+                });
+            }
+        }
+        this.checkedChatModel = true;
+        return this.chatModel;
+    }
+
+    public async refreshCachedChatModel(): Promise<vscode.LanguageModelChat | undefined> {
+        this.chatModel = undefined;
+        this.checkedChatModel = false;
+        return this.getCachedChatModel();
+    }
+
     public async provideHover(document: vscode.TextDocument, position: vscode.Position, token: vscode.CancellationToken): Promise<vscode.Hover | undefined> {
         await this.client.ready;
 
@@ -43,12 +78,9 @@ export class CopilotHoverProvider implements vscode.HoverProvider {
         }
 
         // Ensure the user has access to Copilot.
-        const vscodelm = getVSCodeLanguageModel();
-        if (vscodelm) {
-            const [model] = await vscodelm.selectChatModels(modelSelector);
-            if (!model) {
-                return undefined;
-            }
+        const model = await this.getCachedChatModel();
+        if (!model) {
+            return undefined;
         }
 
         const newHover = this.isNewHover(document, position);
diff --git a/Extension/src/LanguageServer/extension.ts b/Extension/src/LanguageServer/extension.ts
index 2c072eff3..f4d3417b2 100644
--- a/Extension/src/LanguageServer/extension.ts
+++ b/Extension/src/LanguageServer/extension.ts
@@ -17,7 +17,7 @@ import { TargetPopulation } from 'vscode-tas-client';
 import * as which from 'which';
 import { logAndReturn } from '../Utility/Async/returns';
 import * as util from '../common';
-import { isWindows, modelSelector } from '../constants';
+import { isWindows } from '../constants';
 import { instrument } from '../instrumentation';
 import { getCrashCallStacksChannel } from '../logger';
 import { PlatformInformation } from '../platform';
@@ -1471,8 +1471,12 @@ async function onCopilotHover(): Promise<void> {
 
     let chatResponse: vscode.LanguageModelChatResponse | undefined;
     try {
-        // Select the chat model.
-        const [model] = await vscodelm.selectChatModels(modelSelector);
+        // Select the chat model (refresh from cache).
+        const model = await copilotHoverProvider.refreshCachedChatModel();
+        if (!model) {
+            await reportCopilotFailure(copilotHoverProvider, hoverDocument, hoverPosition, "Copilot model not available.");
+            return;
+        }
 
         chatResponse = await model.sendRequest(
             messages,