fix(chat): preserve session model selection

src/providers/ChatViewProvider.ts

@@ -100,7 +100,7 @@
 import * as path from "path";
 import * as vscode from "vscode";
 import { ErrorBuilder } from "./chat/ErrorBuilder";
 import type { DisplayError } from "./chat/types";
 import {
   CssGenerator,
   FileThemeProcessor,
@@ -713,7 +713,7 @@
       let permissions: unknown[] = [];
 
       try {
         const questionResponse = await (client as any).question.list();
         questions = extractList(questionResponse, "questions").filter(belongsToSession);
       } catch (questionError) {
         this.logger.warn("Failed to list pending SDK questions", {
@@ -723,7 +723,7 @@
       }
 
       try {
         const permissionResponse = await (client as any).permission.list();
         permissions = extractList(permissionResponse, "permissions").filter(belongsToSession);
       } catch (permissionError) {
         this.logger.warn("Failed to list pending SDK permissions", {
@@ -857,8 +857,8 @@
   private lastSendMessageArgs?: {
     text: string;
     files?: string[];
     contexts?: any[];
     images?: any[];
     agent?: string;
   };
   /** OpenCode v2 accepts structured output only through the typed `format` field. */
@@ -951,7 +951,7 @@
     this.fileThemeProcessor.subscribe(this);
 
     // Load persisted model selection
     const savedModel = this.context.globalState.get<any>("selectedModel");
     if (
       savedModel &&
       typeof savedModel.providerID === "string" &&
@@ -1089,7 +1089,7 @@
    * Wire callbacks between modules and the shell
    */
   private wireModuleCallbacks(): void {
     const postMessage = (msg: any) => {
       this.view?.webview.postMessage(msg);
     };
 
@@ -1138,7 +1138,7 @@
       clientRequestId?: string;
       text?: string;
       files?: string[];
       contexts?: any[];
       images?: any[];
       agent?: string;
       userFacingText?: string;
@@ -2008,7 +2008,7 @@
       this.clearSessionTodos(sessionId);
 
       // Restore per-session agent / model / thinking selections
-      await this.modelAndAgentManager.applySessionSettings(sessionId);
+      await this.applySessionSettings(sessionId);
       if (abandonIfStale("applySessionSettings")) return;
 
       // ============================================================================
@@ -9288,7 +9288,9 @@
    * Applies session-specific model, agent, and thinking level
    */
   private async applySessionSettings(sessionId: string): Promise<void> {
-    return this.modelAndAgentManager.applySessionSettings(sessionId);
+    await this.modelAndAgentManager.applySessionSettings(sessionId);
+    this.selectedModel = this.modelAndAgentManager.getSelectedModel();
+    this.selectedAgent = this.modelAndAgentManager.getSelectedAgent() ?? "build";
   }
 
   /**

tests/regression/session-model-selection-regression.test.mjs

@@ -0,0 +1,32 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { extractFunctionBody, joinFromRoot, readSource } from "../helpers/source-utils.mjs";
+
+const provider = readSource(
+  [joinFromRoot("src", "providers", "ChatViewProvider.ts")],
+  "ChatViewProvider.ts",
+);
+
+test("session switches synchronize the prompt model with restored session settings", () => {
+  const applySessionSettings = extractFunctionBody(
+    provider,
+    "private async applySessionSettings(sessionId: string): Promise<void>",
+  );
+
+  assert.match(
+    applySessionSettings,
+    /await this\.modelAndAgentManager\.applySessionSettings\(sessionId\)/,
+    "session settings must be restored before synchronizing prompt state",
+  );
+  assert.match(
+    applySessionSettings,
+    /this\.selectedModel\s*=\s*this\.modelAndAgentManager\.getSelectedModel\(\)/,
+    "prompts must use the model restored for the active session",
+  );
+  assert.match(
+    provider,
+    /await this\.applySessionSettings\(sessionId\);/,
+    "session loading must use the synchronized restore path",
+  );
+});