fix(code): persist model selection during task creation

apps/code/src/main/services/agent/schemas.ts

@@ -30,6 +30,8 @@ export const sessionConfigSchema = z.object({
   additionalDirectories: z.array(z.string()).optional(),
   /** Permission mode to use for the session (e.g. "default", "acceptEdits", "plan", "bypassPermissions") */
   permissionMode: z.string().optional(),
+  /** Preferred model ID for the session (e.g. "claude-sonnet-4-6") */
+  model: z.string().optional(),
 });
 
 export type SessionConfig = z.infer<typeof sessionConfigSchema>;
@@ -49,6 +51,7 @@ export const startSessionInput = z.object({
   additionalDirectories: z.array(z.string()).optional(),
   customInstructions: z.string().max(2000).optional(),
   effort: effortLevelSchema.optional(),
+  model: z.string().optional(),
 });
 
 export type StartSessionInput = z.infer<typeof startSessionInput>;

apps/code/src/main/services/agent/service.ts

@@ -189,6 +189,8 @@ interface SessionConfig {
   customInstructions?: string;
   /** Effort level for Claude sessions */
   effort?: EffortLevel;
+  /** Model to use for the session (e.g. "claude-sonnet-4-6") */
+  model?: string;
 }
 
 interface ManagedSession {
@@ -465,6 +467,7 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
       permissionMode,
       customInstructions,
       effort,
+      model,
     } = config;
 
     // Preview sessions don't need a real repo — use a temp directory
@@ -644,6 +647,7 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
                   additionalDirectories,
                 }),
                 ...(effort && { effort }),
+                ...(model && { model }),
                 plugins,
               },
             },
@@ -673,6 +677,7 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
               options: {
                 ...(additionalDirectories?.length && { additionalDirectories }),
                 ...(effort && { effort }),
+                ...(model && { model }),
                 plugins,
               },
             },
@@ -1362,6 +1367,7 @@ For git operations while detached:
       customInstructions:
         "customInstructions" in params ? params.customInstructions : undefined,
       effort: "effort" in params ? params.effort : undefined,
+      model: "model" in params ? params.model : undefined,
     };
   }
 

apps/code/src/renderer/features/sessions/service/service.ts

@@ -548,6 +548,7 @@ export class SessionService {
       effort: effortLevelSchema.safeParse(reasoningLevel).success
         ? (reasoningLevel as EffortLevel)
         : undefined,
+      model,
     });
 
     const session = this.createBaseSession(taskRun.id, taskId, taskTitle);

apps/code/src/renderer/features/task-detail/components/TaskInput.tsx

@@ -78,6 +78,11 @@ export function TaskInput({ onTaskCreated }: TaskInputProps = {}) {
     null,
   );
 
+  // Track the user's explicit model selection independently of the preview
+  // session. The preview session's config can be reset (e.g. adapter change),
+  // which would lose the user's choice if we only read from the store.
+  const [selectedModel, setSelectedModel] = useState<string | null>(null);
+
   const [selectedDirectory, setSelectedDirectory] = useState("");
   const workspaceMode = lastUsedWorkspaceMode || "local";
   const adapter = lastUsedAdapter;
@@ -94,8 +99,10 @@ export function TaskInput({ onTaskCreated }: TaskInputProps = {}) {
       setLastUsedLocalWorkspaceMode(mode);
     }
   };
-  const setAdapter = (newAdapter: AgentAdapter) =>
+  const setAdapter = (newAdapter: AgentAdapter) => {
     setLastUsedAdapter(newAdapter);
+    setSelectedModel(null);
+  };
 
   const { githubIntegration, repositories, isLoadingRepos } =
     useRepositoryIntegration();
@@ -192,8 +199,11 @@ export function TaskInput({ onTaskCreated }: TaskInputProps = {}) {
 
   // Get current values from preview session config options for task creation.
   // Defaults ensure values are always passed even before the preview session loads.
-  const currentModel =
+  // Prefer the user's explicit selection (local state) over the preview session value,
+  // since the preview session's config can be transiently reset.
+  const previewModel =
     modelOption?.type === "select" ? modelOption.currentValue : undefined;
+  const currentModel = selectedModel ?? previewModel;
   const modeFallback =
     defaultInitialTaskMode === "last_used" ? lastUsedInitialTaskMode : "plan";
   const currentExecutionMode =
@@ -461,6 +471,7 @@ export function TaskInput({ onTaskCreated }: TaskInputProps = {}) {
             previewTaskId={previewTaskId}
             onAdapterChange={setAdapter}
             isPreviewConnecting={isConnecting}
+            onModelChange={setSelectedModel}
           />
 
           <ModeIndicatorInput

packages/agent/src/adapters/claude/claude-agent.ts

@@ -780,6 +780,9 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
     const meta = params._meta as NewSessionMeta | undefined;
     const taskId = meta?.persistence?.taskId;
     const effort = meta?.claudeCode?.options?.effort as EffortLevel | undefined;
+    const modelOverride = meta?.claudeCode?.options?.model as
+      | string
+      | undefined;
 
     // We want to create a new session id unless it is resume,
     // but not resume + forkSession.
@@ -919,10 +922,13 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
       });
     }
 
-    // Resolve model: settings model takes priority, then gateway
+    // Resolve model: explicit UI selection takes priority, then settings, then gateway default
     const settingsModel = settingsManager.getSettings().model;
-    const modelOptions = await this.getModelConfigOptions();
-    const resolvedModelId = settingsModel || modelOptions.currentModelId;
+    const modelOptions = await this.getModelConfigOptions(
+      modelOverride ?? undefined,
+    );
+    const resolvedModelId =
+      modelOverride || settingsModel || modelOptions.currentModelId;
     session.modelId = resolvedModelId;
     session.lastContextWindowSize =
       this.getContextWindowForModel(resolvedModelId);