refactor(core,cli): useAlternateBuffer read from config (#20346)

Co-authored-by: Jacob Richman <jacob314@gmail.com>

packages/core/src/config/config.test.ts

@@ -941,6 +941,31 @@ describe('Server Config (config.ts)', () => {
     });
   });
 
+  describe('UseAlternateBuffer Configuration', () => {
+    it('should default useAlternateBuffer to false when not provided', () => {
+      const config = new Config(baseParams);
+      expect(config.getUseAlternateBuffer()).toBe(false);
+    });
+
+    it('should set useAlternateBuffer to true when provided as true', () => {
+      const paramsWithAlternateBuffer: ConfigParameters = {
+        ...baseParams,
+        useAlternateBuffer: true,
+      };
+      const config = new Config(paramsWithAlternateBuffer);
+      expect(config.getUseAlternateBuffer()).toBe(true);
+    });
+
+    it('should set useAlternateBuffer to false when explicitly provided as false', () => {
+      const paramsWithAlternateBuffer: ConfigParameters = {
+        ...baseParams,
+        useAlternateBuffer: false,
+      };
+      const config = new Config(paramsWithAlternateBuffer);
+      expect(config.getUseAlternateBuffer()).toBe(false);
+    });
+  });
+
   describe('UseWriteTodos Configuration', () => {
     it('should default useWriteTodos to true when not provided', () => {
       const config = new Config(baseParams);

packages/core/src/config/config.ts

@@ -519,6 +519,7 @@ export interface ConfigParameters {
   interactive?: boolean;
   trustedFolder?: boolean;
   useBackgroundColor?: boolean;
+  useAlternateBuffer?: boolean;
   useRipgrep?: boolean;
   enableInteractiveShell?: boolean;
   skipNextSpeakerCheck?: boolean;
@@ -702,6 +703,7 @@ export class Config {
   private readonly enableInteractiveShell: boolean;
   private readonly skipNextSpeakerCheck: boolean;
   private readonly useBackgroundColor: boolean;
+  private readonly useAlternateBuffer: boolean;
   private shellExecutionConfig: ShellExecutionConfig;
   private readonly extensionManagement: boolean = true;
   private readonly truncateToolOutputThreshold: number;
@@ -900,6 +902,7 @@ export class Config {
     this.directWebFetch = params.directWebFetch ?? false;
     this.useRipgrep = params.useRipgrep ?? true;
     this.useBackgroundColor = params.useBackgroundColor ?? true;
+    this.useAlternateBuffer = params.useAlternateBuffer ?? false;
     this.enableInteractiveShell = params.enableInteractiveShell ?? false;
     this.skipNextSpeakerCheck = params.skipNextSpeakerCheck ?? true;
     this.shellExecutionConfig = {
@@ -2521,6 +2524,10 @@ export class Config {
     return this.useBackgroundColor;
   }
 
+  getUseAlternateBuffer(): boolean {
+    return this.useAlternateBuffer;
+  }
+
   getEnableInteractiveShell(): boolean {
     return this.enableInteractiveShell;
   }