feat(plan): implement plan slash command (#17698)

packages/core/src/config/config.ts

@@ -627,9 +627,12 @@ export class Config {
   private latestApiRequest: GenerateContentParameters | undefined;
   private lastModeSwitchTime: number = Date.now();
 
+  private approvedPlanPath: string | undefined;
+
   constructor(params: ConfigParameters) {
     this.sessionId = params.sessionId;
     this.clientVersion = params.clientVersion ?? 'unknown';
+    this.approvedPlanPath = undefined;
     this.embeddingModel =
       params.embeddingModel ?? DEFAULT_GEMINI_EMBEDDING_MODEL;
     this.fileSystemService = new StandardFileSystemService();
@@ -1706,6 +1709,14 @@ export class Config {
     return this.planEnabled;
   }
 
+  getApprovedPlanPath(): string | undefined {
+    return this.approvedPlanPath;
+  }
+
+  setApprovedPlanPath(path: string | undefined): void {
+    this.approvedPlanPath = path;
+  }
+
   isAgentsEnabled(): boolean {
     return this.enableAgents;
   }

packages/core/src/tools/exit-plan-mode.test.ts

@@ -38,6 +38,7 @@ describe('ExitPlanModeTool', () => {
     mockConfig = {
       getTargetDir: vi.fn().mockReturnValue(tempRootDir),
       setApprovalMode: vi.fn(),
+      setApprovedPlanPath: vi.fn(),
       storage: {
         getProjectTempPlansDir: vi.fn().mockReturnValue(mockPlansDir),
       } as unknown as Config['storage'],
@@ -200,6 +201,7 @@ The approved implementation plan is stored at: ${expectedPath}
 Read and follow the plan strictly during implementation.`,
         returnDisplay: `Plan approved: ${expectedPath}`,
       });
+      expect(mockConfig.setApprovedPlanPath).toHaveBeenCalledWith(expectedPath);
     });
 
     it('should return approval message when plan is approved with AUTO_EDIT mode', async () => {
@@ -230,6 +232,7 @@ Read and follow the plan strictly during implementation.`,
       expect(mockConfig.setApprovalMode).toHaveBeenCalledWith(
         ApprovalMode.AUTO_EDIT,
       );
+      expect(mockConfig.setApprovedPlanPath).toHaveBeenCalledWith(expectedPath);
     });
 
     it('should return feedback message when plan is rejected with feedback', async () => {

packages/core/src/tools/exit-plan-mode.ts

@@ -224,6 +224,7 @@ export class ExitPlanModeInvocation extends BaseToolInvocation<
     if (payload?.approved) {
       const newMode = payload.approvalMode ?? ApprovalMode.DEFAULT;
       this.config.setApprovalMode(newMode);
+      this.config.setApprovedPlanPath(resolvedPlanPath);
 
       const description = getApprovalModeDescription(newMode);