feat(sessions): add resuming to geminiChat and add CLI flags for session management (#10719)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

packages/cli/src/config/config.test.ts

@@ -451,6 +451,36 @@ describe('parseArguments', () => {
     mockConsoleError.mockRestore();
   });
 
+  it('should throw an error when resuming a session without prompt in non-interactive mode', async () => {
+    const originalIsTTY = process.stdin.isTTY;
+    process.stdin.isTTY = false;
+    process.argv = ['node', 'script.js', '--resume', 'session-id'];
+
+    const mockExit = vi.spyOn(process, 'exit').mockImplementation(() => {
+      throw new Error('process.exit called');
+    });
+
+    const mockConsoleError = vi
+      .spyOn(console, 'error')
+      .mockImplementation(() => {});
+
+    try {
+      await expect(parseArguments({} as Settings)).rejects.toThrow(
+        'process.exit called',
+      );
+
+      expect(mockConsoleError).toHaveBeenCalledWith(
+        expect.stringContaining(
+          'When resuming a session, you must provide a message via --prompt (-p) or stdin',
+        ),
+      );
+    } finally {
+      mockExit.mockRestore();
+      mockConsoleError.mockRestore();
+      process.stdin.isTTY = originalIsTTY;
+    }
+  });
+
   it('should support comma-separated values for --allowed-tools', async () => {
     process.argv = [
       'node',

packages/cli/src/config/config.ts

@@ -61,6 +61,9 @@ export interface CliArgs {
   experimentalAcp: boolean | undefined;
   extensions: string[] | undefined;
   listExtensions: boolean | undefined;
+  resume: string | 'latest' | undefined;
+  listSessions: boolean | undefined;
+  deleteSession: string | undefined;
   includeDirectories: string[] | undefined;
   screenReader: boolean | undefined;
   useSmartEdit: boolean | undefined;
@@ -172,6 +175,35 @@ export async function parseArguments(settings: Settings): Promise<CliArgs> {
           type: 'boolean',
           description: 'List all available extensions and exit.',
         })
+        .option('resume', {
+          alias: 'r',
+          type: 'string',
+          // `skipValidation` so that we can distinguish between it being passed with a value, without
+          // one, and not being passed at all.
+          skipValidation: true,
+          description:
+            'Resume a previous session. Use "latest" for most recent or index number (e.g. --resume 5)',
+          coerce: (value: string): string => {
+            // When --resume passed with a value (`gemini --resume 123`): value = "123" (string)
+            // When --resume passed without a value (`gemini --resume`): value = "" (string)
+            // When --resume not passed at all: this `coerce` function is not called at all, and
+            //   `yargsInstance.argv.resume` is undefined.
+            if (value === '') {
+              return 'latest';
+            }
+            return value;
+          },
+        })
+        .option('list-sessions', {
+          type: 'boolean',
+          description:
+            'List available sessions for the current project and exit.',
+        })
+        .option('delete-session', {
+          type: 'string',
+          description:
+            'Delete a session by index number (use --list-sessions to see available sessions).',
+        })
         .option('include-directories', {
           type: 'array',
           string: true,
@@ -227,6 +259,11 @@ export async function parseArguments(settings: Settings): Promise<CliArgs> {
           if (argv['prompt'] && argv['promptInteractive']) {
             return 'Cannot use both --prompt (-p) and --prompt-interactive (-i) together';
           }
+          if (argv.resume && !argv.prompt && !process.stdin.isTTY) {
+            throw new Error(
+              'When resuming a session, you must provide a message via --prompt (-p) or stdin',
+            );
+          }
           if (argv.yolo && argv['approvalMode']) {
             return 'Cannot use both --yolo (-y) and --approval-mode together. Use --approval-mode=yolo instead.';
           }
@@ -585,6 +622,8 @@ export async function loadCliConfig(
     maxSessionTurns: settings.model?.maxSessionTurns ?? -1,
     experimentalZedIntegration: argv.experimentalAcp || false,
     listExtensions: argv.listExtensions || false,
+    listSessions: argv.listSessions || false,
+    deleteSession: argv.deleteSession,
     enabledExtensions: argv.extensions,
     extensionLoader: extensionManager,
     enableExtensionReloading: settings.experimental?.extensionReloading,