refactor(core): centralize path validation and allow temp dir access for tools (#17185)

Co-authored-by: Your Name <joshualitt@google.com>

packages/cli/src/ui/hooks/atCommandProcessor.test.ts

@@ -75,15 +75,46 @@ describe('handleAtCommand', () => {
       getFileSystemService: () => new StandardFileSystemService(),
       getEnableRecursiveFileSearch: vi.fn(() => true),
       getWorkspaceContext: () => ({
-        isPathWithinWorkspace: () => true,
+        isPathWithinWorkspace: (p: string) =>
+          p.startsWith(testRootDir) || p.startsWith('/private' + testRootDir),
         getDirectories: () => [testRootDir],
       }),
+      storage: {
+        getProjectTempDir: () => path.join(os.tmpdir(), 'gemini-cli-temp'),
+      },
+      isPathAllowed(this: Config, absolutePath: string): boolean {
+        if (this.interactive && path.isAbsolute(absolutePath)) {
+          return true;
+        }
+
+        const workspaceContext = this.getWorkspaceContext();
+        if (workspaceContext.isPathWithinWorkspace(absolutePath)) {
+          return true;
+        }
+
+        const projectTempDir = this.storage.getProjectTempDir();
+        const resolvedProjectTempDir = path.resolve(projectTempDir);
+        return (
+          absolutePath.startsWith(resolvedProjectTempDir + path.sep) ||
+          absolutePath === resolvedProjectTempDir
+        );
+      },
+      validatePathAccess(this: Config, absolutePath: string): string | null {
+        if (this.isPathAllowed(absolutePath)) {
+          return null;
+        }
+
+        const workspaceDirs = this.getWorkspaceContext().getDirectories();
+        const projectTempDir = this.storage.getProjectTempDir();
+        return `Path validation failed: Attempted path "${absolutePath}" resolves outside the allowed workspace directories: ${workspaceDirs.join(', ')} or the project temp directory: ${projectTempDir}`;
+      },
       getMcpServers: () => ({}),
       getMcpServerCommand: () => undefined,
       getPromptRegistry: () => ({
         getPromptsByServer: () => [],
       }),
       getDebugMode: () => false,
+      getWorkingDir: () => '/working/dir',
       getFileExclusions: () => ({
         getCoreIgnorePatterns: () => COMMON_IGNORE_PATTERNS,
         getDefaultExcludePatterns: () => [],