Add support for `.geminiignore` file (#757)

4 files changed, 307 insertions, 2 deletions

diff --git a/packages/cli/src/config/config.ts b/packages/cli/src/config/config.ts
index 952ecbcf..dd55b26d 100644
--- a/packages/cli/src/config/config.ts
+++ b/packages/cli/src/config/config.ts
@@ -123,6 +123,7 @@ export interface LoadCliConfigResult {
 
 export async function loadCliConfig(
   settings: Settings,
+  geminiIgnorePatterns: string[],
 ): Promise<LoadCliConfigResult> {
   loadEnvironment();
 
@@ -211,6 +212,7 @@ export async function loadCliConfig(
     vertexai: useVertexAI,
     showMemoryUsage:
       argv.show_memory_usage || settings.showMemoryUsage || false,
+    geminiIgnorePatterns,
     accessibility: settings.accessibility,
     // Git-aware file filtering settings
     fileFilteringRespectGitIgnore: settings.fileFiltering?.respectGitIgnore,
diff --git a/packages/cli/src/gemini.tsx b/packages/cli/src/gemini.tsx
index fc42bdec..f9b73074 100644
--- a/packages/cli/src/gemini.tsx
+++ b/packages/cli/src/gemini.tsx
@@ -17,6 +17,7 @@ import { LoadedSettings, loadSettings } from './config/settings.js';
 import { themeManager } from './ui/themes/theme-manager.js';
 import { getStartupWarnings } from './utils/startupWarnings.js';
 import { runNonInteractive } from './nonInteractiveCli.js';
+import { loadGeminiIgnorePatterns } from './utils/loadIgnorePatterns.js';
 import {
   ApprovalMode,
   Config,
@@ -56,9 +57,12 @@ async function main() {
       process.env.GEMINI_CODE_SANDBOX_IMAGE; // Corrected to GEMINI_SANDBOX_IMAGE_NAME
   }
 
-  const settings = loadSettings(process.cwd());
+  const workspaceRoot = process.cwd();
+  const settings = loadSettings(workspaceRoot);
+  const geminiIgnorePatterns = loadGeminiIgnorePatterns(workspaceRoot);
+
   const { config, modelWasSwitched, originalModelBeforeSwitch, finalModel } =
-    await loadCliConfig(settings.merged);
+    await loadCliConfig(settings.merged, geminiIgnorePatterns);
 
   // Initialize centralized FileDiscoveryService
   await config.getFileService();
@@ -150,6 +154,7 @@ main().catch((error) => {
   }
   process.exit(1);
 });
+
 async function loadNonInteractiveConfig(
   config: Config,
   settings: LoadedSettings,
@@ -185,6 +190,7 @@ async function loadNonInteractiveConfig(
   };
   const nonInteractiveConfigResult = await loadCliConfig(
     nonInteractiveSettings,
+    config.getGeminiIgnorePatterns(),
   );
   return nonInteractiveConfigResult.config;
 }
diff --git a/packages/cli/src/utils/loadIgnorePatterns.test.ts b/packages/cli/src/utils/loadIgnorePatterns.test.ts
new file mode 100644
index 00000000..6cec9d51
--- /dev/null
+++ b/packages/cli/src/utils/loadIgnorePatterns.test.ts
@@ -0,0 +1,226 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {
+  vi,
+  describe,
+  it,
+  expect,
+  beforeEach,
+  afterEach,
+  Mock,
+  beforeAll,
+} from 'vitest';
+import * as path from 'node:path';
+import { loadGeminiIgnorePatterns } from './loadIgnorePatterns.js';
+import os from 'node:os';
+
+// Define the type for our mock function explicitly.
+type ReadFileSyncMockType = Mock<
+  (path: string, encoding: string) => string | Buffer
+>;
+
+// Declare a variable to hold our mock function instance.
+let mockedFsReadFileSync: ReadFileSyncMockType;
+
+vi.mock('node:fs', async () => {
+  const actualFsModule =
+    await vi.importActual<typeof import('node:fs')>('node:fs');
+  return {
+    ...actualFsModule,
+    readFileSync: vi.fn(), // The factory creates and returns the vi.fn() instance.
+  };
+});
+
+let actualFs: typeof import('node:fs');
+
+describe('loadGeminiIgnorePatterns', () => {
+  let tempDir: string;
+  let consoleLogSpy: Mock<
+    (message?: unknown, ...optionalParams: unknown[]) => void
+  >;
+  let consoleWarnSpy: Mock<
+    (message?: unknown, ...optionalParams: unknown[]) => void
+  >;
+
+  beforeAll(async () => {
+    actualFs = await vi.importActual<typeof import('node:fs')>('node:fs');
+    const mockedFsModule = await import('node:fs');
+    mockedFsReadFileSync =
+      mockedFsModule.readFileSync as unknown as ReadFileSyncMockType;
+  });
+
+  beforeEach(() => {
+    tempDir = actualFs.mkdtempSync(
+      path.join(os.tmpdir(), 'gemini-ignore-test-'),
+    );
+    consoleLogSpy = vi
+      .spyOn(console, 'log')
+      .mockImplementation(() => {}) as Mock<
+      (message?: unknown, ...optionalParams: unknown[]) => void
+    >;
+    consoleWarnSpy = vi
+      .spyOn(console, 'warn')
+      .mockImplementation(() => {}) as Mock<
+      (message?: unknown, ...optionalParams: unknown[]) => void
+    >;
+    mockedFsReadFileSync.mockReset();
+  });
+
+  afterEach(() => {
+    if (actualFs.existsSync(tempDir)) {
+      actualFs.rmSync(tempDir, { recursive: true, force: true });
+    }
+    consoleLogSpy.mockRestore();
+    consoleWarnSpy.mockRestore();
+  });
+
+  it('should load and parse patterns from .geminiignore, ignoring comments and empty lines', () => {
+    const ignoreContent = [
+      '# This is a comment',
+      'pattern1',
+      '  pattern2  ', // Should be trimmed
+      '', // Empty line
+      'pattern3 # Inline comment', // Handled by trim
+      '*.log',
+      '!important.file',
+    ].join('\n');
+    const ignoreFilePath = path.join(tempDir, '.geminiignore');
+    actualFs.writeFileSync(ignoreFilePath, ignoreContent);
+
+    mockedFsReadFileSync.mockImplementation((p: string, encoding: string) => {
+      if (p === ignoreFilePath && encoding === 'utf-8') return ignoreContent;
+      throw new Error(
+        `Mock fs.readFileSync: Unexpected call with path: ${p}, encoding: ${encoding}`,
+      );
+    });
+
+    const patterns = loadGeminiIgnorePatterns(tempDir);
+
+    expect(patterns).toEqual([
+      'pattern1',
+      'pattern2',
+      'pattern3 # Inline comment',
+      '*.log',
+      '!important.file',
+    ]);
+    expect(consoleLogSpy).toHaveBeenCalledWith(
+      expect.stringContaining('Loaded 5 patterns from .geminiignore'),
+    );
+    expect(mockedFsReadFileSync).toHaveBeenCalledWith(ignoreFilePath, 'utf-8');
+  });
+
+  it('should return an empty array and log info if .geminiignore is not found', () => {
+    const ignoreFilePath = path.join(tempDir, '.geminiignore');
+    mockedFsReadFileSync.mockImplementation((p: string, encoding: string) => {
+      if (p === ignoreFilePath && encoding === 'utf-8') {
+        const error = new Error('File not found') as NodeJS.ErrnoException;
+        error.code = 'ENOENT';
+        throw error;
+      }
+      throw new Error(
+        `Mock fs.readFileSync: Unexpected call with path: ${p}, encoding: ${encoding}`,
+      );
+    });
+
+    const patterns = loadGeminiIgnorePatterns(tempDir);
+    expect(patterns).toEqual([]);
+    expect(consoleLogSpy).toHaveBeenCalledWith(
+      '[INFO] No .geminiignore file found. Proceeding without custom ignore patterns.',
+    );
+    expect(mockedFsReadFileSync).toHaveBeenCalledWith(ignoreFilePath, 'utf-8');
+  });
+
+  it('should return an empty array if .geminiignore is empty', () => {
+    const ignoreFilePath = path.join(tempDir, '.geminiignore');
+    actualFs.writeFileSync(ignoreFilePath, '');
+    mockedFsReadFileSync.mockImplementation((p: string, encoding: string) => {
+      if (p === ignoreFilePath && encoding === 'utf-8') return ''; // Return string for empty file
+      throw new Error(
+        `Mock fs.readFileSync: Unexpected call with path: ${p}, encoding: ${encoding}`,
+      );
+    });
+
+    const patterns = loadGeminiIgnorePatterns(tempDir);
+    expect(patterns).toEqual([]);
+    expect(consoleLogSpy).not.toHaveBeenCalledWith(
+      expect.stringContaining('Loaded 0 patterns from .geminiignore'),
+    );
+    expect(consoleLogSpy).not.toHaveBeenCalledWith(
+      expect.stringContaining('No .geminiignore file found'),
+    );
+    expect(mockedFsReadFileSync).toHaveBeenCalledWith(ignoreFilePath, 'utf-8');
+  });
+
+  it('should return an empty array if .geminiignore contains only comments and empty lines', () => {
+    const ignoreContent = [
+      '# Comment 1',
+      '  # Comment 2 with leading spaces',
+      '',
+      '   ', // Whitespace only line
+    ].join('\n');
+    const ignoreFilePath = path.join(tempDir, '.geminiignore');
+    actualFs.writeFileSync(ignoreFilePath, ignoreContent);
+    mockedFsReadFileSync.mockImplementation((p: string, encoding: string) => {
+      if (p === ignoreFilePath && encoding === 'utf-8') return ignoreContent;
+      throw new Error(
+        `Mock fs.readFileSync: Unexpected call with path: ${p}, encoding: ${encoding}`,
+      );
+    });
+
+    const patterns = loadGeminiIgnorePatterns(tempDir);
+    expect(patterns).toEqual([]);
+    expect(consoleLogSpy).not.toHaveBeenCalledWith(
+      expect.stringContaining('Loaded 0 patterns from .geminiignore'),
+    );
+    expect(consoleLogSpy).not.toHaveBeenCalledWith(
+      expect.stringContaining('No .geminiignore file found'),
+    );
+    expect(mockedFsReadFileSync).toHaveBeenCalledWith(ignoreFilePath, 'utf-8');
+  });
+
+  it('should handle read errors (other than ENOENT) and log a warning', () => {
+    const ignoreFilePath = path.join(tempDir, '.geminiignore');
+    mockedFsReadFileSync.mockImplementation((p: string, encoding: string) => {
+      if (p === ignoreFilePath && encoding === 'utf-8') {
+        const error = new Error('Test read error') as NodeJS.ErrnoException;
+        error.code = 'EACCES';
+        throw error;
+      }
+      throw new Error(
+        `Mock fs.readFileSync: Unexpected call with path: ${p}, encoding: ${encoding}`,
+      );
+    });
+
+    const patterns = loadGeminiIgnorePatterns(tempDir);
+    expect(patterns).toEqual([]);
+    expect(consoleWarnSpy).toHaveBeenCalledWith(
+      expect.stringContaining(
+        `[WARN] Could not read .geminiignore file at ${ignoreFilePath}: Test read error`,
+      ),
+    );
+    expect(mockedFsReadFileSync).toHaveBeenCalledWith(ignoreFilePath, 'utf-8');
+  });
+
+  it('should correctly handle patterns with inline comments if not starting with #', () => {
+    const ignoreContent = 'src/important # but not this part';
+    const ignoreFilePath = path.join(tempDir, '.geminiignore');
+    actualFs.writeFileSync(ignoreFilePath, ignoreContent);
+    mockedFsReadFileSync.mockImplementation((p: string, encoding: string) => {
+      if (p === ignoreFilePath && encoding === 'utf-8') return ignoreContent;
+      throw new Error(
+        `Mock fs.readFileSync: Unexpected call with path: ${p}, encoding: ${encoding}`,
+      );
+    });
+
+    const patterns = loadGeminiIgnorePatterns(tempDir);
+    expect(patterns).toEqual(['src/important # but not this part']);
+    expect(consoleLogSpy).toHaveBeenCalledWith(
+      expect.stringContaining('Loaded 1 patterns from .geminiignore'),
+    );
+    expect(mockedFsReadFileSync).toHaveBeenCalledWith(ignoreFilePath, 'utf-8');
+  });
+});
diff --git a/packages/cli/src/utils/loadIgnorePatterns.ts b/packages/cli/src/utils/loadIgnorePatterns.ts
new file mode 100644
index 00000000..3d0a1968
--- /dev/null
+++ b/packages/cli/src/utils/loadIgnorePatterns.ts
@@ -0,0 +1,71 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import * as fs from 'node:fs';
+import * as path from 'node:path';
+
+const GEMINI_IGNORE_FILE_NAME = '.geminiignore';
+
+/**
+ * Loads and parses a .geminiignore file from the given workspace root.
+ * The .geminiignore file follows a format similar to .gitignore:
+ * - Each line specifies a glob pattern.
+ * - Lines are trimmed of leading and trailing whitespace.
+ * - Blank lines (after trimming) are ignored.
+ * - Lines starting with a pound sign (#) (after trimming) are treated as comments and ignored.
+ * - Patterns are case-sensitive and follow standard glob syntax.
+ * - If a # character appears elsewhere in a line (not at the start after trimming),
+ *   it is considered part of the glob pattern.
+ *
+ * @param workspaceRoot The absolute path to the workspace root where the .geminiignore file is expected.
+ * @returns An array of glob patterns extracted from the .geminiignore file. Returns an empty array
+ *          if the file does not exist or contains no valid patterns.
+ */
+export function loadGeminiIgnorePatterns(workspaceRoot: string): string[] {
+  const ignoreFilePath = path.join(workspaceRoot, GEMINI_IGNORE_FILE_NAME);
+  const patterns: string[] = [];
+
+  try {
+    const fileContent = fs.readFileSync(ignoreFilePath, 'utf-8');
+    const lines = fileContent.split(/\r?\n/);
+
+    for (const line of lines) {
+      const trimmedLine = line.trim();
+      if (trimmedLine && !trimmedLine.startsWith('#')) {
+        patterns.push(trimmedLine);
+      }
+    }
+    if (patterns.length > 0) {
+      console.log(
+        `[INFO] Loaded ${patterns.length} patterns from .geminiignore`,
+      );
+    }
+  } catch (error: unknown) {
+    if (
+      error instanceof Error &&
+      'code' in error &&
+      typeof error.code === 'string'
+    ) {
+      if (error.code === 'ENOENT') {
+        // .geminiignore not found, which is fine.
+        console.log(
+          '[INFO] No .geminiignore file found. Proceeding without custom ignore patterns.',
+        );
+      } else {
+        // Other error reading the file (e.g., permissions)
+        console.warn(
+          `[WARN] Could not read .geminiignore file at ${ignoreFilePath}: ${error.message}`,
+        );
+      }
+    } else {
+      // For other types of errors, or if code is not available
+      console.warn(
+        `[WARN] An unexpected error occurred while trying to read ${ignoreFilePath}: ${String(error)}`,
+      );
+    }
+  }
+  return patterns;
+}