fix(core): whitelist TERM and COLORTERM in environment sanitization (#20514)

Co-authored-by: Sri Pasumarthi <sripas@google.com>
Co-authored-by: Sri Pasumarthi <111310667+sripasg@users.noreply.github.com>

CONTRIBUTING.md

@@ -320,11 +320,9 @@ npm run lint
 
 - Please adhere to the coding style, patterns, and conventions used throughout
   the existing codebase.
-- Consult
+- Consult [GEMINI.md](../GEMINI.md) (typically found in the project root) for
-  [GEMINI.md](https://github.com/google-gemini/gemini-cli/blob/main/GEMINI.md)
+  specific instructions related to AI-assisted development, including
-  (typically found in the project root) for specific instructions related to
+  conventions for React, comments, and Git usage.
-  AI-assisted development, including conventions for React, comments, and Git
-  usage.
 - **Imports:** Pay special attention to import paths. The project uses ESLint to
   enforce restrictions on relative imports between packages.
 

packages/core/src/services/environmentSanitization.test.ts

@@ -32,6 +32,29 @@ describe('sanitizeEnvironment', () => {
     expect(sanitized).toEqual(env);
   });
 
+  it('should allow TERM and COLORTERM environment variables', () => {
+    const env = {
+      TERM: 'xterm-256color',
+      COLORTERM: 'truecolor',
+    };
+    const sanitized = sanitizeEnvironment(env, EMPTY_OPTIONS);
+    expect(sanitized).toEqual(env);
+  });
+
+  it('should preserve TERM and COLORTERM even in strict sanitization mode', () => {
+    const env = {
+      GITHUB_SHA: 'abc123',
+      TERM: 'xterm-256color',
+      COLORTERM: 'truecolor',
+      SOME_OTHER_VAR: 'value',
+    };
+    const sanitized = sanitizeEnvironment(env, EMPTY_OPTIONS);
+    expect(sanitized).toEqual({
+      TERM: 'xterm-256color',
+      COLORTERM: 'truecolor',
+    });
+  });
+
   it('should allow variables prefixed with GEMINI_CLI_', () => {
     const env = {
       GEMINI_CLI_FOO: 'bar',

packages/core/src/services/environmentSanitization.ts

@@ -69,6 +69,10 @@ export const ALWAYS_ALLOWED_ENVIRONMENT_VARIABLES: ReadonlySet<string> =
     'TMPDIR',
     'USER',
     'LOGNAME',
+    // Terminal capability variables (needed by editors like vim/emacs and
+    // interactive commands like top)
+    'TERM',
+    'COLORTERM',
     // GitHub Action-related variables
     'ADDITIONAL_CONTEXT',
     'AVAILABLE_LABELS',