diff --git a/packages/cli/src/config/config.test.ts b/packages/cli/src/config/config.test.ts
index a4cd313034..ebf448930f 100644
--- a/packages/cli/src/config/config.test.ts
+++ b/packages/cli/src/config/config.test.ts
@@ -114,13 +114,24 @@ vi.mock('@google/gemini-cli-core', async () => {
   };
 });
 
+// Global setup to ensure clean environment for all tests in this file
+const originalArgv = process.argv;
+const originalGeminiModel = process.env['GEMINI_MODEL'];
+
+beforeEach(() => {
+  delete process.env['GEMINI_MODEL'];
+});
+
+afterEach(() => {
+  process.argv = originalArgv;
+  if (originalGeminiModel !== undefined) {
+    process.env['GEMINI_MODEL'] = originalGeminiModel;
+  } else {
+    delete process.env['GEMINI_MODEL'];
+  }
+});
+
 describe('parseArguments', () => {
-  const originalArgv = process.argv;
-
-  afterEach(() => {
-    process.argv = originalArgv;
-  });
-
   it('should throw an error when both --prompt and --prompt-interactive are used together', async () => {
     process.argv = [
       'node',
@@ -494,8 +505,6 @@ describe('parseArguments', () => {
 });
 
 describe('loadCliConfig', () => {
-  const originalArgv = process.argv;
-
   beforeEach(() => {
     vi.resetAllMocks();
     vi.mocked(os.homedir).mockReturnValue('/mock/home/user');
@@ -503,7 +512,6 @@ describe('loadCliConfig', () => {
   });
 
   afterEach(() => {
-    process.argv = originalArgv;
     vi.unstubAllEnvs();
     vi.restoreAllMocks();
   });
@@ -1168,8 +1176,6 @@ describe('Approval mode tool exclusion logic', () => {
 });
 
 describe('loadCliConfig with allowed-mcp-server-names', () => {
-  const originalArgv = process.argv;
-
   beforeEach(() => {
     vi.resetAllMocks();
     vi.mocked(os.homedir).mockReturnValue('/mock/home/user');
@@ -1177,7 +1183,6 @@ describe('loadCliConfig with allowed-mcp-server-names', () => {
   });
 
   afterEach(() => {
-    process.argv = originalArgv;
     vi.unstubAllEnvs();
     vi.restoreAllMocks();
   });
@@ -1498,8 +1503,6 @@ describe('loadCliConfig model selection with model router', () => {
 });
 
 describe('loadCliConfig folderTrust', () => {
-  const originalArgv = process.argv;
-
   beforeEach(() => {
     vi.resetAllMocks();
     vi.mocked(os.homedir).mockReturnValue('/mock/home/user');
@@ -1507,7 +1510,6 @@ describe('loadCliConfig folderTrust', () => {
   });
 
   afterEach(() => {
-    process.argv = originalArgv;
     vi.unstubAllEnvs();
     vi.restoreAllMocks();
   });
@@ -1550,8 +1552,6 @@ describe('loadCliConfig folderTrust', () => {
 });
 
 describe('loadCliConfig with includeDirectories', () => {
-  const originalArgv = process.argv;
-
   beforeEach(() => {
     vi.resetAllMocks();
     vi.mocked(os.homedir).mockReturnValue('/mock/home/user');
@@ -1562,8 +1562,6 @@ describe('loadCliConfig with includeDirectories', () => {
   });
 
   afterEach(() => {
-    process.argv = originalArgv;
-    vi.unstubAllEnvs();
     vi.restoreAllMocks();
   });
 
@@ -1604,8 +1602,6 @@ describe('loadCliConfig with includeDirectories', () => {
 });
 
 describe('loadCliConfig chatCompression', () => {
-  const originalArgv = process.argv;
-
   beforeEach(() => {
     vi.resetAllMocks();
     vi.mocked(os.homedir).mockReturnValue('/mock/home/user');
@@ -1613,7 +1609,6 @@ describe('loadCliConfig chatCompression', () => {
   });
 
   afterEach(() => {
-    process.argv = originalArgv;
     vi.unstubAllEnvs();
     vi.restoreAllMocks();
   });
@@ -1644,8 +1639,6 @@ describe('loadCliConfig chatCompression', () => {
 });
 
 describe('loadCliConfig useRipgrep', () => {
-  const originalArgv = process.argv;
-
   beforeEach(() => {
     vi.resetAllMocks();
     vi.mocked(os.homedir).mockReturnValue('/mock/home/user');
@@ -1653,7 +1646,6 @@ describe('loadCliConfig useRipgrep', () => {
   });
 
   afterEach(() => {
-    process.argv = originalArgv;
     vi.unstubAllEnvs();
     vi.restoreAllMocks();
   });
@@ -1710,8 +1702,6 @@ describe('loadCliConfig useRipgrep', () => {
 });
 
 describe('screenReader configuration', () => {
-  const originalArgv = process.argv;
-
   beforeEach(() => {
     vi.resetAllMocks();
     vi.mocked(os.homedir).mockReturnValue('/mock/home/user');
@@ -1719,7 +1709,6 @@ describe('screenReader configuration', () => {
   });
 
   afterEach(() => {
-    process.argv = originalArgv;
     vi.unstubAllEnvs();
     vi.restoreAllMocks();
   });
@@ -1764,7 +1753,6 @@ describe('screenReader configuration', () => {
 });
 
 describe('loadCliConfig tool exclusions', () => {
-  const originalArgv = process.argv;
   const originalIsTTY = process.stdin.isTTY;
 
   beforeEach(() => {
@@ -1779,7 +1767,6 @@ describe('loadCliConfig tool exclusions', () => {
   });
 
   afterEach(() => {
-    process.argv = originalArgv;
     process.stdin.isTTY = originalIsTTY;
     vi.unstubAllEnvs();
     vi.restoreAllMocks();
@@ -1872,7 +1859,6 @@ describe('loadCliConfig tool exclusions', () => {
 });
 
 describe('loadCliConfig interactive', () => {
-  const originalArgv = process.argv;
   const originalIsTTY = process.stdin.isTTY;
 
   beforeEach(() => {
@@ -1883,7 +1869,6 @@ describe('loadCliConfig interactive', () => {
   });
 
   afterEach(() => {
-    process.argv = originalArgv;
     process.stdin.isTTY = originalIsTTY;
     vi.unstubAllEnvs();
     vi.restoreAllMocks();