diff --git a/src/supervisor/env-sanitizer.ts b/src/supervisor/env-sanitizer.ts
index 8280cbf97e..f7c1d59a75 100644
--- a/src/supervisor/env-sanitizer.ts
+++ b/src/supervisor/env-sanitizer.ts
@@ -30,6 +30,7 @@ export const ENV_PRESERVE = new Set([
   'CLAUDE_CODE_GIT_BASH_PATH',
   'CLAUDE_CODE_USE_BEDROCK',
   'CLAUDE_CODE_USE_VERTEX',
+  'CLAUDE_CODE_USE_FOUNDRY',
   'CLAUDE_CODE_SKIP_BEDROCK_AUTH',
   'CLAUDE_CODE_SKIP_VERTEX_AUTH',
   'ANTHROPIC_BEDROCK_BASE_URL',
diff --git a/tests/supervisor/env-sanitizer.test.ts b/tests/supervisor/env-sanitizer.test.ts
index de6a5abbf3..9cacd66edd 100644
--- a/tests/supervisor/env-sanitizer.test.ts
+++ b/tests/supervisor/env-sanitizer.test.ts
@@ -134,6 +134,18 @@ describe('sanitizeEnv', () => {
     expect(result.HOME).toBe('/home/user');
   });
 
+  it('preserves CLAUDE_CODE_USE_FOUNDRY through sanitization', () => {
+    const result = sanitizeEnv({
+      CLAUDE_CODE_USE_FOUNDRY: '1',
+      PATH: '/usr/bin',
+      HOME: '/home/user'
+    });
+
+    expect(result.CLAUDE_CODE_USE_FOUNDRY).toBe('1');
+    expect(result.PATH).toBe('/usr/bin');
+    expect(result.HOME).toBe('/home/user');
+  });
+
   it('preserves proxy env vars (uppercase, lowercase, and npm config) for SDK subprocess network access', () => {
     const result = sanitizeEnv({
       HTTP_PROXY: 'http://corp-proxy:1234',
@@ -170,6 +182,7 @@ describe('sanitizeEnv', () => {
       CLAUDE_CODE_GIT_BASH_PATH: '/usr/bin/bash',
       CLAUDE_CODE_USE_BEDROCK: '1',
       CLAUDE_CODE_USE_VERTEX: '1',
+      CLAUDE_CODE_USE_FOUNDRY: '1',
       CLAUDE_CODE_SKIP_BEDROCK_AUTH: '1',
       CLAUDE_CODE_SKIP_VERTEX_AUTH: '1',
       CLAUDE_CODE_EFFORT_LEVEL: 'high',
@@ -183,6 +196,7 @@ describe('sanitizeEnv', () => {
     expect(result.CLAUDE_CODE_GIT_BASH_PATH).toBe('/usr/bin/bash');
     expect(result.CLAUDE_CODE_USE_BEDROCK).toBe('1');
     expect(result.CLAUDE_CODE_USE_VERTEX).toBe('1');
+    expect(result.CLAUDE_CODE_USE_FOUNDRY).toBe('1');
     expect(result.CLAUDE_CODE_SKIP_BEDROCK_AUTH).toBe('1');
     expect(result.CLAUDE_CODE_SKIP_VERTEX_AUTH).toBe('1');