diff --git a/containers/api-proxy/server.js b/containers/api-proxy/server.js
index 317f125e..27a8b0c1 100644
--- a/containers/api-proxy/server.js
+++ b/containers/api-proxy/server.js
@@ -207,6 +207,53 @@ function deriveCopilotApiTarget() {
 }
 const COPILOT_API_TARGET = deriveCopilotApiTarget();
 
+// GitHub REST API target host for endpoints that need the GitHub REST API
+// (e.g., enterprise-specific endpoints). Currently unused — /models is served
+// by the Copilot API, not the REST API — but kept for future GHES/GHEC needs.
+// Priority: GITHUB_API_URL env var (hostname extracted) > auto-derive from GITHUB_SERVER_URL > default
+function deriveGitHubApiTarget() {
+  // Explicit GITHUB_API_URL takes priority — this is the canonical source for enterprise deployments
+  if (process.env.GITHUB_API_URL) {
+    const target = normalizeApiTarget(process.env.GITHUB_API_URL);
+    if (target) return target;
+  }
+  // Auto-derive from GITHUB_SERVER_URL for GHEC tenants (*.ghe.com)
+  const serverUrl = process.env.GITHUB_SERVER_URL;
+  if (serverUrl) {
+    try {
+      const hostname = new URL(serverUrl).hostname;
+      if (hostname !== 'github.com' && hostname.endsWith('.ghe.com')) {
+        // GHEC: GitHub REST API lives at api.<subdomain>.ghe.com
+        const subdomain = hostname.slice(0, -8); // Remove '.ghe.com'
+        return `api.${subdomain}.ghe.com`;
+      }
+    } catch {
+      // Invalid URL — fall through to default
+    }
+  }
+  return 'api.github.com';
+}
+
+/**
+ * Extract the base path from GITHUB_API_URL for GHES deployments
+ * (e.g. https://ghes.example.com/api/v3 → '/api/v3').
+ * Returns '' for github.com or when no path component is present.
+ */
+function deriveGitHubApiBasePath() {
+  const raw = process.env.GITHUB_API_URL;
+  if (!raw) return '';
+  try {
+    const parsed = new URL(raw.trim().startsWith('http') ? raw.trim() : `https://${raw.trim()}`);
+    const p = parsed.pathname.replace(/\/+$/, '');
+    return p === '/' ? '' : p;
+  } catch {
+    return '';
+  }
+}
+
+const GITHUB_API_TARGET = deriveGitHubApiTarget();
+const GITHUB_API_BASE_PATH = deriveGitHubApiBasePath();
+
 // Squid proxy configuration (set via HTTP_PROXY/HTTPS_PROXY in docker-compose)
 const HTTPS_PROXY = process.env.HTTPS_PROXY || process.env.HTTP_PROXY;
 
@@ -218,6 +265,7 @@ logRequest('info', 'startup', {
     anthropic: ANTHROPIC_API_TARGET,
     gemini: GEMINI_API_TARGET,
     copilot: COPILOT_API_TARGET,
+    github: GITHUB_API_TARGET,
   },
   api_base_paths: {
     openai: OPENAI_API_BASE_PATH || '(none)',
@@ -1036,4 +1084,4 @@ if (require.main === module) {
 }
 
 // Export for testing
-module.exports = { normalizeApiTarget, deriveCopilotApiTarget, normalizeBasePath, buildUpstreamPath, proxyWebSocket, resolveCopilotAuthToken };
+module.exports = { normalizeApiTarget, deriveCopilotApiTarget, deriveGitHubApiTarget, deriveGitHubApiBasePath, normalizeBasePath, buildUpstreamPath, proxyWebSocket, resolveCopilotAuthToken };
diff --git a/containers/api-proxy/server.test.js b/containers/api-proxy/server.test.js
index 56ce7f02..9e7ea6c9 100644
--- a/containers/api-proxy/server.test.js
+++ b/containers/api-proxy/server.test.js
@@ -5,7 +5,7 @@
 const http = require('http');
 const tls = require('tls');
 const { EventEmitter } = require('events');
-const { normalizeApiTarget, deriveCopilotApiTarget, normalizeBasePath, buildUpstreamPath, proxyWebSocket, resolveCopilotAuthToken } = require('./server');
+const { normalizeApiTarget, deriveCopilotApiTarget, deriveGitHubApiTarget, deriveGitHubApiBasePath, normalizeBasePath, buildUpstreamPath, proxyWebSocket, resolveCopilotAuthToken } = require('./server');
 
 describe('normalizeApiTarget', () => {
   it('should strip https:// prefix', () => {
@@ -165,6 +165,127 @@ describe('deriveCopilotApiTarget', () => {
   });
 });
 
+describe('deriveGitHubApiTarget', () => {
+  let originalEnv;
+
+  beforeEach(() => {
+    originalEnv = {
+      GITHUB_API_URL: process.env.GITHUB_API_URL,
+      GITHUB_SERVER_URL: process.env.GITHUB_SERVER_URL,
+    };
+    delete process.env.GITHUB_API_URL;
+    delete process.env.GITHUB_SERVER_URL;
+  });
+
+  afterEach(() => {
+    if (originalEnv.GITHUB_API_URL !== undefined) {
+      process.env.GITHUB_API_URL = originalEnv.GITHUB_API_URL;
+    } else {
+      delete process.env.GITHUB_API_URL;
+    }
+    if (originalEnv.GITHUB_SERVER_URL !== undefined) {
+      process.env.GITHUB_SERVER_URL = originalEnv.GITHUB_SERVER_URL;
+    } else {
+      delete process.env.GITHUB_SERVER_URL;
+    }
+  });
+
+  describe('GITHUB_API_URL env var (highest priority)', () => {
+    it('should return hostname from GITHUB_API_URL full URL', () => {
+      process.env.GITHUB_API_URL = 'https://api.github.com';
+      expect(deriveGitHubApiTarget()).toBe('api.github.com');
+    });
+
+    it('should return hostname from GITHUB_API_URL for GHES', () => {
+      process.env.GITHUB_API_URL = 'https://github.internal/api/v3';
+      expect(deriveGitHubApiTarget()).toBe('github.internal');
+    });
+
+    it('should prefer GITHUB_API_URL over GITHUB_SERVER_URL', () => {
+      process.env.GITHUB_API_URL = 'https://api.mycompany.ghe.com';
+      process.env.GITHUB_SERVER_URL = 'https://mycompany.ghe.com';
+      expect(deriveGitHubApiTarget()).toBe('api.mycompany.ghe.com');
+    });
+  });
+
+  describe('GHEC (*.ghe.com)', () => {
+    it('should return api.<subdomain>.ghe.com for GHEC tenant', () => {
+      process.env.GITHUB_SERVER_URL = 'https://mycompany.ghe.com';
+      expect(deriveGitHubApiTarget()).toBe('api.mycompany.ghe.com');
+    });
+
+    it('should handle multiple-level subdomains', () => {
+      process.env.GITHUB_SERVER_URL = 'https://sub.example.ghe.com';
+      expect(deriveGitHubApiTarget()).toBe('api.sub.example.ghe.com');
+    });
+  });
+
+  describe('Default behavior', () => {
+    it('should return api.github.com when no env vars are set', () => {
+      expect(deriveGitHubApiTarget()).toBe('api.github.com');
+    });
+
+    it('should return api.github.com for github.com GITHUB_SERVER_URL', () => {
+      process.env.GITHUB_SERVER_URL = 'https://github.com';
+      expect(deriveGitHubApiTarget()).toBe('api.github.com');
+    });
+
+    it('should return api.github.com for GHES without GITHUB_API_URL', () => {
+      // GHES without an explicit GITHUB_API_URL falls back to api.github.com.
+      // This is a known limitation: GHES deployments should set GITHUB_API_URL explicitly
+      // so deriveGitHubApiTarget() resolves to the correct enterprise API hostname.
+      process.env.GITHUB_SERVER_URL = 'https://github.internal';
+      expect(deriveGitHubApiTarget()).toBe('api.github.com');
+    });
+
+    it('should return api.github.com when GITHUB_SERVER_URL is invalid', () => {
+      process.env.GITHUB_SERVER_URL = 'not-a-valid-url';
+      expect(deriveGitHubApiTarget()).toBe('api.github.com');
+    });
+  });
+});
+
+describe('deriveGitHubApiBasePath', () => {
+  const savedEnv = {};
+
+  beforeEach(() => {
+    savedEnv.GITHUB_API_URL = process.env.GITHUB_API_URL;
+    delete process.env.GITHUB_API_URL;
+  });
+
+  afterEach(() => {
+    if (savedEnv.GITHUB_API_URL !== undefined) {
+      process.env.GITHUB_API_URL = savedEnv.GITHUB_API_URL;
+    } else {
+      delete process.env.GITHUB_API_URL;
+    }
+  });
+
+  it('should return empty string when GITHUB_API_URL is not set', () => {
+    expect(deriveGitHubApiBasePath()).toBe('');
+  });
+
+  it('should extract /api/v3 from GHES-style GITHUB_API_URL', () => {
+    process.env.GITHUB_API_URL = 'https://ghes.example.com/api/v3';
+    expect(deriveGitHubApiBasePath()).toBe('/api/v3');
+  });
+
+  it('should return empty string for github.com API URL (no path)', () => {
+    process.env.GITHUB_API_URL = 'https://api.github.com';
+    expect(deriveGitHubApiBasePath()).toBe('');
+  });
+
+  it('should strip trailing slashes', () => {
+    process.env.GITHUB_API_URL = 'https://ghes.example.com/api/v3/';
+    expect(deriveGitHubApiBasePath()).toBe('/api/v3');
+  });
+
+  it('should return empty string for invalid URL', () => {
+    process.env.GITHUB_API_URL = '://invalid';
+    expect(deriveGitHubApiBasePath()).toBe('');
+  });
+});
+
 describe('normalizeBasePath', () => {
   it('should return empty string for undefined', () => {
     expect(normalizeBasePath(undefined)).toBe('');
diff --git a/src/docker-manager.ts b/src/docker-manager.ts
index 00e4803c..2127a384 100644
--- a/src/docker-manager.ts
+++ b/src/docker-manager.ts
@@ -1535,8 +1535,8 @@ export function generateDockerCompose(
         ...(config.geminiApiBasePath && { GEMINI_API_BASE_PATH: config.geminiApiBasePath }),
         // Forward GITHUB_SERVER_URL so api-proxy can auto-derive enterprise endpoints
         ...(process.env.GITHUB_SERVER_URL && { GITHUB_SERVER_URL: process.env.GITHUB_SERVER_URL }),
-        // Forward GITHUB_API_URL so api-proxy can use the correct GitHub REST API hostname
-        // on GHES/GHEC (e.g. https://ghes.example.com/api/v3 or api.mycompany.ghe.com)
+        // Forward GITHUB_API_URL so api-proxy can route /models to the correct GitHub REST API
+        // target on GHES/GHEC (e.g. api.mycompany.ghe.com instead of api.github.com)
         ...(process.env.GITHUB_API_URL && { GITHUB_API_URL: process.env.GITHUB_API_URL }),
         // Route through Squid to respect domain whitelisting
         HTTP_PROXY: `http://${networkConfig.squidIp}:${SQUID_PORT}`,