diff --git a/containers/api-proxy/copilot-adapter-enterprise.test.js b/containers/api-proxy/copilot-adapter-enterprise.test.js
index 79be4fe8a..830ff46f0 100644
--- a/containers/api-proxy/copilot-adapter-enterprise.test.js
+++ b/containers/api-proxy/copilot-adapter-enterprise.test.js
@@ -2,9 +2,9 @@ const { createCopilotAdapter } = require('./providers/copilot');
 
 const bearerByokKey = ['Bearer', 'sk-byok-key'].join(' ');
 const bearerStandardToken = ['Bearer', 'ghu_standard_token_123'].join(' ');
-const bearerGhecToken = ['Bearer', 'ghu_ghec_token_123'].join(' ');
 const bearerCustomToken = ['Bearer', 'ghu_standard_token_123'].join(' ');
 const bearerGithubComOverrideToken = ['Bearer', 'ghu_token_123'].join(' ');
+const tokenGhecToken = ['token', 'ghu_ghec_token_123'].join(' ');
 
 describe('createCopilotAdapter — GHE enterprise auth format', () => {
   const fakeReq = { url: '/v1/chat/completions', method: 'POST', headers: {} };
@@ -56,13 +56,32 @@ describe('createCopilotAdapter — GHE enterprise auth format', () => {
     expect(headers['Authorization']).toBe(bearerStandardToken);
   });
 
-  it('uses "Bearer" prefix for GHEC tenant (*.ghe.com)', () => {
+  it('uses "token" prefix for a derived GHEC data-residency target', () => {
     const adapter = createCopilotAdapter({
       COPILOT_GITHUB_TOKEN: 'ghu_ghec_token_123',
       GITHUB_SERVER_URL: 'https://mycompany.ghe.com',
     });
     const headers = adapter.getAuthHeaders(fakeReq);
-    expect(headers['Authorization']).toBe(bearerGhecToken);
+    expect(headers['Authorization']).toBe(tokenGhecToken);
+  });
+
+  it('uses "token" prefix for /models on a derived GHEC data-residency target', () => {
+    const adapter = createCopilotAdapter({
+      COPILOT_GITHUB_TOKEN: 'ghu_ghec_token_123',
+      GITHUB_SERVER_URL: 'https://mycompany.ghe.com',
+    });
+    const headers = adapter.getAuthHeaders(fakeModelsReq);
+    expect(headers['Authorization']).toBe(tokenGhecToken);
+  });
+
+  it('uses "token" prefix for a GHEC target when AWF_PLATFORM_TYPE=ghec', () => {
+    const adapter = createCopilotAdapter({
+      COPILOT_GITHUB_TOKEN: 'ghu_ghec_token_123',
+      AWF_PLATFORM_TYPE: 'ghec',
+      GITHUB_SERVER_URL: 'https://mycompany.ghe.com',
+    });
+    const headers = adapter.getAuthHeaders(fakeReq);
+    expect(headers['Authorization']).toBe(tokenGhecToken);
   });
 
   it('strips "token " prefix from COPILOT_GITHUB_TOKEN before re-prefixing for GHES', () => {
diff --git a/containers/api-proxy/copilot-auth.test.js b/containers/api-proxy/copilot-auth.test.js
index a5838ea87..fdbf040ef 100644
--- a/containers/api-proxy/copilot-auth.test.js
+++ b/containers/api-proxy/copilot-auth.test.js
@@ -309,10 +309,24 @@ describe('copilotTargetRequiresGitHubTokenPrefix', () => {
     expect(copilotTargetRequiresGitHubTokenPrefix('api.githubcopilot.com', {})).toBe(false);
   });
 
-  it('returns false for a *.ghe.com (GHEC) Copilot target', () => {
+  it('returns true for a GHEC data-residency Copilot target', () => {
     expect(copilotTargetRequiresGitHubTokenPrefix('copilot-api.myorg.ghe.com', {
       GITHUB_SERVER_URL: 'https://myorg.ghe.com',
-    })).toBe(false);
+    })).toBe(true);
+  });
+
+  it('returns true for a GHEC data-residency Copilot target with AWF_PLATFORM_TYPE=ghec', () => {
+    expect(copilotTargetRequiresGitHubTokenPrefix('copilot-api.myorg.ghe.com', {
+      AWF_PLATFORM_TYPE: 'ghec',
+      GITHUB_SERVER_URL: 'https://myorg.ghe.com',
+    })).toBe(true);
+  });
+
+  it('returns false for malformed or non-canonical GHEC data-residency target shapes', () => {
+    const env = { GITHUB_SERVER_URL: 'https://myorg.ghe.com' };
+    expect(copilotTargetRequiresGitHubTokenPrefix('copilot-api..ghe.com', env)).toBe(false);
+    expect(copilotTargetRequiresGitHubTokenPrefix('copilot-api.a.b.ghe.com', env)).toBe(false);
+    expect(copilotTargetRequiresGitHubTokenPrefix('copilot-api.myorg.ghe.com.evil.com', env)).toBe(false);
   });
 
   it('returns false when no token-prefix indicators are present', () => {
diff --git a/containers/api-proxy/providers/copilot-auth.js b/containers/api-proxy/providers/copilot-auth.js
index b662990d6..7557520cc 100644
--- a/containers/api-proxy/providers/copilot-auth.js
+++ b/containers/api-proxy/providers/copilot-auth.js
@@ -235,27 +235,29 @@ function isGhesInstance(resolvedTarget, env = process.env) {
  * directly and therefore require the `token <value>` Authorization prefix
  * (rather than `Bearer <value>`) for GitHub credentials.
  *
- * Both the Enterprise and Business endpoints behave this way; the standard
- * `api.githubcopilot.com` endpoint instead expects a Copilot token with the
- * `Bearer` prefix.
+ * Enterprise, Business, and GHEC data-residency endpoints behave this way; the
+ * standard `api.githubcopilot.com` endpoint instead expects a Copilot token
+ * with the `Bearer` prefix.
  */
 const GITHUB_TOKEN_PREFIX_COPILOT_TARGETS = new Set([
   'api.enterprise.githubcopilot.com',
   'api.business.githubcopilot.com',
 ]);
 
+function isGhecCopilotApiTarget(target) {
+  return /^copilot-api\.[^.]+\.ghe\.com$/.test(target);
+}
+
 /**
  * Decide whether a GitHub OAuth/PAT token sent to the Copilot API must use the
  * `token <value>` Authorization prefix instead of `Bearer <value>`.
  *
  * This is true when either:
  *   1. The resolved target is a known GitHub-hosted Copilot endpoint that
- *      authenticates the GitHub token directly — i.e. the Enterprise or Business
- *      host. This check takes highest priority and is NOT overridable by
- *      AWF_PLATFORM_TYPE. Without this ordering, gh-aw's automatic
- *      AWF_PLATFORM_TYPE=ghec injection on *.ghe.com runners would suppress the
- *      `token` prefix for Copilot Business customers who set
- *      COPILOT_API_TARGET=api.business.githubcopilot.com.
+ *      authenticates the GitHub token directly — i.e. the Enterprise, Business,
+ *      or GHEC data-residency host. This check takes highest priority and is NOT
+ *      overridable by AWF_PLATFORM_TYPE. Without this ordering, an explicit
+ *      AWF_PLATFORM_TYPE=ghec would suppress the required `token` prefix.
  *   2. The environment is a GHES instance (see {@link isGhesInstance}).
  *
  * An explicit non-GHES AWF_PLATFORM_TYPE overrides the GHES heuristics (case 2)
@@ -272,10 +274,12 @@ function copilotTargetRequiresGitHubTokenPrefix(resolvedTarget, env = process.en
   // Known GitHub-hosted Copilot endpoints always require the 'token' prefix for
   // GitHub OAuth/PAT credentials, regardless of platform type. This check must
   // come before the AWF_PLATFORM_TYPE guard so that an explicit platform type
-  // (e.g. AWF_PLATFORM_TYPE=ghec set by gh-aw on *.ghe.com runners) does not
-  // suppress the required 'token' prefix for Business/Enterprise endpoints.
+  // does not suppress the required 'token' prefix.
   const target = normalizeApiTarget(resolvedTarget);
-  if (target && GITHUB_TOKEN_PREFIX_COPILOT_TARGETS.has(target)) return true;
+  if (target && (
+    GITHUB_TOKEN_PREFIX_COPILOT_TARGETS.has(target)
+    || isGhecCopilotApiTarget(target)
+  )) return true;
 
   // An explicit non-GHES platform type overrides the GHES heuristics below
   // for custom/unknown targets but never overrides catalog endpoints (above).
diff --git a/containers/api-proxy/server.auth-matrix.test.js b/containers/api-proxy/server.auth-matrix.test.js
index c47098fe6..62ad08d01 100644
--- a/containers/api-proxy/server.auth-matrix.test.js
+++ b/containers/api-proxy/server.auth-matrix.test.js
@@ -277,13 +277,13 @@ describe('Auth Matrix — Copilot', () => {
   });
 
   describe('GitHub OAuth token — GHEC (*.ghe.com)', () => {
-    it('sends Authorization: Bearer (not token) for GHEC', () => {
+    it('sends Authorization: token for GHEC data-residency targets', () => {
       const adapter = createCopilotAdapter({
         COPILOT_GITHUB_TOKEN: 'ghu_ghec_token',
         GITHUB_SERVER_URL: 'https://mycompany.ghe.com',
       });
       const headers = adapter.getAuthHeaders(fakeReq());
-      expect(headers.Authorization).toBe('Bearer ghu_ghec_token');
+      expect(headers.Authorization).toBe('token ghu_ghec_token');
     });
 
     it('derives correct copilot-api target for GHEC', () => {
diff --git a/docs-site/package-lock.json b/docs-site/package-lock.json
index 9f3e0c4b3..d6ffb4688 100644
--- a/docs-site/package-lock.json
+++ b/docs-site/package-lock.json
@@ -6651,9 +6651,9 @@
       "license": "MIT"
     },
     "node_modules/nanoid": {
-      "version": "3.3.16",
-      "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.16.tgz",
-      "integrity": "sha512-bzlKTyNJ7+LdGIIwy8ijFpIqEQIvafahV7eYykJ8Cvh42EdJeODoJ6gUJXpQJvej1BddH8OqTXZNE/KfbWAu8Q==",
+      "version": "5.1.16",
+      "resolved": "https://ms-feed-17.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/nanoid/-/nanoid-5.1.16.tgz",
+      "integrity": "sha1-/jRcCh+QB8Mvu1wTnhIIv9P0Hvc=",
       "funding": [
         {
           "type": "github",
@@ -6662,10 +6662,10 @@
       ],
       "license": "MIT",
       "bin": {
-        "nanoid": "bin/nanoid.cjs"
+        "nanoid": "bin/nanoid.js"
       },
       "engines": {
-        "node": "^10 || ^12 || ^13.7 || ^14 || >=15.0.1"
+        "node": "^18 || >=20"
       }
     },
     "node_modules/neotraverse": {
diff --git a/docs-site/package.json b/docs-site/package.json
index b2be16d3d..fc121e770 100644
--- a/docs-site/package.json
+++ b/docs-site/package.json
@@ -23,6 +23,7 @@
     "diff": "8.0.3",
     "esbuild": "^0.28.1",
     "ajv": "8.16.0",
+    "nanoid": "5.1.16",
     "postcss": "8.5.23",
     "svgo": "^4.0.2",
     "vite": "8.0.16",