diff --git a/scripts/publish_zhenxun.py b/scripts/publish_zhenxun.py
index 42d6a0b..3065ae0 100644
--- a/scripts/publish_zhenxun.py
+++ b/scripts/publish_zhenxun.py
@@ -13,9 +13,12 @@ REPOSITORY = "Shu-Ying/zhenxun_plugin_farm"
 BRANCH = "farm-preview"
 
 
-def github(method, path, payload, token):
+def github(method, path, payload, token, allow_missing=False):
+    url = f"https://api.github.com/repos/{REPOSITORY}"
+    if path:
+        url += f"/{path}"
     request = Request(
-        f"https://api.github.com/repos/{REPOSITORY}/{path}",
+        url,
         data=json.dumps(payload).encode() if payload is not None else None,
         headers={"Authorization": f"Bearer {token}",
                  "Accept": "application/vnd.github+json",
@@ -26,10 +29,10 @@ def github(method, path, payload, token):
         with urlopen(request, timeout=30) as response:
             return json.load(response)
     except HTTPError as error:
-        if error.code == 404 and method == "GET":
+        if error.code == 404 and method == "GET" and allow_missing:
             return None
         raise RuntimeError(
-            f"GitHub request failed: HTTP {error.code}",
+            f"GitHub request failed: {method} {url}: HTTP {error.code}",
         ) from None
 
 
@@ -47,9 +50,12 @@ def publish(package, confirmed=False, request=None):
         raise ValueError("Configure FARM_RELEASE_TOKEN in a protected job")
     call = request or (lambda method, path, data: github(
         method, path, data, token,
+        allow_missing=path.startswith(("git/ref/heads/", "contents/")),
     ))
     repository = call("GET", "", None)
-    if not repository or repository.get("default_branch") == BRANCH:
+    if not repository:
+        raise ValueError(f"Target repository is not accessible: {REPOSITORY}")
+    if repository.get("default_branch") == BRANCH:
         raise ValueError("Preview must not be the repository default branch")
     ref = call("GET", f"git/ref/heads/{BRANCH}", None)
     parent = ref["object"]["sha"] if ref else None
diff --git a/tests/test_zhenxun_package.py b/tests/test_zhenxun_package.py
index 5351398..d53280e 100644
--- a/tests/test_zhenxun_package.py
+++ b/tests/test_zhenxun_package.py
@@ -7,6 +7,7 @@ import tempfile
 import unittest
 from zipfile import ZipFile
 from unittest.mock import patch
+from urllib.error import HTTPError
 
 ROOT = Path(__file__).resolve().parents[1]
 sys.path.insert(0, str(ROOT / "scripts"))
@@ -18,6 +19,40 @@ except ImportError:
     build = None
 
 
+class PublisherRequestTests(unittest.TestCase):
+    def test_repository_url_has_no_trailing_slash(self):
+        from publish_zhenxun import github
+        with patch("publish_zhenxun.urlopen") as opened:
+            opened.return_value.__enter__.return_value.read.return_value = (
+                b'{"default_branch": "main"}'
+            )
+            self.assertEqual(github("GET", "", None, "test-token"), {
+                "default_branch": "main",
+            })
+        request = opened.call_args.args[0]
+        self.assertEqual(request.full_url,
+                         "https://api.github.com/repos/"
+                         "Shu-Ying/zhenxun_plugin_farm")
+
+    def test_repository_404_is_not_treated_as_missing_branch(self):
+        from publish_zhenxun import github
+        error = HTTPError("https://api.github.com", 404, "Not Found",
+                          {}, None)
+        with patch("publish_zhenxun.urlopen", side_effect=error):
+            with self.assertRaisesRegex(RuntimeError, "HTTP 404"):
+                github("GET", "", None, "test-token")
+
+    def test_optional_resource_404_returns_none(self):
+        from publish_zhenxun import github
+        error = HTTPError("https://api.github.com", 404, "Not Found",
+                          {}, None)
+        with patch("publish_zhenxun.urlopen", side_effect=error):
+            self.assertIsNone(github(
+                "GET", "git/ref/heads/farm-preview", None, "test-token",
+                allow_missing=True,
+            ))
+
+
 class ZhenxunPackageTests(unittest.TestCase):
     def setUp(self):
         self.assertIsNotNone(build, "真寻打包功能未实现")
@@ -136,6 +171,33 @@ class ZhenxunPackageTests(unittest.TestCase):
                         "sha":"created", "force":False,
                     }), calls)
 
+    def test_publish_creates_missing_preview_branch(self):
+        from publish_zhenxun import publish
+        package, _ = self.clean_package()
+        calls = []
+
+        def request(method, path, data):
+            calls.append((method, path, data))
+            if path == "":
+                return {"default_branch": "main"}
+            if method == "GET":
+                return None
+            return {"sha": "created"}
+
+        with patch.dict("os.environ", {"FARM_RELEASE_TOKEN": "unit-test"}):
+            self.assertTrue(publish(package, True, request)["published"])
+        self.assertIn(("POST", "git/refs", {
+            "ref": "refs/heads/farm-preview", "sha": "created",
+        }), calls)
+        self.assertFalse(any(c[0] == "PATCH" for c in calls))
+
+    def test_inaccessible_repository_has_distinct_error(self):
+        from publish_zhenxun import publish
+        package, _ = self.clean_package()
+        with patch.dict("os.environ", {"FARM_RELEASE_TOKEN": "unit-test"}):
+            with self.assertRaisesRegex(ValueError, "not accessible"):
+                publish(package, True, lambda *args: None)
+
     def test_symlink_duplicate_and_default_branch_rejected(self):
         from publish_zhenxun import publish
         from zipfile import ZipInfo