diff --git a/gittensor/cli/miner_commands/post.py b/gittensor/cli/miner_commands/post.py
index 40551ded..3fdb6dc1 100644
--- a/gittensor/cli/miner_commands/post.py
+++ b/gittensor/cli/miner_commands/post.py
@@ -206,6 +206,8 @@ def _validate_pat_locally(pat: str) -> str | None:
         if user_resp.status_code != 200:
             return None
         login: str | None = user_resp.json().get('login') or None
+        if not login:
+            return None
 
         # Check GraphQL access (same test the validator runs during PAT broadcast)
         gql_resp = requests.post(
@@ -220,6 +222,20 @@ def _validate_pat_locally(pat: str) -> str | None:
             )
             return None
 
+        payload = gql_resp.json()
+        if payload.get('errors'):
+            err_console.print(
+                '[red]PAT lacks GraphQL API access. Fine-grained PATs need "Public Repositories (read-only)" permission.[/red]'
+            )
+            return None
+
+        viewer = (payload.get('data') or {}).get('viewer')
+        if viewer is None:
+            err_console.print(
+                '[red]PAT lacks GraphQL API access. Fine-grained PATs need "Public Repositories (read-only)" permission.[/red]'
+            )
+            return None
+
         return login
     except requests.RequestException:
         return None
diff --git a/tests/cli/test_miner_commands.py b/tests/cli/test_miner_commands.py
index fc610898..a8bbbfed 100644
--- a/tests/cli/test_miner_commands.py
+++ b/tests/cli/test_miner_commands.py
@@ -18,6 +18,7 @@
     _pat_post_row_category,
     _require_validator_axons,
 )
+from gittensor.cli.miner_commands.post import _validate_pat_locally
 
 
 def _fake_metagraph(rows: list[tuple[float, bool, float]]):
@@ -308,3 +309,26 @@ def test_no_response_is_not_collapsed_into_rejected(self):
         counts = _pat_post_aggregate_counts(results)
         assert counts['rejected'] == 1
         assert counts['no_response'] == 1
+
+
+class TestValidatePatLocally:
+    @patch('gittensor.cli.miner_commands.post.requests.post')
+    @patch('gittensor.cli.miner_commands.post.requests.get')
+    def test_rejects_graphql_200_with_errors(self, mock_get, mock_post):
+        mock_get.return_value = SimpleNamespace(status_code=200, json=lambda: {'login': 'miner1'})
+        mock_post.return_value = SimpleNamespace(status_code=200, json=lambda: {'errors': [{'message': 'forbidden'}]})
+        assert _validate_pat_locally('ghp_test') is None
+
+    @patch('gittensor.cli.miner_commands.post.requests.post')
+    @patch('gittensor.cli.miner_commands.post.requests.get')
+    def test_rejects_graphql_200_with_null_viewer(self, mock_get, mock_post):
+        mock_get.return_value = SimpleNamespace(status_code=200, json=lambda: {'login': 'miner1'})
+        mock_post.return_value = SimpleNamespace(status_code=200, json=lambda: {'data': {'viewer': None}})
+        assert _validate_pat_locally('ghp_test') is None
+
+    @patch('gittensor.cli.miner_commands.post.requests.post')
+    @patch('gittensor.cli.miner_commands.post.requests.get')
+    def test_accepts_graphql_200_with_viewer(self, mock_get, mock_post):
+        mock_get.return_value = SimpleNamespace(status_code=200, json=lambda: {'login': 'miner1'})
+        mock_post.return_value = SimpleNamespace(status_code=200, json=lambda: {'data': {'viewer': {'login': 'miner1'}}})
+        assert _validate_pat_locally('ghp_test') == 'miner1'