diff --git a/owilix/core/tasks/remote.py b/owilix/core/tasks/remote.py
--- a/owilix/core/tasks/remote.py
+++ b/owilix/core/tasks/remote.py
@@ -284,6 +284,32 @@
     total_files = sum(d.metadata.get('fileCount', 0) or 0 for d in datasets)
     console.print(f"\n[bold]Summary:[/bold] {len(datasets)} datasets found, {total_size/1e9:.1f} GB, {total_files:,} files")
 
+    # Matching nothing is not success.
+    #
+    # This used to fall through to the success path below, so a specifier that
+    # selected no datasets at all was indistinguishable from one whose datasets
+    # were already in sync -- both printed a summary and exited 0. That is how
+    # the `--push-to` source bug survived: an OWI mirror ran nightly against a
+    # specifier that could never match, recorded success every time, and moved
+    # nothing for weeks.
+    #
+    # "Nothing to transfer" is still success and still exits 0; that case has
+    # datasets and simply finds their files present. What is reported here is
+    # narrower: discovery matched no dataset, so nothing was even considered.
+    if not datasets:
+        from owilix.core.types import ErrorType, ExitCode
+        return CommandResult(
+            success=False,
+            object={"datasets": [], "specifier": specifier},
+            msg=(
+                f"No datasets matched specifier '{specifier}'"
+                + (f" (push target {push_to_remote})" if push_to_remote else "")
+            ),
+            error_type=ErrorType.DATA,
+            exit_code=ExitCode.DATA_ERROR,
+            command="remote pull",
+        )
+
     _add = "" if push_to_remote is None else f" and push to {push_to_remote}"
 
     failed_files: List[tuple] = []  # (file_path, error_message)
diff --git a/tests/owilix/core/tasks/test_remote.py b/tests/owilix/core/tasks/test_remote.py
--- a/tests/owilix/core/tasks/test_remote.py
+++ b/tests/owilix/core/tasks/test_remote.py
@@ -745,11 +745,47 @@
         args, _ = manager.remote_data.list.call_args
         assert args[0] == "lexis"
 
-    def test_no_datasets_found(self):
+    def test_no_datasets_found_is_a_failure_not_a_quiet_success(self):
+        """Matching nothing must be distinguishable from being up to date.
+
+        This asserted `success is True` until 2026-08-04. That is precisely how
+        the `--push-to` source bug stayed hidden: an OWI mirror ran nightly
+        against a specifier that could never match, took this path every time,
+        exited 0, and moved nothing for weeks. A caller had no way to tell
+        "already in sync" from "selected nothing at all".
+        """
+        from owilix.core.types import ErrorType, ExitCode
+
         manager = _make_mock_manager(datasets=[])
         result = remote_pull(manager, specifier="dc1/public", auto_yes=True, console=MagicMock())
+
+        assert result.success is False
+        assert result.exit_code == ExitCode.DATA_ERROR
+        assert result.error_type == ErrorType.DATA
+        # The specifier is in the message, because "no datasets" without it
+        # sends the reader looking in the wrong place.
+        assert "dc1/public" in result.msg
+
+    @patch("owilix.core.tasks.remote.currentItemProgress")
+    @patch("owilix.core.tasks.remote.ask_yes_no", return_value=True)
+    def test_datasets_found_but_nothing_to_transfer_is_still_success(
+        self, mock_ask, mock_progress, tmp_path
+    ):
+        """The case that must NOT be swept up: discovery worked, files are present.
+
+        "Nothing to do" and "nothing found" are different states and only the
+        second is a fault; conflating them would make an idle mirror look broken
+        every night.
+        """
+        ds = _make_mock_dataset()
+        manager = _make_mock_manager(datasets=[ds])
+        manager.remote_data.files.return_value = []
+
+        result = remote_pull(
+            manager, specifier="dc1/public", files="['**/*']", console=MagicMock()
+        )
+
         assert result.success is True
-        assert "0 datasets" in result.msg
 
     @patch("owilix.core.tasks.remote.ask_yes_no", return_value=False)
     def test_user_declines(self, mock_ask):