From ca57722ba149f320a5c96fc4efb1e7c7b87da888 Mon Sep 17 00:00:00 2001
From: wittekin <6079900+wittekin@users.noreply.github.com>
Date: Sat, 7 Mar 2026 17:25:45 -0800
Subject: [PATCH] Block --split-task for remote providers

Remote tasklist backends (Jira/Linear/GitHub) manage task structure
natively, so local task splitting is not applicable. Exit early with
a clear error message directing users to their provider's interface.

Generated with millstone orchestrator
---
 src/millstone/runtime/orchestrator.py | 11 +++++++++++
 tests/test_orchestrator.py            | 20 ++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/src/millstone/runtime/orchestrator.py b/src/millstone/runtime/orchestrator.py
index fae89a2..2d9a0f8 100755
--- a/src/millstone/runtime/orchestrator.py
+++ b/src/millstone/runtime/orchestrator.py
@@ -4325,6 +4325,17 @@ def main():
 
     # Handle --split-task: analyze a task and suggest subtasks
     if args.split_task is not None:
+        using_remote_provider = config.get("tasklist_provider", "file") != "file"
+        if using_remote_provider:
+            print(
+                "Task splitting is not supported for remote providers.",
+                file=sys.stderr,
+            )
+            print(
+                "Use your provider's native interface to manage tasks.",
+                file=sys.stderr,
+            )
+            sys.exit(1)
         orchestrator = Orchestrator(
             tasklist=args.tasklist,
             dry_run=False,
diff --git a/tests/test_orchestrator.py b/tests/test_orchestrator.py
index 691e9ee..314a466 100644
--- a/tests/test_orchestrator.py
+++ b/tests/test_orchestrator.py
@@ -16277,6 +16277,26 @@ def mock_run_claude(prompt, **kwargs):
         finally:
             orch.cleanup()
 
+    def test_split_task_remote_provider_exits_with_error(self, temp_repo, monkeypatch, capsys):
+        """--split-task with remote provider prints error and exits 1."""
+        import sys
+
+        from millstone.runtime.orchestrator import main
+
+        # Configure remote provider
+        config_dir = temp_repo / ".millstone"
+        config_dir.mkdir(exist_ok=True)
+        (config_dir / "config.toml").write_text('tasklist_provider = "mcp"\n')
+
+        monkeypatch.setattr(sys, "argv", ["millstone", "--split-task", "1"])
+
+        with pytest.raises(SystemExit) as exc_info:
+            main()
+
+        assert exc_info.value.code == 1
+        captured = capsys.readouterr()
+        assert "not supported for remote providers" in captured.err
+
 
 class TestProgressEstimation:
     """Tests for progress estimation functionality."""