add one-time migration for legacy global cron store

When upgrading, if jobs.json exists at the old global path and not yet
at the workspace path, move it automatically.  Prevents silent loss of
existing cron jobs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_commands.py

@@ -523,6 +523,47 @@ def test_gateway_uses_config_directory_for_cron_store(monkeypatch, tmp_path: Pat
     assert seen["cron_store"] == config.workspace_path / "cron" / "jobs.json"
 
 
+def test_migrate_cron_store_moves_legacy_file(tmp_path: Path) -> None:
+    """Legacy global jobs.json is moved into the workspace on first run."""
+    from nanobot.cli.commands import _migrate_cron_store
+
+    legacy_dir = tmp_path / "global" / "cron"
+    legacy_dir.mkdir(parents=True)
+    legacy_file = legacy_dir / "jobs.json"
+    legacy_file.write_text('{"jobs": []}')
+
+    config = Config()
+    config.agents.defaults.workspace = str(tmp_path / "workspace")
+    workspace_cron = config.workspace_path / "cron" / "jobs.json"
+
+    with patch("nanobot.config.paths.get_cron_dir", return_value=legacy_dir):
+        _migrate_cron_store(config)
+
+    assert workspace_cron.exists()
+    assert workspace_cron.read_text() == '{"jobs": []}'
+    assert not legacy_file.exists()
+
+
+def test_migrate_cron_store_skips_when_workspace_file_exists(tmp_path: Path) -> None:
+    """Migration does not overwrite an existing workspace cron store."""
+    from nanobot.cli.commands import _migrate_cron_store
+
+    legacy_dir = tmp_path / "global" / "cron"
+    legacy_dir.mkdir(parents=True)
+    (legacy_dir / "jobs.json").write_text('{"old": true}')
+
+    config = Config()
+    config.agents.defaults.workspace = str(tmp_path / "workspace")
+    workspace_cron = config.workspace_path / "cron" / "jobs.json"
+    workspace_cron.parent.mkdir(parents=True)
+    workspace_cron.write_text('{"new": true}')
+
+    with patch("nanobot.config.paths.get_cron_dir", return_value=legacy_dir):
+        _migrate_cron_store(config)
+
+    assert workspace_cron.read_text() == '{"new": true}'
+
+
 def test_gateway_uses_configured_port_when_cli_flag_is_missing(monkeypatch, tmp_path: Path) -> None:
     config_file = tmp_path / "instance" / "config.json"
     config_file.parent.mkdir(parents=True)