Add GPU selection to job launcher

backend/tests/test_jobs.py

@@ -1,7 +1,10 @@
 from fastapi.testclient import TestClient
 
+from app import jobs
+from app.commands import CommandSpec
 from app.jobs import default_conda_env_for_job
 from app.main import _job_with_progress, app
+from app.schemas import JobCreate
 
 
 def test_mmseg_jobs_use_mmseg_conda_env_by_default():
@@ -9,6 +12,16 @@ def test_mmseg_jobs_use_mmseg_conda_env_by_default():
     assert default_conda_env_for_job("segmodel.train") == "seg_smp"
 
 
+def test_build_task_sets_cuda_visible_devices(tmp_path, monkeypatch):
+    def fake_build_module_task(job_type, params, conda_env):
+        return CommandSpec(["python", "-c", "print('ok')"], tmp_path, "fake task")
+
+    monkeypatch.setattr(jobs, "build_module_task", fake_build_module_task)
+    spec = jobs._build_task(JobCreate(type="mock.echo", params={}, gpus=[2, 0]))
+
+    assert spec.env["CUDA_VISIBLE_DEVICES"] == "2,0"
+
+
 def test_job_progress_reports_log_size(tmp_path):
     log_path = tmp_path / "job.log"
     log_path.write_text("line one\nline two\n", encoding="utf-8")