feat(music-lab): get_last_failed_step — 파이프라인 재개용 실패 step 판별

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

music-lab/tests/test_pipeline_retry.py

@@ -0,0 +1,24 @@
+import pytest
+from app import db
+
+
+@pytest.fixture
+def fresh_db(monkeypatch, tmp_path):
+    db_path = tmp_path / "music.db"
+    monkeypatch.setattr(db, "DB_PATH", str(db_path))
+    db.init_db()
+    return db_path
+
+
+def test_get_last_failed_step_returns_step(fresh_db):
+    pid = db.create_pipeline(track_id=1)
+    job_id = db.create_pipeline_job(pid, "video")
+    db.update_pipeline_job(job_id, status="failed", error="boom")
+    db.update_pipeline_state(pid, "failed", failed_reason="video: boom")
+    assert db.get_last_failed_step(pid) == "video"
+
+
+def test_get_last_failed_step_none_when_no_failure(fresh_db):
+    pid = db.create_pipeline(track_id=1)
+    db.create_pipeline_job(pid, "cover")
+    assert db.get_last_failed_step(pid) is None