From 5bf63c7c6008012d79d5746175d12b2773514d96 Mon Sep 17 00:00:00 2001
From: Brad Anderson <brad@branderson.io>
Date: Mon, 27 Jul 2026 02:16:39 -0700
Subject: [PATCH] feat: remove the output folder a rebuild superseded

---
 src/karaoke_maker/web.py | 18 ++++++++++++-
 tests/test_web.py        | 57 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/src/karaoke_maker/web.py b/src/karaoke_maker/web.py
index e6eba24..acdfc13 100644
--- a/src/karaoke_maker/web.py
+++ b/src/karaoke_maker/web.py
@@ -114,6 +114,20 @@ def create_app(cfg: Config, runner=run_pipeline) -> FastAPI:
             f" ({', '.join(changed) if changed else 'nothing'} changed)")
         return force_from
 
+    def _drop_superseded_output(job: Job, log) -> None:
+        if not job.rebuilt_from:
+            return
+        with lock:
+            parent = jobs.get(job.rebuilt_from)
+        if parent is None or parent.status != "done":
+            return
+        old = rebuild_policy.superseded_output(parent.output_dir, job.output_dir,
+                                                cfg.output_dir)
+        if old is None:
+            return
+        shutil.rmtree(old, ignore_errors=True)
+        log(f"[rebuild] removed superseded {old.name}")
+
     def worker():
         while True:
             job_id = todo.get()
@@ -132,9 +146,11 @@ def create_app(cfg: Config, runner=run_pipeline) -> FastAPI:
                 force_from = _prepare_rebuild(job, log)
                 result = runner(job.inp, cfg, log=log, force_from=force_from)
                 with lock:
-                    job.status = "done"
                     job.output_dir = str(result.output_dir)
                     job.warnings = list(result.warnings)
+                _drop_superseded_output(job, log)
+                with lock:
+                    job.status = "done"
                 # uploads survive a failure so the job stays rerunnable; acquire
                 # has already copied the video into the work dir by now.
                 _cleanup_uploads(cfg, job_id, job.inp.video_path)
diff --git a/tests/test_web.py b/tests/test_web.py
index b5fa5d1..3ef8492 100644
--- a/tests/test_web.py
+++ b/tests/test_web.py
@@ -821,3 +821,60 @@ def test_rebuild_of_a_running_job_is_409(tmp_path):
 def test_rebuild_of_an_unknown_job_is_404(tmp_path):
     client, _ = make_client(tmp_path, ok_runner)
     assert client.post("/api/jobs/nope/rebuild", data=rebuild_form()).status_code == 404
+
+
+def slug_runner(inp, cfg, log=print, force_from=None, stages=None):
+    out = cfg.output_dir / song_slug(inp)
+    out.mkdir(parents=True, exist_ok=True)
+    (out / "song.txt").write_text(f"#TITLE:{inp.title}\n")
+    return PipelineResult(output_dir=out)
+
+
+def test_rebuild_removes_the_output_it_replaced(tmp_path):
+    client, cfg = make_client(tmp_path, slug_runner)
+    parent = make_done_job(client)
+    assert (cfg.output_dir / "A - T" / "song.txt").exists()
+    child = client.post(f"/api/jobs/{parent}/rebuild",
+                        data=rebuild_form(title="T2")).json()["id"]
+    job = wait_status(client, child, "done")
+    assert (cfg.output_dir / "A - T2" / "song.txt").exists()
+    assert not (cfg.output_dir / "A - T").exists()
+    assert any("superseded" in line for line in job["log"])
+
+
+def test_rebuild_keeps_the_output_when_the_slug_is_unchanged(tmp_path):
+    client, cfg = make_client(tmp_path, slug_runner)
+    parent = make_done_job(client)
+    child = client.post(f"/api/jobs/{parent}/rebuild",
+                        data=rebuild_form(year="1998")).json()["id"]
+    wait_status(client, child, "done")
+    assert (cfg.output_dir / "A - T" / "song.txt").exists()
+
+
+def test_rebuild_of_a_failed_parent_removes_nothing(tmp_path):
+    calls = []
+
+    def flaky(inp, cfg, log=print, force_from=None, stages=None):
+        calls.append(1)
+        if len(calls) == 1:
+            raise PipelineError("boom")
+        return slug_runner(inp, cfg, log=log)
+
+    client, cfg = make_client(tmp_path, flaky)
+    parent = client.post("/api/jobs", data=rebuild_form()).json()["id"]
+    wait_status(client, parent, "failed")
+    (cfg.output_dir / "A - T").mkdir(parents=True)
+    (cfg.output_dir / "A - T" / "keep.txt").write_text("mine")
+    child = client.post(f"/api/jobs/{parent}/rebuild",
+                        data=rebuild_form(title="T2")).json()["id"]
+    wait_status(client, child, "done")
+    assert (cfg.output_dir / "A - T" / "keep.txt").exists()
+
+
+def test_a_plain_job_never_removes_anything(tmp_path):
+    client, cfg = make_client(tmp_path, slug_runner)
+    make_done_job(client)
+    stray = cfg.output_dir / "A - Other"
+    stray.mkdir(parents=True)
+    make_done_job(client, title="T2")
+    assert stray.exists()