fix(docker): the slow-ingest line names which part of the Docker persist took the time (#5181)

persist_host_docker marks docker.status, .swarm, .disk, .logs, .metrics,
.events, .containers, .alerts and .reap on the ingest's phase timer, each
flushed before its mark so a part's writes are charged to it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/integration/test_docker.py

@@ -383,6 +383,41 @@ def test_vanished_container_is_reaped(app):
     assert after == ["keep"]   # the vanished container was reaped
 
 
+@_NEEDS_DB
+def test_persist_marks_each_part_for_the_slow_ingest_line(app):
+    """Each part of the docker persist is marked, so the slow-ingest line
+    names the part its time went to (#5181)."""
+    from steward.models.hosts import Host
+
+    class _Marks:
+        def __init__(self):
+            self.names = []
+
+        def mark(self, name):
+            self.names.append(name)
+
+    persist = _persist_fn(app)
+    at = datetime(2026, 10, 6, 23, 0, 0, tzinfo=timezone.utc)
+    c = {"name": "web", "status": "running", "cpu_pct": 1.0, "mem_pct": 1.0,
+         "restart_count": 0, "exit_code": None, "oom_killed": False, "health": None}
+    logs = [(at, [{"container": "web", "stream": "stdout", "ts": None, "line": "hello"}])]
+    marks = _Marks()
+
+    async def _go():
+        async with app.db_sessionmaker() as s:
+            async with s.begin():
+                h = Host(id=str(uuid.uuid4()), name="marks", address="10.9.9.7")
+                s.add(h)
+                await s.flush()
+                await persist(s, h, [(at, [c])], None, None, logs,
+                              {"status": "ok", "detail": None, "at": at, "swarm_manager": None},
+                              phases=marks)
+
+    asyncio.run(_go())
+    assert marks.names == ["docker.status", "docker.logs", "docker.metrics", "docker.events",
+                           "docker.containers", "docker.alerts", "docker.reap"]
+
+
 @_NEEDS_DB
 def test_an_empty_snapshot_from_a_docker_that_answered_clears_the_host(app):
     """Docker answering with no containers removes the host's rows (#5152); a