Say plainly when several live models hold different adapters

Round three of the adapter review found two leftovers from the previous fix.

With three or more live runtimes the reason read "another live model still
holds adapter-a and adapter-b", a singular subject attributing several
adapters to one model, when each runtime attaches one adapter per kind. The
subject now agrees in number with what is held.

LoadRecord still stored its own copy of the manifest sha256, which is the
same second source of truth this work removed for kind, adapter_id and path:
the only constructor copied it, and nothing stopped a caller from passing a
hash that disagreed with the source handed in. It is a property now, so
runtime.py keeps reading record.sha256 and there is one value.

Also recorded, measured by the reviewer and deliberately not treated as
defects: a row for a kind with nothing on disk now reports base_model as null
rather than the runtime's model id, since that row describes no adapter at
all; the same adapter id can appear in both a loaded row and a shadowed row
when it is attached while another copy wins the mount, and both rows are
true; and when the attached adapter is deleted from disk the row says missing
with null identity instead of claiming a gone model.

Three tests carry this: the three-runtime case asserts the plural wording, and
both fixes were mutation-checked (dropping the plural branch fails two tests,
restoring the stored hash fails the generation test).

pytest -q: 228 passed. ruff clean. mypy cold cache on the three touched source
files: 2 errors, identical to the stashed HEAD tree, net zero. pyright: 2
errors, both the known qwen_vl_utils tuple artifact.

backend/tests/test_adapters.py

@@ -133,8 +133,14 @@ def test_a_library_adapter_is_selected_for_its_kind(tmp_path: Path) -> None:
 
 def test_an_adapter_on_another_base_model_is_deferred_naming_both_models(tmp_path: Path) -> None:
     settings = _settings(tmp_path)
-    _write_adapter(settings.adapters_dir / "router", kind=TrainingAdapterKind.hme_router, base_model="Qwen/Qwen3.5-0.8B")
-    source, state, reason = adapters.resolve(adapters.library_sources(settings), settings, TrainingAdapterKind.hme_router)
+    _write_adapter(
+        settings.adapters_dir / "router",
+        kind=TrainingAdapterKind.hme_router,
+        base_model="Qwen/Qwen3.5-0.8B",
+    )
+    source, state, reason = adapters.resolve(
+        adapters.library_sources(settings), settings, TrainingAdapterKind.hme_router
+    )
     assert source is None
     assert state == "deferred"
     assert "trained on Qwen/Qwen3.5-0.8B" in reason and f"runtime holds {MODEL}" in reason
@@ -153,7 +159,9 @@ def test_the_mounted_cartridge_copy_wins_over_the_library(tmp_path: Path) -> Non
     database = Database(settings)
     _write_adapter(settings.adapters_dir / "core", adapter_id="library-copy")
     cartridge_root = _cartridge(settings, database, "cart-home")
-    cartridge_copy = _write_adapter(cartridge_root / "adapters" / "hme_core_lora", adapter_id="cartridge-copy")
+    cartridge_copy = _write_adapter(
+        cartridge_root / "adapters" / "hme_core_lora", adapter_id="cartridge-copy"
+    )
     sources, mounted = adapters.discover(settings, database)
     assert mounted == ["cart-home"]
     source, state, reason = adapters.resolve(sources, settings, CORE)
@@ -197,7 +205,9 @@ def test_stub_weights_prove_the_load_branch_runs(tmp_path: Path, monkeypatch) ->
     assert attached == [(mock.ANY, chosen)], "peft was never asked to attach the stub adapter"
     assert model.evalled is True
     assert [record.adapter_id for record in adapters.load_records()] == ["adapter-1"]
-    row = next(item for item in adapters.plan(settings, Database(settings)).adapters if item.kind == CORE)
+    row = next(
+        item for item in adapters.plan(settings, Database(settings)).adapters if item.kind == CORE
+    )
     assert row.state == "loaded" and "attached to the live model" in row.reason
 
 
@@ -219,7 +229,9 @@ def test_unload_stops_claiming_a_model_that_is_gone(tmp_path: Path, monkeypatch)
     assert "that model is gone" in row.reason, row.reason
 
 
-def test_a_loaded_row_names_the_adapter_that_is_actually_attached(tmp_path: Path, monkeypatch) -> None:
+def test_a_loaded_row_names_the_adapter_that_is_actually_attached(
+    tmp_path: Path, monkeypatch
+) -> None:
     settings = _settings(tmp_path)
     attached = _write_adapter(settings.adapters_dir / "x", adapter_id="adapter-x")
     monkeypatch.setattr(adapters, "load_into_model", lambda model, path: _FakeModel())
@@ -227,9 +239,13 @@ def test_a_loaded_row_names_the_adapter_that_is_actually_attached(tmp_path: Path
     runtime = QwenRuntime(settings)
     runtime._load_transformers()
     _write_adapter(settings.adapters_dir / "y", adapter_id="adapter-y")
-    row = next(item for item in adapters.plan(settings, Database(settings)).adapters if item.kind == CORE)
+    row = next(
+        item for item in adapters.plan(settings, Database(settings)).adapters if item.kind == CORE
+    )
     assert row.state == "loaded"
-    assert row.adapter_id == "adapter-x", f"the row promises {row.adapter_id} but {attached} is attached"
+    assert row.adapter_id == "adapter-x", (
+        f"the row promises {row.adapter_id} but {attached} is attached"
+    )
     assert row.path == str(attached) and row.reason.endswith(str(attached)), row.reason
 
 
@@ -256,14 +272,39 @@ def test_one_unload_does_not_declare_another_live_model_gone(tmp_path: Path, mon
     assert row.state == "available" and "that model is gone" in row.reason, row.reason
 
 
+def test_three_live_models_are_named_as_models_not_one_model(tmp_path: Path, monkeypatch) -> None:
+    settings = _settings(tmp_path)
+    monkeypatch.setattr(adapters, "load_into_model", lambda model, path: _FakeModel())
+    monkeypatch.setattr(QwenRuntime, "_load_base_model", lambda self: (_FakeModel(), object()))
+    runtimes = []
+    for name in ("a", "b", "c"):
+        _write_adapter(settings.adapters_dir / name, adapter_id=f"adapter-{name}")
+        runtime = QwenRuntime(settings)
+        runtime._load_transformers()
+        runtimes.append(runtime)
+    row = next(item for item in adapters.plan(settings, Database(settings)).adapters if item.kind == CORE)
+    assert row.state == "loaded" and row.adapter_id == "adapter-c"
+    assert "other live models still hold adapter-a and adapter-b" in row.reason, row.reason
+    assert "another live model" not in row.reason, row.reason
+
+
 def test_a_rejected_candidate_does_not_claim_another_adapter_won(tmp_path: Path) -> None:
     settings = _settings(tmp_path)
-    _write_adapter(settings.adapters_dir / "router", kind=TrainingAdapterKind.hme_router, base_model="Qwen/Qwen3.5-0.8B")
+    _write_adapter(
+        settings.adapters_dir / "router",
+        kind=TrainingAdapterKind.hme_router,
+        base_model="Qwen/Qwen3.5-0.8B",
+    )
     report = adapters.plan(settings, Database(settings))
     router_rows = [row for row in report.adapters if row.kind == TrainingAdapterKind.hme_router]
     assert len(router_rows) == 1, "a rejected candidate was published as a shadow row"
-    assert router_rows[0].state == "deferred" and "trained on Qwen/Qwen3.5-0.8B" in router_rows[0].reason
-    assert not any(row.shadowed for row in report.adapters), "nothing won, so nothing may claim a winner"
+    assert (
+        router_rows[0].state == "deferred"
+        and "trained on Qwen/Qwen3.5-0.8B" in router_rows[0].reason
+    )
+    assert not any(row.shadowed for row in report.adapters), (
+        "nothing won, so nothing may claim a winner"
+    )
 
 
 def test_the_shadow_row_names_the_adapter_that_won(tmp_path: Path) -> None:
@@ -292,9 +333,15 @@ def test_a_cartridge_tagged_adapter_outranks_an_untagged_one(tmp_path: Path) ->
 def test_generation_reports_the_adapter_it_attached(tmp_path: Path, monkeypatch) -> None:
     settings = _settings(tmp_path)
     chosen = _write_adapter(settings.adapters_dir / "core")
-    monkeypatch.setitem(sys.modules, "qwen_vl_utils", SimpleNamespace(process_vision_info=lambda _messages: ([], None)))
+    monkeypatch.setitem(
+        sys.modules,
+        "qwen_vl_utils",
+        SimpleNamespace(process_vision_info=lambda _messages: ([], None)),
+    )
     monkeypatch.setattr(adapters, "load_into_model", lambda model, path: _FakeModel())
-    monkeypatch.setattr(QwenRuntime, "_load_base_model", lambda self: (_FakeModel(), _FakeProcessor()))
+    monkeypatch.setattr(
+        QwenRuntime, "_load_base_model", lambda self: (_FakeModel(), _FakeProcessor())
+    )
     generation = QwenRuntime(settings).generate_prompt("what does the cartridge hold?")
     assert generation.adapter_path == str(chosen)
     assert generation.adapter_kind == CORE.value and generation.adapter_id == "adapter-1"