diff --git a/studio/backend/routes/inference.py b/studio/backend/routes/inference.py
index 4bd3774ff7..5e56880c3d 100644
--- a/studio/backend/routes/inference.py
+++ b/studio/backend/routes/inference.py
@@ -4291,10 +4291,22 @@ async def _maybe_auto_switch_model(
                         # different configs), then the bare ids. Both the advertised
                         # repo id and the concrete load path are tried: a local folder
                         # or a non-active HF cache is configured against its path.
+                        # A standalone .gguf needs no quant sub-selection, so the
+                        # resolver reports variant=None for it. The picker still
+                        # keys its config by the quant label it derives from the
+                        # filename (LocalModelInfo.format_variant), which is never
+                        # empty, so those settings live under "<path>:LABEL" and no
+                        # bare key would ever reach them.
+                        file_variant = None
+                        if not variant and target_id.lower().endswith(".gguf"):
+                            from hub.utils.gguf import extract_quant_label
+
+                            file_variant = extract_quant_label(os.path.basename(target_id))
                         override = {}
                         for override_key in (
                             f"{override_id}:{variant}" if variant else None,
                             f"{target_id}:{variant}" if variant else None,
+                            f"{target_id}:{file_variant}" if file_variant else None,
                             override_id,
                             target_id,
                         ):
diff --git a/studio/backend/routes/settings.py b/studio/backend/routes/settings.py
index 052c643519..cc8844ad4d 100644
--- a/studio/backend/routes/settings.py
+++ b/studio/backend/routes/settings.py
@@ -411,8 +411,14 @@ def update_openai_auto_switch_override(
             target_id = resolve_model_override_key(payload.model_id) or payload.model_id
             set_model_override(target_id, llama_extra_args = [], max_seq_length = None)
         else:
+            # Save under the key a load would resolve to, for the same reason the
+            # removal branch does. The browser normalizes casing before storing,
+            # so saving the literal id leaves a second entry for one model, and
+            # two equivalent keys make every other casing ambiguous: the lookup
+            # then matches neither and the model silently loses its settings.
+            target_id = resolve_model_override_key(payload.model_id) or payload.model_id
             set_model_override(
-                payload.model_id,
+                target_id,
                 llama_extra_args = extra_args,
                 max_seq_length = payload.max_seq_length,
                 custom_context_length = payload.custom_context_length,
diff --git a/studio/backend/tests/test_openai_auto_switch.py b/studio/backend/tests/test_openai_auto_switch.py
index bf4f41c818..55484e67d3 100644
--- a/studio/backend/tests/test_openai_auto_switch.py
+++ b/studio/backend/tests/test_openai_auto_switch.py
@@ -4748,6 +4748,25 @@ def test_removal_clears_the_entry_a_load_would_actually_resolve(monkeypatch):
     assert settings.get_model_override("unsloth/B-GGUF:Q4_K_M") == {}
 
 
+def test_save_updates_the_existing_case_variant_instead_of_forking_it(monkeypatch):
+    # The backfill stores normalized (lowercase) keys while a later UI save carries
+    # the catalog's casing. Writing that literally leaves two keys for one model,
+    # and with two equivalent keys present any third casing resolves ambiguously,
+    # so the model silently loses every saved setting on the API path.
+    import routes.settings as settings_route
+
+    _mock_override_store(monkeypatch)
+    settings.set_model_override("unsloth/b-gguf:q4_k_m", max_seq_length = 8192)
+    settings_route.update_openai_auto_switch_override(
+        settings_route.ModelOverridePayload(
+            model_id = "unsloth/B-GGUF:Q4_K_M", max_seq_length = 4096
+        ),
+        "tester",
+    )
+    assert list(settings.get_model_overrides()) == ["unsloth/b-gguf:q4_k_m"]
+    assert settings.get_model_override("Unsloth/B-GGUF:Q4_K_M")["max_seq_length"] == 4096
+
+
 def test_removal_of_a_path_still_only_touches_the_exact_key(monkeypatch):
     import routes.settings as settings_route