perf(cost): read the response model's price row without building full model info

An unpriced display name like Qwen 3.8 Max made the price check build full
model info, and Fireworks' supported params lookup scans the whole cost map
for an unknown name. The row check now resolves the cost map key through the
cached model info helper, so that pick takes about 0.45 ms instead of several.

A regional test covers a Bedrock call whose response names an unpriced display
name with no model passed, which bills the requested model's regional row.
The duplicate get_model_info wrapper goes, since its twin already does the
same thing.

litellm/cost_calculator.py

@@ -1032,8 +1032,16 @@ def _cost_map_model_name(model: str, custom_llm_provider: str | None, region_nam
     return _strip_unregistered_leading_segments(f"{provider_prefix}/{model}", region_name)
 
 
+def _cost_map_row_key(model: str, custom_llm_provider: str | None) -> str | None:
+    try:
+        return cached_get_model_info_helper(model=model, custom_llm_provider=custom_llm_provider)["key"]
+    except Exception:
+        return None
+
+
 def _row_declares_rates(model: str, custom_llm_provider: str | None) -> bool:
-    return _declares_rates(_cost_map_model_info(model, custom_llm_provider))
+    key: Final = _cost_map_row_key(model, custom_llm_provider)
+    return key is not None and cost_map_key_prices_anything(key)
 
 
 def _rule_declares_rates(model: str, custom_llm_provider: str | None) -> bool:
@@ -3491,7 +3499,7 @@ def _cost_map_entry_declares_pricing(model_name: str, custom_llm_provider: str)
     lookups cannot strip that prefix, so a zero-rated override read as declaring nothing, and a
     session that should bill nothing fell through to the public rates instead.
     """
-    resolved: Final = _get_model_info_or_none(model_name, custom_llm_provider)
+    resolved: Final = _cost_map_model_info(model_name, custom_llm_provider)
     entries: Final = (
         litellm.model_cost.get(resolved.get("key")) if resolved is not None else None,
         litellm.model_cost.get(model_name),
@@ -3687,9 +3695,9 @@ def handle_realtime_transcription_cost_calculation(
         return 0.0
 
     model_name: Final = _get_transcription_model_name_from_results(results) or litellm_model_name
-    model_info: Final = _get_model_info_or_none(model_name, custom_llm_provider)
+    model_info: Final = _cost_map_model_info(model_name, custom_llm_provider)
     override_info: Final = (
-        _get_model_info_or_none(custom_pricing_model, custom_llm_provider) if custom_pricing_model is not None else None
+        _cost_map_model_info(custom_pricing_model, custom_llm_provider) if custom_pricing_model is not None else None
     )
 
     total_cost = 0.0
@@ -3720,13 +3728,6 @@ def _get_transcription_model_name_from_results(
     return None
 
 
-def _get_model_info_or_none(model: str, custom_llm_provider: str) -> ModelInfo | None:
-    try:
-        return litellm.get_model_info(model=model, custom_llm_provider=custom_llm_provider)
-    except Exception:
-        return None
-
-
 _TranscriptionRateKey: TypeAlias = Literal[
     "input_cost_per_second", "input_cost_per_audio_token", "input_cost_per_token", "output_cost_per_token"
 ]

tests/unit/test_cost_calculator.py

@@ -581,6 +581,30 @@ def test_completion_cost_bills_requested_model_from_hidden_params_when_no_model_
     assert cost == pytest.approx(_token_rates_cost(litellm.model_cost[requested_model], usage))
 
 
+def test_completion_cost_bills_requested_model_regional_row_when_response_names_an_unmapped_display_name(
+    _local_model_cost_map: None, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    monkeypatch.setitem(
+        litellm.model_cost,
+        "bedrock/sol-regional-test",
+        {"litellm_provider": "bedrock", "mode": "chat", "input_cost_per_token": 3e-6, "output_cost_per_token": 7e-6},
+    )
+    monkeypatch.setitem(
+        litellm.model_cost,
+        "bedrock/eu-central-1/sol-regional-test",
+        {"litellm_provider": "bedrock", "mode": "chat", "input_cost_per_token": 5e-6, "output_cost_per_token": 11e-6},
+    )
+    usage: Final = Usage(prompt_tokens=1000, completion_tokens=500, total_tokens=1500)
+    response: Final = ModelResponse(model="Sol Regional Display", choices=[], usage=usage)
+    response._hidden_params.update(
+        {"litellm_model_name": "bedrock/sol-regional-test", "region_name": "eu-central-1", "custom_llm_provider": "bedrock"}
+    )
+
+    cost: Final = completion_cost(completion_response=response)
+
+    assert cost == pytest.approx(_token_rates_cost(litellm.model_cost["bedrock/eu-central-1/sol-regional-test"], usage))
+
+
 def test_completion_cost_orders_candidates_without_extra_huggingface_config_requests(
     _local_model_cost_map: None,
 ) -> None: