feat: add cache_creation_input_tokens to usage metrics

src/webwright/models/anthropic_model.py

@@ -101,11 +101,13 @@ def _usage_from_anthropic_payload(payload: dict[str, Any]) -> dict[str, int]:
     input_tokens = _safe_int(usage.get("input_tokens"))
     output_tokens = _safe_int(usage.get("output_tokens"))
     cached_input_tokens = _safe_int(usage.get("cache_read_input_tokens"))
+    cache_creation_input_tokens = _safe_int(usage.get("cache_creation_input_tokens"))
     return {
         "input_tokens": input_tokens,
         "output_tokens": output_tokens,
         "total_tokens": input_tokens + output_tokens,
         "cached_input_tokens": cached_input_tokens,
+        "cache_creation_input_tokens": cache_creation_input_tokens,
         "reasoning_output_tokens": 0,
     }
 

src/webwright/models/base.py

@@ -197,6 +197,7 @@ def _request_metrics_from_serialized_input(serialized_input: list[dict[str, Any]
     "output_tokens",
     "total_tokens",
     "cached_input_tokens",
+    "cache_creation_input_tokens",
     "reasoning_output_tokens",
 )
 
@@ -326,6 +327,7 @@ def _usage_snapshot(self) -> dict[str, dict[str, int]]:
                 "image_part_count": self._last_request_metrics["image_part_count"],
                 "input_tokens": self._last_usage_metrics["input_tokens"],
                 "cached_input_tokens": self._last_usage_metrics["cached_input_tokens"],
+                "cache_creation_input_tokens": self._last_usage_metrics["cache_creation_input_tokens"],
             },
             "last_response": dict(self._last_usage_metrics),
             "cumulative_request": {
@@ -334,6 +336,7 @@ def _usage_snapshot(self) -> dict[str, dict[str, int]]:
                 "image_part_count": self._cumulative_request_metrics["image_part_count"],
                 "input_tokens": self._cumulative_usage_metrics["input_tokens"],
                 "cached_input_tokens": self._cumulative_usage_metrics["cached_input_tokens"],
+                "cache_creation_input_tokens": self._cumulative_usage_metrics["cache_creation_input_tokens"],
             },
             "cumulative_response": dict(self._cumulative_usage_metrics),
         }

src/webwright/models/openai_model.py

@@ -98,6 +98,7 @@ def _usage_metrics_from_response_payload(payload: dict[str, Any]) -> dict[str, i
         "output_tokens": _safe_int(usage.get("output_tokens")),
         "total_tokens": _safe_int(usage.get("total_tokens")),
         "cached_input_tokens": _safe_int(input_details.get("cached_tokens")),
+        "cache_creation_input_tokens": 0,
         "reasoning_output_tokens": _safe_int(output_details.get("reasoning_tokens")),
     }
 

src/webwright/models/openrouter_model.py

@@ -113,6 +113,7 @@ def _usage_metrics_from_chat_completions(payload: dict[str, Any]) -> dict[str, i
         "output_tokens": _safe_int(usage.get("completion_tokens")),
         "total_tokens": _safe_int(usage.get("total_tokens")),
         "cached_input_tokens": 0,
+        "cache_creation_input_tokens": 0,
         "reasoning_output_tokens": 0,
     }
 

tests/unit/test_cache_creation_tokens.py

@@ -0,0 +1,33 @@
+from webwright.models.anthropic_model import _usage_from_anthropic_payload
+from webwright.models.base import _USAGE_METRIC_KEYS
+
+
+def test_cache_creation_input_tokens_in_metric_keys() -> None:
+    assert "cache_creation_input_tokens" in _USAGE_METRIC_KEYS
+
+
+def test_anthropic_payload_extracts_cache_creation_tokens() -> None:
+    payload = {
+        "usage": {
+            "input_tokens": 100,
+            "output_tokens": 50,
+            "cache_read_input_tokens": 20,
+            "cache_creation_input_tokens": 30,
+        }
+    }
+    metrics = _usage_from_anthropic_payload(payload)
+    assert metrics["cache_creation_input_tokens"] == 30
+    assert metrics["cached_input_tokens"] == 20
+
+
+def test_anthropic_payload_defaults_cache_creation_to_zero() -> None:
+    payload = {"usage": {"input_tokens": 100, "output_tokens": 50}}
+    metrics = _usage_from_anthropic_payload(payload)
+    assert metrics["cache_creation_input_tokens"] == 0
+
+
+def test_anthropic_payload_returns_all_metric_keys() -> None:
+    payload = {"usage": {"input_tokens": 10, "output_tokens": 5}}
+    metrics = _usage_from_anthropic_payload(payload)
+    for key in _USAGE_METRIC_KEYS:
+        assert key in metrics, f"missing key: {key}"