feat: updated cached read/write input token metrics

Author: poshinchen

src/strands/telemetry/metrics.py

@@ -350,9 +350,9 @@ def _metrics_summary_to_lines(event_loop_metrics: EventLoopMetrics, allowed_name
 
     # Add cached token info if present
     if summary["accumulated_usage"].get("cacheReadInputTokens"):
-        token_parts.append(f"cache_read={summary['accumulated_usage']['cacheReadInputTokens']}")
+        token_parts.append(f"cache_read_input_tokens={summary['accumulated_usage']['cacheReadInputTokens']}")
     if summary["accumulated_usage"].get("cacheWriteInputTokens"):
-        token_parts.append(f"cache_write={summary['accumulated_usage']['cacheWriteInputTokens']}")
+        token_parts.append(f"cache_write_input_tokens={summary['accumulated_usage']['cacheWriteInputTokens']}")
 
     yield f"├─ Tokens: {', '.join(token_parts)}"
     yield f"├─ Bedrock Latency: {summary['accumulated_metrics']['latencyMs']}ms"

tests/strands/telemetry/test_metrics.py

@@ -90,7 +90,7 @@ def usage(request):
         "inputTokens": 1,
         "outputTokens": 2,
         "totalTokens": 3,
-        "cacheWriteInputTokens": 10,
+        "cacheWriteInputTokens": 2,
     }
     if hasattr(request, "param"):
         params.update(request.param)
@@ -316,7 +316,7 @@ def test_event_loop_metrics_update_usage(usage, event_loop_metrics, mock_get_met
         event_loop_metrics.update_usage(usage)
 
     tru_usage = event_loop_metrics.accumulated_usage
-    exp_usage = Usage(inputTokens=3, outputTokens=6, totalTokens=9, cacheWriteInputTokens=30)
+    exp_usage = Usage(inputTokens=3, outputTokens=6, totalTokens=9, cacheWriteInputTokens=6)
 
     assert tru_usage == exp_usage
     mock_get_meter_provider.return_value.get_meter.assert_called()