[LEADS-348] API Latency Calculation

config/system.yaml

@@ -274,6 +274,7 @@ storage:
       - "response"
       - "api_input_tokens"
       - "api_output_tokens"
+      - "api_latency"
       # Streaming performance metrics (only populated when using streaming endpoint)
       - "time_to_first_token"    # Time to first token in seconds
       - "streaming_duration"      # Total streaming duration in seconds

src/lightspeed_evaluation/core/constants.py

@@ -106,6 +106,7 @@
     # Streaming performance metrics
     "time_to_first_token",
     "streaming_duration",
+    "api_latency",
     "tokens_per_second",
     "tool_calls",
     "contexts",

src/lightspeed_evaluation/core/models/data.py

@@ -84,6 +84,11 @@ class TurnData(StreamingMetricsMixin):
         default=0, ge=0, description="Output tokens used by API call"
     )
 
+    # API execution time tracking (per turn)
+    api_latency: float = Field(
+        default=0, ge=0, description="API call latency for this turn in seconds"
+    )
+
     # Per-turn metrics support
     turn_metrics: Optional[list[str]] = Field(
         default=None,
@@ -507,6 +512,11 @@ class EvaluationResult(MetricResult, StreamingMetricsMixin):
     execution_time: float = Field(
         default=0, ge=0, description="Execution time in seconds"
     )
+    api_latency: float = Field(
+        default=0,
+        ge=0,
+        description="API latency in seconds (per turn or average for conversation)",
+    )
     api_input_tokens: int = Field(default=0, ge=0, description="API input tokens used")
     api_output_tokens: int = Field(
         default=0, ge=0, description="API output tokens used"

src/lightspeed_evaluation/core/models/quality.py

@@ -5,11 +5,18 @@
 """
 
 import logging
-from typing import Optional
+from typing import TYPE_CHECKING, Optional
 
 from pydantic import BaseModel, Field
 
-from lightspeed_evaluation.core.models.summary import MetricStats, ScoreStatistics
+from lightspeed_evaluation.core.models.summary import (
+    MetricStats,
+    NumericStats,
+    ScoreStatistics,
+)
+
+if TYPE_CHECKING:
+    from lightspeed_evaluation.core.models.data import EvaluationResult
 
 logger = logging.getLogger(__name__)
 
@@ -44,8 +51,8 @@ class QualityReport(BaseModel):
         default_factory=list,
         description="Warnings about quality metrics configuration or usage",
     )
-    api_latency: float = Field(
-        default=0.0, description="[Placeholder] Average API response time in seconds"
+    api_latency: Optional[NumericStats] = Field(
+        default=None, description="API latency statistics"
     )
     api_tokens: int = Field(
         default=0,
@@ -55,7 +62,9 @@ class QualityReport(BaseModel):
     @staticmethod
     def create_report(
         by_metric: dict[str, MetricStats],
+        api_latency_summary: Optional[NumericStats],
         quality_score_metrics: list[str],
+        results: Optional[list["EvaluationResult"]] = None,
     ) -> Optional["QualityReport"]:
         """Creates a quality report with aggregated quality score from selected metrics.
 
@@ -66,6 +75,7 @@ def create_report(
             by_metric: Dictionary mapping metric identifiers to their computed statistics.
             quality_score_metrics: Metric identifiers to include in quality score calculation.
                 All specified metrics must exist in by_metric.
+            results: Optional list of EvaluationResult for computing API latency statistics.
 
         Returns:
             QualityReport with aggregated quality score and separated quality/extra metrics,
@@ -75,6 +85,7 @@ def create_report(
             ValueError: If any quality_score_metrics are not found in by_metric.
         """
         warnings: list[str] = []
+        _ = results
 
         # Validate all quality score metrics exist in computed metrics (by_metric)
         missing_metrics = [m for m in quality_score_metrics if m not in by_metric]
@@ -148,14 +159,12 @@ def create_report(
                 if stats is not None:
                     extra_metrics[metric_id] = stats
 
-        # Calculate aggregated quality score
-        aggregated_score = QualityReport._calculate_quality_score(quality_metrics)
-
         return QualityReport(
-            quality_score=aggregated_score,
+            quality_score=QualityReport._calculate_quality_score(quality_metrics),
             quality_metrics=quality_metrics,
             extra_metrics=extra_metrics,
             warnings=warnings,
+            api_latency=api_latency_summary,
         )
 
     @staticmethod

src/lightspeed_evaluation/core/models/summary.py

@@ -14,20 +14,23 @@
 from lightspeed_evaluation.core.models.data import EvaluationData, EvaluationResult
 from lightspeed_evaluation.core.output.statistics import (
     bootstrap_intervals,
+    calculate_api_latency_stats,
     calculate_api_token_usage,
     calculate_streaming_stats,
 )
 
 
 class NumericStats(BaseModel):
-    """Numeric statistics for a set of values (e.g., TTFT, duration)."""
+    """Numeric statistics for a set of values (e.g., TTFT, duration, latency)."""
 
     count: int = Field(default=0, description="Number of values")
     mean: Optional[float] = Field(default=None, description="Mean value")
     median: Optional[float] = Field(default=None, description="Median value")
     std: Optional[float] = Field(default=None, description="Standard deviation")
     min_value: Optional[float] = Field(default=None, description="Minimum value")
     max_value: Optional[float] = Field(default=None, description="Maximum value")
+    p95: Optional[float] = Field(default=None, description="95th percentile")
+    p99: Optional[float] = Field(default=None, description="99th percentile")
 
 
 class ScoreStatistics(BaseModel):
@@ -137,6 +140,9 @@ class EvaluationSummary(BaseModel):
     api_tokens: Optional[ApiTokenUsage] = Field(
         default=None, description="API token usage (when evaluation data provided)"
     )
+    api_latency: Optional[NumericStats] = Field(
+        default=None, description="API latency statistics (when API enabled)"
+    )
     streaming: Optional[StreamingStats] = Field(
         default=None, description="Streaming performance stats (when available)"
     )
@@ -178,6 +184,9 @@ def from_results(
             api_tokens = _compute_api_token_usage(evaluation_data)
             streaming = _compute_streaming_stats(evaluation_data)
 
+        # Compute API latency statistics from results
+        api_latency = _compute_api_latency_stats(results)
+
         return cls(
             timestamp=timestamp,
             results=results,
@@ -186,6 +195,7 @@ def from_results(
             by_conversation=by_conversation,
             by_tag=by_tag,
             api_tokens=api_tokens,
+            api_latency=api_latency,
             streaming=streaming,
         )
 
@@ -417,7 +427,7 @@ def _numeric_stats_from_dict(raw: dict[str, Any]) -> Optional[NumericStats]:
     """Convert a raw numeric stats dictionary to a NumericStats model.
 
     Args:
-        raw: Dictionary with count, mean, median, std, min, max keys.
+        raw: Dictionary with count, mean, median, std, min, max, p95, p99 keys.
 
     Returns:
         NumericStats instance, or None if count is 0.
@@ -432,6 +442,8 @@ def _numeric_stats_from_dict(raw: dict[str, Any]) -> Optional[NumericStats]:
         std=raw.get("std"),
         min_value=raw.get("min"),
         max_value=raw.get("max"),
+        p95=raw.get("p95"),
+        p99=raw.get("p99"),
     )
 
 
@@ -454,6 +466,23 @@ def _compute_api_token_usage(
     )
 
 
+def _compute_api_latency_stats(
+    results: Optional[list[EvaluationResult]],
+) -> Optional[NumericStats]:
+    """Compute API latency statistics from evaluation results.
+
+    Args:
+        results: List of evaluation results containing API latency data.
+
+    Returns:
+        NumericStats instance, or None if no API latency data available.
+    """
+    if not results:
+        return None
+    raw = calculate_api_latency_stats(results)
+    return _numeric_stats_from_dict(raw)
+
+
 def _compute_streaming_stats(
     evaluation_data: list[EvaluationData],
 ) -> Optional[StreamingStats]:

src/lightspeed_evaluation/core/output/generator.py

@@ -21,6 +21,7 @@
     ConversationStats,
     EvaluationSummary,
     MetricStats,
+    NumericStats,
     OverallStats,
     StreamingStats,
     TagStats,
@@ -91,7 +92,9 @@ def generate_reports(
         if quality_score_metrics:
             quality_report = QualityReport.create_report(
                 summary.by_metric,
+                summary.api_latency,
                 quality_score_metrics,
+                results=results,
             )
 
         # Prepare timestamped base filename
@@ -350,7 +353,11 @@ def _generate_quality_score_report(
                 }
                 for metric_id, stats in quality_report.extra_metrics.items()
             },
-            "api_latency": quality_report.api_latency,
+            "api_latency": (
+                quality_report.api_latency.model_dump()
+                if quality_report.api_latency
+                else None
+            ),
             "api_tokens": quality_report.api_tokens,
             "warnings": quality_report.warnings,
         }
@@ -408,6 +415,9 @@ def _generate_text_summary_from_model(
             # Token usage statistics
             self._write_token_stats(f, basic_stats, api_tokens)
 
+            # API latency statistics
+            self._write_api_latency_stats(f, summary.api_latency)
+
             # Streaming performance statistics
             self._write_streaming_stats(f, streaming_stats)
 
@@ -456,6 +466,24 @@ def _write_token_stats(
         f.write(f"Output Tokens: {api_tokens.get('total_api_output_tokens', 0):,}\n")
         f.write(f"Total Tokens: {api_tokens.get('total_api_tokens', 0):,}\n\n")
 
+    def _write_api_latency_stats(
+        self, f: Any, api_latency: Optional["NumericStats"]
+    ) -> None:
+        """Write API latency statistics section."""
+        if api_latency is None or api_latency.count == 0:
+            return  # No API latency data available
+
+        f.write("API Latency (seconds):\n")
+        f.write("-" * 20 + "\n")
+        f.write(f"Count: {api_latency.count}\n")
+        f.write(f"Mean: {api_latency.mean:.3f}s\n")
+        f.write(f"Median: {api_latency.median:.3f}s\n")
+        f.write(f"Std Dev: {api_latency.std:.3f}s\n")
+        f.write(f"Min: {api_latency.min_value:.3f}s\n")
+        f.write(f"Max: {api_latency.max_value:.3f}s\n")
+        f.write(f"P95: {api_latency.p95:.3f}s\n")
+        f.write(f"P99: {api_latency.p99:.3f}s\n\n")
+
     def _write_streaming_stats(self, f: Any, streaming_stats: dict[str, Any]) -> None:
         """Write streaming performance statistics section."""
         # Check if there are any streaming metrics
@@ -704,6 +732,9 @@ def _build_json_summary_stats(summary: EvaluationSummary) -> dict[str, Any]:
         "by_tag": _tag_stats_to_dict(summary.by_tag),
     }
 
+    if summary.api_latency is not None:
+        result["api_latency"] = summary.api_latency.model_dump()
+
     if summary.streaming is not None:
         result["streaming_performance"] = _streaming_stats_to_dict(summary.streaming)
 
@@ -735,6 +766,7 @@ def _result_to_json_dict(r: EvaluationResult) -> dict[str, Any]:
         ),
         "time_to_first_token": r.time_to_first_token,
         "streaming_duration": r.streaming_duration,
+        "api_latency": r.api_latency,
         "tokens_per_second": r.tokens_per_second,
     }
 

src/lightspeed_evaluation/core/output/statistics.py

@@ -181,7 +181,7 @@ def _calculate_numeric_stats(values: list[float]) -> dict[str, Any]:
         values: List of numeric values.
 
     Returns:
-        Dictionary containing count, mean, median, std, min, max.
+        Dictionary containing count, mean, median, std, min, max, p95, p99.
     """
     if not values:
         return {"count": 0}
@@ -193,6 +193,8 @@ def _calculate_numeric_stats(values: list[float]) -> dict[str, Any]:
         "std": statistics.stdev(values) if len(values) > 1 else 0.0,
         "min": min(values),
         "max": max(values),
+        "p95": float(np.percentile(values, 95)),
+        "p99": float(np.percentile(values, 99)),
     }
 
 
@@ -304,3 +306,21 @@ def calculate_streaming_stats(
         "streaming_duration": _calculate_numeric_stats(duration_values),
         "tokens_per_second": _calculate_numeric_stats(throughput_values),
     }
+
+
+def calculate_api_latency_stats(results: list[EvaluationResult]) -> dict[str, Any]:
+    """Calculate API latency statistics from evaluation results.
+
+    Args:
+        results: List of evaluation results containing API latency data.
+
+    Returns:
+        Dictionary containing API latency statistics with percentiles (p50, p95, p99).
+    """
+    api_latency_values: list[float] = []
+
+    for result in results:
+        if result.api_latency > 0:
+            api_latency_values.append(result.api_latency)
+
+    return _calculate_numeric_stats(api_latency_values)

src/lightspeed_evaluation/core/storage/sql_storage.py

@@ -66,6 +66,7 @@ class EvaluationResultDB(Base):  # pylint: disable=too-few-public-methods
     judge_scores = Column(Text, nullable=True)
     time_to_first_token = Column(Float, nullable=True)
     streaming_duration = Column(Float, nullable=True)
+    api_latency = Column(Float, nullable=True)
     tokens_per_second = Column(Float, nullable=True)
     tool_calls = Column(Text, nullable=True)
     contexts = Column(Text, nullable=True)
@@ -326,6 +327,7 @@ def _result_to_db_record(self, result: EvaluationResult) -> EvaluationResultDB:
             judge_scores=self._serialize_judge_scores(result.judge_scores),
             time_to_first_token=result.time_to_first_token,
             streaming_duration=result.streaming_duration,
+            api_latency=result.api_latency,
             tokens_per_second=result.tokens_per_second,
             tool_calls=result.tool_calls,
             contexts=result.contexts,

src/lightspeed_evaluation/pipeline/evaluation/amender.py

@@ -1,6 +1,7 @@
 """API Data Amendment module - handles API data enrichment."""
 
 import logging
+import time
 from typing import Any, Optional
 
 from lightspeed_evaluation.core.api import APIClient
@@ -37,12 +38,15 @@ def amend_single_turn(
         logger.debug("Amending turn %s with API data", turn_data.turn_id)
 
         try:
+            # Track API call execution time
+            api_start_time = time.perf_counter()
             api_response = self.api_client.query(
                 query=turn_data.query,
                 conversation_id=conversation_id,
                 attachments=turn_data.attachments,
                 extra_request_params=turn_data.extra_request_params,
             )
+            api_latency = time.perf_counter() - api_start_time
 
             # AMEND EVALUATION DATA: This modifies the loaded TurnData object in-place
             # Update response from API
@@ -63,11 +67,15 @@ def amend_single_turn(
             # Update token usage from API output (with fallback to 0 if not present)
             turn_data.api_input_tokens = getattr(api_response, "input_tokens", 0)
             turn_data.api_output_tokens = getattr(api_response, "output_tokens", 0)
+
+            # Update API latency
+            turn_data.api_latency = api_latency
             logger.debug(
-                "Token usage for turn %s: input=%d, output=%d",
+                "Token usage for turn %s: input=%d, output=%d, API latency=%.3fs",
                 turn_data.turn_id,
                 turn_data.api_input_tokens,
                 turn_data.api_output_tokens,
+                api_latency,
             )
 
             # Update streaming performance metrics (only available for streaming endpoint)