fix(aci): Translate percent threshold value correctly for metric monitors

[malwilley]

Fixes ISWF-2278

Metric monitors with percent change thresholds were translating the value incorrectly. 110 should display as 10% higher, not 110% higher.

See this for an example: https://sentry.sentry.io/monitors/2809101/

Before:

After:

[linear-code]

ISWF-2278 Metric monitors with percent change thresholds use wrong values

[saponifi3d]

lgtm - there might be a few nits / refactor things we might be able to decompose, but none of it really feels related to this work.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

There are 2 total unresolved issues (including 1 from previous review).

Autofix Details

Bugbot Autofix prepared a fix for the issue found in the latest run.

• ✅ Fixed: Preview chart shows wrong threshold for percent detectors
  • Added isConditionsInDeltaFormat parameter to skip the absolute-to-delta conversion when conditions are already in delta format from the form.

Or push these changes by commenting:

@cursor push 50dfe91189

Preview (50dfe91189)

diff --git a/static/app/views/detectors/components/forms/metric/metricDetectorChart.tsx b/static/app/views/detectors/components/forms/metric/metricDetectorChart.tsx
--- a/static/app/views/detectors/components/forms/metric/metricDetectorChart.tsx
+++ b/static/app/views/detectors/components/forms/metric/metricDetectorChart.tsx
@@ -209,6 +209,7 @@
       conditions,
       detectionType,
       comparisonSeries,
+      isConditionsInDeltaFormat: true,
     });
 
   const isAnomalyDetection = detectionType === 'dynamic';

diff --git a/static/app/views/detectors/hooks/useMetricDetectorThresholdSeries.tsx b/static/app/views/detectors/hooks/useMetricDetectorThresholdSeries.tsx
--- a/static/app/views/detectors/hooks/useMetricDetectorThresholdSeries.tsx
+++ b/static/app/views/detectors/hooks/useMetricDetectorThresholdSeries.tsx
@@ -106,7 +106,8 @@
 function extractThresholdsFromConditions(
   conditions: Array<Omit<MetricCondition, 'id'>>,
   aggregate: string,
-  detectionType: MetricDetectorConfig['detectionType']
+  detectionType: MetricDetectorConfig['detectionType'],
+  isConditionsInDeltaFormat: boolean
 ): {
   thresholds: Array<{
     priority: DetectorPriorityLevel;
@@ -123,7 +124,7 @@
     )
     .map(condition => {
       let value = normalizePercentageThreshold(aggregate, Number(condition.comparison));
-      if (detectionType === 'percent') {
+      if (detectionType === 'percent' && !isConditionsInDeltaFormat) {
         value = percentThresholdAbsoluteToDelta(value);
       }
       return {
@@ -143,7 +144,7 @@
       ? {
           type: resolutionCondition.type,
           value:
-            detectionType === 'percent'
+            detectionType === 'percent' && !isConditionsInDeltaFormat
               ? percentThresholdAbsoluteToDelta(
                   normalizePercentageThreshold(
                     aggregate,
@@ -168,6 +169,11 @@
   conditions: Array<Omit<MetricCondition, 'id'>> | undefined;
   detectionType: MetricDetectorConfig['detectionType'];
   comparisonSeries?: Series[];
+  /**
+   * When true, conditions are already in user-facing delta format (e.g., 10 for "10% higher").
+   * When false (default), conditions are in backend absolute format (e.g., 110) and need conversion.
+   */
+  isConditionsInDeltaFormat?: boolean;
 }
 
 interface UseMetricDetectorThresholdSeriesResult {
@@ -186,6 +192,7 @@
   detectionType,
   aggregate,
   comparisonSeries = [],
+  isConditionsInDeltaFormat = false,
 }: UseMetricDetectorThresholdSeriesProps): UseMetricDetectorThresholdSeriesResult {
   const theme = useTheme();
 
@@ -197,7 +204,8 @@
     const {thresholds, resolution} = extractThresholdsFromConditions(
       conditions,
       aggregate,
-      detectionType
+      detectionType,
+      isConditionsInDeltaFormat
     );
     const additional: LineSeriesOption[] = [];
 
@@ -315,5 +323,5 @@
 
     // Other detection types not supported yet
     return {maxValue: undefined, additionalSeries: additional};
-  }, [aggregate, conditions, detectionType, comparisonSeries, theme]);
+  }, [aggregate, conditions, detectionType, comparisonSeries, isConditionsInDeltaFormat, theme]);
 }

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

There are 2 total unresolved issues (including 1 from previous review).

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