fix(profile): handle empty profiles and fix percentage calculation

- Make shared.profiles optional in schema (may be absent when no data)
- Handle null values for sample_durations_ns and sample_counts
- Fix hot path percentage calculation to use total self time

Author: BYK

src/lib/profile/analyzer.ts

@@ -60,14 +60,13 @@ export function hasProfileData(flamegraph: Flamegraph): boolean {
 }
 
 /**
- * Get the total weight (time) across all samples.
+ * Get the total self time across all frames.
+ * This gives the total CPU time spent in all functions.
  */
-function getTotalWeight(flamegraph: Flamegraph): number {
+function getTotalSelfTime(flamegraph: Flamegraph): number {
   let total = 0;
-  for (const profile of flamegraph.profiles) {
-    for (const weight of profile.weights) {
-      total += weight;
-    }
+  for (const info of flamegraph.shared.frame_infos) {
+    total += info.sumSelfTime;
   }
   return total;
 }
@@ -87,9 +86,9 @@ export function analyzeHotPaths(
   userCodeOnly: boolean
 ): HotPath[] {
   const { frames, frame_infos } = flamegraph.shared;
-  const totalWeight = getTotalWeight(flamegraph);
+  const totalSelfTime = getTotalSelfTime(flamegraph);
 
-  if (totalWeight === 0 || frames.length === 0) {
+  if (totalSelfTime === 0 || frames.length === 0) {
     return [];
   }
 
@@ -125,7 +124,7 @@ export function analyzeHotPaths(
   return topFrames.map(({ frame, info }) => ({
     frames: [frame], // Single frame for now (could expand to full call stack)
     frameInfo: info,
-    percentage: (info.sumSelfTime / totalWeight) * 100,
+    percentage: (info.sumSelfTime / totalSelfTime) * 100,
   }));
 }
 

src/types/profile.ts

@@ -102,9 +102,9 @@ export const FlamegraphProfileSchema = z
     /** Time weights for each sample */
     weights: z.array(z.number()),
     /** Sample durations in nanoseconds */
-    sample_durations_ns: z.array(z.number()).optional(),
+    sample_durations_ns: z.array(z.number()).nullish(),
     /** Sample counts */
-    sample_counts: z.array(z.number()).optional(),
+    sample_counts: z.array(z.number()).nullish(),
   })
   .passthrough();
 
@@ -132,8 +132,8 @@ export const FlamegraphSchema = z
       frames: z.array(FlamegraphFrameSchema),
       /** Statistics for each frame (parallel array to frames) */
       frame_infos: z.array(FlamegraphFrameInfoSchema),
-      /** Profile metadata */
-      profiles: z.array(FlamegraphProfileMetadataSchema),
+      /** Profile metadata (may be absent when no profiles exist) */
+      profiles: z.array(FlamegraphProfileMetadataSchema).optional(),
     }),
     /** Transaction name this flamegraph represents */
     transactionName: z.string().optional(),