chore: remove unnecessary comments

The trace_summary MV stores max(timestamp) as 'end', which is the maximum
span *start* time. For the final span of a trace, this misses the span's
duration entirely, making EndTimestampMillis shorter than the actual trace end.

FlamegraphTrace already computed the correct end via updateTimeRange
(end = max(span_start + duration)) but only used it internally for bucket
sampling. Add TimeRange() to expose these span-derived bounds and use them
in both getFullFlamegraph and getWindowedFlamegraph instead of summary.End.

The waterfall was unaffected — NewWaterfallTraceFromSpans already computes
endTime = max(span.TimeUnix + span.DurationNano) from actual spans.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GxTqz7CqqmoFEPHFqhJUCa

pkg/modules/tracedetail/impltracedetail/module.go

@@ -182,7 +182,8 @@ func (m *module) getFullFlamegraph(ctx context.Context, traceID string, summary
 		return nil, spantypes.ErrTraceNotFound
 	}
 	flamegraphTrace := spantypes.NewFlamegraphTraceFromStorable(fullSpans, selectFields)
-	return spantypes.NewGettableFlamegraphTrace(flamegraphTrace.GetAllLevels(), summary.Start, summary.End, false), nil
+	start, end := flamegraphTrace.TimeRange()
+	return spantypes.NewGettableFlamegraphTrace(flamegraphTrace.GetAllLevels(), start, end, false), nil
 }
 
 // getWindowedFlamegraph returns a window of a max levels and max sampled spans per level around the selected span.
@@ -198,6 +199,8 @@ func (m *module) getWindowedFlamegraph(ctx context.Context, traceID, selectedSpa
 	flamegraphTrace := spantypes.NewFlamegraphTraceFromMinimal(minimalSpans)
 	minimalSpans = nil //nolint:ineffassign,wastedassign // release backing array before further db calls
 
+	start, end := flamegraphTrace.TimeRange()
+
 	cfg := m.config.Flamegraph
 	selectedSpans := flamegraphTrace.GetSelectedLevels(selectedSpanID, cfg.MaxSelectedLevels, cfg.MaxSpansPerLevel, cfg.SamplingTopLatencySpansCount, cfg.SamplingBucketCount)
 	if len(selectedSpans) == 0 {
@@ -210,5 +213,5 @@ func (m *module) getWindowedFlamegraph(ctx context.Context, traceID, selectedSpa
 	}
 
 	enrichedSpans := flamegraphTrace.EnrichSelectedSpans(selectedSpans, fullSpans, selectFields)
-	return spantypes.NewGettableFlamegraphTrace(enrichedSpans, summary.Start, summary.End, true), nil
+	return spantypes.NewGettableFlamegraphTrace(enrichedSpans, start, end, true), nil
 }

pkg/types/spantypes/flamegraph_trace.go

@@ -2,6 +2,7 @@ package spantypes
 
 import (
 	"sort"
+	"time"
 
 	"github.com/SigNoz/signoz/pkg/types/telemetrytypes"
 )
@@ -121,6 +122,11 @@ func (t *FlamegraphTrace) updateTimeRange(timestamp, durationNano uint64) {
 	}
 }
 
+// TimeRange returns the actual trace start and end computed from span timestamps.
+func (t *FlamegraphTrace) TimeRange() (start, end time.Time) {
+	return time.Unix(0, int64(t.startTime)), time.Unix(0, int64(t.endTime))
+}
+
 func (t *FlamegraphTrace) buildSpanTree() {
 	for _, node := range t.nodeByID {
 		if node.ParentSpanID != "" {

pkg/types/spantypes/flamegraph_trace_test.go

@@ -126,6 +126,55 @@ func TestGetAllLevels(t *testing.T) {
 	}
 }
 
+// ─────────────────────────────────────────────────────────────────────────────
+// TimeRange
+// ─────────────────────────────────────────────────────────────────────────────
+
+func TestTimeRange(t *testing.T) {
+	tests := []struct {
+		name      string
+		spans     []MinimalSpan
+		wantStart uint64 // nanoseconds since epoch
+		wantEnd   uint64 // nanoseconds since epoch (max of span_start + span_duration)
+	}{
+		{
+			// Single span: end must include duration, not just start.
+			name:      "single_span_end_includes_duration",
+			spans:     []MinimalSpan{mkMinimal("a", "", 1_000_000_000, 500_000_000)},
+			wantStart: 1_000_000_000,
+			wantEnd:   1_500_000_000,
+		},
+		{
+			// Two spans: end is the max of (start+duration) across all spans, not max(start).
+			name: "end_from_longest_span_not_latest_start",
+			spans: []MinimalSpan{
+				mkMinimal("a", "", 1_000_000_000, 1_000_000_000), // ends at 2_000_000_000
+				mkMinimal("b", "", 1_800_000_000, 100_000_000),   // ends at 1_900_000_000; starts later but ends sooner
+			},
+			wantStart: 1_000_000_000,
+			wantEnd:   2_000_000_000, // must NOT be 1_900_000_000 (max start + its duration)
+		},
+		{
+			// Missing parent: synthetic span must not influence TimeRange beyond its children.
+			name: "missing_parent_does_not_skew_range",
+			spans: []MinimalSpan{
+				mkMinimal("child", "ghost", 1_000_000_000, 200_000_000),
+			},
+			wantStart: 1_000_000_000,
+			wantEnd:   1_200_000_000,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			trace := NewFlamegraphTraceFromMinimal(tc.spans)
+			start, end := trace.TimeRange()
+			assert.Equal(t, tc.wantStart, uint64(start.UnixNano()), "start mismatch")
+			assert.Equal(t, tc.wantEnd, uint64(end.UnixNano()), "end mismatch")
+		})
+	}
+}
+
 // ─────────────────────────────────────────────────────────────────────────────
 // GetSelectedLevels
 // ─────────────────────────────────────────────────────────────────────────────