1 files changed, 113 insertions, 0 deletions
diff --git a/internal/statsengine/snapshot.go b/internal/statsengine/snapshot.go
new file mode 100644
index 0000000..3534731
--- /dev/null
+++ b/internal/statsengine/snapshot.go
@@ -0,0 +1,113 @@
+package statsengine
+
+import (
+	"ior/internal/types"
+	"time"
+)
+
+// TrendDirection is the direction of a time-window comparison.
+type TrendDirection string
+
+const (
+	// TrendStable indicates no meaningful movement between windows.
+	TrendStable TrendDirection = "stable"
+	// TrendRising indicates the most recent window is higher than the previous one.
+	TrendRising TrendDirection = "rising"
+	// TrendFalling indicates the most recent window is lower than the previous one.
+	TrendFalling TrendDirection = "falling"
+)
+
+// Trend describes movement between two equivalent time windows.
+type Trend struct {
+	Direction    TrendDirection
+	DeltaPercent float64
+}
+
+// Snapshot is an immutable point-in-time view of all aggregated statistics.
+type Snapshot struct {
+	GeneratedAt time.Time
+	Elapsed     time.Duration
+
+	TotalSyscalls uint64
+	TotalErrors   uint64
+	TotalBytes    uint64
+
+	SyscallRatePerSec float64
+	ErrorRatePerSec   float64
+	ReadBytesPerSec   float64
+	WriteBytesPerSec  float64
+
+	LatencyMeanNs float64
+	GapMeanNs     float64
+
+	LatencyTrend    Trend
+	GapTrend        Trend
+	ThroughputTrend Trend
+
+	LatencySeriesNs   []float64
+	GapSeriesNs       []float64
+	ThroughputSeriesB []float64
+
+	Syscalls  []SyscallSnapshot
+	Files     []FileSnapshot
+	Processes []ProcessSnapshot
+
+	LatencyHistogram HistogramSnapshot
+	GapHistogram     HistogramSnapshot
+}
+
+// SyscallSnapshot is the per-syscall view used by the syscall table.
+type SyscallSnapshot struct {
+	TraceID types.TraceId
+	Name    string
+
+	Count      uint64
+	RatePerSec float64
+	Errors     uint64
+	Bytes      uint64
+
+	LatencyMinNs  uint64
+	LatencyMaxNs  uint64
+	LatencyMeanNs float64
+	LatencyP50Ns  uint64
+	LatencyP95Ns  uint64
+	LatencyP99Ns  uint64
+}
+
+// FileSnapshot is an aggregated per-file ranking entry.
+type FileSnapshot struct {
+	Path string
+
+	Accesses     uint64
+	BytesRead    uint64
+	BytesWritten uint64
+
+	AvgLatencyNs float64
+	MaxLatencyNs uint64
+}
+
+// ProcessSnapshot is an aggregated per-process entry.
+type ProcessSnapshot struct {
+	PID  uint32
+	Comm string
+
+	Syscalls   uint64
+	RatePerSec float64
+	Bytes      uint64
+
+	AvgLatencyNs float64
+}
+
+// HistogramBucketSnapshot is one bucket of a histogram snapshot.
+type HistogramBucketSnapshot struct {
+	Label   string
+	LowerNs uint64
+	UpperNs uint64
+	Count   uint64
+}
+
+// HistogramSnapshot is an immutable histogram view at snapshot time.
+type HistogramSnapshot struct {
+	Total   uint64
+	Buckets []HistogramBucketSnapshot
+}