tui: add fd trace drilldown and fd column in stream

6 files changed, 258 insertions, 11 deletions

diff --git a/internal/tui/eventstream/model.go b/internal/tui/eventstream/model.go
index fc423cb..8b162e5 100644
--- a/internal/tui/eventstream/model.go
+++ b/internal/tui/eventstream/model.go
@@ -24,11 +24,20 @@ type Model struct {
 	scrollOffset int
 	autoScroll   bool
 	selectedIdx  int
+	fdTraceView  fdTraceViewState
 
 	width  int
 	height int
 }
 
+type fdTraceViewState struct {
+	visible bool
+	pid     uint32
+	fd      int32
+	events  []StreamEvent
+	offset  int
+}
+
 func NewModel(source *RingBuffer) Model {
 	return Model{
 		source:      source,
@@ -79,8 +88,42 @@ func (m *Model) HandleKey(keyStr string) bool {
 		}
 		return true
 	}
+	if m.fdTraceView.visible {
+		switch keyStr {
+		case "j", "down":
+			m.scrollFDTraceByLines(1)
+			return true
+		case "k", "up":
+			m.scrollFDTraceByLines(-1)
+			return true
+		case "pgdown", "pgdn", "pagedown":
+			m.scrollFDTraceByLines(m.pageStep())
+			return true
+		case "pgup", "pageup":
+			m.scrollFDTraceByLines(-m.pageStep())
+			return true
+		case "g":
+			m.fdTraceView.offset = 0
+			return true
+		case "G":
+			m.fdTraceView.offset = m.maxFDTraceOffset()
+			return true
+		case "esc", "q":
+			m.fdTraceView.visible = false
+			m.fdTraceView.events = nil
+			m.fdTraceView.offset = 0
+			return true
+		default:
+			return false
+		}
+	}
 
 	switch keyStr {
+	case "enter":
+		if m.paused {
+			return m.openFDTraceView()
+		}
+		return false
 	case " ", "space":
 		m.paused = !m.paused
 		if !m.paused {
@@ -165,6 +208,10 @@ func (m *Model) HandleTeaKey(msg tea.KeyMsg) bool {
 		return m.HandleKey("pgdown")
 	case tea.KeySpace:
 		return m.HandleKey("space")
+	case tea.KeyEsc:
+		return m.HandleKey("esc")
+	case tea.KeyEnter:
+		return m.HandleKey("enter")
 	case tea.KeyRunes:
 		if len(msg.Runes) == 1 {
 			return m.HandleKey(string(msg.Runes[0]))
@@ -183,6 +230,10 @@ func (m *Model) View(width, height int) string {
 	m.width = width
 	m.height = height
 
+	if m.fdTraceView.visible {
+		return m.viewFDTrace(width)
+	}
+
 	rows := m.visibleRows()
 	start := clamp(m.scrollOffset, 0, m.maxScrollOffset())
 	end := start + rows
@@ -203,7 +254,7 @@ func (m *Model) View(width, height int) string {
 	base := RenderStreamTable(width, m.paused, len(m.allEvents), len(m.filtered), bufferLen, ringBufferCapacity, m.filter, visible, selectedVisibleIdx)
 	status := fmt.Sprintf("Row %d/%d | space:pause f:filter G:tail g:top c:clear j/k:scroll", rowNumber(start, len(m.filtered)), len(m.filtered))
 	if m.paused && m.selectedIdx >= 0 {
-		status = fmt.Sprintf("Row %d/%d | Sel %d/%d | space:pause f:filter G:tail g:top c:clear j/k:select", rowNumber(start, len(m.filtered)), len(m.filtered), rowNumber(m.selectedIdx, len(m.filtered)), len(m.filtered))
+		status = fmt.Sprintf("Row %d/%d | Sel %d/%d | enter:fd-trace space:pause f:filter G:tail g:top c:clear j/k:select", rowNumber(start, len(m.filtered)), len(m.filtered), rowNumber(m.selectedIdx, len(m.filtered)), len(m.filtered))
 	}
 	out := base + "\n" + status
 
@@ -307,6 +358,75 @@ func (m *Model) scrollByLines(delta int) {
 	}
 }
 
+func (m *Model) openFDTraceView() bool {
+	if m.fdTraceView.visible || m.selectedIdx < 0 || m.selectedIdx >= len(m.filtered) {
+		return false
+	}
+	selected := m.filtered[m.selectedIdx]
+	if selected.FD < 0 {
+		return false
+	}
+
+	snapshot := m.allEvents
+	if m.source != nil {
+		snapshot = m.source.Snapshot()
+	}
+
+	matches := make([]StreamEvent, 0, len(snapshot))
+	for i := range snapshot {
+		ev := snapshot[i]
+		if ev.PID == selected.PID && ev.FD == selected.FD {
+			matches = append(matches, ev)
+		}
+	}
+	if len(matches) == 0 {
+		return false
+	}
+
+	m.fdTraceView.visible = true
+	m.fdTraceView.pid = selected.PID
+	m.fdTraceView.fd = selected.FD
+	m.fdTraceView.events = matches
+	m.fdTraceView.offset = 0
+	return true
+}
+
+func (m *Model) viewFDTrace(width int) string {
+	rows := m.visibleRows()
+	start := clamp(m.fdTraceView.offset, 0, m.maxFDTraceOffset())
+	end := start + rows
+	if end > len(m.fdTraceView.events) {
+		end = len(m.fdTraceView.events)
+	}
+	visible := m.fdTraceView.events[start:end]
+	base := RenderFDTraceTable(width, m.fdTraceView.pid, m.fdTraceView.fd, len(m.fdTraceView.events), visible)
+	status := fmt.Sprintf("FD Trace Row %d/%d | esc:back j/k:scroll", rowNumber(start, len(m.fdTraceView.events)), len(m.fdTraceView.events))
+	return base + "\n" + status
+}
+
+func (m *Model) maxFDTraceOffset() int {
+	rows := m.visibleRows()
+	if len(m.fdTraceView.events) <= rows {
+		return 0
+	}
+	return len(m.fdTraceView.events) - rows
+}
+
+func (m *Model) scrollFDTraceByLines(delta int) {
+	if delta == 0 {
+		return
+	}
+	max := m.maxFDTraceOffset()
+	next := m.fdTraceView.offset + delta
+	if next < 0 {
+		next = 0
+	}
+	if next > max {
+		next = max
+	}
+	m.fdTraceView.offset = next
+}
+
 func (m *Model) moveSelectionBy(delta int) {
 	if len(m.filtered) == 0 {
 		m.selectedIdx = -1
diff --git a/internal/tui/eventstream/model_test.go b/internal/tui/eventstream/model_test.go
index ade1010..3dac038 100644
--- a/internal/tui/eventstream/model_test.go
+++ b/internal/tui/eventstream/model_test.go
@@ -1,6 +1,9 @@
 package eventstream
 
-import "testing"
+import (
+	"strings"
+	"testing"
+)
 
 func pushEvents(rb *RingBuffer, count int) {
 	for i := 0; i < count; i++ {
@@ -16,6 +19,7 @@ func pushEvents(rb *RingBuffer, count int) {
 			FileName:   "/tmp/file",
 			RetVal:     int64(i),
 			IsError:    i%3 == 0,
+			FD:         UnknownFD,
 		})
 	}
 }
@@ -368,3 +372,64 @@ func TestPausedSelectionMovesAndRecentersWithJKAndArrows(t *testing.T) {
 		t.Fatalf("expected centered viewport after up")
 	}
 }
+
+func TestPausedEnterOpensFDTraceViewScopedByPIDAndFD(t *testing.T) {
+	rb := NewRingBuffer()
+	rb.Push(StreamEvent{Seq: 1, PID: 10, TID: 101, FD: 3, Syscall: "read", FileName: "/a"})
+	rb.Push(StreamEvent{Seq: 2, PID: 10, TID: 102, FD: 3, Syscall: "write", FileName: "/a"}) // same pid/fd, different tid
+	rb.Push(StreamEvent{Seq: 3, PID: 10, TID: 103, FD: 4, Syscall: "read", FileName: "/b"})  // different fd
+	rb.Push(StreamEvent{Seq: 4, PID: 11, TID: 104, FD: 3, Syscall: "read", FileName: "/c"})  // different pid
+
+	m := NewModel(rb)
+	m.height = 20
+	m.Refresh()
+	if !m.HandleKey("space") {
+		t.Fatalf("space should pause")
+	}
+
+	// Pick the first row (pid=10, fd=3).
+	m.selectedIdx = 0
+	if !m.HandleKey("enter") {
+		t.Fatalf("enter should open fd trace view")
+	}
+	if !m.fdTraceView.visible {
+		t.Fatalf("expected fd trace view visible")
+	}
+	if m.fdTraceView.pid != 10 || m.fdTraceView.fd != 3 {
+		t.Fatalf("expected pid/fd 10/3, got %d/%d", m.fdTraceView.pid, m.fdTraceView.fd)
+	}
+	if len(m.fdTraceView.events) != 2 {
+		t.Fatalf("expected 2 matching events, got %d", len(m.fdTraceView.events))
+	}
+	for _, ev := range m.fdTraceView.events {
+		if ev.PID != 10 || ev.FD != 3 {
+			t.Fatalf("unexpected event in fd trace view: pid=%d fd=%d", ev.PID, ev.FD)
+		}
+	}
+}
+
+func TestFDTraceViewRendersAndClosesOnEsc(t *testing.T) {
+	rb := NewRingBuffer()
+	rb.Push(StreamEvent{Seq: 1, PID: 10, TID: 101, FD: 5, Syscall: "read", FileName: "/x"})
+	rb.Push(StreamEvent{Seq: 2, PID: 10, TID: 102, FD: 5, Syscall: "write", FileName: "/x"})
+	m := NewModel(rb)
+	m.height = 20
+	m.Refresh()
+	_ = m.HandleKey("space")
+	m.selectedIdx = 0
+	_ = m.HandleKey("enter")
+
+	view := m.View(120, 24)
+	if !strings.Contains(view, "FD Trace (ring snapshot)") {
+		t.Fatalf("expected fd trace header in view")
+	}
+	if !strings.Contains(view, "PID:10 FD:5 matched:2") {
+		t.Fatalf("expected pid/fd summary in fd trace view")
+	}
+	if !m.HandleKey("esc") {
+		t.Fatalf("esc should close fd trace view")
+	}
+	if m.fdTraceView.visible {
+		t.Fatalf("expected fd trace view closed")
+	}
+}
diff --git a/internal/tui/eventstream/render.go b/internal/tui/eventstream/render.go
index 92a70be..e9d44f1 100644
--- a/internal/tui/eventstream/render.go
+++ b/internal/tui/eventstream/render.go
@@ -15,6 +15,7 @@ type columnLayout struct {
 	comm    int
 	pidTid  int
 	syscall int
+	fd      int
 	ret     int
 	bytes   int
 	file    int
@@ -42,6 +43,23 @@ func RenderStreamTable(width int, paused bool, totalCount, filteredCount, buffer
 	return common.PanelStyle.Width(contentWidth).Render(strings.Join(lines, "\n"))
 }
 
+func RenderFDTraceTable(width int, pid uint32, fd int32, totalCount int, events []StreamEvent) string {
+	if width <= 0 {
+		width = 100
+	}
+	contentWidth := panelContentWidth(width)
+
+	lines := make([]string, 0, len(events)+3)
+	lines = append(lines, common.HeaderStyle.Render("FD Trace (ring snapshot)"))
+	lines = append(lines, fmt.Sprintf("PID:%d FD:%d matched:%d", pid, fd, totalCount))
+	lines = append(lines, renderColumnHeader(contentWidth))
+	for _, ev := range events {
+		lines = append(lines, renderEventRow(ev, contentWidth, false))
+	}
+
+	return common.PanelStyle.Width(contentWidth).Render(strings.Join(lines, "\n"))
+}
+
 func renderStatusLine(paused bool, totalCount, filteredCount, bufferLen, bufferCap int) string {
 	state := common.HighlightStyle.Render("LIVE")
 	if paused {
@@ -64,12 +82,13 @@ func renderFilterLine(filter Filter) string {
 
 func renderColumnHeader(width int) string {
 	cols := computeColumnLayout(width)
-	header := fmt.Sprintf("%-*s %-*s %-*s %-*s %-*s %-*s %-*s %s",
+	header := fmt.Sprintf("%-*s %-*s %-*s %-*s %-*s %-*s %-*s %-*s %s",
 		cols.gap, "Gap",
 		cols.latency, "Latency",
 		cols.comm, "Comm",
 		cols.pidTid, "PID.TID",
 		cols.syscall, "Syscall",
+		cols.fd, "FD",
 		cols.ret, "Ret",
 		cols.bytes, "Bytes",
 		"File",
@@ -80,12 +99,17 @@ func renderColumnHeader(width int) string {
 func renderEventRow(ev StreamEvent, width int, selected bool) string {
 	cols := computeColumnLayout(width)
 	pidTid := fmt.Sprintf("%d.%d", ev.PID, ev.TID)
-	row := fmt.Sprintf("%-*s %-*s %-*s %-*s %-*s %-*s %-*s %s",
+	fd := "-"
+	if ev.FD >= 0 {
+		fd = strconv.FormatInt(int64(ev.FD), 10)
+	}
+	row := fmt.Sprintf("%-*s %-*s %-*s %-*s %-*s %-*s %-*s %-*s %s",
 		cols.gap, fitCell(formatDurationNs(ev.GapNs), cols.gap),
 		cols.latency, fitCell(formatDurationNs(ev.DurationNs), cols.latency),
 		cols.comm, fitCell(ev.Comm, cols.comm),
 		cols.pidTid, fitCell(pidTid, cols.pidTid),
 		cols.syscall, fitCell(ev.Syscall, cols.syscall),
+		cols.fd, fitCell(fd, cols.fd),
 		cols.ret, fitCell(strconv.FormatInt(ev.RetVal, 10), cols.ret),
 		cols.bytes, fitCell(strconv.FormatUint(ev.Bytes, 10), cols.bytes),
 		fitCell(ev.FileName, cols.file),
@@ -110,9 +134,10 @@ func computeColumnLayout(width int) columnLayout {
 	comm := 10
 	pidTid := 10
 	syscall := 9
+	fd := 4
 	ret := 5
 	bytes := 8
-	fixed := gap + latency + comm + pidTid + syscall + ret + bytes + 7
+	fixed := gap + latency + comm + pidTid + syscall + fd + ret + bytes + 8
 	file := width - fixed
 	if file >= 28 {
 		// On wider terminals, give a little more room back to descriptive columns.
@@ -120,24 +145,25 @@ func computeColumnLayout(width int) columnLayout {
 			comm = 12
 			syscall = 11
 			pidTid = 11
-			fixed = gap + latency + comm + pidTid + syscall + ret + bytes + 7
+			fixed = gap + latency + comm + pidTid + syscall + fd + ret + bytes + 8
 			file = width - fixed
 		}
-		return columnLayout{gap: gap, latency: latency, comm: comm, pidTid: pidTid, syscall: syscall, ret: ret, bytes: bytes, file: file}
+		return columnLayout{gap: gap, latency: latency, comm: comm, pidTid: pidTid, syscall: syscall, fd: fd, ret: ret, bytes: bytes, file: file}
 	}
 
 	// Very narrow widths: compress further but keep file column readable.
 	comm = 8
 	pidTid = 9
 	syscall = 8
+	fd = 3
 	ret = 4
 	bytes = 7
-	fixed = gap + latency + comm + pidTid + syscall + ret + bytes + 7
+	fixed = gap + latency + comm + pidTid + syscall + fd + ret + bytes + 8
 	file = width - fixed
 	if file < 12 {
 		file = 12
 	}
-	return columnLayout{gap: gap, latency: latency, comm: comm, pidTid: pidTid, syscall: syscall, ret: ret, bytes: bytes, file: file}
+	return columnLayout{gap: gap, latency: latency, comm: comm, pidTid: pidTid, syscall: syscall, fd: fd, ret: ret, bytes: bytes, file: file}
 }
 
 func formatDurationNs(v uint64) string {
diff --git a/internal/tui/eventstream/render_test.go b/internal/tui/eventstream/render_test.go
index 8c2d39a..33e5b38 100644
--- a/internal/tui/eventstream/render_test.go
+++ b/internal/tui/eventstream/render_test.go
@@ -34,6 +34,14 @@ func TestRenderPausedAndErrorRow(t *testing.T) {
 	}
 }
 
+func TestRenderShowsFDWhenPresent(t *testing.T) {
+	events := []StreamEvent{{Syscall: "read", Comm: "worker", PID: 1, TID: 2, FD: 9, DurationNs: 10, GapNs: 1, Bytes: 8, FileName: "/tmp/b", RetVal: 8}}
+	out := RenderStreamTable(120, false, 1, 1, 1, 10000, Filter{}, events, -1)
+	if !strings.Contains(out, "FD") || !strings.Contains(out, " 9 ") {
+		t.Fatalf("expected FD column/value in output\n%s", out)
+	}
+}
+
 func TestRenderHeaderAndTruncate(t *testing.T) {
 	events := []StreamEvent{{
 		Syscall:    "very_long_syscall_name",
@@ -48,7 +56,7 @@ func TestRenderHeaderAndTruncate(t *testing.T) {
 	}}
 	out := RenderStreamTable(80, false, 1, 1, 1, 10000, Filter{}, events, -1)
 
-	for _, col := range []string{"Gap", "Latency", "Comm", "PID.TID", "Syscall", "Ret", "Bytes", "File"} {
+	for _, col := range []string{"Gap", "Latency", "Comm", "PID.TID", "Syscall", "FD", "Ret", "Bytes", "File"} {
 		if !strings.Contains(out, col) {
 			t.Fatalf("missing column %q\n%s", col, out)
 		}
@@ -98,7 +106,7 @@ func TestRenderEventRowIsSingleLineWithControlCharsAndLongValues(t *testing.T) {
 
 func TestComputeColumnLayoutGivesFileMoreSpace(t *testing.T) {
 	cols := computeColumnLayout(120)
-	if cols.file < 55 {
+	if cols.file < 50 {
 		t.Fatalf("expected file column to get most width, got %d", cols.file)
 	}
 }
@@ -124,3 +132,15 @@ func TestRenderStreamTableFitsRequestedWidth(t *testing.T) {
 		}
 	}
 }
+
+func TestRenderFDTraceTableShowsHeaderAndScope(t *testing.T) {
+	out := RenderFDTraceTable(100, 123, 7, 2, []StreamEvent{
+		{Syscall: "read", PID: 123, TID: 1, FD: 7, FileName: "/tmp/a"},
+		{Syscall: "write", PID: 123, TID: 2, FD: 7, FileName: "/tmp/a"},
+	})
+	for _, want := range []string{"FD Trace (ring snapshot)", "PID:123 FD:7 matched:2", "read", "write"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("output missing %q\n%s", want, out)
+		}
+	}
+}
diff --git a/internal/tui/eventstream/streamevent.go b/internal/tui/eventstream/streamevent.go
index 85ea217..9e89488 100644
--- a/internal/tui/eventstream/streamevent.go
+++ b/internal/tui/eventstream/streamevent.go
@@ -18,8 +18,11 @@ type StreamEvent struct {
 	Bytes      uint64
 	RetVal     int64
 	IsError    bool
+	FD         int32
 }
 
+const UnknownFD int32 = -1
+
 func NewStreamEvent(seq uint64, pair *event.Pair) StreamEvent {
 	e := StreamEvent{
 		Seq:        seq,
@@ -32,6 +35,10 @@ func NewStreamEvent(seq uint64, pair *event.Pair) StreamEvent {
 		DurationNs: pair.Duration,
 		GapNs:      pair.DurationToPrev,
 		Bytes:      pair.Bytes,
+		FD:         UnknownFD,
+	}
+	if fd, ok := pair.FileDescriptor(); ok {
+		e.FD = fd
 	}
 
 	if retEv, ok := pair.ExitEv.(*types.RetEvent); ok {
diff --git a/internal/tui/eventstream/streamevent_test.go b/internal/tui/eventstream/streamevent_test.go
index d053072..6be7407 100644
--- a/internal/tui/eventstream/streamevent_test.go
+++ b/internal/tui/eventstream/streamevent_test.go
@@ -41,6 +41,9 @@ func TestNewStreamEventPopulatesFields(t *testing.T) {
 	if got.DurationNs != 66 || got.GapNs != 19 || got.Bytes != 512 {
 		t.Fatalf("DurationNs/GapNs/Bytes = %d/%d/%d, want 66/19/512", got.DurationNs, got.GapNs, got.Bytes)
 	}
+	if got.FD != 7 {
+		t.Fatalf("FD = %d, want 7", got.FD)
+	}
 	if got.RetVal != -2 {
 		t.Fatalf("RetVal = %d, want -2", got.RetVal)
 	}
@@ -69,6 +72,9 @@ func TestNewStreamEventCopiesBeforeRecycle(t *testing.T) {
 	if got.RetVal != 8 || got.IsError {
 		t.Fatalf("RetVal/IsError = %d/%v, want 8/false", got.RetVal, got.IsError)
 	}
+	if got.FD != 3 {
+		t.Fatalf("FD = %d, want 3", got.FD)
+	}
 }
 
 func TestNewStreamEventWithoutRetEvent(t *testing.T) {
@@ -84,4 +90,7 @@ func TestNewStreamEventWithoutRetEvent(t *testing.T) {
 	if got.IsError {
 		t.Fatalf("IsError = true, want false")
 	}
+	if got.FD != UnknownFD {
+		t.Fatalf("FD = %d, want %d", got.FD, UnknownFD)
+	}
 }