task 363: animate flamegraph data refresh transitions

3 files changed, 111 insertions, 14 deletions

diff --git a/internal/tui/flamegraph/animation.go b/internal/tui/flamegraph/animation.go
index 900231d..de3635d 100644
--- a/internal/tui/flamegraph/animation.go
+++ b/internal/tui/flamegraph/animation.go
@@ -117,6 +117,11 @@ func (a AnimationState) CurrentFrames() []tuiFrame {
 	return frames
 }
 
+// Settled reports whether all active springs are at rest.
+func (a AnimationState) Settled() bool {
+	return a.settled
+}
+
 func isSpringSettled(s frameSpring) bool {
 	return math.Abs(s.currentW-s.targetW) < springEpsilon &&
 		math.Abs(s.currentCol-s.targetCol) < springEpsilon &&
diff --git a/internal/tui/flamegraph/model.go b/internal/tui/flamegraph/model.go
index 11475b8..c1693b1 100644
--- a/internal/tui/flamegraph/model.go
+++ b/internal/tui/flamegraph/model.go
@@ -7,6 +7,7 @@ import (
 	coreflamegraph "ior/internal/flamegraph"
 	common "ior/internal/tui/common"
 	"sort"
+	"time"
 
 	"charm.land/bubbles/v2/key"
 	"charm.land/bubbles/v2/textinput"
@@ -20,6 +21,10 @@ type snapshotNode struct {
 	Children []*snapshotNode `json:"c,omitempty"`
 }
 
+type animTickMsg struct{}
+
+const animFrameDuration = 33 * time.Millisecond
+
 type zoomState struct {
 	path                string
 	previousSelectedIdx int
@@ -74,10 +79,11 @@ type Model struct {
 	fieldPresets [][]string
 	fieldIndex   int
 
-	springs []frameSpring
-	paused  bool
-	isDark  bool
-	keys    flameKeyMap
+	animation AnimationState
+	animating bool
+	paused    bool
+	isDark    bool
+	keys      flameKeyMap
 }
 
 // tuiFrame stores one terminal flamegraph frame cell.
@@ -112,8 +118,9 @@ func NewModel(liveTrie *coreflamegraph.LiveTrie) Model {
 			{"tracepoint", "comm", "path"},
 			{"pid", "path", "tracepoint"},
 		},
-		isDark: true,
-		keys:   defaultFlameKeyMap(),
+		isDark:    true,
+		keys:      defaultFlameKeyMap(),
+		animation: NewAnimationState(30, 6.0, 1.0),
 	}
 }
 
@@ -125,6 +132,18 @@ func (m Model) Init() tea.Cmd {
 // Update handles incoming messages.
 func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	switch msg := msg.(type) {
+	case animTickMsg:
+		if !m.animating {
+			return m, nil
+		}
+		m.animating = m.animation.Tick(0)
+		m.frames = m.animation.CurrentFrames()
+		m.clampSelection()
+		m.subtreeSet = computeSubtreeSet(m.frames, m.selectedIdx)
+		if m.animating {
+			return m, animTickCmd()
+		}
+		return m, nil
 	case tea.KeyPressMsg:
 		if m.searchActive {
 			switch msg.String() {
@@ -209,6 +228,8 @@ func (m *Model) SetLiveTrie(liveTrie *coreflamegraph.LiveTrie) {
 	m.zoomRoot = nil
 	m.zoomPath = ""
 	m.subtreeSet = make(map[int]bool)
+	m.animation = NewAnimationState(30, 6.0, 1.0)
+	m.animating = false
 }
 
 // RefreshFromLiveTrie loads a new snapshot when the source version changes.
@@ -235,7 +256,7 @@ func (m *Model) RefreshFromLiveTrie() bool {
 	} else {
 		m.zoomRoot = nil
 	}
-	m.rebuildFrames()
+	m.rebuildFrames(true)
 	m.lastVersion = version
 	return true
 }
@@ -245,6 +266,14 @@ func (m Model) LastVersion() uint64 {
 	return m.lastVersion
 }
 
+// AnimationCmd returns a frame animation tick command when animation is active.
+func (m Model) AnimationCmd() tea.Cmd {
+	if !m.animating {
+		return nil
+	}
+	return animTickCmd()
+}
+
 // Paused reports whether live refresh is paused.
 func (m Model) Paused() bool {
 	return m.paused
@@ -254,7 +283,7 @@ func (m Model) Paused() bool {
 func (m *Model) SetViewport(width, height int) {
 	m.width = width
 	m.height = height
-	m.rebuildFrames()
+	m.rebuildFrames(false)
 }
 
 // SetDarkMode sets the active color theme mode.
@@ -263,7 +292,7 @@ func (m *Model) SetDarkMode(isDark bool) {
 	m.searchInput.SetStyles(textinput.DefaultStyles(isDark))
 }
 
-func (m *Model) rebuildFrames() {
+func (m *Model) rebuildFrames(animate bool) {
 	var root *snapshotNode
 	rootPath := ""
 	if m.zoomRoot != nil {
@@ -273,7 +302,14 @@ func (m *Model) rebuildFrames() {
 		root = m.snapshot
 	}
 	m.targetFrames = buildTerminalLayoutWithPath(root, m.width, m.height, rootPath)
-	m.frames = append(m.frames[:0], m.targetFrames...)
+	m.animation.SetTargets(m.targetFrames)
+	if animate && len(m.frames) > 0 && !m.animation.Settled() {
+		m.animating = true
+		m.frames = m.animation.CurrentFrames()
+	} else {
+		m.animating = false
+		m.frames = append(m.frames[:0], m.targetFrames...)
+	}
 	m.clampSelection()
 	m.subtreeSet = computeSubtreeSet(m.frames, m.selectedIdx)
 }
@@ -295,7 +331,7 @@ func (m *Model) zoomIn() {
 	m.zoomRoot = target
 	m.zoomPath = selectedPath
 	m.selectedIdx = 0
-	m.rebuildFrames()
+	m.rebuildFrames(false)
 }
 
 func (m *Model) zoomUndo() {
@@ -311,7 +347,7 @@ func (m *Model) zoomUndo() {
 		m.zoomRoot = findNodeByPath(m.snapshot, m.zoomPath)
 	}
 	m.selectedIdx = last.previousSelectedIdx
-	m.rebuildFrames()
+	m.rebuildFrames(false)
 }
 
 func (m *Model) zoomReset() {
@@ -321,7 +357,7 @@ func (m *Model) zoomReset() {
 	m.zoomRoot = nil
 	m.zoomPath = ""
 	m.zoomStack = nil
-	m.rebuildFrames()
+	m.rebuildFrames(false)
 }
 
 func (m *Model) moveVertical(delta int) {
@@ -415,3 +451,7 @@ func abs(v int) int {
 	}
 	return v
 }
+
+func animTickCmd() tea.Cmd {
+	return tea.Tick(animFrameDuration, func(time.Time) tea.Msg { return animTickMsg{} })
+}
diff --git a/internal/tui/flamegraph/model_test.go b/internal/tui/flamegraph/model_test.go
index 5271dee..45e0c48 100644
--- a/internal/tui/flamegraph/model_test.go
+++ b/internal/tui/flamegraph/model_test.go
@@ -275,6 +275,58 @@ func TestControlHelpToggle(t *testing.T) {
 	}
 }
 
+func TestDataRefreshAnimationConvergesOverTicks(t *testing.T) {
+	m := NewModel(nil)
+	m.width = 120
+	m.height = 20
+	m.snapshot = &snapshotNode{
+		Name:  "root",
+		Total: 100,
+		Children: []*snapshotNode{
+			{Name: "A", Total: 60},
+			{Name: "B", Total: 40},
+		},
+	}
+	m.rebuildFrames(false)
+	initial := append([]tuiFrame(nil), m.frames...)
+
+	m.snapshot = &snapshotNode{
+		Name:  "root",
+		Total: 100,
+		Children: []*snapshotNode{
+			{Name: "A", Total: 20},
+			{Name: "B", Total: 80},
+		},
+	}
+	m.rebuildFrames(true)
+	if !m.animating {
+		t.Fatalf("expected animation to start after animated rebuild")
+	}
+
+	next, _ := m.Update(animTickMsg{})
+	m = next.(Model)
+	if len(m.frames) != len(initial) {
+		t.Fatalf("expected frame count to remain stable during animation")
+	}
+
+	for i := 0; i < 180 && m.animating; i++ {
+		next, _ = m.Update(animTickMsg{})
+		m = next.(Model)
+	}
+	if m.animating {
+		t.Fatalf("expected animation to settle within 180 ticks")
+	}
+	if len(m.frames) != len(m.targetFrames) {
+		t.Fatalf("expected settled frame count to match targets")
+	}
+	for i := range m.frames {
+		if m.frames[i].Width != m.targetFrames[i].Width || m.frames[i].Col != m.targetFrames[i].Col {
+			t.Fatalf("frame %d did not converge to target: got col=%d width=%d want col=%d width=%d",
+				i, m.frames[i].Col, m.frames[i].Width, m.targetFrames[i].Col, m.targetFrames[i].Width)
+		}
+	}
+}
+
 func newZoomModel() Model {
 	m := NewModel(nil)
 	m.width = 120
@@ -294,7 +346,7 @@ func newZoomModel() Model {
 			{Name: "B", Total: 40},
 		},
 	}
-	m.rebuildFrames()
+	m.rebuildFrames(false)
 	return m
 }