feat: replace sync status in header with session ↑/↓ transfer stats

Snapshots Syncthing's total inBytesTotal/outBytesTotal at startup,
polls every 5s, and shows the session delta as:
  ↑ 1.2 MB  ↓ 3.4 MB

Replaces the "Up to Date" / "⠹ Syncing 73%" text which conveyed
redundant info already visible in the file list badges.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: gitcoder89431

internal/app/app.go

@@ -53,6 +53,8 @@ type Model struct {
 	lastActivityState syncthing.FolderState
 	activitySeeded    bool
 	currentSyncItem   string // file currently being transferred, shown in header
+	transferIn        int64  // session bytes received
+	transferOut       int64  // session bytes sent
 }
 
 func New(meta BuildInfo, client *syncthing.Client, syncthingURL string) Model {
@@ -95,6 +97,10 @@ func (m Model) Init() tea.Cmd {
 			}
 			return deviceIDMsg{id: dev.ID, name: dev.Name}
 		},
+		func() tea.Msg {
+			client.InitTransferStats()
+			return transferStatsMsg{}
+		},
 	}
 	for _, screen := range m.screens {
 		cmds = append(cmds, screen.Init())

internal/app/update.go

@@ -14,6 +14,8 @@ import (
 	"github.com/gitcoder89431/meshd/internal/theme"
 )
 
+type transferStatsMsg struct{ in, out int64 }
+
 func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	switch msg := msg.(type) {
 	case tea.WindowSizeMsg:
@@ -40,6 +42,14 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.deviceID = msg.id
 		m.deviceName = msg.name
 		return m, nil
+	case transferStatsMsg:
+		m.transferIn = msg.in
+		m.transferOut = msg.out
+		client := m.client
+		return m, tea.Tick(5*time.Second, func(time.Time) tea.Msg {
+			in, out, _ := client.GetTransferStats()
+			return transferStatsMsg{in: in, out: out}
+		})
 	case spinnerTickMsg:
 		m.spinnerFrame = (m.spinnerFrame + 1) % len(spinnerFrames)
 		if m.spinnerActive {

internal/app/view.go

@@ -23,7 +23,7 @@ func (m Model) View() tea.View {
 	dims := layout.Calculate(m.width, m.height, m.showSidebar)
 	active := m.screens[m.activeScreen]
 
-	head := clipHeight(header.View(header.Model{AppName: config.AppName, DeviceID: m.deviceID, DeviceName: m.deviceName, SyncStatus: m.syncStatus}, dims.Header.Width, dims.Header.Height, m.theme), dims.Header.Height)
+	head := clipHeight(header.View(header.Model{AppName: config.AppName, DeviceID: m.deviceID, DeviceName: m.deviceName, TransferIn: m.transferIn, TransferOut: m.transferOut}, dims.Header.Width, dims.Header.Height, m.theme), dims.Header.Height)
 
 	footBindings := m.keys.ShortHelp()
 	type footerBinder interface{ FooterBindings() []key.Binding }

internal/components/header/header.go

@@ -1,17 +1,19 @@
 package header
 
 import (
+	"fmt"
 	"strings"
 
 	"charm.land/lipgloss/v2"
 	"github.com/gitcoder89431/meshd/internal/theme"
 )
 
 type Model struct {
-	AppName    string
-	DeviceID   string // full device ID (fallback if no name)
-	DeviceName string // human-readable device name (preferred)
-	SyncStatus string // pre-rendered sync status shown on the right
+	AppName     string
+	DeviceID    string // full device ID (fallback if no name)
+	DeviceName  string // human-readable device name (preferred)
+	TransferIn  int64  // session bytes received
+	TransferOut int64  // session bytes sent
 }
 
 func View(m Model, width, height int, t theme.Theme) string {
@@ -30,9 +32,24 @@ func View(m Model, width, height int, t theme.Theme) string {
 	if label != "" {
 		left += t.Border.Render("  |  ") + t.Muted.Render(label)
 	}
-	right := m.SyncStatus
+	right := t.Muted.Render("↑ "+formatBytes(m.TransferOut)) +
+		t.Border.Render("  ") +
+		t.Muted.Render("↓ "+formatBytes(m.TransferIn))
 	rightW := lipgloss.Width(right)
 	gap := max(0, innerWidth-lipgloss.Width(left)-rightW)
 	content := left + lipgloss.NewStyle().Width(gap).Render("") + right
 	return t.Header.Width(width).Height(height).Render(content)
 }
+
+func formatBytes(b int64) string {
+	switch {
+	case b >= 1<<30:
+		return fmt.Sprintf("%.1f GB", float64(b)/(1<<30))
+	case b >= 1<<20:
+		return fmt.Sprintf("%.1f MB", float64(b)/(1<<20))
+	case b >= 1<<10:
+		return fmt.Sprintf("%.0f KB", float64(b)/(1<<10))
+	default:
+		return fmt.Sprintf("%d B", b)
+	}
+}

internal/syncthing/client.go

@@ -26,6 +26,8 @@ type Client struct {
 	longPollHTTP *http.Client // separate client for 60s long-polls (#8)
 	folderPath   string       // cached after first EnsureMeshdFolder (#14)
 	initEventID  int          // event ID at startup, used by GetRecentEvents (#10)
+	baselineIn   int64        // inBytesTotal at session start
+	baselineOut  int64        // outBytesTotal at session start
 }
 
 func New(baseURL, apiKey string) *Client {
@@ -583,6 +585,45 @@ func (c *Client) InitEventID() {
 	}
 }
 
+// InitTransferStats snapshots current connection totals so GetTransferStats
+// can return session-relative deltas.
+func (c *Client) InitTransferStats() {
+	in, out, err := c.connectionTotals()
+	if err == nil {
+		c.baselineIn = in
+		c.baselineOut = out
+	}
+}
+
+// GetTransferStats returns bytes received and sent since InitTransferStats was called.
+func (c *Client) GetTransferStats() (in, out int64, err error) {
+	curIn, curOut, err := c.connectionTotals()
+	if err != nil {
+		return 0, 0, err
+	}
+	return max64(0, curIn-c.baselineIn), max64(0, curOut-c.baselineOut), nil
+}
+
+func (c *Client) connectionTotals() (in, out int64, err error) {
+	var result struct {
+		Total struct {
+			InBytesTotal  int64 `json:"inBytesTotal"`
+			OutBytesTotal int64 `json:"outBytesTotal"`
+		} `json:"total"`
+	}
+	if err := c.get("/rest/system/connections", &result); err != nil {
+		return 0, 0, err
+	}
+	return result.Total.InBytesTotal, result.Total.OutBytesTotal, nil
+}
+
+func max64(a, b int64) int64 {
+	if a > b {
+		return a
+	}
+	return b
+}
+
 // GetRecentEvents returns Syncthing events since this session started. (#10)
 func (c *Client) GetRecentEvents(limit int) ([]SyncEvent, error) {
 	// use initEventID so we only see events from this session, not all history