perf(ui): improve large-file ingestion and scrolling stability

Author: RajeshkannanRamakrishnan

internal/ui/model.go

@@ -133,7 +133,16 @@ type Model struct {
 func InitialModel(filename string, lines []string, reader io.Reader) Model {
 	var streamer *Streamer
 	if reader != nil {
-		streamer = NewStreamer(reader)
+		cfg := StreamerConfig{
+			BatchLines: 200,
+			FlushEvery: 50 * time.Millisecond,
+		}
+		// File startup backfill should favor throughput over ultra-low latency.
+		if filename != "Stdin" {
+			cfg.BatchLines = 5000
+			cfg.FlushEvery = 100 * time.Millisecond
+		}
+		streamer = NewStreamerWithConfig(reader, cfg)
 	}
 
 	ti := textinput.New()
@@ -215,10 +224,7 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			// Handle error?
 		} else if msg.NewContent != "" {
 			// Append new content
-			newLines := strings.Split(msg.NewContent, "\n")
-			// Handle edge case where last line was incomplete?
-			// For simplicity, just append. Ideally we handle partial lines.
-
+			newLines := splitIncomingContent(msg.NewContent)
 			m.appendIncomingLines(newLines)
 
 			m.fileSize = msg.NewOffset
@@ -708,6 +714,15 @@ func (m *Model) appendIncomingLines(newLines []string) {
 	m.applyFilters(false)
 }
 
+func splitIncomingContent(content string) []string {
+	lines := strings.Split(content, "\n")
+	// File appends usually end with '\n', which creates a trailing empty element.
+	if len(lines) > 0 && lines[len(lines)-1] == "" {
+		lines = lines[:len(lines)-1]
+	}
+	return lines
+}
+
 func (m *Model) applyFilters(resetView bool) {
 	var filtered []string
 	// Directly iterate over originalLines

internal/ui/stream.go

@@ -8,6 +8,11 @@ import (
 	tea "github.com/charmbracelet/bubbletea"
 )
 
+const (
+	defaultStreamBatchLines = 1000
+	defaultStreamFlushEvery = 50 * time.Millisecond
+)
+
 // LogChunkMsg can carry a chunk of raw string or a slice of lines.
 // For efficient TUI updates, sending a batch of lines is preferred.
 type LogChunkMsg struct {
@@ -21,7 +26,26 @@ type Streamer struct {
 	err   chan error
 }
 
+type StreamerConfig struct {
+	BatchLines int
+	FlushEvery time.Duration
+}
+
 func NewStreamer(r io.Reader) *Streamer {
+	return NewStreamerWithConfig(r, StreamerConfig{
+		BatchLines: defaultStreamBatchLines,
+		FlushEvery: defaultStreamFlushEvery,
+	})
+}
+
+func NewStreamerWithConfig(r io.Reader, cfg StreamerConfig) *Streamer {
+	if cfg.BatchLines <= 0 {
+		cfg.BatchLines = defaultStreamBatchLines
+	}
+	if cfg.FlushEvery <= 0 {
+		cfg.FlushEvery = defaultStreamFlushEvery
+	}
+
 	s := &Streamer{
 		lines: make(chan []string),
 		err:   make(chan error),
@@ -38,7 +62,7 @@ func NewStreamer(r io.Reader) *Streamer {
 			batch = append(batch, scanner.Text())
 
 			// Flush if batch is big enough or time passed
-			if len(batch) >= 100 || time.Since(lastSend) > 50*time.Millisecond {
+			if len(batch) >= cfg.BatchLines || time.Since(lastSend) > cfg.FlushEvery {
 				s.lines <- batch
 				batch = nil // Reset
 				lastSend = time.Now()