fix: resolve golangci-lint issues and shrink README screenshots

Fix errcheck (os.Stdin.Read, term.Restore), prealloc (centerBlock),
revive (package comment, clear shadowing builtin), and formatting.
Reduce screenshot height to 160px so all three render side by side.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: retr0h

README.md

@@ -26,9 +26,9 @@ ____________   _____________________
 A terminal lock screen for macOS that uses **Touch ID** for biometric unlock with **macOS password** fallback. Drop it into tmux as your `lock-command` and walk away.
 
 <p align="center">
-  <a href="asset/screensaver.png"><img src="asset/screensaver.png" height="220" alt="Worm Screensaver"></a>
-  <a href="asset/passphrase.png"><img src="asset/passphrase.png" height="220" alt="Passphrase Prompt"></a>
-  <a href="asset/touchid.png"><img src="asset/touchid.png" height="220" alt="Touch ID Prompt"></a>
+  <a href="asset/screensaver.png"><img src="asset/screensaver.png" height="160" alt="Worm Screensaver"></a>
+  <a href="asset/passphrase.png"><img src="asset/passphrase.png" height="160" alt="Passphrase Prompt"></a>
+  <a href="asset/touchid.png"><img src="asset/touchid.png" height="160" alt="Touch ID Prompt"></a>
 </p>
 
 ## ✨ Features

main.go

@@ -1,3 +1,5 @@
+// Package main implements tlock, a terminal lock screen for macOS with
+// Touch ID and password authentication.
 package main
 
 /*
@@ -129,7 +131,7 @@ func centerText(text string, width int) string {
 
 func centerBlock(block string, width int) string {
 	lines := strings.Split(block, "\n")
-	var result []string
+	result := make([]string, 0, len(lines))
 	for _, line := range lines {
 		result = append(result, centerText(line, width))
 	}
@@ -387,10 +389,10 @@ const (
 )
 
 type gridCell struct {
-	state   int
-	wormIdx int
+	state    int
+	wormIdx  int
 	trailAge int
-	color   lipgloss.Color
+	color    lipgloss.Color
 }
 
 type worm struct {
@@ -399,8 +401,8 @@ type worm struct {
 	length   int     // current drawn length (grows from 0 to cap)
 	dir      int     // 0=up, 1=right, 2=down, 3=left
 	color    lipgloss.Color
-	turnCool int     // ticks before next turn allowed
-	minRun   int     // minimum straight cells before turning
+	turnCool int // ticks before next turn allowed
+	minRun   int // minimum straight cells before turning
 }
 
 // Retro phosphor CRT palette
@@ -421,8 +423,10 @@ var wormColors = []lipgloss.Color{
 }
 
 // Direction deltas: up, right, down, left (cardinal only, in grid coords)
-var dx = []int{0, 1, 0, -1}
-var dy = []int{-1, 0, 1, 0}
+var (
+	dx = []int{0, 1, 0, -1}
+	dy = []int{-1, 0, 1, 0}
+)
 
 // Trail fade stages
 var trailBlocks = []string{"\u2588", "\u2593", "\u2592", "\u2591"}
@@ -500,7 +504,10 @@ func runWormDemo(numWorms int) bool {
 	// Shuffle colors and assign — no two adjacent worms share a color
 	shuffled := make([]lipgloss.Color, len(wormColors))
 	copy(shuffled, wormColors)
-	rand.Shuffle(len(shuffled), func(a, b int) { shuffled[a], shuffled[b] = shuffled[b], shuffled[a] })
+	rand.Shuffle(
+		len(shuffled),
+		func(a, b int) { shuffled[a], shuffled[b] = shuffled[b], shuffled[a] },
+	)
 	assignedColors := make([]lipgloss.Color, numWorms)
 	colorIdx := 0
 	for j := range assignedColors {
@@ -525,7 +532,7 @@ func runWormDemo(numWorms int) bool {
 		for attempts := 0; attempts < 500; attempts++ {
 			sx = rand.Intn(gridW-4) + 2
 			sy = rand.Intn(gridH-4) + 2
-			clear := true
+			open := true
 			// Check the full body line + 1 cell padding around it
 			for j := -1; j <= bodyLen; j++ {
 				for pad := -1; pad <= 1; pad++ {
@@ -539,20 +546,20 @@ func runWormDemo(numWorms int) bool {
 					}
 					if cx < 0 || cx >= gridW || cy < 0 || cy >= gridH {
 						if j >= 0 && j < bodyLen {
-							clear = false
+							open = false
 						}
 						continue
 					}
 					if grid[cy][cx].state != cellEmpty {
-						clear = false
+						open = false
 						break
 					}
 				}
-				if !clear {
+				if !open {
 					break
 				}
 			}
-			if clear {
+			if open {
 				break
 			}
 		}
@@ -587,8 +594,9 @@ func runWormDemo(numWorms int) bool {
 	startKeyReader := func() {
 		go func() {
 			buf := make([]byte, 1)
-			os.Stdin.Read(buf)
-			keyCh <- buf[0]
+			if _, err := os.Stdin.Read(buf); err == nil {
+				keyCh <- buf[0]
+			}
 		}()
 	}
 	startKeyReader()
@@ -763,10 +771,18 @@ func runWormDemo(numWorms int) bool {
 }
 
 func main() {
-	snake := flag.Bool("snake", false, "Screensaver on immediately (shortcut for --screensaver --screensaver-delay 0)")
+	snake := flag.Bool(
+		"snake",
+		false,
+		"Screensaver on immediately (shortcut for --screensaver --screensaver-delay 0)",
+	)
 	snakeCount := flag.Int("snake-count", 0, "Number of worms (0 = auto based on terminal size)")
 	screensaver := flag.Bool("screensaver", false, "Enable xlock-style worm screensaver")
-	screensaverDelay := flag.Int("screensaver-delay", 30, "Seconds idle before screensaver starts (0 = immediate)")
+	screensaverDelay := flag.Int(
+		"screensaver-delay",
+		30,
+		"Seconds idle before screensaver starts (0 = immediate)",
+	)
 	flag.Parse()
 
 	fd := int(os.Stdin.Fd())
@@ -775,7 +791,7 @@ func main() {
 		fmt.Fprintf(os.Stderr, "failed to set raw mode: %v\n", err)
 		os.Exit(1)
 	}
-	defer term.Restore(fd, oldState)
+	defer func() { _ = term.Restore(fd, oldState) }()
 
 	hideCursor()
 	defer showCursor()