Fix scrollback-limit byte handling

Sources/AppDelegate.swift

@@ -7811,8 +7811,19 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
         guard let tabManager else { return }
         let tab = tabManager.addTab()
         let config = GhosttyConfig.load()
-        let lineCount = min(max(config.scrollbackLimit * 2, 2000), 60000)
-        let command = "for i in {1..\(lineCount)}; do printf \"scrollback %06d\\n\" $i; done\n"
+        let minimumTargetBytes = 2_000_000
+        let maximumTargetBytes = 200_000_000
+        let minimumLineCount = 2000
+        let effectiveLimit = max(config.scrollbackLimit, 0)
+        let doubledLimit = min(effectiveLimit, maximumTargetBytes / 2) * 2
+        let targetBytes = min(max(doubledLimit, minimumTargetBytes), maximumTargetBytes)
+        // `%06d` guarantees at least a 6-digit field width. Any lines beyond
+        // 999,999 only get wider, so this conservative floor always emits at
+        // least `targetBytes` without oscillating at digit-count boundaries.
+        let baseBytesPerLine = "scrollback 000000\n".utf8.count
+        let lineCount = max((targetBytes + baseBytesPerLine - 1) / baseBytesPerLine, minimumLineCount)
+
+        let command = #"awk 'BEGIN { for (i = 1; i <= \#(lineCount); ++i) printf "scrollback %06d\n", i }'"# + "\n"
         sendTextWhenReady(command, to: tab)
     }
 

Sources/GhosttyConfig.swift

@@ -16,7 +16,8 @@ struct GhosttyConfig {
     var surfaceTabBarFontSize: CGFloat = 11
     var theme: String?
     var workingDirectory: String?
-    var scrollbackLimit: Int = 10000
+    // Ghostty measures scrollback-limit in bytes, not lines.
+    var scrollbackLimit: Int = 10_000_000
     var unfocusedSplitOpacity: Double = 0.7
     var unfocusedSplitFill: NSColor?
     var splitDividerColor: NSColor?
@@ -252,7 +253,7 @@ struct GhosttyConfig {
                 case "working-directory":
                     workingDirectory = value
                 case "scrollback-limit":
-                    if let limit = Int(value) {
+                    if let limit = Self.parseIntegerLiteral(value) {
                         scrollbackLimit = limit
                     }
                 case "background":
@@ -316,6 +317,16 @@ struct GhosttyConfig {
         }
     }
 
+    private static func parseIntegerLiteral(_ value: String) -> Int? {
+        // Strip digit-group separators (for example 10_000_000).
+        // Hex and float literals are intentionally unsupported here.
+        let normalized = value.replacingOccurrences(of: "_", with: "")
+        guard let parsed = Int(normalized), parsed >= 0 else {
+            return nil
+        }
+        return parsed
+    }
+
     mutating func loadTheme(_ name: String) {
         loadTheme(
             name,

web/app/[locale]/docs/configuration/page.tsx

@@ -247,7 +247,7 @@ touch ~/.config/ghostty/config`}</CodeBlock>
       <CodeBlock title="~/.config/ghostty/config" lang="ini">{`font-family = SF Mono
 font-size = 13
 theme = One Dark
-scrollback-limit = 50000
+scrollback-limit = 50000000
 split-divider-color = #3e4451
 working-directory = ~/code`}</CodeBlock>