Fix diff pane corruption from binary file content

Binary files like .DS_Store were being read with os.ReadFile and
rendered directly into the diff viewport. The raw bytes contained
null bytes and control characters that corrupted the terminal's
rendering state, causing the display to jumble on scroll.

Add isBinary() detection (null-byte check in first 8KB, same
heuristic git uses) and show "Binary file: <path>" instead.

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

Author: cwsaylor

CHANGELOG.md

@@ -5,6 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.9.0] - 2026-03-22
+
+### Fixed
+
+- Fix diff pane corruption caused by binary file content (e.g., .DS_Store) being rendered directly to the terminal
+- Detect binary files using null-byte heuristic (same approach as git) and display "Binary file" message instead of raw content
+
 ## [0.8.1] - 2026-03-19
 
 ### Fixed

git.go

@@ -89,6 +89,21 @@ func isGitRepository(path string) bool {
 	return err == nil
 }
 
+// isBinary reports whether content appears to be binary by checking
+// for null bytes in the first 8KB (same heuristic git uses).
+func isBinary(data []byte) bool {
+	n := len(data)
+	if n > 8192 {
+		n = 8192
+	}
+	for i := 0; i < n; i++ {
+		if data[i] == 0 {
+			return true
+		}
+	}
+	return false
+}
+
 func getFileDiff(repoPath, filePath string) (string, error) {
 	// First try working directory changes
 	cmd := exec.Command("git", "diff", "HEAD", "--", filePath)
@@ -113,6 +128,9 @@ func getFileDiff(repoPath, filePath string) (string, error) {
 				if strings.HasPrefix(cleanPath, filepath.Clean(repoPath)+string(filepath.Separator)) {
 					content, contentErr := os.ReadFile(cleanPath)
 					if contentErr == nil {
+						if isBinary(content) {
+							return fmt.Sprintf("Binary file: %s", filePath), nil
+						}
 						return fmt.Sprintf("New file: %s\n\n%s", filePath, string(content)), nil
 					}
 				}
@@ -123,6 +141,9 @@ func getFileDiff(repoPath, filePath string) (string, error) {
 	if err != nil {
 		return "", err
 	}
+	if isBinary(output) {
+		return fmt.Sprintf("Binary file: %s", filePath), nil
+	}
 	return string(output), nil
 }
 

main.go

@@ -21,7 +21,7 @@ import (
 )
 
 // Version is set via ldflags at build time
-var Version = "0.8.1"
+var Version = "0.9.0"
 
 
 type focusedPane int