fix: tab characters breaking the layout

internal/runner/runner.go

@@ -12,6 +12,15 @@ import (
 	"sync"
 )
 
+// sanitizeLine removes control sequences that can corrupt terminal rendering
+func sanitizeLine(s string) string {
+	// Remove carriage returns
+	s = strings.ReplaceAll(s, "\r", "")
+	// Convert tabs to spaces (tabs cause width calculation issues)
+	s = strings.ReplaceAll(s, "\t", "        ")
+	return s
+}
+
 // Line represents a single line of output with its line number
 type Line struct {
 	Number  int
@@ -141,7 +150,7 @@ func (r *Runner) Run(ctx context.Context) (Result, error) {
 	for scanner.Scan() {
 		lines = append(lines, Line{
 			Number:  lineNum,
-			Content: scanner.Text(),
+			Content: sanitizeLine(scanner.Text()),
 		})
 		lineNum++
 	}
@@ -151,7 +160,7 @@ func (r *Runner) Run(ctx context.Context) (Result, error) {
 	for stderrScanner.Scan() {
 		lines = append(lines, Line{
 			Number:  lineNum,
-			Content: stderrScanner.Text(),
+			Content: sanitizeLine(stderrScanner.Text()),
 		})
 		lineNum++
 	}
@@ -265,7 +274,7 @@ func (r *Runner) RunStreaming(ctx context.Context) *StreamingResult {
 				result.mu.Lock()
 				*result.Lines = append(*result.Lines, Line{
 					Number:  currentLineNum,
-					Content: scanner.Text(),
+					Content: sanitizeLine(scanner.Text()),
 				})
 				result.mu.Unlock()
 			}

internal/runner/runner_test.go

@@ -320,3 +320,61 @@ func TestSplitLines(t *testing.T) {
 		})
 	}
 }
+
+func TestSanitizeLine(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  string
+	}{
+		{
+			name:  "plain text unchanged",
+			input: "hello world",
+			want:  "hello world",
+		},
+		{
+			name:  "tabs converted to spaces",
+			input: "col1\tcol2\tcol3",
+			want:  "col1        col2        col3",
+		},
+		{
+			name:  "carriage returns removed",
+			input: "line with\r\nwindows ending",
+			want:  "line with\nwindows ending",
+		},
+		{
+			name:  "carriage return only removed",
+			input: "progress\roverwrite",
+			want:  "progressoverwrite",
+		},
+		{
+			name:  "ANSI color codes preserved",
+			input: "\x1b[32mgreen text\x1b[0m",
+			want:  "\x1b[32mgreen text\x1b[0m",
+		},
+		{
+			name:  "mixed tabs and colors",
+			input: "\x1b[1m?\x1b[0m\tpackage\t[no test files]",
+			want:  "\x1b[1m?\x1b[0m        package        [no test files]",
+		},
+		{
+			name:  "empty string",
+			input: "",
+			want:  "",
+		},
+		{
+			name:  "multiple tabs",
+			input: "\t\t\t",
+			want:  "                        ",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := sanitizeLine(tt.input)
+			if got != tt.want {
+				t.Errorf("sanitizeLine(%q) = %q, want %q", tt.input, got, tt.want)
+			}
+		})
+	}
+}