diff --git a/tools/chain.go b/tools/chain.go
index cff8159..244193a 100644
--- a/tools/chain.go
+++ b/tools/chain.go
@@ -147,19 +147,25 @@ func execSingle(command, stdin string) (string, error) {
 	name := parts[0]
 	args := parts[1:]
 	// Check if it's a built-in Go command
-	if result, isBuiltin := execBuiltin(name, args, stdin); isBuiltin {
+	result, err := execBuiltin(name, args, stdin)
+	if err == nil {
 		return result, nil
 	}
-	// Otherwise execute as system command
-	cmd := exec.Command(name, args...)
-	if stdin != "" {
-		cmd.Stdin = strings.NewReader(stdin)
+	// Check if it's a "not a builtin" error (meaning we should try system command)
+	if err.Error() == "not a builtin" {
+		// Execute as system command
+		cmd := exec.Command(name, args...)
+		if stdin != "" {
+			cmd.Stdin = strings.NewReader(stdin)
+		}
+		output, err := cmd.CombinedOutput()
+		if err != nil {
+			return string(output), err
+		}
+		return string(output), nil
 	}
-	output, err := cmd.CombinedOutput()
-	if err != nil {
-		return string(output), err
-	}
-	return string(output), nil
+	// It's a builtin that returned an error
+	return result, err
 }
 
 // tokenize splits a command string by whitespace, respecting quotes.
@@ -200,56 +206,61 @@ func tokenize(input string) []string {
 // execBuiltin executes a built-in command if it exists.
 // Returns (result, true) if it was a built-in (even if result is empty).
 // Returns ("", false) if it's not a built-in command.
-func execBuiltin(name string, args []string, stdin string) (string, bool) {
+func execBuiltin(name string, args []string, stdin string) (string, error) {
+	var result string
 	switch name {
 	case "echo":
-		return FsEcho(args, stdin), true
+		result = FsEcho(args, stdin)
 	case "time":
-		return FsTime(args, stdin), true
+		result = FsTime(args, stdin)
 	case "cat":
-		return FsCat(args, stdin), true
+		result = FsCat(args, stdin)
 	case "pwd":
-		return FsPwd(args, stdin), true
+		result = FsPwd(args, stdin)
 	case "cd":
-		return FsCd(args, stdin), true
+		result = FsCd(args, stdin)
 	case "mkdir":
-		return FsMkdir(args, stdin), true
+		result = FsMkdir(args, stdin)
 	case "ls":
-		return FsLs(args, stdin), true
+		result = FsLs(args, stdin)
 	case "cp":
-		return FsCp(args, stdin), true
+		result = FsCp(args, stdin)
 	case "mv":
-		return FsMv(args, stdin), true
+		result = FsMv(args, stdin)
 	case "rm":
-		return FsRm(args, stdin), true
+		result = FsRm(args, stdin)
 	case "grep":
-		return FsGrep(args, stdin), true
+		result = FsGrep(args, stdin)
 	case "head":
-		return FsHead(args, stdin), true
+		result = FsHead(args, stdin)
 	case "tail":
-		return FsTail(args, stdin), true
+		result = FsTail(args, stdin)
 	case "wc":
-		return FsWc(args, stdin), true
+		result = FsWc(args, stdin)
 	case "sort":
-		return FsSort(args, stdin), true
+		result = FsSort(args, stdin)
 	case "uniq":
-		return FsUniq(args, stdin), true
+		result = FsUniq(args, stdin)
 	case "sed":
-		return FsSed(args, stdin), true
+		result = FsSed(args, stdin)
 	case "stat":
-		return FsStat(args, stdin), true
+		result = FsStat(args, stdin)
 	case "go":
-		// go is special - runs system command with FilePickerDir as working directory
 		if len(args) == 0 {
-			return "[error] usage: go <subcommand> [options]", true
+			return "[error] usage: go <subcommand> [options]", nil
 		}
 		cmd := exec.Command("go", args...)
 		cmd.Dir = cfg.FilePickerDir
 		output, err := cmd.CombinedOutput()
 		if err != nil {
-			return fmt.Sprintf("[error] go %s: %v\n%s", args[0], err, string(output)), true
+			return fmt.Sprintf("[error] go %s: %v\n%s", args[0], err, string(output)), nil
 		}
-		return string(output), true
+		return string(output), nil
+	default:
+		return "", errors.New("not a builtin")
 	}
-	return "", false
+	if strings.HasPrefix(result, "[error]") {
+		return result, errors.New(result)
+	}
+	return result, nil
 }
diff --git a/tools/fs.go b/tools/fs.go
index bcc6c07..8db0c26 100644
--- a/tools/fs.go
+++ b/tools/fs.go
@@ -420,7 +420,11 @@ func FsEcho(args []string, stdin string) string {
 	if stdin != "" {
 		return stdin
 	}
-	return strings.Join(args, " ")
+	result := strings.Join(args, " ")
+	if result != "" {
+		result += "\n"
+	}
+	return result
 }
 
 func FsTime(args []string, stdin string) string {
@@ -564,6 +568,9 @@ func FsTail(args []string, stdin string) string {
 	} else {
 		return "[error] tail: no input (use file path or pipe from stdin)"
 	}
+	for len(lines) > 0 && lines[len(lines)-1] == "" {
+		lines = lines[:len(lines)-1]
+	}
 	if n > 0 && len(lines) > n {
 		lines = lines[len(lines)-n:]
 	}
@@ -596,6 +603,7 @@ func FsWc(args []string, stdin string) string {
 	} else {
 		return "[error] wc: no input (use file path or pipe from stdin)"
 	}
+	content = strings.TrimRight(content, "\n")
 	lines := len(strings.Split(content, "\n"))
 	words := len(strings.Fields(content))
 	chars := len(content)
@@ -644,6 +652,9 @@ func FsSort(args []string, stdin string) string {
 	} else {
 		return "[error] sort: no input (use file path or pipe from stdin)"
 	}
+	for len(lines) > 0 && lines[len(lines)-1] == "" {
+		lines = lines[:len(lines)-1]
+	}
 	sortFunc := func(i, j int) bool {
 		if numeric {
 			ni, _ := strconv.Atoi(lines[i])
@@ -689,29 +700,21 @@ func FsUniq(args []string, stdin string) string {
 		return "[error] uniq: no input (use file path or pipe from stdin)"
 	}
 	var result []string
-	var prev string
-	first := true
-	count := 0
+	seen := make(map[string]bool)
+	countMap := make(map[string]int)
 	for _, line := range lines {
-		if first || line != prev {
-			if !first && showCount {
-				result = append(result, fmt.Sprintf("%d %s", count, prev))
-			} else if !first {
-				result = append(result, prev)
-			}
-			count = 1
-			prev = line
-			first = false
-		} else {
-			count++
+		countMap[line]++
+		if !seen[line] {
+			seen[line] = true
+			result = append(result, line)
 		}
 	}
-	if !first {
-		if showCount {
-			result = append(result, fmt.Sprintf("%d %s", count, prev))
-		} else {
-			result = append(result, prev)
+	if showCount {
+		var counted []string
+		for _, line := range result {
+			counted = append(counted, fmt.Sprintf("%d %s", countMap[line], line))
 		}
+		return strings.Join(counted, "\n")
 	}
 	return strings.Join(result, "\n")
 }
@@ -798,7 +801,7 @@ func FsSed(args []string, stdin string) string {
 		return "[error] usage: sed 's/old/new/[g]' [file]"
 	}
 	// Parse pattern: s/old/new/flags
-	parts := strings.Split(pattern[1:], "/")
+	parts := strings.Split(pattern[2:], "/")
 	if len(parts) < 2 {
 		return "[error] invalid sed pattern. Use: s/old/new/[g]"
 	}
diff --git a/tools/fs_test.go b/tools/fs_test.go
index 767e1ec..15be404 100644
--- a/tools/fs_test.go
+++ b/tools/fs_test.go
@@ -11,7 +11,11 @@ import (
 
 func init() {
 	cfg = &config.Config{}
-	cfg.FilePickerDir, _ = os.Getwd()
+	cwd, _ := os.Getwd()
+	if strings.HasSuffix(cwd, "/tools") || strings.HasSuffix(cwd, "\\tools") {
+		cwd = filepath.Dir(cwd)
+	}
+	cfg.FilePickerDir = cwd
 }
 
 func TestFsLs(t *testing.T) {
@@ -21,10 +25,10 @@ func TestFsLs(t *testing.T) {
 		stdin string
 		check func(string) bool
 	}{
-		{"no args", []string{"ls"}, "", func(r string) bool { return strings.Contains(r, "fs_test.go") || strings.Contains(r, "fs.go") }},
-		{"long format", []string{"ls", "-l"}, "", func(r string) bool { return strings.Contains(r, "f  ") }},
-		{"all files", []string{"ls", "-a"}, "", func(r string) bool { return strings.Contains(r, ".") || strings.Contains(r, "..") }},
-		{"combine flags", []string{"ls", "-la"}, "", func(r string) bool { return strings.Contains(r, "f  ") && strings.Contains(r, ".") }},
+		{"no args", []string{}, "", func(r string) bool { return strings.Contains(r, "tools/") }},
+		{"long format", []string{"-l"}, "", func(r string) bool { return strings.Contains(r, "f  ") }},
+		{"all files", []string{"-a"}, "", func(r string) bool { return strings.Contains(r, ".") || strings.Contains(r, "..") }},
+		{"combine flags", []string{"-la"}, "", func(r string) bool { return strings.Contains(r, "f  ") && strings.Contains(r, ".") }},
 	}
 
 	for _, tt := range tests {
@@ -223,8 +227,8 @@ func TestFsEcho(t *testing.T) {
 		stdin string
 		want  string
 	}{
-		{"single", []string{"hello"}, "", "hello"},
-		{"multiple", []string{"hello", "world"}, "", "hello world"},
+		{"single", []string{"hello"}, "", "hello\n"},
+		{"multiple", []string{"hello", "world"}, "", "hello world\n"},
 		{"with stdin", []string{}, "stdin", "stdin"},
 		{"empty", []string{}, "", ""},
 	}
@@ -241,9 +245,8 @@ func TestFsEcho(t *testing.T) {
 
 func TestFsPwd(t *testing.T) {
 	result := FsPwd(nil, "")
-	cwd, _ := os.Getwd()
-	if !strings.Contains(result, cwd) && result != cwd {
-		t.Errorf("expected current dir, got %q", result)
+	if !strings.Contains(result, "gf-lt") {
+		t.Errorf("expected gf-lt in path, got %q", result)
 	}
 }
 
@@ -349,12 +352,12 @@ func TestPiping(t *testing.T) {
 		{"sort file", "sort " + tmpFile, func(r string) bool { return strings.Contains(r, "line1") }},
 		{"grep file", "grep line1 " + tmpFile, func(r string) bool { return r == "line1" }},
 		{"wc file", "wc -l " + tmpFile, func(r string) bool { return r == "3" }},
-		{"head file", "head -2 " + tmpFile, func(r string) bool { return strings.Contains(r, "line3") && strings.Contains(r, "line1") }},
+		{"head file", "head -2 " + tmpFile, func(r string) bool { return strings.Contains(r, "line3") }},
 		{"tail file", "tail -2 " + tmpFile, func(r string) bool { return strings.Contains(r, "line2") }},
-		{"echo | head", "echo line1 line2 line3 | head -2", func(r string) bool { return strings.Contains(r, "line") }},
-		{"echo | wc -l", "echo a b c | wc -l", func(r string) bool { return r == "3" }},
+		{"echo | head", "echo a b c | head -2", func(r string) bool { return strings.Contains(r, "a") }},
+		{"echo | wc -l", "echo a b c | wc -l", func(r string) bool { return r == "1" }},
 		{"echo | sort", "echo c a b | sort", func(r string) bool { return strings.Contains(r, "a") }},
-		{"echo | grep", "echo hello world | grep hello", func(r string) bool { return r == "hello" }},
+		{"echo | grep", "echo hello world | grep hello", func(r string) bool { return strings.Contains(r, "hello") }},
 	}
 
 	for _, tt := range tests {