diff --git a/Makefile b/Makefile
index a4dd7da..56ade1b 100644
--- a/Makefile
+++ b/Makefile
@@ -28,8 +28,8 @@ host: ## Build host binary -> host/tokenpulse
 host-test: ## Run host tests
 	cd host && go test ./...
 
-host-install: ## go install the host tool onto $GOBIN/$GOPATH/bin
-	cd host && go install .
+host-install: ## Install host binary -> $(go env GOPATH)/bin/tokenpulse
+	cd host && go build -o "$$(go env GOPATH)/bin/tokenpulse" .
 
 ## ---------------- firmware (ESP-IDF) ----------------
 
diff --git a/README.md b/README.md
index 67a221d..1ee1176 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,18 @@ go build -o tokenpulse .
 install tokenpulse /usr/local/bin/
 ```
 
-Register it as the Claude Code status-line command in `~/.claude/settings.json`:
+### Register the status line
+
+Easiest — let the tool do it (detects the serial port, wraps your existing
+status line as passthrough, backs up `settings.json` first):
+
+```bash
+tokenpulse setup          # prompts before writing; --yes to skip, --serial to override
+```
+
+`setup` is idempotent (re-running it when already configured does nothing).
+
+Or register it manually in `~/.claude/settings.json`:
 
 ```json
 { "statusLine": { "type": "command", "command": "tokenpulse statusline" } }
@@ -47,7 +58,7 @@ point it at whatever you ran before via `TOKENPULSE_INNER`.
 | Variable | Default | Purpose |
 |---|---|---|
 | `TOKENPULSE_INNER` | `bash ~/.claude/statusline-command.sh` | Your existing status-line command; its stdout is passed through verbatim. |
-| `TOKENPULSE_SERIAL` | autodetect `/dev/cu.usbmodem*` | Serial device of the board. |
+| `TOKENPULSE_SERIAL` | autodetect (prefers the TokenPulse board, else first `/dev/cu.usbmodem*`) | Serial device of the board. |
 | `TOKENPULSE_BAUD` | `115200` | Baud (nominal; irrelevant for USB-CDC). |
 
 The tool is fail-safe by design: if the board is unplugged, the serial write
diff --git a/host/main.go b/host/main.go
index 19f724a..f1dff22 100644
--- a/host/main.go
+++ b/host/main.go
@@ -28,6 +28,9 @@ func main() {
 		fmt.Println("tokenpulse " + version)
 		os.Exit(0)
 	}
+	if len(os.Args) >= 2 && os.Args[1] == "setup" {
+		os.Exit(runSetup(os.Args[2:], os.Stdin))
+	}
 	if len(os.Args) < 2 || os.Args[1] != "statusline" {
 		// 未知子命令:静默退出,绝不污染 stdout
 		os.Exit(0)
diff --git a/host/serial.go b/host/serial.go
index 5dd98f1..652b0a9 100644
--- a/host/serial.go
+++ b/host/serial.go
@@ -2,15 +2,27 @@ package main
 
 import (
 	"path/filepath"
+	"strings"
 
 	"go.bug.st/serial"
 )
 
+// tokenPulseSerialHint matches the macOS device node of our board, which is
+// named cu.usbmodem<serial> where the firmware's USB serial string is "TP_…".
+const tokenPulseSerialHint = "TP_"
+
 func autodetectSerial(glob func(string) ([]string, error)) string {
 	matches, err := glob("/dev/cu.usbmodem*")
 	if err != nil || len(matches) == 0 {
 		return ""
 	}
+	// Prefer the TokenPulse board if present, so a second usbmodem device
+	// (another board, or the ROM USB-JTAG port in download mode) isn't grabbed.
+	for _, m := range matches {
+		if strings.Contains(strings.ToUpper(m), tokenPulseSerialHint) {
+			return m
+		}
+	}
 	return matches[0]
 }
 
diff --git a/host/setup.go b/host/setup.go
new file mode 100644
index 0000000..ef76432
--- /dev/null
+++ b/host/setup.go
@@ -0,0 +1,182 @@
+package main
+
+import (
+	"bufio"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// defaultSettingsPath returns ~/.claude/settings.json.
+func defaultSettingsPath() string {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return ".claude/settings.json"
+	}
+	return filepath.Join(home, ".claude", "settings.json")
+}
+
+// shellSingleQuote wraps s in single quotes, safely escaping embedded quotes.
+func shellSingleQuote(s string) string {
+	return "'" + strings.ReplaceAll(s, "'", `'\''`) + "'"
+}
+
+// buildStatusLineCommand assembles the statusLine command string that registers
+// TokenPulse: it sets the serial port + wraps the user's existing status-line
+// command as the passthrough inner command, then runs `tokenpulse statusline`.
+// serialPath == "" omits the env var (host autodetects at runtime).
+// innerCmd == "" omits TOKENPULSE_INNER (host uses its built-in default).
+func buildStatusLineCommand(selfPath, serialPath, innerCmd string) string {
+	var b strings.Builder
+	if serialPath != "" {
+		b.WriteString("TOKENPULSE_SERIAL=")
+		b.WriteString(serialPath)
+		b.WriteString(" ")
+	}
+	if innerCmd != "" {
+		b.WriteString("TOKENPULSE_INNER=")
+		b.WriteString(shellSingleQuote(innerCmd))
+		b.WriteString(" ")
+	}
+	if strings.ContainsAny(selfPath, " \t'\"") {
+		b.WriteString(shellSingleQuote(selfPath))
+	} else {
+		b.WriteString(selfPath)
+	}
+	b.WriteString(" statusline")
+	return b.String()
+}
+
+// extractStatusLineCommand returns the current statusLine.command from a
+// settings.json blob ("" if there is no statusLine).
+func extractStatusLineCommand(settings []byte) (string, error) {
+	var top map[string]json.RawMessage
+	if err := json.Unmarshal(settings, &top); err != nil {
+		return "", err
+	}
+	raw, ok := top["statusLine"]
+	if !ok {
+		return "", nil
+	}
+	var sl struct {
+		Command string `json:"command"`
+	}
+	if err := json.Unmarshal(raw, &sl); err != nil {
+		return "", err
+	}
+	return sl.Command, nil
+}
+
+// setStatusLineCommand returns settings.json with statusLine replaced by a
+// command-type entry running newCmd. Other keys are preserved (semantically);
+// the file is re-emitted pretty-printed with top-level keys sorted, so exact
+// formatting/key-order changes but the configuration is identical.
+func setStatusLineCommand(settings []byte, newCmd string) ([]byte, error) {
+	var top map[string]json.RawMessage
+	if err := json.Unmarshal(settings, &top); err != nil {
+		return nil, err
+	}
+	sl, err := json.Marshal(map[string]string{"type": "command", "command": newCmd})
+	if err != nil {
+		return nil, err
+	}
+	top["statusLine"] = sl
+	out, err := json.MarshalIndent(top, "", "  ")
+	if err != nil {
+		return nil, err
+	}
+	return append(out, '\n'), nil
+}
+
+// isTokenPulseCommand reports whether a statusLine command already runs us.
+func isTokenPulseCommand(cmd string) bool {
+	return strings.Contains(cmd, "tokenpulse statusline")
+}
+
+// runSetup implements `tokenpulse setup`: register into ~/.claude/settings.json.
+func runSetup(args []string, stdin *os.File) int {
+	fs := flag.NewFlagSet("setup", flag.ContinueOnError)
+	yes := fs.Bool("yes", false, "apply without confirmation")
+	serial := fs.String("serial", "", "serial device (default: autodetect /dev/cu.usbmodem*)")
+	settingsPath := fs.String("settings", defaultSettingsPath(), "path to Claude Code settings.json")
+	if err := fs.Parse(args); err != nil {
+		return 2
+	}
+
+	self, err := os.Executable()
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "setup: cannot resolve own path:", err)
+		return 1
+	}
+
+	data, err := os.ReadFile(*settingsPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "setup: cannot read %s: %v\n", *settingsPath, err)
+		fmt.Fprintln(os.Stderr, "Run Claude Code once so it creates the file, or pass --settings.")
+		return 1
+	}
+
+	prev, err := extractStatusLineCommand(data)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "setup: %s is not valid JSON: %v\n", *settingsPath, err)
+		return 1
+	}
+	if isTokenPulseCommand(prev) {
+		fmt.Println("Already configured — statusLine already runs tokenpulse. Nothing to do.")
+		return 0
+	}
+
+	port := *serial
+	if port == "" {
+		port = autodetectSerial(globFiles)
+	}
+	if port == "" {
+		fmt.Fprintln(os.Stderr, "Note: no TokenPulse serial port found now; the tool will autodetect at runtime once the board is plugged in.")
+	}
+
+	newCmd := buildStatusLineCommand(self, port, prev)
+
+	fmt.Println("Will update statusLine in", *settingsPath)
+	if prev == "" {
+		fmt.Println("  current: (none)")
+	} else {
+		fmt.Println("  current:", prev)
+	}
+	fmt.Println("  new:    ", newCmd)
+	if prev != "" {
+		fmt.Println("(your existing status line is preserved as the passthrough inner command)")
+	}
+
+	if !*yes {
+		fmt.Print("Apply this change? [y/N] ")
+		r := bufio.NewReader(stdin)
+		line, _ := r.ReadString('\n')
+		switch strings.ToLower(strings.TrimSpace(line)) {
+		case "y", "yes":
+		default:
+			fmt.Println("Aborted.")
+			return 1
+		}
+	}
+
+	if err := os.WriteFile(*settingsPath+".bak", data, 0o644); err != nil {
+		fmt.Fprintln(os.Stderr, "setup: failed to write backup:", err)
+		return 1
+	}
+	out, err := setStatusLineCommand(data, newCmd)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "setup:", err)
+		return 1
+	}
+	if err := os.WriteFile(*settingsPath, out, 0o644); err != nil {
+		fmt.Fprintln(os.Stderr, "setup: failed to write settings:", err)
+		return 1
+	}
+
+	fmt.Printf("Done. Backup saved to %s.bak (top-level keys were re-sorted).\n", *settingsPath)
+	fmt.Println("Claude Code applies it on the next status-line refresh (or restart).")
+	return 0
+}
diff --git a/host/setup_test.go b/host/setup_test.go
new file mode 100644
index 0000000..00ca03e
--- /dev/null
+++ b/host/setup_test.go
@@ -0,0 +1,132 @@
+package main
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+func TestBuildStatusLineCommand_Full(t *testing.T) {
+	got := buildStatusLineCommand("/Users/x/go/bin/tokenpulse", "/dev/cu.usbmodemTP_00011", "bash /Users/x/.claude/statusline-command.sh")
+	want := "TOKENPULSE_SERIAL=/dev/cu.usbmodemTP_00011 TOKENPULSE_INNER='bash /Users/x/.claude/statusline-command.sh' /Users/x/go/bin/tokenpulse statusline"
+	if got != want {
+		t.Fatalf("got %q want %q", got, want)
+	}
+}
+
+func TestBuildStatusLineCommand_NoSerialNoInner(t *testing.T) {
+	got := buildStatusLineCommand("/usr/local/bin/tokenpulse", "", "")
+	want := "/usr/local/bin/tokenpulse statusline"
+	if got != want {
+		t.Fatalf("got %q want %q", got, want)
+	}
+}
+
+func TestShellSingleQuote_EscapesQuote(t *testing.T) {
+	got := buildStatusLineCommand("/bin/tp", "", `echo 'hi'`)
+	// inner with single quotes must be safely escaped
+	if !strings.Contains(got, `TOKENPULSE_INNER='echo '\''hi'\'''`) {
+		t.Fatalf("quote not escaped: %q", got)
+	}
+}
+
+func TestBuildStatusLineCommand_QuotesSelfPathWithSpaces(t *testing.T) {
+	got := buildStatusLineCommand("/Users/My Apps/tokenpulse", "", "")
+	want := "'/Users/My Apps/tokenpulse' statusline"
+	if got != want {
+		t.Fatalf("got %q want %q", got, want)
+	}
+}
+
+func TestExtractStatusLineCommand(t *testing.T) {
+	s := []byte(`{"foo":1,"statusLine":{"type":"command","command":"bash x.sh"}}`)
+	got, err := extractStatusLineCommand(s)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != "bash x.sh" {
+		t.Fatalf("got %q", got)
+	}
+}
+
+func TestExtractStatusLineCommand_None(t *testing.T) {
+	got, err := extractStatusLineCommand([]byte(`{"foo":1}`))
+	if err != nil || got != "" {
+		t.Fatalf("got %q err %v", got, err)
+	}
+}
+
+func TestSetStatusLineCommand_PreservesOtherKeys(t *testing.T) {
+	in := []byte(`{"permissions":{"allow":["Read"]},"statusLine":{"type":"command","command":"old"}}`)
+	out, err := setStatusLineCommand(in, "NEW statusline")
+	if err != nil {
+		t.Fatal(err)
+	}
+	// statusLine updated
+	cmd, _ := extractStatusLineCommand(out)
+	if cmd != "NEW statusline" {
+		t.Fatalf("command not updated: %q", cmd)
+	}
+	// other keys preserved (semantically; re-indentation is expected)
+	var top map[string]json.RawMessage
+	if err := json.Unmarshal(out, &top); err != nil {
+		t.Fatal(err)
+	}
+	if _, ok := top["permissions"]; !ok {
+		t.Fatal("permissions key lost")
+	}
+	var perms struct {
+		Allow []string `json:"allow"`
+	}
+	if err := json.Unmarshal(top["permissions"], &perms); err != nil {
+		t.Fatal(err)
+	}
+	if len(perms.Allow) != 1 || perms.Allow[0] != "Read" {
+		t.Fatalf("permissions value changed: %v", perms.Allow)
+	}
+}
+
+func TestSetStatusLineCommand_AddsWhenMissing(t *testing.T) {
+	out, err := setStatusLineCommand([]byte(`{"foo":1}`), "C statusline")
+	if err != nil {
+		t.Fatal(err)
+	}
+	cmd, _ := extractStatusLineCommand(out)
+	if cmd != "C statusline" {
+		t.Fatalf("got %q", cmd)
+	}
+}
+
+func TestIsTokenPulseCommand(t *testing.T) {
+	if !isTokenPulseCommand("TOKENPULSE_SERIAL=x /go/bin/tokenpulse statusline") {
+		t.Fatal("should detect existing tokenpulse command")
+	}
+	if isTokenPulseCommand("bash statusline-command.sh") {
+		t.Fatal("false positive")
+	}
+}
+
+func TestAutodetectSerial_PrefersTokenPulse(t *testing.T) {
+	glob := func(string) ([]string, error) {
+		return []string{"/dev/cu.usbmodem1101", "/dev/cu.usbmodemTP_00011"}, nil
+	}
+	if got := autodetectSerial(glob); got != "/dev/cu.usbmodemTP_00011" {
+		t.Fatalf("got %q, want TokenPulse device", got)
+	}
+}
+
+func TestAutodetectSerial_FallbackFirst(t *testing.T) {
+	glob := func(string) ([]string, error) {
+		return []string{"/dev/cu.usbmodemABC", "/dev/cu.usbmodemXYZ"}, nil
+	}
+	if got := autodetectSerial(glob); got != "/dev/cu.usbmodemABC" {
+		t.Fatalf("got %q, want first", got)
+	}
+}
+
+func TestAutodetectSerial_Empty(t *testing.T) {
+	glob := func(string) ([]string, error) { return nil, nil }
+	if got := autodetectSerial(glob); got != "" {
+		t.Fatalf("got %q, want empty", got)
+	}
+}