fix: ShowBrowser merge behavior and consistent browser defaults

- Change ShowBrowser from bool to *bool so nil means "don't override"
  in mergeOptions(), fixing the bug where it always overwrote the base
- Add Bool() helper for convenient *bool construction
- Align NewInteractiveBrowser default from Chromium to Firefox to match
  NewBrowser
- Update README example and CLI flags for the *bool change

Closes #15, #16

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -118,7 +118,7 @@ extractor.BrowserOptions{
     Browser:       extractor.BrowserFirefox, // or BrowserChromium, BrowserWebKit
     Timeout:       &timeout,                 // default 30s, 0 for no timeout
     CookieJar:     jar,                      // load/save cookies automatically
-    ShowBrowser:   true,                     // show browser window (non-headless)
+    ShowBrowser:   extractor.Bool(true),     // show browser window (non-headless)
     Dimensions:    extractor.Size{1280, 720},
     DarkMode:      true,
     ServerAddress: "ws://...",               // remote Playwright server

browser_init.go

@@ -70,8 +70,9 @@ func initBrowser(opt BrowserOptions) (*browserInitResult, error) {
 	}
 
 	if launch {
+		headless := opt.ShowBrowser == nil || !*opt.ShowBrowser
 		browser, err = bt.Launch(playwright.BrowserTypeLaunchOptions{
-			Headless: playwright.Bool(!opt.ShowBrowser),
+			Headless: playwright.Bool(headless),
 		})
 		if err != nil {
 			return nil, fmt.Errorf("failed to launch browser: %w", err)
@@ -154,7 +155,9 @@ func mergeOptions(base BrowserOptions, opts []BrowserOptions) BrowserOptions {
 		if o.UseLocalOnly {
 			base.UseLocalOnly = true
 		}
+		if o.ShowBrowser != nil {
 			base.ShowBrowser = o.ShowBrowser
 		}
+	}
 	return base
 }

cmd/browser/pkg/browser/flags.go

@@ -70,7 +70,9 @@ func FromCommand(ctx context.Context, cmd *cli.Command) (extractor.Browser, erro
 		opts.CookieJar = cookies
 	}
 
-	opts.ShowBrowser = cmd.Bool("visible")
+	if cmd.IsSet("visible") {
+		opts.ShowBrowser = extractor.Bool(cmd.Bool("visible"))
+	}
 
 	return extractor.NewBrowser(ctx, opts)
 }

interactive.go

@@ -60,7 +60,7 @@ func NewInteractiveBrowser(ctx context.Context, opts ...BrowserOptions) (Interac
 	var thirtySeconds = 30 * time.Second
 	opt := mergeOptions(BrowserOptions{
 		UserAgent: "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:142.0) Gecko/20100101 Firefox/142.0",
-		Browser:   BrowserChromium,
+		Browser:   BrowserFirefox,
 		Timeout:   &thirtySeconds,
 		Dimensions: Size{
 			Width:  1280,

playwright.go

@@ -36,6 +36,9 @@ const (
 	BrowserWebKit   BrowserSelection = "webkit"
 )
 
+// Bool returns a pointer to the given bool value.
+func Bool(v bool) *bool { return &v }
+
 type Size struct {
 	Width  int
 	Height int
@@ -49,7 +52,7 @@ type BrowserOptions struct {
 	// browser into the cookie jar for each request.
 	CookieJar
 
-	ShowBrowser bool // If false, browser will be headless
+	ShowBrowser *bool // If nil, defaults to false (headless). Set to ptr to override.
 
 	Dimensions Size
 	DarkMode   bool