Fix Cloudflare headless detection: use non-headless with hidden window

Cloudflare detects headless Chrome and loops the JS challenge forever.
Switch to non-headless mode with an off-screen window. Also save
Cloudflare cookies (cf_clearance, __cf_bm) after Chrome fallback so
subsequent plain HTTP requests can reuse them.

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

internal/fetcher/fetcher.go

@@ -7,6 +7,9 @@ import (
 	"log"
 	"math"
 	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
 	"sync"
 	"time"
 
@@ -34,13 +37,21 @@ type ParsedUsage struct {
 type UpdateCallback func(ParsedUsage)
 
 // doRequest performs an authenticated HTTP GET to the Claude API.
+// Includes any saved Cloudflare cookies from previous Chrome fallbacks.
 func doRequest(url, sessionKey string) ([]byte, int, error) {
 	client := &http.Client{Timeout: 10 * time.Second}
 	req, err := http.NewRequest("GET", url, nil)
 	if err != nil {
 		return nil, 0, err
 	}
-	req.Header.Set("Cookie", "sessionKey="+sessionKey)
+
+	cookie := "sessionKey=" + sessionKey
+	// Append Cloudflare cookies if available (saved by Chrome fallback)
+	if cfCookies := loadCFCookies(); cfCookies != "" {
+		cookie += "; " + cfCookies
+	}
+
+	req.Header.Set("Cookie", cookie)
 	req.Header.Set("User-Agent", userAgent)
 	req.Header.Set("Accept", "application/json")
 	req.Header.Set("Referer", "https://claude.ai/")
@@ -58,6 +69,24 @@ func doRequest(url, sessionKey string) ([]byte, int, error) {
 	return body, resp.StatusCode, nil
 }
 
+// loadCFCookies reads saved Cloudflare cookies from the cf-cookies file.
+func loadCFCookies() string {
+	data, err := os.ReadFile(filepath.Join(config.ConfigDir(), "cf-cookies"))
+	if err != nil {
+		return ""
+	}
+	// File has one cookie per line (name=value), join with "; "
+	lines := strings.Split(strings.TrimSpace(string(data)), "\n")
+	var valid []string
+	for _, l := range lines {
+		l = strings.TrimSpace(l)
+		if l != "" {
+			valid = append(valid, l)
+		}
+	}
+	return strings.Join(valid, "; ")
+}
+
 // fetchWithFallback tries a plain HTTP request first, then falls back to
 // headless Chrome (which can solve Cloudflare JS challenges) on 403.
 func fetchWithFallback(url, sessionKey string) ([]byte, error) {