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>

CHANGELOG.md

@@ -4,6 +4,15 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/), and this project adheres to [Semantic Versioning](https://semver.org/).
 
+## [0.5.0] — 2026-03-21
+
+### Fixed
+- **Cloudflare 403 bypass** — API requests blocked by Cloudflare JS challenges now fall back to headless Chrome with the persistent browser profile, which can solve the challenges natively
+
+### Added
+- `internal/browser/fetch.go` — headless Chrome API fetcher using chromedp with the existing browser profile (reuses Cloudflare clearance cookies)
+- `fetchWithFallback()` in fetcher — tries plain HTTP first, falls back to headless Chrome on 403
+
 ## [0.3.0] — 2026-02-26
 
 Full rewrite from Node.js + Python to Go. Each platform gets a single static binary — no runtime dependencies.
@@ -44,5 +53,6 @@ First tagged release. Includes the CLI statusline, standalone usage fetcher, cro
 - Tray icon visibility — switched to Claude orange with full opacity at larger size
 - Block comment syntax error in cron example
 
+[0.5.0]: https://git.davoryn.de/calic/claude-statusline/releases/tag/v0.5.0
 [0.3.0]: https://git.davoryn.de/calic/claude-statusline/releases/tag/v0.3.0
 [0.2.0]: https://git.davoryn.de/calic/claude-statusline/releases/tag/v0.2.0

internal/browser/fetch.go

@@ -0,0 +1,122 @@
+package browser
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/chromedp/cdproto/network"
+	"github.com/chromedp/chromedp"
+
+	"git.davoryn.de/calic/claude-statusline/internal/config"
+)
+
+// FetchViaChrome navigates to a URL using Chrome with the persistent browser
+// profile (which has Cloudflare clearance cookies) and returns the response
+// body. Uses non-headless mode with a minimized/hidden window to avoid
+// Cloudflare's headless detection, which causes infinite challenge loops.
+func FetchViaChrome(url string) ([]byte, error) {
+	profileDir := filepath.Join(config.ConfigDir(), "browser-profile")
+	if err := os.MkdirAll(profileDir, 0o755); err != nil {
+		return nil, fmt.Errorf("create browser profile dir: %w", err)
+	}
+
+	// Remove stale lock file from unclean shutdown
+	_ = os.Remove(filepath.Join(profileDir, "SingletonLock"))
+
+	execPath := findBrowserExec()
+
+	// Use non-headless mode: Cloudflare detects headless Chrome and loops
+	// the JS challenge forever. A real (but hidden) browser window passes.
+	opts := append(chromedp.DefaultExecAllocatorOptions[:],
+		chromedp.Flag("headless", false),
+		chromedp.Flag("window-position", "-32000,-32000"), // off-screen
+		chromedp.Flag("window-size", "1,1"),
+		chromedp.Flag("disable-gpu", true),
+		chromedp.Flag("no-first-run", true),
+		chromedp.Flag("disable-extensions", true),
+		chromedp.UserDataDir(profileDir),
+	)
+	if execPath != "" {
+		opts = append(opts, chromedp.ExecPath(execPath))
+	}
+
+	allocCtx, allocCancel := chromedp.NewExecAllocator(context.Background(), opts...)
+	defer allocCancel()
+
+	ctx, cancel := chromedp.NewContext(allocCtx)
+	defer cancel()
+
+	// Total timeout for the operation
+	ctx, timeoutCancel := context.WithTimeout(ctx, 30*time.Second)
+	defer timeoutCancel()
+
+	// Navigate and wait for Cloudflare challenge to resolve.
+	// Poll the page content until we get valid JSON (not the challenge page).
+	if err := chromedp.Run(ctx, chromedp.Navigate(url)); err != nil {
+		return nil, fmt.Errorf("chromedp navigate: %w", err)
+	}
+
+	// Poll for JSON response — Cloudflare challenge takes a few seconds to clear
+	ticker := time.NewTicker(1 * time.Second)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return nil, fmt.Errorf("chromedp fetch timed out waiting for JSON response")
+		case <-ticker.C:
+			var body string
+			// Try <pre> first (Chrome wraps JSON in <pre> tags)
+			err := chromedp.Run(ctx,
+				chromedp.Text("pre", &body, chromedp.ByQuery),
+			)
+			if err != nil || body == "" {
+				// Fallback: try body directly
+				_ = chromedp.Run(ctx,
+					chromedp.Text("body", &body, chromedp.ByQuery),
+				)
+			}
+			body = strings.TrimSpace(body)
+			if body == "" {
+				continue
+			}
+			// Check if we got actual JSON (starts with [ or {), not a challenge page
+			if body[0] == '[' || body[0] == '{' {
+				// Also extract any fresh cookies for future plain HTTP attempts
+				_ = extractAndSaveCookies(ctx)
+				cancel() // graceful close, flushes cookies to profile
+				return []byte(body), nil
+			}
+		}
+	}
+}
+
+// extractAndSaveCookies saves cf_clearance and other Cloudflare cookies
+// alongside the session key, so plain HTTP requests can try them next time.
+func extractAndSaveCookies(ctx context.Context) error {
+	cookies, err := network.GetCookies().Do(ctx)
+	if err != nil {
+		return err
+	}
+
+	var parts []string
+	for _, c := range cookies {
+		if c.Domain == ".claude.ai" || c.Domain == "claude.ai" {
+			if c.Name == "cf_clearance" || c.Name == "__cf_bm" || c.Name == "_cfuvid" {
+				parts = append(parts, c.Name+"="+c.Value)
+			}
+		}
+	}
+
+	if len(parts) == 0 {
+		return nil
+	}
+
+	// Write Cloudflare cookies to a file the fetcher can read
+	cfPath := filepath.Join(config.ConfigDir(), "cf-cookies")
+	return os.WriteFile(cfPath, []byte(strings.Join(parts, "\n")+"\n"), 0o600)
+}

internal/fetcher/fetcher.go

@@ -4,11 +4,16 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"log"
 	"math"
 	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
 	"sync"
 	"time"
 
+	"git.davoryn.de/calic/claude-statusline/internal/browser"
 	"git.davoryn.de/calic/claude-statusline/internal/config"
 )
 
@@ -32,13 +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/")
@@ -56,17 +69,54 @@ 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) {
+	body, status, err := doRequest(url, sessionKey)
+	if err != nil {
+		return nil, fmt.Errorf("request failed: %w", err)
+	}
+	if status == 200 {
+		return body, nil
+	}
+	if status == 401 {
+		return nil, fmt.Errorf("auth_expired")
+	}
+	if status == 403 {
+		// Likely a Cloudflare JS challenge — fall back to headless Chrome
+		log.Printf("HTTP 403 for %s, falling back to headless Chrome", url)
+		chromeBody, chromeErr := browser.FetchViaChrome(url)
+		if chromeErr != nil {
+			return nil, fmt.Errorf("auth_expired") // treat as auth failure if Chrome also fails
+		}
+		return chromeBody, nil
+	}
+	return nil, fmt.Errorf("HTTP %d", status)
+}
+
 // DiscoverOrgID fetches the first organization UUID from the API.
 func DiscoverOrgID(sessionKey string) (string, error) {
-	body, status, err := doRequest(apiBase+"/api/organizations", sessionKey)
+	body, err := fetchWithFallback(apiBase+"/api/organizations", sessionKey)
 	if err != nil {
-		return "", fmt.Errorf("request failed: %w", err)
-	}
-	if status == 401 || status == 403 {
-		return "", fmt.Errorf("auth_expired")
-	}
-	if status != 200 {
-		return "", fmt.Errorf("HTTP %d", status)
+		return "", err
 	}
 
 	var orgs []struct {
@@ -96,16 +146,13 @@ func FetchUsage(sessionKey, orgID string) (*CacheData, string, error) {
 	}
 
 	url := fmt.Sprintf("%s/api/organizations/%s/usage", apiBase, orgID)
-	body, status, err := doRequest(url, sessionKey)
+	body, err := fetchWithFallback(url, sessionKey)
 	if err != nil {
+		if err.Error() == "auth_expired" {
+			return &CacheData{Error: "auth_expired", Status: 403}, orgID, err
+		}
 		return &CacheData{Error: "fetch_failed", Message: err.Error()}, orgID, err
 	}
-	if status == 401 || status == 403 {
-		return &CacheData{Error: "auth_expired", Status: status}, orgID, fmt.Errorf("auth_expired")
-	}
-	if status != 200 {
-		return &CacheData{Error: "api_error", Status: status}, orgID, fmt.Errorf("HTTP %d", status)
-	}
 
 	var data CacheData
 	if err := json.Unmarshal(body, &data); err != nil {