Auto headless + Xvfb for headless servers

Enable Chromium on machines without DISPLAY: Python auto headless
with Xvfb hints, and start.sh installs/starts Xvfb (xvfb-run or
persistent :99) so registration can run headed under a virtual display.

cpa_export.py

@@ -351,8 +351,38 @@ def export_cpa_xai_for_account(
             or os.environ.get("http_proxy")
             or ""
         ).strip()
-    # Default headed: headless is frequently Cloudflare-blocked on accounts.x.ai
-    headless = bool(cfg.get("cpa_headless", False))
+    # Default headed when a display exists; headless is frequently Cloudflare-blocked.
+    # On servers without DISPLAY, always force headless so Chromium can start.
+    has_disp = sys.platform == "win32" or bool(
+        (os.environ.get("DISPLAY") or "").strip()
+        or (os.environ.get("WAYLAND_DISPLAY") or "").strip()
+    )
+    cpa_hl_raw = cfg.get("cpa_headless", None)
+    if cpa_hl_raw is None:
+        # inherit browser_headless auto / explicit if set
+        cpa_hl_raw = cfg.get("browser_headless", "auto")
+    if isinstance(cpa_hl_raw, bool):
+        headless = cpa_hl_raw
+    else:
+        s = str(cpa_hl_raw or "auto").strip().lower()
+        if s in ("1", "true", "yes", "on", "headless"):
+            headless = True
+        elif s in ("0", "false", "no", "off", "headed", "gui"):
+            headless = False
+        else:
+            headless = not has_disp
+    if not has_disp and not headless:
+        headless = True
+        _log(
+            f"cpa browser forced headless (no DISPLAY={os.environ.get('DISPLAY', '')!r}); "
+            "prefer xvfb-run for Turnstile; protocol mint still preferred first"
+        )
+    elif headless and not bool(cfg.get("cpa_headless", False)):
+        _log(
+            "cpa browser headless auto/on "
+            f"(DISPLAY={os.environ.get('DISPLAY', '')!r}); "
+            "protocol mint still preferred first"
+        )
     probe = bool(cfg.get("cpa_probe_after_write", True))
     probe_chat = bool(cfg.get("cpa_probe_chat", False))
     timeout = float(cfg.get("cpa_mint_timeout_sec", 240))