From f4fd6db8faa15bf02f38a14b652cc46936f8d6bf Mon Sep 17 00:00:00 2001 From: Christophe Besson Date: Thu, 17 Sep 2026 03:40:52 +0200 Subject: spa: a blank page can never be silent again MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit boot-guard.js is a classic script loaded before the module graph, so it survives the graph failing to link. If #app is still empty after ten seconds it names what failed and offers a reset of this origin — cache, storage, databases and the service worker, which clearing the cache does not touch. Two real defects found building it: openDB never settled when an upgrade was blocked by another tab, and a connection it gave up on stayed open and squatted the database. Co-Authored-By: Claude Opus 5 --- .../meshbay-hub/tests/harness/boot_guard_probe.py | 260 +++++++++++++++++++++ 1 file changed, 260 insertions(+) create mode 100644 packages/meshbay-hub/tests/harness/boot_guard_probe.py (limited to 'packages/meshbay-hub/tests/harness') diff --git a/packages/meshbay-hub/tests/harness/boot_guard_probe.py b/packages/meshbay-hub/tests/harness/boot_guard_probe.py new file mode 100644 index 0000000..01751ba --- /dev/null +++ b/packages/meshbay-hub/tests/harness/boot_guard_probe.py @@ -0,0 +1,260 @@ +#!/usr/bin/env python3 +""" +The shell cannot end up silently blank, and there is a way out of it. + +A reader spent an evening on a white page: the shell arrived, every module came +from the browser's own store so not one request reached the hub, and nothing +rendered. Clearing the site's data fixed it — clearing the *cache*, three times, +did not, because the cache is not where a service worker or IndexedDB lives. + +What is measured here is the guard, not the cause. Three things have to hold: +it says nothing when the application mounts; it appears, with the failure named +on screen, when the module graph does not link; and its reset button genuinely +empties this origin — a button that claims to and does not would be worse than +none. + +The last case is why the guard is a classic script and not part of the module +graph: it has to survive the graph failing to link, which is exactly when a +reader needs it. + + boot_guard_probe.py + +Prints JSON: one entry per case. +""" + +import http.server +import json +import socketserver +import subprocess +import sys +import tempfile +import threading +import time +from pathlib import Path + +STATIC = Path(__file__).resolve().parents[2] / "src" / "meshbay_hub" / "static" +PORT = 8763 +RECORDS = [] +socketserver.TCPServer.allow_reuse_address = True + +# The shell, as `webapp.py` builds it: the guard first, as a classic script, +# then the module graph. `?fail=1` asks for a module that is not there. +SHELL = r""" +

+ + +""" + +MOUNTS = r"""// A successful mount: the guard must stay out of the way. +document.getElementById('app').appendChild( + Object.assign(document.createElement('p'), { textContent: 'the application' })); +""" + +BLOCKED = r""" +""" + + +PAGE = r""" +

""" + + +class H(http.server.BaseHTTPRequestHandler): + def log_message(self, *a): + pass + + def do_POST(self): + length = int(self.headers.get("Content-Length") or 0) + if self.path == "/log": + RECORDS.append(json.loads(self.rfile.read(length).decode())) + else: + self.rfile.read(length) + self.send_response(204) + self.end_headers() + + def _send(self, body: bytes, ctype: str, code: int = 200) -> None: + self.send_response(code) + self.send_header("Content-Type", ctype) + self.send_header("Content-Length", str(len(body))) + self.end_headers() + self.wfile.write(body) + + def do_GET(self): + path, _, query = self.path.partition("?") + if path == "/": + self._send(PAGE.encode(), "text/html; charset=utf-8") + elif path == "/blocked": + self._send(BLOCKED.encode(), "text/html; charset=utf-8") + elif path == "/shell": + self._send(SHELL.encode(), "text/html; charset=utf-8") + elif path == "/__case.js": + # The referring frame decides: one mounts, the other is missing — + # a 404 on a module, which is what a graph that will not link looks + # like from the outside. + if "case=fails" in (self.headers.get("Referer") or ""): + self._send(b"not here", "text/plain", 404) + else: + self._send(MOUNTS.encode(), "text/javascript") + else: + asset = (STATIC / path.lstrip("/")).resolve() + if not str(asset).startswith(str(STATIC)) or not asset.is_file(): + self.send_response(404) + self.end_headers() + return + self._send(asset.read_bytes(), "text/javascript") + + +def main() -> int: + with socketserver.TCPServer(("127.0.0.1", PORT), H) as srv: + threading.Thread(target=srv.serve_forever, daemon=True).start() + with tempfile.TemporaryDirectory(ignore_cleanup_errors=True) as profile: + proc = subprocess.Popen( + ["google-chrome", "--headless=new", "--disable-gpu", "--no-sandbox", + f"--user-data-dir={profile}", "--window-size=900,900", + f"http://127.0.0.1:{PORT}/"], + stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL) + for _ in range(600): + if RECORDS: + break + time.sleep(0.1) + proc.terminate() + try: + proc.wait(timeout=10) + except subprocess.TimeoutExpired: + proc.kill() + proc.wait() + if not RECORDS: + print(json.dumps({"error": "no measurement"}), file=sys.stderr) + return 1 + print(json.dumps(RECORDS[0], indent=1, ensure_ascii=False)) + return 0 + + +if __name__ == "__main__": + raise SystemExit(main()) -- cgit v1.2.3