MeshBay

From 5dea19d9950518887be7eb14696f600ee023dbbd Mon Sep 17 00:00:00 2001 From: Christophe Besson Date: Sun, 16 Aug 2026 20:57:52 +0200 Subject: fix(hub): serve the SPA under a fingerprint of what it is MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit `Cache-Control: no-cache` requires a browser to revalidate, but it only binds one that asks. A browser that cached app.js before that header existed applies heuristic freshness instead — a fraction of the file's age, which for a file dated weeks ago is days — and never asks. It then runs an old player against a new node. That cost most of a session. A phone kept a player without the read-ahead bound and filled the browser's buffer ceiling at 106 MB, the exact symptom the bound had been written to remove, for an hour after the bounded player went live. A fix that is written, tested, deployed and served, and still not what runs, is indistinguishable from a fix that does not work. The whole module graph now lives under `/a//`. A path prefix rather than a query string, because relative imports inherit it: `app.js` reaching for `./i18n.js` gets the build it was written against, and never a mixture of two — which does not render a stale page, it fails to link. The URL changes with the content, so those may be cached hard. `sw.js` stays at the root. Its scope is its own path, and under the prefix it would no longer control the pages whose downloads it exists to intercept. --- packages/meshbay-hub/src/meshbay_hub/api/webapp.py | 49 ++++++++-- packages/meshbay-hub/src/meshbay_hub/app.py | 31 ++++++- .../meshbay-hub/tests/test_asset_versioning.py | 103 +++++++++++++++++++++ packages/meshbay-hub/tests/test_hub_api.py | 19 ++-- 4 files changed, 188 insertions(+), 14 deletions(-) create mode 100644 packages/meshbay-hub/tests/test_asset_versioning.py (limited to 'packages') diff --git a/packages/meshbay-hub/src/meshbay_hub/api/webapp.py b/packages/meshbay-hub/src/meshbay_hub/api/webapp.py index f804ec5..392e8d1 100644 --- a/packages/meshbay-hub/src/meshbay_hub/api/webapp.py +++ b/packages/meshbay-hub/src/meshbay_hub/api/webapp.py @@ -11,6 +11,7 @@ Static files are served from meshbay_hub/static/ via Starlette StaticFiles. The root route (/) returns the SPA HTML shell. """ +import hashlib from pathlib import Path from fastapi import APIRouter @@ -20,6 +21,33 @@ STATIC_DIR = Path(__file__).parent.parent / "static" router = APIRouter(tags=["webapp"]) +# Assets the shell pulls in, in load order. Everything else is imported by +# app.js and rides on the same query string via window.__MB_ASSET_V. +_ASSETS = ("style.css", "keyderive.js", "crypto.js", "transport.js", "app.js", + "i18n.js", "downloads.js", "transfers.js", "zipstream.js") + + +def _asset_version() -> str: + """A fingerprint of what we are actually serving. + + `Cache-Control: no-cache` only binds a browser that asks. One that cached + app.js *before* that header existed applies heuristic freshness — a + fraction of the file's age, which for a file dated weeks ago is days — and + never asks at all. It then runs last week's player against this week's node + for as long as that lasts, which is indistinguishable from the fix not + working. Changing the URL is the only thing that reaches such a browser, + and a content hash changes it exactly when the content changes. + """ + h = hashlib.sha256() + for name in _ASSETS: + path = STATIC_DIR / name + if path.exists(): + h.update(path.read_bytes()) + return h.hexdigest()[:12] + + +ASSET_V = _asset_version() + @router.get("/app", response_class=HTMLResponse) async def app_root(): @@ -43,18 +71,25 @@ _HTML = """\ MeshBay - +

+ + - - - - - + + + + + -""" +""".replace("{v}", ASSET_V) diff --git a/packages/meshbay-hub/src/meshbay_hub/app.py b/packages/meshbay-hub/src/meshbay_hub/app.py index 6240785..423ad03 100644 --- a/packages/meshbay-hub/src/meshbay_hub/app.py +++ b/packages/meshbay-hub/src/meshbay_hub/app.py @@ -35,7 +35,7 @@ from meshbay_hub.api.relay import router as relay_router from meshbay_hub.api.signaling import router as signaling_router from meshbay_hub.api.admin import router as admin_router from meshbay_hub.api.notifications import router as notifications_router -from meshbay_hub.api.webapp import router as webapp_router, STATIC_DIR +from meshbay_hub.api.webapp import router as webapp_router, STATIC_DIR, ASSET_V from meshbay_hub.api.middleware import limiter @@ -145,6 +145,35 @@ def create_app(cfg: HubConfig | None = None) -> FastAPI: response.headers.setdefault("Cache-Control", "no-cache") return response + class VersionedStatics(StaticFiles): + """The same files under a URL that changes when they do. + + `no-cache` above only binds a browser that asks. One that cached the SPA + before that header existed applies heuristic freshness and does not ask + at all, so it runs an old player against a new node — a fix that is + deployed, served, and not running, which looks exactly like a fix that + does not work. Measured: a phone kept a player without the read-ahead + bound and filled the browser's buffer ceiling at 106 MB, while the + server had been serving the bounded one for an hour. + + Serving the graph under /a// solves it for every file at + once, because relative imports inherit the prefix: `app.js` reaching for + `./i18n.js` gets the version it was built against, and never a mixture. + The URL changes with the content, so these may be cached hard. + """ + + async def get_response(self, path, scope): + response = await super().get_response(path, scope) + response.headers["Cache-Control"] = ( + "public, max-age=31536000, immutable") + return response + + # Before "/", which would otherwise swallow it. + app.mount(f"/a/{ASSET_V}", VersionedStatics(directory=STATIC_DIR), + name="static-versioned") + # Still served unversioned: sw.js must stay at the root or its scope stops + # covering the pages it intercepts downloads for, and old bookmarks of + # /style.css and the like should not 404. app.mount("/", RevalidatingStatics(directory=STATIC_DIR), name="static") return app diff --git a/packages/meshbay-hub/tests/test_asset_versioning.py b/packages/meshbay-hub/tests/test_asset_versioning.py new file mode 100644 index 0000000..e5889f0 --- /dev/null +++ b/packages/meshbay-hub/tests/test_asset_versioning.py @@ -0,0 +1,103 @@ +""" +Making sure the browser runs the build we deployed. + +A fix can be written, tested, deployed, and served, and still not be what runs. +`Cache-Control: no-cache` requires a browser to revalidate — but it only binds +one that asks, and a browser that cached the SPA *before* that header existed +applies heuristic freshness instead: a fraction of the file's age, which for a +file dated weeks ago is days. It does not ask, so it never learns. + +That happened here. A phone ran a player without the read-ahead bound and filled +the browser's buffer ceiling at 106 MB — the exact symptom the bound was written +to remove — for an hour after the bounded player went live. Two sessions were +spent looking at the node. + +So the URL now carries a fingerprint of what is being served, and the whole +module graph lives under it: `/a//app.js` importing `./i18n.js` resolves +to `/a//i18n.js`. A URL that changes with the content cannot serve +yesterday's build, and cannot serve half of each. +""" + +import re + +import pytest +from fastapi.testclient import TestClient + +from meshbay_hub.api.webapp import ASSET_V, STATIC_DIR, _asset_version +from meshbay_hub.app import create_app + + +@pytest.fixture(scope="module") +def client(): + return TestClient(create_app()) + + +def _shell_refs(html: str) -> list[str]: + return re.findall(r'(?:src|href)="([^"]+)"', html) + + +def test_every_asset_the_shell_loads_is_versioned(client): + refs = _shell_refs(client.get("/").text) + assert refs, "the shell references nothing at all" + stale = [u for u in refs if not u.startswith(f"/a/{ASSET_V}/")] + assert not stale, ( + f"served from an unversioned URL, so a stale cache can win: {stale}") + + +def test_the_module_graph_resolves_under_the_same_prefix(client): + """The point of a path prefix rather than a query string. + + `import './i18n.js'` from a versioned app.js resolves against the versioned + directory. A query string on app.js alone would not: its imports would fall + back to the bare paths, and the graph could be assembled from two builds — + which does not render a stale page, it fails to link at all. + """ + for path in ("app.js", "i18n.js", "locales/fr.js", "transport.js", + "vendor/argon2.min.js"): + r = client.get(f"/a/{ASSET_V}/{path}") + assert r.status_code == 200, f"{path} is not served under the version" + + +def test_versioned_assets_may_be_cached_hard(client): + """Which is the trade the fingerprint buys.""" + cc = client.get(f"/a/{ASSET_V}/app.js").headers.get("cache-control", "") + assert "immutable" in cc and "max-age=31536000" in cc, ( + f"versioned assets are served as {cc!r} — the whole point of a URL that " + "changes with the content is that it need never be revalidated") + + +def test_the_unversioned_path_still_revalidates(client): + """It still answers — old bookmarks, and sw.js has to live there.""" + r = client.get("/app.js") + assert r.status_code == 200 + assert r.headers.get("cache-control") == "no-cache" + + +def test_the_service_worker_is_not_versioned(client): + """Its scope is its own path. + + Served from /a//sw.js it would only control /a//, and the + pages whose downloads it exists to intercept are not under there. + """ + assert client.get("/sw.js").status_code == 200 + assert "/sw.js" not in _shell_refs(client.get("/").text) + + +def test_the_fingerprint_follows_the_content(tmp_path, monkeypatch): + """Otherwise it is decoration. + + Pinning this to the file contents rather than to the package version is + deliberate: a redeploy without a version bump is the common case during a + debugging session, and that is exactly when a stale player costs the most. + """ + before = _asset_version() + target = STATIC_DIR / "app.js" + original = target.read_bytes() + try: + target.write_bytes(original + b"\n// touched\n") + assert _asset_version() != before, ( + "the fingerprint did not move when app.js did, so a redeploy " + "serves the new file at the old URL") + finally: + target.write_bytes(original) + assert _asset_version() == before, "the fingerprint is not reproducible" diff --git a/packages/meshbay-hub/tests/test_hub_api.py b/packages/meshbay-hub/tests/test_hub_api.py index 5314b93..724c8ec 100644 --- a/packages/meshbay-hub/tests/test_hub_api.py +++ b/packages/meshbay-hub/tests/test_hub_api.py @@ -722,19 +722,26 @@ async def test_ip_log_cleanup(app): @pytest.mark.asyncio async def test_webapp_html_includes_scripts(client): - """SPA HTML shell includes all required script tags.""" + """SPA HTML shell includes all required script tags. + + The paths carry a build fingerprint (`/a//app.js`) so that a browser + cannot serve an older build out of its own cache — see + test_asset_versioning.py. What this test still owns is that every piece is + referenced at all, and in an order where each one's dependencies are + already loaded. + """ + from meshbay_hub.api.webapp import ASSET_V + r = await client.get("/") assert r.status_code == 200 html = r.text assert "" in html assert '

' in html - assert 'src="/keyderive.js"' in html - assert 'src="/crypto.js"' in html - assert 'src="/transport.js"' in html - assert 'src="/app.js"' in html + for asset in ("keyderive.js", "crypto.js", "transport.js", "app.js"): + assert f'src="/a/{ASSET_V}/{asset}"' in html, f"{asset} is not loaded" assert 'type="module"' in html assert 'rel="stylesheet"' in html - assert 'href="/style.css"' in html + assert f'href="/a/{ASSET_V}/style.css"' in html # ── Password split (T1 fix) ───────────────────────────────────────────────── -- cgit v1.2.3