An update you can ask for, and a boundary that stays where it was

The button cannot do the work, and that is the whole design. The service runs as
an unprivileged account, cannot restart itself, and should not be able to: a web
application that can restart its own service is one whose worst day is much
worse. So /admin/updates writes a file, and an opt-in systemd .path unit runs
deploy/update.sh as root.

Three properties hold it up, and each is a thing that could have been got wrong.
The request file carries nothing that reaches a command line -- no branch, no
ref, no arguments -- because the branch is baked into the unit at install time,
so pressing the button is always "deploy the branch this host was configured
with" and can never be "deploy something else". It is off unless somebody passes
INSTALL_UPDATE_HELPER=1, and re-running the installer without it removes both
units and the marker. And without the helper the page says so and prints the
manual command rather than writing a file nothing is watching, which would be a
button that reports success and does nothing.

The card that says all of this is rendered whether or not there is anything to
apply. It was inside the "there is an update" branch first, so an administrator
could not discover the helper was missing until the day they needed it, which is
the worst possible moment.

Opening the page makes no network request; Check is the one thing that fetches.
And it shows the log between, not a count: "3 behind" is a number somebody has to
go and look up, while the subjects are what decides whether this is worth
restarting for right now.

Docker is one stage, because there is nothing to build -- no Node, no compiled
assets. It bakes no secret key (one in an image is one every copy shares, and
rotating it makes stored API keys unreadable), no data, and no .git, so
/admin/updates inside a container correctly reports that it was not installed
from a checkout. Compose publishes on loopback and refuses to start without a
key. TLS in front is a constraint rather than a recommendation: the service
worker and the microphone both require HTTPS or localhost.

The image was built and run before this was committed, which is how the missing
COPY of LICENSE was found -- pyproject declares it and the build backend reads
it, so the failure reads like a packaging problem and is one line.

deploy/lxc-install.sh creates an unprivileged Debian container and runs the
existing installer inside it. A wrapper, not a second install path: a parallel
installer is two things to keep correct and one of them rots.

/healthz opens the database rather than only proving the socket is listening -- a
process that is up with a database it cannot open answers every page with a 500
-- and says nothing about what is here, being reachable without signing in.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/lembas/api/pages.py

@@ -435,6 +435,32 @@ async def home(user: RequiredUser):
 # has by definition no server to ask who is looking at it.
 
 
+@router.get("/healthz", include_in_schema=False)
+async def healthz() -> Response:
+    """Is the process up and can it reach its database.
+
+    Unauthenticated, like the three below, and for a fourth reason: a
+    healthcheck that needed a session would be a healthcheck nothing could run.
+    It says nothing about *what* is here -- no version, no counts -- because it
+    is reachable without signing in and a health endpoint is a common place to
+    leak the first fact an attacker wants.
+
+    The query is what makes it worth having. A process that is up with a
+    database it cannot open answers every page with a 500, and a check that only
+    proved the socket was listening would call that healthy.
+    """
+    from sqlalchemy import text
+
+    from lembas.db.session import session_scope
+
+    try:
+        with session_scope() as db:
+            db.execute(text("SELECT 1"))
+    except Exception:  # noqa: BLE001 - the answer is the status code
+        return JSONResponse({"status": "error"}, status_code=503)
+    return JSONResponse({"status": "ok"})
+
+
 @router.get("/manifest.webmanifest", include_in_schema=False)
 async def manifest(db: Db) -> Response:
     """The web app manifest.