dashboards/README.md

# Homelab Dashboards

Four dashboards, one domain, one process, one SQLite file:

| Page        | What it answers                                                                 | Source                                             |
| ----------- | ------------------------------------------------------------------------------- | -------------------------------------------------- |
| `/`         | Is anything wrong, and which dashboard do I need?                               | all four, in one request (`/api/summary`)          |
| `/system`   | What are my machines doing — CPU, memory, disk, GPU, network, and the history of all of it | `agent/host_agent.py`, our own stdlib agent per host |
| `/disks`    | Are any of my **physical** disks failing, and which one — health, temperature, power-on hours, wear, sector alarms | the same agents, running `smartctl -i -A -H` per whole drive (never a partition or a mount) |
| `/llm`      | Tokens/sec, active sessions, queue depth, KV-cache pressure, latency percentiles | llama.cpp-family (gufo) `/metrics` + `/slots`, vLLM `/metrics` — read-only |
| `/ups`      | Battery health, runtime left, power events, and battery-test buttons             | NUT `upsd`, on whatever port it really listens on (its own wire-protocol client) |

No Prometheus, no Grafana, no CDN, no build step. Nothing is fetched from the internet at
runtime; every asset is served by this app.

Three more pages are not dashboards: `/login` (the one thing an anonymous visitor sees),
`/settings` — `⚙ Account` in the masthead of every dashboard — which shows this browser's
session, signs it out, and changes the admin password, and `/certs` — `⚷ Certs`, beside it —
which is the certificate authority the agents are dialled with: the root CA, this dashboard's
own client certificate, and one row per host with its rotate, revoke and bundle download.

Working on this repo? **[`AGENTS.md`](AGENTS.md)** holds the invariants (read-only by
construction, never invent a number, unconfigured ≠ broken), the locked decisions, the real
fleet facts, and the known gaps.

## Quickstart

```bash
uv sync --python 3.14                       # deps + the package, editable
cp .env.example .env                        # then edit — including DASH_ADMIN_PASSWORD
uv run dashboards                           # http://127.0.0.1:8090
uv run uvicorn dashboards.app:app --port 8090   # equivalent
uv run pytest                               # unit tests, no network needed
```

The first start needs a password to seed: with no `DASH_ADMIN_PASSWORD` and no verifier stored
in `DASH_DB` yet, the process prints the reason and exits non-zero rather than serving the fleet
open (see *Signing in*). The dev password this project uses locally is
`testpass`; production gets a real one. The first thing a browser meets is `/login` — every page
and every `/api` route except the four listed under *What the session covers* asks for it, while
`/api/health` stays open for the container healthcheck and `./scripts/dev-server.sh status`.

Developing against the real fleet from a laptop — dev dials exactly the addresses the deployed
dashboard dials, so there is nothing to tunnel and no port to forward:

```bash
cp .env.dev.example .env.dev                # your host addresses + agent tokens (chmod 0600)
sudo deploy/install-agent.sh --bind <addr> --port 9120
                                            # once per monitored host: the agent as a systemd
                                            # service, printing its bearer token exactly once
set -a; . ./.env.dev; set +a
uv run dashboards                           # foreground
./scripts/dev-server.sh restart             # or backgrounded, with a pidfile + logs
```

Local dev signs in with the `DASH_ADMIN_PASSWORD` in that file — the word the template's comment
names (`testpass`, what the hermetic suite uses) — and without it a fresh database exits non-zero
for the same reason production does. `.env.dev` is gitignored and `0600`: it holds the agent
tokens and the upsd password too.

Each `HOST_TARGETS` entry carries that token as URL userinfo
(`driveripper=http://<token>@<addr>:9120`); `parse_targets` moves it into an `Authorization`
header, so `Target.url`, `/api/config` and every error message stay credential-free. No root
shell on a host? `deploy/agent-sudoers` is the one-line grant that lets `ops` run the installer,
and running the installer without root prints that exact line. upsd is dialled at
`NUT_HOST`/`NUT_PORT` on the port it really answers on (3051 on driveripper, not the stock
3493) — see the NUT section below for who may connect.

## The host agent

`agent/host_agent.py` is one file, **stdlib only**, Python 3.10+. It reads `/proc`,
`/sys/block`, `/sys/class/drm` and `statvfs` and answers `GET /snapshot` (everything, one
JSON document; `?top=N` trims the process lists), `GET /info` (slow-changing identity: OS,
kernel, CPU model, GPU list), `GET /schema` (the schema version plus this document) and
`GET /health` (the one route that needs no credential) as JSON, with a plain HTML status
page at `GET /` so a browser pointed at an agent learns what it is looking at.

```bash
python3 host_agent.py --once                                # print one snapshot, exit
python3 host_agent.py --host 0.0.0.0 --port 9120 --token-file /etc/dashboards-agent.token
python3 host_agent.py --host 0.0.0.0 --port 9120 --cert-bundle /etc/dashboards-agent.certs
sudo deploy/install-agent.sh                                # systemd unit + user + token
sudo deploy/install-agent.sh --cert-bundle agent.bundle     # ...or the TLS install (bundle from /certs)
sudo deploy/install-agent.sh --as-root --caps CAP_SYS_RAWIO,CAP_SYS_ADMIN
                                            # ...or a kernel-gated host (SMART passthrough, below)
sudo deploy/install-agent.sh --force        # ...only when it must overwrite a unit it would change
deploy/install-agent.sh --status                            # unit state and /health (https when TLS)
sudo deploy/install-agent.sh --uninstall
```

Re-running the installer is the silent, idempotent path it has always been **as long as the unit
it would write is the unit already on disk**. When the two differ the run stops: it prints
`refusing to overwrite …` with the unified diff on stdout and exits 1 before writing the unit,
before `daemon-reload` and before the service is re-enabled, so a routine redeploy can never undo
a fix somebody made by hand on the host (`--as-root`/`--caps` on a host already running the
dedicated user is exactly such a change, and installing a TLS bundle onto a token-mode host is
another). `--force` prints the same diff and then applies it.

No root shell on the monitored host? `deploy/agent-sudoers` is the single sudoers line that
lets the fleet's unprivileged `ops` account run the installer; run it without root and it
prints that exact line with the script's own resolved path instead of saying "run as root".

It is read-only by construction: there is no code path that writes, and the HTTP server
only answers `GET`. Counters are reported as counters — the dashboard computes rates over
a labelled window, so the agent never has to remember who polled it last.

Per-disk `smart` health is a best-effort add-on on the whole-disk `/sys/block` list (no
partitions): the agent runs `smartctl -i -A -H` per physical disk — 5 s bound per device,
a pass budget of 20 s as a floor that scales to 5 s × the disk count, results cached 4 minutes —
and parses health, temperature, power-on hours,
the sector alarms and SSD wear into `disk_io.devices[].smart`. Refreshing an expired cache
happens on a background thread while the request is served the previous result, so a wedged
disk can never cost a poll more than its own timeout (only the very first pass after the
agent starts runs inline). A host without
`smartmontools`, or whose agent user cannot read the block devices, is *not broken*: every
disk reports `smart: null` with one explanatory `errors` line, and that line never makes
the system page amber. Enable SMART with `smartmontools` plus the `disk` group (which
`deploy/install-agent.sh` grants when it exists) — the agent shells `smartctl` as itself and
never calls `sudo`, so a sudoers rule alone is not enough — and **redeploy the agent**, since
one installed before phase 09 has no SMART pass to run. Opt out silently with `--no-smart`.
The drive truth this is all developed against lives in `tests/fixtures/smartctl_driveripper_*.txt`:
16 real drives, recorded with serials scrubbed, each one parsed by a test.

**TLS mode is `--cert-bundle` (env `AGENT_CERT_BUNDLE`)**: one installed PEM the dashboard
signed — this host's server certificate and key, the dashboard's root CA, a `# BUNDLE-REV <n>`
line and the `# REVOKED <serial>` denylist. The agent then serves `https://` and answers every
path but `/health` only to a **client certificate signed by that root and not on the list**: 403
`client certificate required` for a peer that proved nothing, 403 `client certificate revoked`
for one the operator withdrew (a revoked identity is refused on `/health` too — that path is open
to the installer's probe, which holds the CA and no certificate, not to a certificate that was
taken away). The denylist is re-read when the bundle file's stamp changes, so a re-deployed
bundle takes effect on the next request rather than the next restart; the certificate itself needs
a restart, because `ssl` cannot swap a chain under a live socket. The unpacked PEMs exist only
long enough to load into the context and are then deleted, and the private key is written `0600`
in the unit's `RuntimeDirectory` when it has one. In this mode `/snapshot` gains two additive
fields — `tls: true` and the `bundle_rev` the bundle carried, which is how the dashboard tells a
stale install from a current one (they reach `/api/system/snapshot` and `/api/disks/snapshot` as
`agent.tls` / `agent.bundle_rev`) — and **the bearer token is not read**: the handshake is the
auth, and a token that kept working after a revocation would defeat the list. The dashboard's half
is `collectors.AgentTls`: point that host's `HOST_TARGETS` entry at `https://` and the fetch
presents the dashboard's client certificate and verifies the agent against the same root, and a
host revoked in `certs.agents` is refused before a socket is opened. A bundle that will
not load is exit 2 naming the file; there is no "fall back to plain HTTP" path.

`deploy/install-agent.sh --cert-bundle <file>` is how that file gets there. It validates the
bundle first by the same text shape (two certificates and exactly one key, plus the
`# BUNDLE-REV` line) — before touching anything, before the root check, and without ever
dialling the dashboard — then installs it to `/etc/dashboards-agent.certs` as
`0640 root:dashboards-agent`, the token-file idiom: the agent opens the bundle *itself* at
startup and re-reads it when its stamp changes, so the service user must be able to read it
and no other account may. The unit gains `--cert-bundle` and a private `RuntimeDirectory` for
the PEM blocks, `--status` probes `https://…/health` with the bundle's CA and no client
certificate (python3 `ssl`, never an external TLS binary), `--uninstall` removes the bundle
with the token, and a re-run without the flag leaves an installed bundle in place — the
token-reuse idiom.

Binding off-loopback without a token *or* a bundle is refused (exit 2) rather than warned about.
Prefer `--token-file` over `--token`: argv is world-readable through `ps`, and this token guards
hostname, mounts, disk and GPU models, and process names. `deploy/install-agent.sh` creates
a system user, generates a token once (re-runs reuse it; `--rotate-token` for a new one),
stores it `0640 root:dashboards-agent` — the unit hands the agent the *path*, and the agent
opens it as its own user, so the file must be readable by that user and by nobody else —
and runs the agent under `ProtectSystem=strict` with an empty `CapabilityBoundingSet` (unless
`--caps` is asked for, below) and **no device filter**.
SMART device access is DAC: the installer adds the service user to the `disk` group and SELinux
stays in front of it. The strict device policy this script used to write is what locked
`driveripper`'s whole device namespace — systemd matches those globs by name against
`/proc/devices`, where kernel 7.2 lists NVMe as `blkext`, so `/dev/nvme*` matched nothing and a
strict policy denies whatever a list fails to match. `PrivateDevices=false` is still written out
explicitly, because a private `/dev` with no device list is what dies at spawn
(`status=208/STDIN`).

When DAC is not enough — a **kernel gate** — `--as-root` and `--caps` write the two unit lines
that gate checks accept. Kernel 7.2 gates smartctl's raw passthrough behind *capabilities*, not
uid: an NVMe SMART-log read through the block node needs `CAP_SYS_ADMIN` unless the drive's
firmware advertises the page, and SATA SMART behind a SAT layer is an ATA pass-through the
unprivileged `SG_IO` allow-list does not include (`CAP_SYS_RAWIO` is what the kernel names for
it). So `--as-root` writes `User=root` and `--caps CAP_SYS_RAWIO,CAP_SYS_ADMIN` writes
`CapabilityBoundingSet=CAP_SYS_RAWIO CAP_SYS_ADMIN` (comma-separated in, space-separated out);
both default off, because a host whose drives answer through the `disk` group needs neither.
`--caps` without `--as-root` is refused with exit 1 — a capability grant on the dedicated
service user is not the kernel-gate fix — and `--as-root` alone proceeds with a note, because a
root process under the default empty bounding set is capability-less (`CapEff 0`) and reads no
more than the unprivileged service user did. The token file, its `0640 root:dashboards-agent`
mode and the `--status` probe are deliberately unchanged by these flags: root reads the token
either way, and a probe of a port cannot see who owns the process behind it.

### Managing the certificates

The dashboard is the authority, and `/certs` (`⚷ Certs` in the masthead) is its page: the **Root
CA** block (CN, serial, expiry as a local timestamp *and* as time left, and **Rotate root CA**),
the **Dashboard client** line (the one certificate every agent verifies the dial against —
display-only, because it is minted with the root and has no route of its own), and one row per
host with its status chip, serial, expiry, issued-vs-deployed bundle revision, the addresses its
certificate is valid for, and **Rotate** / **Revoke** / **bundle**.

Nothing there is coloured: `severity.py` rates no certificate, so an expiry is a date and a
bundle revision is a count. The one verdict on the page is the API's `status` word (`active` green,
`revoked` red, `unissued` grey — a certificate that does not exist never borrows a green pass).
Every write asks a `confirm()` first and prints the server's own sentence afterwards; a root
rotation answers `restart_required`, because the CA and the client pair are startup material — the
table is new at once, the running process keeps dialling with what it loaded, and every host then
needs its new bundle installed. A row whose host has left `HOST_TARGETS` is listed with no buttons
at all, because every per-host route refuses it.

Under the page is the same API a script would call. Every route below is signed-in (and every write
is CSRF-gated like any other), and **none of them dials a host** — the effect of a revocation is
that the *next poll* refuses to dial (see `collectors.AgentTls` above):

| Route | What it does |
| ----- | ------------ |
| `GET /api/certs` | `root` and `client` with serial and expiry, plus one row per host the operator could act on: every `HOST_TARGETS` name and every certificate still in the table. A configured host nobody has installed yet reads `status: "unissued"` with `null` serial rather than going missing; `bundle_rev` is what this dashboard issued and `deployed_bundle_rev` is what that host's agent reported back (so "the box is one bundle behind" is visible, `n/a` when nothing answered). Reads are pure — no page refresh ever mints a certificate |
| `GET /api/certs/<name>/bundle` | the exact bytes of the stored bundle as `application/x-pem-file` with `Content-Disposition: attachment; filename="agent-<name>.bundle"`. That byte-equality is the point: `install-agent.sh` is handed the file and compares nothing else, so a route that re-signed on each read would make "is this the bundle I installed?" unanswerable. It carries that host's **private key**, which is why it is a download behind the session and `no-store` |
| `POST /api/certs/<name>/rotate` | fresh key, fresh serial, `bundle_rev` +1, `status: active` — and it is also how a host gets its **first** bundle (`bundle_rev` 1). The SAN comes from the current `HOST_TARGETS` URLs plus the name, not from the old certificate, because the address a host is dialled by is a deployment fact |
| `POST /api/certs/<name>/revoke` | marks the identity revoked, and **re-seals every other bundle** because the `# REVOKED` denylist lives inside each of them — so the fleet has new bundles to collect, while their `bundle_rev` does not move (their identity did not change). There is no unrevoke: the fix is a rotate |
| `POST /api/certs/root/rotate` | a new root, a new client certificate, every agent re-issued, and `{"ok": true, "restart_required": true}` — the CA and the client pair are startup material, so the table is new at once while the running process keeps dialling with what it loaded. Saying so beats pretending a hot-swap that does not exist |

### Protecting an agent, host by host

Three steps, and they are order-dependent because the dashboard picks its dial from the URL:

```bash
# 1. one bundle per host, from the dashboard that owns the authority (a signed-in GET; it is
#    byte-identical to the stored row and it carries that host's private key, so `curl -o` it
#    somewhere private rather than `cat`ting it into a shell history)
curl -s -H "Authorization: Bearer $SESSION" -o agent-deskwork.bundle \
     http://127.0.0.1:8090/api/certs/deskwork/bundle

# 2. install it beside the token — as root on the host, 0640 root:dashboards-agent. The same run
#    copies the repo's `agent/host_agent.py`, which is how a pre-1.1.0 agent gains TLS mode at all
#    (an older file does not know the `--cert-bundle` flag). The unit gains `--cert-bundle` and its
#    RuntimeDirectory — and then restart the service as root, because the installer's
#    `systemctl enable --now` only *starts* a unit, so an already-running agent keeps serving its
#    old mode until something restarts it.
scp agent-deskwork.bundle <host>-ops:/tmp/
ssh <host>-ops sudo /tmp/install-agent.sh --cert-bundle /tmp/agent-deskwork.bundle --force
ssh <host>-ops sudo systemctl restart dashboards-agent
ssh <host>-ops sudo /tmp/install-agent.sh --status   # https, with the CA and no client cert

# 3. point that host's HOST_TARGETS entry at https with NO userinfo token — the certificate is
#    the auth now — and restart the dashboard. `/certs` should then read issued == deployed rev.
export HOST_TARGETS="deskwork=https://<addr>:9120 …"
```

`--force` in step 2 is not a shortcut: installing a bundle *is* a change to that host's unit (the
`--cert-bundle` flag and its `RuntimeDirectory`), so without it the run prints the diff and stops
by design — read it, then re-run with the flag. The same rule covers every change the installer
applies, which is why the `--status` line above comes *after* the restart: the probe reads the
unit file to decide between http and https, so pointing it at a process that has not been
restarted yet reports "no answer" for a bundle that installed perfectly.
`install-agent.sh --bind … --port 9120` prints the `https://<addr>:9120` line for a bundle install,
so step 3 is a copy rather than a guess. A host left on `http://` keeps working over its bearer
token — the rollout is per host, and one revoked or expired certificate never blinks the others.

A name that is not in `HOST_TARGETS` answers `404 {"configured": false}` **before** any signing, any
dial, and any `meta` write: a typo that minted a key would leave a certificate nobody can install
in the authority forever. Each accepted write leaves one fixed-text event —
`cert-rotated`, `cert-revoked`, `cert-root-rotated` under `source: "certs"`, readable at
`/api/events?source=certs` — and a certificate serial never leaves a `meta` row. Serials are served
as decimal **strings** for that reason: a 64-bit serial through a JS number is a serial the page
cannot match against a denylist.

## Signing in

One admin, one password, and the server **refuses to start** when it has neither a stored
verifier nor `DASH_ADMIN_PASSWORD` — the domain is public and the fleet's hostnames and UPS
controls sit behind this login, so there is no way to run it open by accident. There is no
second account and no per-user view: the five pages (`/`, `/system`, `/disks`, `/llm`, `/ups`),
the two admin pages (`/settings`, `/certs`) and every data route belong to that one operator.

A session is an **HMAC-signed cookie** (`dash_session`), not a row in a table: it carries the
signed-in name and its own expiry, is valid for `DASH_SESSION_HOURS` (default `720` = 30 days),
and is verified with a signing key that also lives in `DASH_DB`. That is why a password change
signs out every other browser at once — it rotates the key, so every cookie minted under the old
one stops verifying on its next request — and why nothing has to be pruned.

`DASH_ADMIN_PASSWORD` is a *seed*, not the credential. The first start hashes it
(PBKDF2-HMAC-SHA256, 600 000 rounds) into the `meta` table of `DASH_DB` as `auth.verifier`, and
from then on the stored verifier wins: remove the variable once the server is up and the same
password still works, change it with `POST /api/auth/password` — or in a browser, on the
`/settings` page (*The account page* below) — with no redeploy, and know that a container env can
never roll a changed password back. If `DASH_ADMIN_PASSWORD` is still set on a box that already has a
verifier, it loses — and the server says so once at startup, in words, without quoting the value.

Forgotten password, or a database you want to hand over? Delete the rows and seed again:

```bash
sqlite3 "$DASH_DB" "DELETE FROM meta WHERE key IN ('auth.verifier','auth.session_secret')"
```

Deleting `auth.session_secret` — which that command does — signs out every browser already
signed in, which is also exactly what changing the password does on purpose. Only the hash and
the signing key are ever written: `grep -c "your password" "$DASH_DB"` comes back `0`, and no log
line, event row, or API response carries the password, the verifier, or a session token.

Nothing that leaves the app carries a credential. A `HOST_TARGETS` userinfo token is parsed
into an `Authorization` header, and every URL the browser can see — `/api/config`, a source's
error string, the event feed — goes through `config.strip_userinfo` first, because an
unreachable host writes its failure message into the event table and `/api/events` serves it.

### What the session covers

The gate is default-deny: **every page and every `/api` route** requires a signed-in admin
except four entries, named next to the middleware they guard in `app.py`:

| Public                     | Why it has to be                                                   |
| -------------------------- | ------------------------------------------------------------------ |
| `/login`                   | the form itself                                                     |
| `POST /api/auth/login`     | you cannot be signed in to sign in                                  |
| `/api/health`              | the Containerfile `HEALTHCHECK` and `./scripts/dev-server.sh status` poll it unsigned, and it publishes no fleet data |
| `/static/…`                | the login page is styled by the same stylesheet as the dashboards    |

Adding a path to that list is a security decision, and a route a future phase forgets fails
`tests/test_auth_api.py::test_every_route_that_is_not_public_requires_a_session`, which walks
the served route table rather than a list written by hand.

What a refusal looks like depends on who asked, so that neither caller has to guess:

```bash
curl -si http://127.0.0.1:8090/system | head -3
# HTTP/1.1 303 See Other        → Location: /login?next=/system  (a browser ends up back here)
curl -s http://127.0.0.1:8090/api/summary
# {"ok":false,"detail":"sign in required","login":"/login"}   (a script never gets HTML)
curl -s -o /dev/null -w '%{http_code}\n' http://127.0.0.1:8090/api/health
# 200
```

The `?next=` value keeps the query string too (`/llm?range=1h` survives the round trip), and it
is judged before it is ever followed: a `next` that leaves the site (`//evil.example`,
`http://evil.example`, the percent-encoded and control-character spellings alike) is dropped to
`/`. `auth.safe_next` is the one function that decides both halves. And every answer the gate
produces — `303`, `401`, `403`, `429`, the route's own `404` — carries `no-store`, because a
cached redirect would park a browser on the login page after it had already signed in.

### The sign-in page

`/login` is one card with one password field — no username, because there is one admin and a field
that is always the same word teaches you that half the form is theatre. It carries the masthead's
brand link and the theme toggle and nothing else from it: no tabs (each would bounce straight back
here) and no status dots, because there is nothing signed in for them to report.

What it does with an answer is the part worth knowing:

| Response | On screen                                                            |
| -------- | -------------------------------------------------------------------- |
| `200`    | straight to `?next=`, or to `/`                                        |
| `401`    | `Wrong password.` under the field, and the text you typed is selected   |
| `429`    | the refusal plus the lockout counting down, button disabled to zero    |
| other    | the server's own `detail`, printed verbatim                            |

The countdown is the server's `Retry-After`, not a guess, and a refusal is written as text rather
than HTML — this is the one page a stranger reaches first. A browser that already holds a session
never sees the form: the server `303`s it to the dashboard, and the script checks
`/api/auth/status` first so the form does not even flash. `?next=` is followed only when it is an
in-app path (`/ups`, not `//evil.example`), judged on the server and again in the page.

### The account page

`/settings` — reached by `⚙ Account` in the masthead of every dashboard — is the session facts and
the one form that changes the password.

| Panel | What it says, and what the button does |
| ----- | ------------------------------------------------------------------------ |
| Session | the signed-in name, the expiry as a local timestamp **and** as time left, and **Sign out** (`POST /api/auth/logout`, then `/login`) |
| Change password | current + new + confirm, then `POST /api/auth/password`; the outcome is one line under the form |

The form checks what it can check itself (a current password typed, at least 8 new characters,
the two new boxes agreeing) so a typo is answered without a round trip, and then reports whatever
the server said: `403` is *the current password is wrong*, `422` names the rule the new password
broke, `429` is the lockout with its own seconds. The page also states the precedence rule in its
own words — the env var seeded the password once, a change here wins, resetting from the
environment means deleting `auth.verifier` and restarting — because that is the sentence that
prevents a support call about an edited `.env` that did nothing.

One detail makes the page more than a form. A change rotates the session-signing secret, which is
what signs out every *other* browser, and it invalidates the CSRF token this browser cached — so
`Dash.resetAuth()` clears that cache after the change (and after any `401` bounce). Without it the
operator changes the password, then every UPS button 403s until they reload.

**Sign out deletes this browser's cookie; it cannot revoke a copy of the token.** A session is
signed rather than stored, so nothing is left to mark as dead — the one thing that reaches every
browser at once is the signing key, and that is what a password change rotates. If a machine is
lost or a session is suspected, change the password here: that is the revocation, and it is why
the same page carries both buttons.

### Writes need the CSRF token

A write authorised by the **cookie** must carry `X-CSRF-Token`, validated against that same
session (`GET /api/auth/status` is where a page that is already signed in reads it — the login and
change-password responses carry it too, minted for the session they just created — and it sits
behind the session because a token is worthless to anyone who cannot read that response). `Dash.fetchJSON`
fetches it once per browser and attaches it to every non-`GET`/`HEAD` request, so page code does
not think about it — and `POST /api/auth/logout` is gated like any other write, because an
`<a href="/logout">` planted on a page you read mid-outage is a CSRF that signs you out.
Mismatched `Origin` or a `Sec-Fetch-Site` that is not `same-origin`/`none` is refused before the
token is even looked at, so a cross-site login post cannot spend your throttle either.

### Changing the password

`POST /api/auth/password` with `{"current": "…", "new": "…"}` — a protected write, so it needs the
session and the CSRF token like everything else:

```bash
curl -s -X POST -H 'content-type: application/json' -H "Cookie: dash_session=$SESSION" \
     -H "X-CSRF-Token: $CSRF" -d '{"current":"…","new":"…"}' \
     http://127.0.0.1:8090/api/auth/password
# {"ok":true,"changed":true,"hint":"other browsers are now signed out",
#  "expires_at":1794982214.0,"csrf":"…"}
```

Nothing forces a change: no expiry, no first-login interstitial, and `DASH_ADMIN_PASSWORD` is never
re-applied after the first boot of a database. The only composition rule is length — at least
`api.MIN_PASSWORD_LENGTH` (8) characters, not empty once stripped, and different from the current
one — each refused with a `422` that names the rule. A symbol/digit mandate produces sticky notes
rather than passwords, and the cost of a guess here is PBKDF2 plus the backoff, not the character
classes.

A wrong `current` is `403 {"ok":false,"detail":"current password is wrong"}` and a
`password-denied` event, and guesses at that field are throttled on their **own** key
(`password:<address>`) — the same arithmetic as the login form, a separate bucket, so this form is
never an unthrottled oracle for the old password once a cookie is stolen and one form's lockout
does not lock out the other.

A right one rewrites `auth.verifier` **and** `auth.session_secret`, which is the whole revocation
story: a session is a signed cookie with no server-side record, so rotating the signing key is the
only way a password change reaches the browsers that are not in front of the form (without it a
stolen cookie would stay valid for another `DASH_SESSION_HOURS`). The response carries a fresh
cookie and a fresh CSRF token minted from the **new** secret, so the caller who just changed the
password is not signed out by their own form, while every other browser gets a `401` on its next
request and signs back in with the new password. `password-changed` lands in the event feed — an
event, not an overview alert, and not a field on `/api/health` (which is public) or `/api/config`.

### Scripting the API

`Authorization: Bearer <session token>` is the scripted caller, and it needs no CSRF token —
another site can make your browser send its cookie but cannot read a token out of your shell.
The session token is in the login response's `Set-Cookie`, not in its body:

```bash
SESSION=$(curl -si -X POST -H 'content-type: application/json' \
              -d '{"password":"…"}' http://127.0.0.1:8090/api/auth/login \
          | tr -d '\r' | sed -n 's/^set-cookie: dash_session=\([^;]*\).*/\1/p' | head -1)
curl -s -H "Authorization: Bearer $SESSION" http://127.0.0.1:8090/api/summary   # 200
curl -s -H "Authorization: Bearer $SESSION" -X POST -H 'content-type: application/json' \
     -d '{"ups":"apc","command":"test.panel.start"}' http://127.0.0.1:8090/api/ups/command
```

That is the app's one write endpoint **that dials anything** (the `/api/auth/*` and `/api/certs/*`
writes change only this process and its SQLite `meta` table — invariant 1 is about the fleet), and
the bearer header changes nothing about its gates: a command that can cut output still needs
`"confirm":"DANGER"`, and is still refused while the UPS is on battery.

### Lockout

Five wrong passwords from one address starts a backoff (`429` with `Retry-After`, exponential
from 60 s, capped at an hour; a good sign-in clears it, and a restart resets the counters). The
change-password form keeps its **own** counter under `password:<address>`, so hammering one form
cannot lock you out of the other and neither form is an unthrottled oracle for the same secret.
The refusal is the same sentence for every kind of failure — one account, so the response must
not rank reasons — and each refused attempt writes a `login-denied` or `password-denied` event you
can read at `/api/events?source=auth`. Neither ever becomes an overview alert: a password guess is
not an outage, and a page that blinks for both trains you to ignore the ones that matter.

## Configuration

Everything comes from the environment (see `.env.example` for the annotated list). At
startup a `.env` next to the checkout is loaded first if it exists — as a *seed*: a
variable the container, systemd unit, or your shell already set always wins. Point
`DASH_ENV_FILE` somewhere else to keep several installs on one box. `.env.example` is
documentation and is never loaded, and `scripts/dev-server.sh` exports `.env.dev` itself
(see the quickstart) because dev settings must not leak into a production process.

| Variable                              | Meaning                                                        |
| ------------------------------------- | -------------------------------------------------------------- |
| `HOST_TARGETS`                        | `name=url` per host running the agent; a bearer token may ride in the URL userinfo (`http://TOKEN@host:9120`). An `https://` URL is dialled as a *protected* agent instead: verified against the dashboard's own root CA and presented with its client certificate, with a revoked host refused before the dial (`certs.py`, `collectors.AgentTls`) |
| `GUFO_BASE_URL` / `VLLM_BASE_URL`     | LLM engines; unset means *not deployed here*, and its half of the page disappears |
| `RATE_WINDOW_SECONDS`                 | the Δ window behind every measured rate — tokens/sec, bytes/sec, jiffies→CPU % (default 10); each value carries the window it actually got, and `/system`'s footnote prints that, not this default. A window the poll loop cannot honour — the ~0.2 s catch-up after a fetch slower than the interval, or a base older than 2× the window — answers one `n/a` instead of a spike, and a rate 8× above the last one is held until a window measured from a **different** sample confirms it (phase 13) |
| `DASH_HOST` / `DASH_PORT`             | bind address for the dashboard itself (default `127.0.0.1:8090`; the container sets `0.0.0.0`) |
| `HOST_INTERVAL_SECONDS` / `LLM_INTERVAL_SECONDS` / `NUT_INTERVAL_SECONDS` | how often each source is polled (10 / 2 / 5 s) |
| `DISKS_INTERVAL_SECONDS` | how often the disk-health source re-reads each agent for SMART (default 300 s — SMART is not a per-second signal). No targets of its own: the `disks:<host>` jobs exist exactly when `HOST_TARGETS` does |
| `HOST_TIMEOUT_SECONDS` / `LLM_TIMEOUT_SECONDS` / `NUT_TIMEOUT_SECONDS` | per-source fetch timeout — one slow source never holds up the others |
| `DISKS_TIMEOUT_SECONDS` | the disks fetch's own budget (default 30 s), because the agent runs `smartctl` inside its snapshot handler and a wedged SMART pass must not read as a dead host |
| `GUFO_API_KEY` / `VLLM_API_KEY`       | only if an engine is behind a bearer token; they never leave the server |
| `NUT_HOST` / `NUT_PORT`               | upsd address — **whatever port it really listens on**, not always 3493. Reads are unauthenticated in stock NUT |
| `NUT_USER` / `NUT_PASSWORD`           | only needed for instant commands (battery tests)                |
| `NUT_ALLOW_ACTIONS`                   | `1` enables the one write endpoint that dials **anything** — the `/api/auth/*` and `/api/certs/*` writes touch only this process and its `meta` table |
| `NUT_SIMULATE`                        | `1` replaces upsd with a **labelled** simulator (development only) |
| `DASH_READ_ONLY`                      | `1` disables every mutating endpoint regardless of other flags  |
| `DASH_DB`                             | SQLite path (default `data/dashboards.sqlite3`)                 |
| `DASH_ADMIN_PASSWORD`                 | the admin password **seed**, needed only on the first boot of a database — see *Signing in* above |
| `DASH_SESSION_HOURS`                  | session lifetime (default `720` = 30 days)                       |
| `DASH_COOKIE_SECURE`                  | `1` marks the session cookie `Secure`; off because dev is `http://127.0.0.1`, and a request that arrived over `X-Forwarded-Proto: https` is treated as secure either way |
| `DASH_PBKDF2_ITERATIONS`              | verifier cost (default `600000`). The knob exists for the test suite; leave it alone in a deployment. Raising it on a real box does take effect: the next successful sign-in re-hashes a cheaper stored verifier and keeps the signing key |
| `POLL_MS_SYSTEM` / `POLL_MS_LLM` / `POLL_MS_UPS` | how often the *browser* refetches each page (10 s / 2 s / 5 s) — shown in the page footer. `/disks` has no `POLL_MS_*` of its own and polls at a fixed 30 s: its payload only moves when the `disks` job re-reads the agents |
| `DASH_RELOAD`                         | `1` makes `uv run dashboards` watch the source and restart on a change — development only, and every poll loop restarts with it |
| `DEBUGPY` / `DEBUGPY_PORT`            | `DEBUGPY=1` opens a debugpy listener (default 5678) without blocking startup |
| `RETAIN_RAW_HOURS` / `RETAIN_MINUTE_DAYS` / `RETAIN_HOUR_DAYS` | history rollup and pruning |

A source that is not configured answers `404 {"configured": false}` **without dialling**,
and the page says "not configured" instead of showing a red panel for something you never
installed.

## Architecture

```
agent/host_agent.py (each host)      gufo / vLLM            upsd (NUT)
        │ GET /snapshot                    │ GET /metrics           │ LIST UPS / LIST VAR / LIST CMD
        │  (twice: system 10s, disks 5m)   │ + /slots (gufo)        │
        ▼                                  ▼                        ▼
src/dashboards/collectors.py ────────────────────────────────────────────┐
        │  parse + Δcounter/Δt (rates.py)                                │
        ▼                                                                ▼
sources/host.py · disks.py · llm.py · nut.py               poller.py (one task per source)
        │        samples                    events                      │
        ▼                                                                 ▼
store.py  ── SQLite (WAL): sample(source,host,metric,res,ts) + event + meta ──  api.py  → web/
                                                    ▲
auth.py ── verifier + session key, loaded once at startup (no row and no seed → no server)
certs.py ─ root CA + client cert, minted once at startup (unreadable row → no server)
```

* `poller.py` — every source gets its own asyncio task, its own health record, and its own
  error handling. A dead host keeps its last good values and is labelled stale; it never
  blanks or blocks another source. Disk health is a source of its own (`disks:<host>` in
  `/api/health`, 5-minute cadence, its own fetch timeout) reading the *same* agent
  `/snapshot` the system page reads — a separate task is what keeps a SMART poll out of the
  10-second utilisation poll and lets drive history go stale without blinking `/system`, and
  `alerts.py` is why one dead agent is still one line on the overview rather than two. And it never quietly *stops*: the task is that source's only
  poller, so a SQLite write that gets refused is reported (`ok: false`, the real reason, the
  numbers aging, one line in the event log) instead of freezing the source under a green dot.
* `store.py` — raw samples roll up to 1-minute and 1-hour averages and the raw rows are
  pruned, so a year of history is a few hundred MB rather than a disk emergency. Nothing a
  per-request path asks is answered by a whole-table scan **on every call** (phase 14): the two
  answers that used to be scanned on every call — `series_names()` behind `/api/metrics` and the
  row counts behind `/api/health` — come from a 60 s / 30 s cache, so the scan is paid once per
  window (its cost is the honest remainder in the known-gaps list) instead of once per request. `series_names`' is ended only by a write that can
  change it: a `(source, host, metric)` the store has never written, or any `DELETE`. A poll of an
  existing series leaves it alone, which is what makes the cache serve at all on a store nine pollers
  write to (task 04's live watch is the proof: 535 ms per call before, 1.8 ms median after), and the
  counts age on the clock. A chart's resolution comes from one capped compound statement instead of
  three full `COUNT`s per series. `last_maintain` and `size_bytes` are deliberately never cached —
  the first is how an operator tells a stalled rollup loop from a healthy one.
  The write side is windowed too: `maintain()` rolls up only the buckets that became due since its
  last run (read from `last_maintain`, overlapped by one bucket and snapped down to a bucket
  boundary, so a gap in polling is a catch-up scan rather than missing charts) and prunes on its
  full retention bound, one statement per resolution. It ends with `PRAGMA optimize` — the store's
  only statistics refresh, deliberately not inside a poller's commit — and the WAL is kept honest by
  `wal_autocheckpoint` plus a 64 MB `journal_size_limit` cap. On a 6.4 M-row store that took the
  once-a-minute write transaction from 5.4 s to a few milliseconds, which is what stopped a poller's
  insert losing its 5 s `busy_timeout` (known gap 4).
  Its `meta` table is the one place state that must outlive a restart goes (`get_meta`/
  `set_meta`/`delete_meta`). Its users are the admin credential below and, since phase 15, the
  certificate authority in `certs.py` — five `certs.*` rows and nothing else.
* `auth.py` — the admin login's decisions, in stdlib and without HTTP: a self-describing
  PBKDF2-HMAC-SHA256 verifier, an HMAC-signed stateless session cookie (no session table, and
  rotating the stored key is what evicts every other browser), a session-bound CSRF token, and
  an in-process login backoff. `load_auth_state()` is the startup half: the environment seeds a
  password **once**, the stored verifier wins from then on, and a server with neither refuses to
  start (see *Signing in*).
* `certs.py` — the fleet's certificate authority, in the same shape as `auth.py`: a pure lifecycle
  over the `meta` table, no clock it cannot be handed, no logging, and one fixed-text raise. The
  first boot of a database mints a **root CA** (`certs.root.key`/`.cert`, self-signed
  `CN=dashboards-root`, 10 years) and the dashboard's own **client** certificate
  (`certs.client.key`/`.cert`, `CN=dashboards`, 1 year); every later boot reads those rows and
  regenerates nothing, because a root that changes on restart untrusts every certificate already
  installed on a host. `issue_agent_cert`/`reissue_agent_cert` sign one server certificate per
  `HOST_TARGETS` name (`CN` = the host, SAN = the addresses it is dialled by) into
  `certs.agents`, and each entry's **bundle** — the agent's cert, the agent's key, the root *cert*
  (never the root key), a `# BUNDLE-REV <n>` line and the current `# REVOKED <serial>` lines — is
  stored verbatim so the bytes an installer places are the bytes the row holds. `revoke` marks the
  host and re-seals every bundle, because the denylist lives inside each of them; `rotate_root`
  replaces the root, the client, and every agent at once. A stored PEM that will not parse (or a
  client leaf the stored root did not sign) is a **fail-closed startup**, the admin-password rule:
  the message is `sqlite3 "<db>" "DELETE FROM meta WHERE key LIKE 'certs.%'"`, after which every
  agent needs a fresh bundle. Every certificate carries a `SubjectKeyIdentifier` and every leaf an
  `AuthorityKeyIdentifier` naming that root, because OpenSSL's strict mode — the one Python's
  `ssl.create_default_context()` turns on, which is what the dial below builds — refuses a chain
  without them. The **dial** is `collectors.AgentTls` (task 03): with an `https://` `HOST_TARGETS`
  entry, the fetch verifies the agent against this root and presents this dashboard's own client
  certificate, so only this dashboard can read the host; a host marked `revoked` fails its `host:`
  and `disks:` jobs with `agent certificate revoked` *before any socket opens*, and because the
  status is a fresh `certs.agents` read on every poll, revoking takes effect on the next poll with
  no restart. An `http://` entry is untouched — same shared client, same bearer token — so the
  rollout is per host. The private keys are credentials like any password: never served, never
  logged, and the root key never leaves the row that holds it.
* `severity.py` — the single green/amber/red table (`THRESHOLDS`, plus `INVERTED` for the
  metrics where lower is worse). Rated values in the API payloads travel with a sibling
  `severity` (`cpu.severity.usage_pct`, `memory.severity`, `disks.severity`, a UPS card's
  `severity.charge_pct`, `severity` inside the rated LLM
  cells such as KV pressure, `/api/summary` rows), computed server-side, so every page
  colours the same way and a value nobody reported renders `n/a` instead of green. A metric
  published as a 0-1 ratio is rescaled *for the verdict only* — the number printed stays
  what the upstream published. There is no `gpu.*` row: these are LLM servers, a busy GPU
  is the job, so the GPU card (and the fleet GPU column) renders uncoloured at every
  utilisation — the `gpu.*` history series are still stored and charted. Drive health gets two
  rows: `disk.temp_c` (amber 50 °C, red 70 °C) and `disk.percentage_used` (amber 80 %, red
  100 % — an SSD that has spent its rated wear is a replacement). The sector counters
  (`disk.reallocated`, `disk.pending`, `disk.uncorrectable`) and `disk.power_on_hours` have
  **no row on purpose**: a non-zero counter is an alarm chip on presence, zero is the absence
  of a chip and never a green "healthy drive", and an odometer has no bad value.
* `alerts.py` — "what is wrong right now", as data. `alerts.build(settings, job_states,
  host_payloads, engine_payloads, ups_payload, recent_events)` is a pure projection of the
  state the poller already keeps plus the verdicts `severity.py` and the UPS health checks
  already reached — no I/O, no thresholds of its own — and `/api/summary` returns it as
  `alerts`, worst first: `{id, severity, source, message, href, at}`. A configured source
  that stopped answering is `fail`; one that is stale but still serving its last good value
  is `warn`; an **unconfigured** source never alerts; a dead source is one line rather than
  one per stale metric; the list dedupes per (source, metric) and is capped at 12 with a
  marker that says how many it hid.
* `api.py` — the JSON every page reads: `/api/config`, `/api/health`, `/api/events`,
  `/api/history`, `/api/metrics`, `/api/summary`, one `snapshot` + `history` pair per
  dashboard (`/api/system/*`, `/api/disks/*`, `/api/llm/*`, `/api/ups/*` — including
  `/api/ups/commands`, which answers what may be sent to each UPS right now and why not when it
  may not), and the certificate authority's own surface (`/api/certs`,
  `/api/certs/<name>/bundle`, `POST …/rotate`, `POST
  …/revoke`, `POST /api/certs/root/rotate`). GETs everywhere except `POST /api/ups/command`,
  which stays the **only** route that dials anything: the `/api/certs/*` writes are `meta` row
  writes through `certs.py`, the same class of write `POST /api/auth/password` is, and a
  revocation's whole effect is that the next poll refuses to dial (see `certs.py` below).
  Reads there are pure — `certs.read_state` is the request-time read and `certs.ensure_certs` the
  startup bootstrap — so refreshing the list cannot mint a certificate, and it reports the
  **stored** authority even after a root rotation the running process has not picked up yet. Two rules make the pages legible: a source with
  no env config answers `404 {"configured": false}` **without dialling** (so a page says
  "not configured" instead of going red), and a history query for a series that does not
  exist answers an empty series instead of an error (so a card asks for every plot it could
  draw and reads `n/a` for the ones the drive never reported). The four `history` routes take
  one batched door into the store (`api._history_batch` → `store.history_many`), so a page's
  chart request is one grouped resolution query plus one index seek per series rather than four
  queries per series — and the JSON it answers with is the same document the per-series loop
  produced, series for series and in the same order (`tests/test_api.py` pins that against
  points read straight out of the store with `query()`). `/api/disks/snapshot` is the
  drive-health surface: one entry per host with its physical disk rows, the agent's `smart`
  block verbatim, `smartctl_available` (`true` / `false` = install smartmontools / `null` =
  the agent never said), a `severity` beside each row's rated numbers, and a `fleet` block
  summed here so the page does no arithmetic — a host that has not answered yet is listed as
  an `unreachable` stub of `n/a`s and counted, never summed. `/api/config` carries
  `disks.interval_seconds`, which is why a drive card four minutes old is behaving, not
  broken. `/api/summary` grew a `disks` block with that page (the same `fleet` sums plus one row
  per host — counts, `smartctl_available`, and `failed_devices`, so a notifier learns *which*
  drive the hardware called `FAILED` without a second call); it is additive, exactly as `alerts`
  was, and the key paths of both are pinned with and without targets configured.
* `web/` — five static dashboard pages (`/`, `/system`, `/disks`, `/llm`, `/ups`) plus the three
  admin pages (`/login`, `/settings`, `/certs`), one stylesheet, hand-rolled
  SVG charts (`charts.js`), and a masthead status dot per dashboard job (`disks` has its own:
  the same agent can answer the 10-second utilisation poll and have a wedged SMART pass). At
  ≤640px the five tab links leave the bar and come back as a dropdown under it, opened by the `☰`
  button (`/login` renders no tabs, so it has no button either), and above it the masthead stays
  the one row it has always been. No framework, no CDN, no bundler, and no narration: a page never
  explains its own pipeline, so the words on screen are the ones you act on — a unit, a `Δ10.0s` provenance tag, a
  `SIMULATED` badge, or the sentence beside an empty panel. The overview (`/`) is exactly two panels — a
  **Warnings & errors** list built from `/api/summary`'s `alerts` (each row links to the
  dashboard that explains it) and the **Fleet** table — and nothing else: an empty alert
  list reads as an explicit "all clear", and a live problem moves the panel above the
  table. A host that is not answering keeps its row — dimmed, every number `n/a` — so the
  fleet never quietly gets smaller and last good values are never mistaken for live ones.
  A big colour-coded number is `Dash.hero(el, {...})` on the
  `.hero` / `.hero-bar` styles, coloured by the `severity` in the payload via
  `Dash.severityFrom()` — the only colour vocabulary is `ok` / `warn` / `fail`, and a value
  with no verdict renders `n/a` with no colour at all. A battery is
  `DashCharts.battery(el, {charge, severity, state, label})`: one inline SVG whose fill *is* the
  charge — clamped to 0–100, never rounded up, clipped to the plate so 0 % is an empty shell —
  coloured only by the payload verdict, with a shape per state (solid shell on line, bolt
  charging, dashed outline on battery, a dash through the body when there is no reading) and a
  `<title>` / `aria-label` that names it ("apc: Charge 100 percent, on line") unless the number
  beside it already does. Each `/system` host is one panel led
  by exactly six of them — CPU %, MEM %, TEMP, DISK % (mount underneath), GPU busy (VRAM, the
  APU pool and the card's temperature in the footnote — no temperature is printed when the
  driver exposes no sensor, never `0 °C`; and likewise never coloured and with no bar: a busy
  GPU is the job on an LLM server), and NET on two lines (↓ in / ↑ out, never coloured: a byte
  rate has no good/bad). Under the numbers, **each panel charts only its own host** — behind a
  collapsed **Charts** toggle, because the default view is current stats and a fleet of ten
  hosts each drawing three plots is noise: the summary reads `▸ Charts` with the window in it
  (`1h`, `24h` …), and opening it is what builds and paints the charts — instantly, from the
  response the last refresh already fetched, and repainted on every refresh after that while it
  stays open. Expanding one panel never stretches its collapsed siblings
  (`.grid.items-start`). The stack is utilisation
  (CPU, memory, worst disk), network (↓ in / ↑ out), and GPU busy for a host that reports
  cards — three 120px SVG charts, each with its own legend and its own `aria-label` naming the
  host and the plotted metrics (`LineChart`'s `ariaLabel` option), never a second host in sight. The
  fleet-wide charts, the nine-figure fleet-totals panel and the host/metric detail picker are gone, and
  so are the per-core charts, while `cpu.usage_pct@coreN` stays in SQLite. Everything else —
  load, clock, disk I/O, uptime, GPU power and the per-label temp breakdown, filesystems,
  processes — folds into a collapsed
  "More detail" disclosure. Each panel pulls its series in **one** `/api/system/history` request
  (`hosts=<that host>&metrics=…&range=…`) every refresh, stack open or not, and a host that stops
  reporting takes its panel, its Charts toggle and its charts off the page.
  `/disks` is the drive-health page: **one card per physical drive** (the agent's
  whole-`/sys/block` list — never a partition, never a mount), led by the device path and the
  drive's own verdict word (`OK` / `FAILED` / `unknown`, coloured only by `severity.health`), then
  three equal cells — **Temp**, **Power-on** hours, **Wear** — coloured by `disk.temp_c` and
  `disk.percentage_used` from the API, with the odometer deliberately uncoloured because
  `severity.py` rates no power-on hours. The sector counters appear as **red chips that exist only
  while non-zero**, so a healthy drive shows no alarm row at all rather than a wall of zeroes.
  A host whose SMART cannot be read keeps its cards, dimmed with every number `n/a` and one
  `.banner` line saying why — `smartctl not available on <host>` when the agent reported the binary
  missing, its own sentence when it reported something else, and "not answering" when the agent is
  down — never a red panel, because a missing binary is unconfigured, not broken. The header's
  drive counts are the API's `fleet` block (hidden below two hosts, so one box's sums never
  duplicate its own cards), and each host's **Charts** disclosure behaves exactly like `/system`'s:
  collapsed, built only while open, and fed by one `/api/disks/history` request per host per
  refresh naming `disk.temp_c@dev` and `disk.percentage_used@dev` for every drive it has.
  `/llm` opens with
  the **fleet**: one block above the panels — `ALL ENGINES`, an `N of M engines` tag, the note
  *sums only engines answering now*, then **running / waiting / prompt tok/s / decode tok/s /
  total tokens** — and every number on it is `fleet_totals()`, so the page sums nothing itself.
  A dead engine keeps its last-good numbers in its own (stale-labelled) panel but is dropped
  from a total presented as current: the tag counts what answered, names the missing engine in
  its tooltip and dims while the sums are partial. Nothing on the block is coloured —
  `severity.py` rates no throughput and no queue depth, because 0 tok/s on an idle fleet is
  healthy — the dot is reachability, and `fleet.seams` (how the two engines count prompt
  tokens differently) is a tooltip on the prompt sum rather than another line of ink. Below
  two configured engines the block is hidden: a cross-engine sum of one engine duplicates that
  engine's panel. Below the fleet block — with the page's shared `.85rem` gap, as everywhere else
  in the section stack — sits the **stats strip**: one card per configured
  engine — reachability dot, name, age stamp, the **KV-cache bar** (the one rated cell: the
  fill and a breach's text take their colour from the payload's `severity` and nothing else),
  then `prompt tok/s` and `decode tok/s` with their provenance tag (`Δ10.0s`, scraped,
  estimated), `total tokens`, the sessions this engine reports (`slots busy` counted from
  gufo's `/slots`, or `running`/`waiting` for vLLM, plus `waiting`), `prefix cache hit`,
  `spec accept` (gufo), `queue time` with its `p95 …` foot (vLLM) — and red alarm chips for
  preemptions / GPU-context losses that exist only while non-zero. Then the engine panels
  hold the detail the strip does not print: two big
  throughput numbers (decode, prompt — uncoloured, because 0 tok/s on an idle server is
  healthy) with their provenance tag, and the latency rows (TTFT, TPOT) each with a `p95 …`
  foot line and its own sparkline over the selected window. Under the gufo panel's
  **`sessions (GET /slots)`** label sits the **slot grid**: one card per parallel slot, keyed by
  the slot's own id, created once and patched in place so a busy slot never flickers — request
  id, prompt tokens (with `processed …` while prefill runs), cache hit and its share of the
  prompt, generated tokens, remaining, context, and the model beside the slot number. A busy
  card is a border, a glyph and the word `processing`, never a green/amber/red verdict (a slot
  generating tokens is the job). Every cell reads exactly one key of the captured `/slots`
  shape — no `a ?? b` fallback chains — so a field rename fails a contract test instead of
  printing dashes, and `-1` sentinels print `idle`/`n/a`, never a negative countdown. When
  `/slots` does not answer, the panel says so with the API's own sentence rather than rendering
  a card of nothing, and vLLM's panel carries one line (*exposes no per-slot JSON*) and no grid.
  No row appears in both places —
  one value, one home — and there is no peak-context cell, because this page prints a number
  the upstream published or `n/a`. The four trend charts sit below the panels
  at half height, and one `/api/llm/history` request per refresh feeds all of it. With a
  single engine configured the page is one clean card in the strip and one clean panel —
  never a red half for a server you do not run. Each UPS card (`/ups`) opens with its battery glyph and
  three big numbers — **charge %**, **load %**, **runtime left** — coloured from the card's
  `severity` dict, with the electrical readings (line in, output, battery volts and amps,
  battery °C) kept below them in smaller muted type because they are what you read *while* the
  UPS is on battery. Health checks, the battery-test buttons (with their `DANGER`
  confirmation) and the NUT variable dump are unchanged, just second. The `Last self-test`
  check grades the **outcome** of the driver's word and not its phrasing: a pass
  (`Done and passed`, the sentence this fleet's CyberPower answers) reads `ok` and raises no
  overview warning, a fail reads `fail`, and a pack that has never been tested —
  `No test initiated` or no variable at all — says the same "run a battery test" sentence as
  `unknown`. Only a word the map has never seen stays a warning, printed verbatim so it can
  be added.
  The four event feeds (`/system`, `/disks`, `/llm`, `/ups`) are a **paged window** over the `event`
  table rather than a printout of it: the list is a bounded box that scrolls, 50 events to a
  page, with `1–50 of 200` between `‹ prev` and `next ›` (disabled at the ends) underneath.
  One helper, `Dash.eventsPager()`, renders every feed and each keeps its own row markup; the fetch
  asks `/api/events` for 200 so there is a page 2 to reach, and the endpoint itself is
  unchanged. Reading page 3 survives a poll; a refresh that brings new events goes back to
  page 1, because page 3 of a list that just changed is not the history you were reading.

## Testing

```bash
uv run pytest                                  # unit + API tests, fully mocked, no network
uv run pytest --cov                            # coverage gate
set -a; . ./.env.dev; set +a                 # the live suite reads the same env as the app
uv run pytest -m live --live                   # optional: real fleet / engines / upsd
uv run pytest -m store_perf --store-perf -s    # optional: the store's hot-path timings (phase 14)
uv run python scripts/store_perf_probe.py      # the same measurements as a report in data/logs/
DASH_WATCH_SECONDS=1500 uv run python scripts/watch-store-perf.py
                                               # ... and the live watch: 25 signed-in minutes against
                                               # the running dev server, counting store-error and WAL
uv run ruff check src tests agent && uv run pyright            # lint + types
./scripts/capture-fixtures.sh                  # re-record ground truth: host agents, UPS replies, gufo /slots
./scripts/capture-fixtures.sh --with-llm        # ... and the engines' /metrics while they are up
SMART_HOSTS="host-a-ops host-b-ops" ./scripts/capture-fixtures.sh
                                               # ... and smartctl per physical disk: plain smartctl,
                                               # `sudo -n` if that is denied; scrubs serials/WWNs
bash .agents/validate.sh                       # all of the above + `node --check` on every page
                                               # script + repo hygiene, with the 94% coverage floor
```

Test philosophy: **real captures as fixtures, mocks for behaviour.** Anything that must
match an upstream (`/proc` layouts, vLLM metric names, NUT protocol framing) is asserted
against a verbatim capture in `tests/fixtures/`; behaviour that needs a failure — upsd
refusing a command, an engine returning 500, a host rebooting — is a fake. The `live` tests
(`tests/test_live_fleet.py`) are the bridge: they SKIP unless you pass `--live`, each one
also skips when its source is unset (**source `.env.dev` first** — run bare and they all skip
quietly, which reads exactly like a pass), they drive the production code paths
(`collectors.*`, `NutMonitor.collect`) against whatever hardware is reachable, and they never
write — a battery test on live hardware is not a unit test.

`tests/auth_contract.py` is two constants and the reason for them: every test that starts a
server seeds the admin password `testpass` (a server with no stored verifier and no seed
refuses to start, so a test that wants a running app has to give it a credential the way
`.env.dev` does) and hashes it at 1 000 rounds through that same `pbkdf2_iterations` setting
instead of the real 600 000 — ~0.3 s per hash times a hundred-odd servers is not a slower suite,
it is a suite nobody runs. The real cost is pinned where it belongs
(`test_the_default_cost_is_the_owasp_figure` and the config default test), so lowering it here
cannot lower it there. Its partner is `tests/auth_client.py`: `sign_in(client)` posts that
password once, asserts the sign-in worked, and puts the returned CSRF token on the client's
default headers — which is what keeps the ~200 pre-existing HTTP assertions asserting the
behaviour they were written for instead of the new gate.

`tests/test_auth_api.py` is the perimeter, and it is deliberately awkward in one place: every
anonymous request runs with `follow_redirects=False`, because a client that follows them would
fetch the login page and report `200` for a route that refused it — the way a gated suite ends
up passing while testing nothing. It also walks the *served* route table
(`test_every_route_that_is_not_public_requires_a_session`), so a route a later phase forgets to
protect fails there rather than in a browser, and it proves the one refusal that matters most on
the wire rather than on a status code: a `POST /api/ups/command` without the CSRF token answers
`403` **and the scripted upsd records nothing**, while the same request with the token still
reaches it — and `driver.killpower` still needs the word `DANGER` behind the session, because a
fifth gate that quietly replaced the fourth would be the worst kind of regression.

`tests/test_auth_docs.py` tests the paperwork, because the paperwork is what an operator holds
when the dashboard will not come up. It reads `.env.example` and `.env.dev.example` and demands
that every `DASH_*` auth setting is declared there and that no secret-shaped **assignment** carries
anything but a placeholder (the same allow-list `bash .agents/validate.sh` enforces through
`git ls-files`, restated so a plain `uv run pytest` catches it on the working tree) — while the
local-testing word stays legal in prose, which is the only place it can be useful. It demands that
`scripts/dev-server.sh` still gets its readiness probe and its `status` from the public
`/api/health` and has grown no session, token or password of its own, and that both docs still name
the four public paths, the reset command, the four variables and the `DASH_COOKIE_SECURE=1`
deployment note. Nothing starts a server there; a sentence that quietly disappears is the bug.

`tests/test_certs.py` is the same kind of file for the certificate authority, and two of its tests
are structural rather than behavioural on purpose: they read `certs.py` itself and fail if it gains
a `logging` import or a raise that interpolates anything, because a stored PEM is a private key and
this app turns log lines and error strings into rows a browser reads. The rest runs the whole
lifecycle over a dict store — first boot persists exactly five rows, a second boot changes no byte,
rotate/revoke/root-rotate and their denylists, the bundle never carrying the root key — and one test
completes a real client-certificate handshake with the material a startup would write.
`tests/test_agent.py` runs the matching TLS matrix against the real agent handler, and
`tests/test_deploy_scripts.py` runs the installer in a sandbox where `install`/`chown` are faked, so
the `0640` mode, the byte-identical bundle and the `--status` probe (against a live TLS agent) are
proven without a root shell.

`tests/store_perf.py` is the second opt-in marker's machinery (`live` is the other). It seeds a
**production-shaped
SQLite file** — `SampleStore`'s own retention (`raw 48 h / 1m 30 d / 1h 400 d`), the fleet's real
metric names, the real 10 s cadence: ~6.4 M rows and ~720 MB, the dev DB's order of magnitude — and
times every hot path of `store.py`/`api.py` against it, with `EXPLAIN QUERY PLAN` for the queries
phase 14 changes and a two-connection race that reproduces the `database is locked` line in the
known-gaps list — beside the **pre-fix control** of the same race, because a clean race that never
met a lock would prove nothing. Every pass that *writes* (a rollup catch-up, a race) runs on a
scratch copy of the seeded file, so the baseline the next measurement compares against comes back
exactly as it went in. The default suite builds that store and asserts its **shape and determinism**
(row counts, retention windows, rollups that are the mean of the raw rows they came from, a second
`maintain()` that changes nothing) but never its wall time — except behind the marker, where
`store_perf.BUDGETS` is the phase's pinned regression table (14 ceilings, 2-3x the measured "after",
`maintain()` < 1 s, a racing insert at zero `database is locked`) and a stale budget pointer fails a
default-run test. The cached reads are reported twice —
**cold** (the cache invalidated before every run) and **cached** — because comparing a cache hit
against the baseline's full scan would book a 1 000x speed-up that is really just a cache. Only
`-m store_perf --store-perf` runs the timing passes, and `scripts/store_perf_probe.py` is the CLI
form that writes `data/logs/store-perf-baseline.{md,json}` (task 03's write-side run is
`store-perf-task03.*`, task 04's budget run `store-perf-task04.*`) for `data/logs/NOTES-store-perf.md`. Two rules keep it
honest: **no test ever opens `data/dashboards.sqlite3`** (the `--dev-db` flag exists for a human
running the probe read-only), and the seeded file is a cache under `data/perf/`
(`DASH_PERF_STORE_DIR` relocates it) because a before/after has to measure the same file — pytest's
`tmp_path` on this box is `tmpfs`, i.e. RAM, which times a store nobody deploys.

The non-timing half of that lives in `tests/test_store.py` and runs every time: a cache hit
issues **no** SQL at all (counted through `sqlite3`'s trace callback, never through a wall clock),
the series list is invalidated by the write that introduces a name and not by the poll that repeats
one (and the tracking that decides has a cap, below which it falls back to invalidating),
`last_maintain` is never served from a cache, and `pick_res_many()`/`history_many()` answer exactly
what the per-series calls answer — on a small store and on the seeded one, at every window.

One more file is worth knowing about: `tests/card_contract.py` is the table of
`/api/system/snapshot` paths the system page's per-host cards are allowed to read. It is
checked against all three captured host shapes (discrete GPU, APU, no GPU), over HTTP, and
again against the live fleet, so a card can never be "fixed" by inventing a number the agent
does not report. `tests/ups_contract.py` does the same job for the UPS page's hero row and
battery glyph (`charge %`, `load %`, `runtime left`, `battery_voltage`, the glyph's
`charger_status` + `on_battery`, the card header), against the two real UPSes — recorded
verbatim as `tests/fixtures/nut_<ups>.vars` by `./scripts/capture-fixtures.sh`, with the
device serials scrubbed — and again against live upsd. The captures earn their place: the
CyberPower answers `battery.mfr.date: CPS`, the APC's `battery.date` is a factory
placeholder, **neither** publishes `battery.temperature` or `battery.charger.status`, and the
two disagree on `ups.test.result` (the CyberPower has run a test and answers `Done and passed`,
the APC still answers the factory `No test initiated`), so a hand-written variable table would
have tested nobody's memory. `tests/slots_contract.py`
pins gufo's `/slots` rows the same way — hermetically from
`tests/fixtures/slots_gufo.json` (the verbatim `/slots` reply, captured whenever
`GUFO_BASE_URL` is set; the idle-slot rows are the shape the grid must handle) and again
against the running engine. It exists because that table was once guessed: the old slot
table read field names the server never published and rendered dashes forever. It also picks
the **canonical name of each fact** — the live server answers `id_task` *and* `task_id` for
one request — and the page renders only the canonical key, so a rename fails a test instead of
quietly becoming a fallback chain. A busy
slot's `prompt` is the user's in-flight request text, so the capture script blanks it and
the page never reads it.

## Battery-test buttons

Instant commands are the only endpoint in the application that changes anything **outside this
process** (`POST /api/ups/command`; the session and certificate-authority writes change only this
app's own rows), and they are gated four times: `NUT_ALLOW_ACTIONS=1`, not `DASH_READ_ONLY`, an `upsd.users`
account that actually has the command, and a confirmation in the UI — destructive ones
(deep test, calibration, `load.off`) require typing `DANGER`. Two more sit in front of those
(since the login landed): a session, and this session's CSRF token when the write arrived on the
cookie — additive, never a replacement, so the typed `DANGER` is still what cuts power. The server
re-checks every gate on every request; hiding a button is not a safety control. Commands that would cut power are refused
outright while the UPS is already on battery.

Give the app a narrowly scoped NUT user instead of a god-mode one — per-command `instcmds`,
not `actions = -`:

```ini
# /etc/ups/upsd.users
[dashboards]
    password = "..."
    instcmds = test.battery.start.quick
    instcmds = test.battery.start.deep
    instcmds = test.battery.stop
```

One command per `instcmds` line — that is what `man 5 upsd.users` specifies ("to specify
multiple commands, use multiple instances of the instcmds field"), and a comma-separated list
on one line is not that. `instcmds = all` is the alternative, and the fleet runs that: every
command the drivers advertise, including the ones that cut output power. Nothing about the
gates changes — the risk tier, the typed `DANGER`, `NUT_ALLOW_ACTIONS` and the on-battery
refusal are what prevent a click from becoming an outage, because upsd gives the dashboard no
way to ask what an account is allowed to send.

upsd authenticates with `USERNAME` + `PASSWORD` (see `HELP` on your own server for the verbs
it accepts — `USER`/`PASS` are not among them in 2.8.5); a user needs `instcmds`, never
`actions = -`.

`deploy/nut-sudoers` is the ruleset that lets the `ops` account read (and scoped-write) those
files: `sudo install -m 0440 -o root -g root deploy/nut-sudoers /etc/sudoers.d/dashboards-nut`.
Read `upsd.users` before you write it — `upsmon` authenticates from the same file, so
overwriting it blind can take the box down at the wrong moment.

Bind upsd to loopback (`LISTEN 127.0.0.1 3051` in `upsd.conf`) when the dashboard runs on the
same box, and to a real interface plus a source-scoped firewall rule when it runs elsewhere —
and do not try to scope it by client inside `upsd.conf` instead: **NUT 2.8
removed the `ACL`/`ACCEPT`/`REJECT` directives** (a build without TCP Wrappers logs
`ACL in upsd.conf is no longer supported - switch to LISTEN` once per line and ignores the
line), so `LISTEN` plus a host firewall rule is the only access control `upsd.conf` offers,
and an unauthenticated `LIST VAR` from any routed source is the normal state of a NUT server.
`NUT_SIMULATE=1` stands in for upsd during
development; everything it produces is badged `SIMULATED`, and it is never the default.

## Deployment

`Containerfile` is a two-stage build: `uv.lock` is resolved in the builder (exactly the
versions the tests ran against) and the runtime stage is slim Python with nothing but the
venv in it. The host agent is copied in too, so one image can monitor the box it runs on.
In the deployment repo the pattern is the same as every other service: quadlet container +
env template + nginx/SNI on the single domain.

```bash
podman build -t dashboards .
podman run --rm -p 8090:8090 --env-file dashboards.env \
    -v dashboards-data:/var/lib/dashboards dashboards
```

It listens on `0.0.0.0:8090` as an unprivileged user, and the SQLite history lives in
`/var/lib/dashboards` — put a volume there or every restart forgets the charts **and** the admin
password, because the verifier and the session key are rows in that database. `dashboards.env`
therefore needs `DASH_ADMIN_PASSWORD` for the first start of a new volume; with neither the seed
nor a stored verifier the container exits non-zero with the reason instead of coming up open, and
the same seed is ignored once the row exists, so it can be dropped from the env file afterwards.
With no sources configured `/api/health` answers `200 {"status": "empty"}`, so the container
passes its health probe before its env file is right instead of crash-looping.

Two more lines belong in that quadlet env template because this service faces the public domain:
`DASH_COOKIE_SECURE=1`, so the session cookie never rides plain HTTP (the app also treats a
request that arrived with `X-Forwarded-Proto: https` as secure, so a misconfigured flag degrades
rather than leaks), and the password itself — set once, then removable, since the stored verifier
wins. The nginx server block, its `X-Forwarded-*` headers and HSTS live in the deployment repo
like every other service here, so a change to how the edge forwards TLS is a change in that repo,
not in this one; the only thing this app reads off the proxy is that one scheme header.