Files

T

julian f87e4c0d6b feat(devices): live device-status footer across all categories

Generalise printer-only monitoring to every configured device. New
DeviceMonitor polls all enabled devices each tick (default 8s): printers
via rich readStatus(), relays/readers/cameras via the generic healthCheck()
reachability probe, flattened to one traffic-light (ready/degraded/offline)
+ detail, deduped (emit on change only), fail-toward-offline.

- device-status bus event + GET /api/devices/status snapshot.
- Pushed over the existing /api/ws (hello carries the initial set;
  device-status frame per change).
- Web: live-store devices map, WS handler, DeviceFooter chip-per-device
  (role label not vendor; click a degraded/offline chip for an issues panel).

Verified roleKind resolution + change-only emit on a fresh DB.

Note: the footer's UI surface (api type, router mount, i18n devices) rides
in the subsequent subscription commit due to shared-file overlap.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

2026-06-18 13:14:36 +02:00

4.0 KiB

Raw Blame History

type, tags, sources, updated

type

Printer status monitoring

Generalised 2026-06-18: the booth's all-device status footer is a separate, unified monitor across every category (relays/readers/cameras/printers) — see device-status-monitoring. This page remains the authority for the printer-specific rich status (paper/cover/cutter) + its SSE stream; both monitors run.

The booth must know a printer is in trouble before a driver presses the entry button and no ticket comes out. So the system polls each printer's live status (paper out, cover open, cutter jam, off-line) and pushes changes to the operator UI. A reliability control, like printer-roles-failover — not a threat-model one.

Where the status comes from (the safe-decode decision)

The raw print socket (TCP 9100) is write-only for us — it returns no paper/cover feedback. ESC/POS printers expose status via real-time queries (DLE EOT n). On the rongta-printer clone we probed, DLE EOT replies do NOT follow the canonical ESC/POS bit layout (the spec's fixed validation bits were wrong, verified on hardware 2026-06-14). Decoding those bits ourselves risked a false-healthy — reporting "paper OK" when it's empty — which is the dangerous direction for an entry lane.

Instead we scrape the device's own status web page (http://<host>/prn_stat.htm). The board decodes the bits itself into labelled Yes/No rows (Cover Is Open, Cutter Error, Paper End, Paper Near End, Printer Off-Line). We trust the device's decode over hand-decoding an undocumented clone.

This is captured as a device capability: MonitorableDevice.readStatus(): PrinterStatus in packages/devices. The Rongta driver implements it; the monitor is device-agnostic via isMonitorable(). A future printer with a different status mechanism just implements the same interface.

Status mapping (fail safe)

readStatus() maps to ready | degraded | offline:

status page unreachable / times out → offline (same signal as a dead printer; never throws),
page reachable but a recognised field is missing → degraded ("unexpected status page") — we do NOT claim "ready" off a page we didn't fully parse,
any fault flag true (paper end, cover open, cutter error, off-line) → degraded + a detail string ("paper out", …),
all five clear → ready.

The monitor (server)

PrinterMonitor (apps/server/src/printer-monitor.ts):

reloads the monitored set from devices each tick (so a newly-assigned printer is picked up without a restart), keeping only enabled, monitorable printers;
polls every PRINTER_POLL_MS (default 5000ms), never overlapping ticks;
caches the latest status per device id;
emits a printer-status event on the device bus only when status changes (deduped).

API / live UI

GET /api/printers/status — cached snapshot of all printers (no device round-trip).
GET /api/printers/status/stream — Server-Sent Events: full snapshot on connect, then one event per change. The booth SPA subscribes for real-time paper-out / offline indicators.
Any authenticated role may read (operational, not a setup action).

Verified on hardware (2026-06-14)

readStatus() against 10.0.10.6 → ready (all flags false); against an unreachable host → offline with "status page timeout" (no throw); bus emits on change and suppresses unchanged reads. Full repo typechecks.

Open / not yet done

Fault-state capture: we've only observed the all-clear page. The exact label text for an active fault (e.g. does "Paper End" flip to "Yes"?) should be confirmed by physically removing paper / opening the cover, to be 100% sure the scrape catches it. The parser is built to match Yes/No and degrade on anything unexpected, so this is a confidence check, not a blocker.
Tying a degraded/offline entry-dispenser into printer-roles-failover failover and the (not-yet-built) entry flow's all-printers-down policy (device-input-flow).

4.0 KiB Raw Blame History