Sidebar system monitor

A Harness Web UI plugin that shows live CPU, memory, root-disk, and /tmp load at the bottom of the left sidebar, in the footer strip beside the Cordis panel action and above Settings.

• Wide sidebar: a 2×2 grid — CPU ▓▓ 34%, MEM ▓▓ 65%, DISK ▓▓ 38G, TMP ▓ 7G — in the footer strip, beside the Cordis panel action and above Settings.
• Collapsed rail: compact CPU / MEM / DSK / TMP lines.
• Hover the meter for CPU 34% · memory 65% · disk 38.2 of 98.0 GB free · /tmp 7.1 of 7.9 GB free.
• Bars shift accent → amber at the warning threshold → red at the critical one.
• Updates on the configured interval; pauses while the tab is hidden and keeps the last good sample when a request fails.
• ⋯ button in the meter opens a quick popover with on/off switches for CPU, Memory, Disk, and /tmp — the same live values as the Settings page.
• Settings → Plugins → System monitor configures every parameter live.

Settings

Everything is optional; the defaults below apply until the profile overrides a field. Open Settings → Plugins → System monitor and change a control — the write is live (no restart) and persists in the profile configuration.

Setting	Default	Meaning
refreshMs	2000	Poll interval in ms, 500–60000
showCpu	true	Render the CPU lane
showMem	true	Render the memory lane
showDisk	true	Render the root-disk lane
showTmp	true	Render the /tmp lane
diskPath	/	Filesystem the DISK lane measures
tmpPath	/tmp	Filesystem the TMP lane measures (falls back to os.tmpdir())
warnPct	60	Used-percent that turns a bar amber
errorPct	85	Used-percent that turns a bar red

How it works

Half	File	Role
Host	index.js	Registers the authenticated read-only route GET /api/sysmon.load on the shared Connection channel. CPU comes from os.cpus() time deltas; memory prefers /proc/meminfo MemAvailable and falls back to os.totalmem()/os.freemem() elsewhere; disk and /tmp capacity come from fs.statfsSync() (/ and /tmp, falling back to os.tmpdir()).
Client	client.js	Registers the meter into sidebar.footer.action and the page into settings.plugins.tab, and polls the route. Writes go through the Settings domain's configForms service, so revisions and persistence are handled by the Host. Styles use only --dsw-* theme tokens; copy is localized through the sysmon namespace (en, zh).

The route sits behind Connection's browser cookie, so the figures are never exposed on an unauthenticated web route.

Install and remove

Installed as the profile bundle @local/sidebar-sysmon from this directory (linked install, so edits here are picked up after the entry restarts):

plugin_manager install_bundle /path/to/dsh-sidebar-sysmon

Disable/hide it without uninstalling:

plugin_manager set_plugin include:sidebar-sysmon false
plugin_manager set_plugin include:sidebar-sysmon true

Remove:

plugin_manager remove_bundle @local/sidebar-sysmon

Development

Install the one runtime dependency (@deepseek-ai/schemastery, for the Config schema), then run the host tests:

npm install
npm test

The host half's route is covered by node:test against a stub Connection registry, including the live re-read of volatile settings.

CI (.github/workflows/ci.yml) parses both halves and runs the tests on Node 20, 22, and 24.

Notes

• The sidebar's global panel list has no insert slot, so the apps+ "More" launcher cannot host extra rows. This plugin uses the supported footer seat closest to it instead.
• CPU is the whole machine's busy share between two polls; a stale or very short gap triggers a fresh 150 ms measurement window.