docs/changelog/2026-07-05.mdx
Live metrics: msb metrics --watch and --follow
msb metrics gains a docker stats-style live mode. --watch refreshes the table in place at a configurable --interval (default 1s); --follow streams one JSON Lines object per sandbox per tick for scripting. Disk and network columns now render as per-second rates derived from consecutive samples — the one-shot table samples twice ~500 ms apart so it reads identically to a watch frame. --sort cpu|mem orders rows by usage.
msb metrics --watch --interval 500ms
msb metrics --follow | jq .cpu_percent
See msb metrics.
Sandbox state in metrics output
Every metrics row now carries a STATE: running, stalled (runtime alive but the sampler has not written a sample within three sampling intervals), or exited (the preserved terminal sample of a stopped sandbox). Named lookups (msb metrics my-app) answer in any state instead of pretending an exited sandbox is live, and --all opts recently exited sandboxes into the fleet view with their cumulative totals. The Rust SDK exposes the same data via SandboxMetricsReport / all_sandbox_metrics_reports_local.
Resize-aware CPU and memory denominators
The CPU column shows cores busy over cores allocated (0.80 / 2c) and MEM shows usage over the configured limit — both resolved from the catalog's active config at read time, so msb modify --cpus/--memory on a running sandbox is reflected on the next tick instead of showing the boot-time limit forever.
Crashed sandboxes no longer report as running
A runtime killed hard (SIGKILL, OOM, host reboot) never released its shared-memory metrics slot, so msb metrics — and the msb-metrics collector — kept reporting its frozen last sample as a running sandbox until slot pressure forced a reclaim. Registry readers now verify the slot owner's PID on every read and retire dead entries on the spot: the CLI reports them as exited, and collector export streams drop the series on the next tick.