Savings and statistics

mbx stats shows what sharing builds has saved on this machine, with the date counting began and durations such as 50m 59s or 2d 4h.

mbx stats
mbx stats --json

The report combines lifetime savings with a snapshot of the cache and its recorded workspaces. The Store screen in mbx tui shows the same savings and sharing figures. mbx cache stats remains the smaller report about what the store currently holds.

What the numbers mean

Figure	Meaning
Compiler time avoided	Estimated compiler work skipped by cache hits, accumulated across builds. Parallel compilation means this is not elapsed wall-clock time saved.
Cache hits	Compilations served from cache since counting began.
Pruned by mbx	Cumulative bytes collected from managed targets and the cache, including both automatic sweeps and explicit mbx gc runs.
Automatically pruned	Bytes collected by automatic sweeps, with a separate start date. Older versions did not distinguish automatic from explicit GC, so their history is not guessed or backfilled.
Requested removals	Bytes removed by confirmed migrations or explicit workspace removals, kept separate from pruning.
Copying avoided	Cumulative output bytes materialized by reflink rather than copying. This is not the amount of disk space currently saved: files may later change or be deleted.
With separate caches	Sum of logical cache bytes reachable by each live recorded workspace, counting shared content once for each workspace.
Duplication avoided	A conservative lower-bound estimate: the separate-cache sum minus the entire shared store, floored at zero. Unclaimed objects in the store make this underestimate sharing.

The sharing estimate covers logical cache bytes, excludes target directories, and includes independent workspaces as well as worktrees. It does not measure physical filesystem blocks. On an active machine, builds can change the store while the report is being read. Workspace attribution walks cache records and targets; the TUI refreshes it every 30 seconds while the Store screen is open.

Dates use UTC. Missing savings history is shown as unrecorded; reading a report does not start a new ledger. The automatic-pruning period begins with the first ledger update from a version that tracks it separately.

A little personality

With the default savings = "quips", the text report and TUI add a line grounded in the recorded figures, such as “321 compilations served reheated. rustc can finish its coffee.” Set savings = "plain" or savings = "off" to omit the quip. Explicitly requested statistics are still shown.

The versioned JSON report includes version, store, savings, cache, and sharing. It uses integer bytes, nanoseconds, and Unix timestamps; an unknown start time is null. Its field names identify estimates and cumulative counters. JSON never contains quips.