Every install mints a uuid and pushes under it, and nothing ever cleans those
directories up. This remote holds 25: two live devices and 23 that stopped
writing. Each dead one still costs a round trip in the log pull and in each of
the three bank syncs -- roughly 400ms per peer per tick -- so they dominate
what is left of the background tick.
Diagnosis first, since the obvious theory was wrong. These are not the residue
of phone reinstalls: seventeen of them are frozen at the *same* instant
(2026-08-13T16:45:04) holding near-identical ~400-record copies of one log,
which is the signature of repeated fresh-install runs, not organic use. That
also means `adb install -r` preserving SharedPreferences was never the issue,
so no Android backup change is warranted on this evidence.
Dry-run by default, and the safety rails are the point:
* `plan_prune` only reads; it is what the default run prints.
* A device is prunable only when every record it holds is already held by a
device being kept. Against the live remote that is 20 devices and **zero**
records lost -- verified before writing the command, not after.
* `pc`/`phone`/`desktop` are never proposed: they carry pre-migration history
and `SYNC_LEGACY_DEVICE_ID` still names one as this device's own former path.
* `--apply` refuses without `--backup-dir`, and every peer's raw bytes are
written to disk before a single delete.
Nothing has been deleted; this commit only adds the tool.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LJ5YnA3CERitQ57HjMu2Qz
