The fold was killed after 120 s on the assumption it takes "well under a second". That holds
for ~100 small packs, not for the checkouts it exists for (#129712: 2,475 packs / 39 GiB): those
need a full repack, and a killed fold restarted from scratch on every update without a word,
so the worst-hit installs never converged.
- Bound raised to 20 minutes (measured: 750 packs / 530 MB of hermes-agent history fold in
5.8 s at 7.4 cores; a 39 GiB pack dir on a slow disk is a different order of magnitude).
- consolidate_lazy_fetch_packs returns None on timeout; the shared update_cmd_check reporter
(used by both `hermes update` and `hermes update --check`) prints the hand-fold command.
- on_fold_start announces a fold that will actually run (pack count past gc.autoPackLimit), so
a multi-minute first fold is not a silent hang.
- Test fixture disables auto-maintenance: each lazy fetch's detached gc otherwise raced the
test and folded the packs itself.
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