The "Restricting permissions on the Synapse secrets" step chowned
$app_dir/data recursively, which also walks data/media_store — files
written by Synapse itself. Under rootless that is invisible (container
root maps to the docker install user, so everything is chownable), but in
rooted mode container root IS host root: the chown runs as the manager and
would fail per file, then fail the step, over files that must keep their
own ownership anyway. Same shape as the stoat fix, caught before it bit.
Scoped to the top-level files the hook actually writes — homeserver.yaml,
log.yaml, signing.key, .lp-admin-token — which is what the step name means.
Note this app was NOT producing the stoat symptom today: matrix's postgres
data lives at $app_dir/postgres, outside the directory being walked.
element/ keeps its recursive chown: one LibrePortal-written config.json
the container never writes.
Verified: reinstall clean, exit 0, homeserver.yaml + signing.key still
0600, media_store untouched.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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