The unit's data files are stamped with the versions that wrote them; the capture keeps the
definition the data belongs to; a restore never starts data under another version's
definition (unit restores refuse a mismatch; the off-site restore writes the snapshot's
definition); every tier's time is its data's; the conversion-copy release needs a dump on
the new engine. File-browser sync single-flight + no empty kept folder (R-695); the kept
view joins the folder's owning group, language switch resyncs (R-691); a restore-generated
login is not shown as the password (R-694). Red-proofs in
felhom.eu/documentation/audits/version-travel-2026-09-26/.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS
A step whose ladder entry carries engine_conversion {service, engine, from, to}
converts the database: the old engine alone, the check (owners, roles,
extensions, per-table row counts), pg_dumpall validated by its completion line,
the volume emptied only after the undo copy's marker is validated again, the new
engine alone, the load with ON_ERROR_STOP, the check again + PG_VERSION. Any
failure goes to the existing undo; a restart during converting is undone.
A PostgreSQL major move without the mark is refused before anything moves.
The old datadir's copy is kept until a backup is proven after the conversion.
17 tests, 9 red-proofs (audits/night-2026-09-26/B/).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS
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