Android half of ios#54. Expired stories were gone from the author's
device too, so there was no way to look back at what you posted.
🔴 This keeps something the interface told everybody would disappear, so
the shape of the feature is the argument for it being acceptable: off
unless switched on, labelled as what it is, and only ever holding stories
this account posted. `Vault.archive` refuses anything else — the caller
filters too, and this is the guard that survives the caller being
rewritten.
🔴 The archive is deliberately NOT written through `saveStories`.
Everything in it is expired by definition, and that path drops expired
stories on write — so reusing it would empty the archive on the next
pass. Separate record, and a test named for exactly that.
Archiving happens in `stories()`, before `saveStories` drops the expired
ones: the only moment they can be caught, since expired bytes leave on
write. That runs on every load, so the fold is idempotent.
⚠️ The setting is injected into `Session` as a lambda. The engine layer
has no Android dependency and must not read preferences, and an absent
value has to read as OFF.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
