Seed the movies demo once instead of on every boot

[tamohannes]

nu demo movies throws away everything you log the moment you restart it.

init ran on every boot and set the whole shelf unconditionally:

init = nu.kv.Transaction(
    State.total.set(len(_SEED_MOVIES))
    | ...
    | State.movies.set(_SEED_MOVIES)
    | State.selected.set(0),
)

So the second start overwrites the store with the four samples. The About page inside that same demo says "Every row lives in rocksdb. Restart, everything is still there," which makes it the worst place for this to happen: persistence is the claim the demo exists to make.

Fix

Guard the seed on State.total.missing() so it fires only against a store that has never been written. selected stays an unconditional set, since it is a cursor into the detail page rather than user data. Both copies get the change, examples/movies.py and the bundled nu demo movies.

Why not .init()

That was the first attempt, since counter, sampled and telegram_echo all seed with .init() and it reads better. On an empty store it left the shelf empty: the item leaves seeded, and State.movies.init(_SEED_MOVIES) wrote nothing, so Missing on a ShapesListRef seems to be false even before anything is written. Might be intended for collection Forms, might be worth its own look. Guarding on one item leaf sidesteps it and has the nicer property of making the seed all or nothing.

Verification

Store wiped between runs, then:

	before	after
first start, empty store	seeds 4 rows	seeds 4 rows
restart with a 5th row added to _SEED_MOVIES	5th row appears in the store, existing rows replaced	store untouched, original rows intact

Editing the seed list is a stand in for a row you logged yourself: it proves whether boot number two writes over what is already there.

🤖 Generated with Claude Code