Products have no durable storage that survives a new device

The need

Scarcity keeps a player's favourited collections. They shape the collection picker and may later feed the pre-selection ranking. Today they sit in host-provided local storage, so they die with the device and do not come back after a reinstall.

Where it stands

At 7475e70c the product storage surface is local_storage with three methods — read, write, clear — keyed by a plain String (rust/crates/truapi/src/api/local_storage.rs:11-53).

No RFC in docs/rfcs/ covers product storage at all. The storage-adjacent RFCs are all open PRs, and none of them is this:

• #603 — localStorage subscriptions and worker pending operations
• #71 — product session restore; same device, best-effort, reserved key
• #16 — Favourites API; the host's bookmarked-product catalogue, and explicitly "local to the host instance — no cross-host sync"

#513 is storage shared between products on one device. #598 (REQ1) explicitly puts this out of scope:

Syncing storage across a user's devices. Storage is per product and per device; nothing here changes that, and no requirement should assume it does.

That exclusion looks right for REQ1 — cross-product and cross-device are different mechanisms. This issue is the need the exclusion leaves without a home, rather than an argument to widen REQ1.

What we need

An answer more than an implementation:

• Whether durable per-product state surviving device replacement is in scope for Release 2, a later release, or not planned
• If it is not planned, that recorded somewhere citable, so products can design around it

Scarcity has an accepted fallback either way: keep favourites on the device and say so in the interface, or keep them out of the default collection choice so both minting surfaces still compute the same default. A documented "not planned" is a usable answer here — what we cannot design against is silence.

Consumer side: paritytech/scarcity-spa row R14 and scarcity-spa#25.

cc @gp0p3

Start with rust/crates/truapi/src/api/local_storage.rs:11-53 and review the referenced storage discussions and RFCs in docs/rfcs/, especially #513, #598, and #603. The work is done when the scope of durable per-product state across device replacement is decided for Release 2 or later, and that decision is recorded somewhere citable, including the not-planned case.