Settings store
A small persistent key-value store for app settings and light state — always
available, no feature flag. Values are arbitrary JSON, saved to a
settings.json file in the OS config directory (keyed by the
About name). For real data, use the database
feature instead.
Frontend API (@elyra/runtime)
import { store } from "@elyra/runtime";
await store.set("theme", "dark");
await store.set("window", { pinned: true, tab: 3 });
const theme = await store.get<string>("theme"); // "dark" | null
const all = await store.all(); // Record<string, unknown>
await store.delete("theme");
await store.clear();
Rust API
The store is bound in the container, so commands can use it too:
use elyra::Store;
#[command]
async fn remember(ctx: Ctx, key: String, value: serde_json::Value) {
ctx.get::<Store>().set(key, value);
}
Store exposes get, set, delete, all, clear, flush and path.
Durability
Writes are atomic: the file is written to settings.json.tmp and renamed over
the target, so a crash mid-write can't leave a truncated settings file. The
previous good version is kept as settings.json.bak and used automatically if the
main file can't be parsed.
Write coalescing
set() / delete() update memory immediately and schedule a debounced flush
(250ms) on a blocking task, so a frontend that persists on every keystroke doesn't
write the file per keystroke. clear() writes through immediately, flush()
forces a write, and the last owner flushes on drop.
Capability
/__store/* is reachable from the frontend with the Store capability (granted by
default); store.clear() additionally needs Capability::StoreClear, which is
opt-in — see security.
Location and tests
The store lives in the app's data directory (settings.json). Store::at(path)
opens a specific file instead, and Store::fake() is an in-memory store that is
never written — swap it in with App::swap(Store::fake()) so a test doesn't
write into the real app-data directory.