pi-mono/packages/chord/test/examples/23-keyed-watches.ts
Mario Zechner e9c0ff4d84 feat(chord): Chord v2 is the package's root
src/next is src (the main export), src/next-node is src/node with short subpaths (/http, /workers, /plugins,
/plugins/runtime, /app, /surfaces, /web, /react, /tui, /tui/launcher); the foundations get /json and /watch;
Chord v1 moves to src/old (/old, /old/node) until p2 runs on v2; tests and docs move likewise (test/, docs/,
test/old, docs/old). Durable and env import the foundations from their subpaths.
2026-11-02 22:36:55 +00:00

84 lines
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TypeScript

// Keyed watches and `at(key)`: a keyed document is watched per key; `handle.at(key)` in the factory makes one key a
// watchable (a state member here) that reads `initial()` while absent. A retirement arrives as `initial()` with
// `retired: true`, so a watcher can tell "deleted" from "changed back".
// Run from packages/chord:
// node --conditions=source --experimental-strip-types test/examples/23-keyed-watches.ts
import { BACKGROUND_CONTEXT } from "../../src/context/index.ts";
import { local, method, obj, str } from "../../src/contracts/index.ts";
import { defineState, type KeyedHandle } from "../../src/documents/index.ts";
import { createHost, defineFacet } from "../../src/host/index.ts";
const context = BACKGROUND_CONTEXT;
type Note = { body: string };
const Notes = defineState("notes", {
schema: obj({ body: str() }),
version: 1,
initial: (): Note => ({ body: "" }),
keyed: true,
});
const Notebook = local("example.notebook", {
version: 1,
params: {},
members: {
// The note "pinned" as a state member: `initial()` while absent.
pinned: obj({ body: str() }),
write: method(obj({ id: str(), body: str() })),
remove: method(str()),
},
});
// The example's own window into the object: its keyed handle, to watch other keys from outside.
let notes: KeyedHandle<Note> | undefined;
const facet = defineFacet((host) => {
host.serve(Notebook, (_, self) => {
notes = self.state(Notes);
const handle = notes;
return {
// Pinned while this attempt lives, and loaded before the object goes live.
pinned: handle.at("pinned"),
write: async ({ id, body }, ctx) => {
await handle.change(
id,
(draft) => {
draft.body = body;
},
ctx,
);
return null;
},
remove: async (id, ctx) => {
await handle.retire(id, ctx);
return null;
},
};
});
});
const host = createHost({ onError: (error) => console.error("background error:", error) });
await host.load([{ name: "@example/notebook", facet }], context);
const notebook = await host.get(Notebook, {}, context);
// A watch of the state member: every value call carries the value, its ops and the retired flag.
const pinned = await notebook.pinned.watch(context);
pinned.start(async (call) => {
if (call.kind === "value") console.log("pinned:", call.value, call.retired ? "(retired)" : "");
});
await notebook.write({ id: "pinned", body: "buy milk" }, context);
// A watch of one key; an absent key gives `undefined` (watch it once it exists, or pin it with `at`).
console.log("watch of an absent key:", await notes!.watch("later", context));
await notebook.write({ id: "later", body: "call Anna" }, context);
const later = (await notes!.watch("later", context))!;
later.start(async (call) => {
if (call.kind === "value") console.log("later:", call.value, call.retired ? "(retired)" : "");
});
await notebook.remove("later", context);
await notebook.remove("pinned", context);
// Frames are delivered after the commit, asynchronously: let them arrive before closing.
await new Promise((resolve) => setTimeout(resolve, 10));
await host.close(context);