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Para

@lyku/para-kit

import { createServerSourceHost, createSyncEndpoint, createSseTransport } from "@lyku/para-kit";

The build + runtime glue that turns .pui sync declarations into a running app (the spec’s P9 projection): para-kit emit writes the server artifacts and manifest, a host runs them, and one endpoint streams SyncEnvelopes to the browser over SSE. The handlers are SvelteKit-shaped but built on pure web standards (Request/Response/ReadableStream), so they run anywhere those exist.

The loop

Section titled “The loop”
.pui ──para-kit emit──▶ *.server-sources.pts + para-sync-manifest.js
                            ▼
        createServerSourceHost(serverSources, { transport })
                            ▼   one createServerSource per LIVE key
        createSyncEndpoint({ transport, host })      ← routes/para-sync/+server.ts
                            ▼   SSE: baseline + every publish
        createSseTransport({ url, eventSource })
                            ▼   the para-sync dumb-pipe contract
        the .pui binding — synced(subKey(declId, params), Schema)

para-kit emit

Section titled “para-kit emit”
Terminal window
para-kit emit src            # artifacts + manifest (+ endpoint, once)
para-kit emit src --check    # CI drift gate — fails if anything is stale

Walks the tree for .pui files, runs the same escape analysis the preprocessor runs inline (same moduleId, so client subscription keys equal host keys by construction), and writes:

  • <name>.server-sources.pts next to each .pui — the readable, ejectable server module (__paraServerSources: one { name, declId, schema, params, policy, run } per declaration). Regenerated boundary files — re-run emit, don’t hand-edit.
  • one flat app manifest ($lib/para-sync-manifest.js).
  • the conventional endpoint route — written once, never regenerated: yours to edit from the first byte.

Runtime pieces

Section titled “Runtime pieces”

createServerSourceHost(serverSources, { transport }) — lazily starts one createServerSource per live subscription key: N clients on one key share one timer and one sequence stream; distinct params are distinct channels. host.seedFor(declId, params) runs/ensures a source and returns its current envelope — the SSR seed for a +page.server.ts load.

createSyncEndpoint({ transport, host, onIntent }) — GET reads ?key=…&key=…, ensures any server sources behind them, sends each current envelope as the baseline, then streams every transport publish for those keys. It subscribes before seeding, so no publish is lost in the gap. POST delegates §13.1 intents to your onIntent (501 without one).

createSseTransport({ url, eventSource }) — the client read-side transport. Key-set changes coalesce into one reconnect per microtask; a late joiner on an already-open key is replayed the last envelope (idempotent — envelopes carry sequences); publish throws, because the read path is one-directional: writes cross as POST intents.

import { configureSynced } from "@lyku/para-sync";
import { createSseTransport } from "@lyku/para-kit";


configureSynced({
  transport: createSseTransport({
    url: "/para-sync",
    eventSource: (u) => new EventSource(u),
  }),
});

Spec

Section titled “Spec”

Ch. 11 §2, projection P9 — nine projections, one spine — and the server-source semantics in ch. 08 §13.8.