Node/Bun backend

The Node/Bun backend owns:

• native engine execution mode (auto | worker | inline)
• frame scheduling and buffer pooling
• transfer of drawlists to the engine and event batches back to core

Most apps should construct the app via:

import { createNodeApp } from "@rezi-ui/node";

const app = createNodeApp({
  initialState: { count: 0 },
  config: {
    executionMode: "auto",
    fpsCap: 60,
    maxEventBytes: 1 << 20,
    useV2Cursor: false,
  },
});

createNodeApp is the recommended path because it keeps core/backend config knobs aligned:

• useV2Cursor and drawlist v2 are paired automatically.
• maxEventBytes is applied to both app parsing and backend transport buffers.
• fpsCap is the single scheduling knob.
• executionMode: "auto" resolves to inline when fpsCap <= 30, worker otherwise.

Execution mode details:

• auto (default): select inline for low-fps workloads (fpsCap <= 30), worker otherwise.
• worker: force worker-thread engine execution.
• inline: run the engine inline on the main JS thread.

NO_COLOR support:

• If NO_COLOR is present in the process environment, createNodeApp(...) forces a monochrome theme (no semantic color accents).
• createNodeApp(...) returns an app object with app.isNoColor so app code can detect this mode.

import { createNodeApp } from "@rezi-ui/node";

const app = createNodeApp({ initialState: {} });
if (app.isNoColor) {
  // Optional app-level behavior for colorless terminals/CI.
}

Emoji width policy:

• emojiWidthPolicy keeps core text measurement and native rendering aligned.
• Allowed values:
  • "auto" (default): resolve from native overrides/env, optional probe, then fallback to "wide".
  • "wide": emoji clusters occupy at least 2 cells.
  • "narrow": emoji clusters occupy at least 1 cell.
• Native overrides (nativeConfig.widthPolicy / width_policy) must match explicit policy values.
• Optional terminal probe is disabled by default and only runs when ZRUI_EMOJI_WIDTH_PROBE=1 (opt-in to avoid startup input races).

Legacy path deprecation:

• createNodeBackend() + createApp() (@rezi-ui/core) manual pairing is deprecated for normal app setup.
• Use createNodeApp() from @rezi-ui/node so related runtime knobs cannot drift.
• If you still compose manually, Rezi throws deterministic ZRUI_INVALID_PROPS errors when cursor/event/fps settings conflict.

Next: Worker model.