osc-progress is a TypeScript library for emitting and removing OSC 9;4 terminal progress sequences. It is intended for Node.js CLIs running in Ghostty, WezTerm, or Windows Terminal and becomes a no-op outside supported TTYs.

pnpm add osc-progress

Node.js 24 or newer is required.

import { setTimeout as delay } from "node:timers/promises";
import { startOscProgress } from "osc-progress";

const stop = startOscProgress({ label: "Indexing", indeterminate: true });
try {
  await delay(1_000);
} finally {
  stop();
}

startOscProgress() writes to stderr by default. In a supported terminal it starts progress and returns an idempotent function that clears it; elsewhere both operations do nothing.

Use a controller when the work already exposes a percentage or moves between states:

import { createOscProgressController } from "osc-progress";

const progress = createOscProgressController({ stallAfterMs: 10_000 });
progress.setIndeterminate("Connecting");
progress.setPercent("Downloading", 42);
progress.done();

Updates are deduplicated and throttled to about one every 150 ms. Percentages are rounded and clamped to 0..100; done() and fail() emit their final state before clearing it.

Progress is enabled only for a TTY recognized as Ghostty, WezTerm, or Windows Terminal. The same detection applies to both startOscProgress() and createOscProgressController().

import { supportsOscProgress } from "osc-progress";

const supported = supportsOscProgress(process.env, process.stderr.isTTY === true, {
  forceEnvVar: "MY_CLI_FORCE_PROGRESS",
  disableEnvVar: "MY_CLI_NO_PROGRESS",
});

The named environment variables take effect when their value is "1". Direct force and disabled options are also available; a non-TTY stream always remains disabled.

Remove progress control sequences before saving captured terminal output:

import { sanitizeOscProgress } from "osc-progress";

function prepareForStorage(output: string): string {
  return sanitizeOscProgress(output, process.stdout.isTTY === true);
}

The parser recognizes sequences terminated by BEL, ST (ESC \\), or C1 ST (0x9c).

The public API includes the timer-based helper, a stateful controller, support detection, label sanitization, sequence discovery, and stripping helpers. See the API reference for signatures, options, exported constants, and OSC 9;4 portability notes.

OSC 9;4 state 4 is interpreted as paused by some terminals and warning by others. The library emits the numeric state without trying to normalize that terminal-specific behavior. Labels are an extra payload outside the canonical OSC 9;4 fields, so terminals may ignore them.

pnpm install
pnpm build
pnpm test
pnpm check

pnpm check runs formatting, linting, typechecking, tests, and coverage thresholds.

MIT. See LICENSE.