can1357/oh-my-pi · error · Error

${availability.reason ?? "Julia kernel unavailable"}

Error message

${availability.reason ?? "Julia kernel unavailable"}

What it means

`JuliaKernel.start` boots a new kernel subprocess and first re-checks availability with `checkJuliaKernelAvailability`, throwing this plain Error (probe reason or generic fallback) when the probe fails. Unlike the executor path, there is no retry or cancellation wrapper here — the error propagates directly to whoever requested a kernel. Note availability probes for a given cwd+interpreter are cached on success only, so a fresh probe runs each time after a failure.

Source

Thrown at packages/coding-agent/src/eval/jl/kernel.ts:149

						if (val !== undefined) {
							const k_b64 = Buffer.from(key).toString("base64");
							const v_b64 = Buffer.from(val).toString("base64");
							envPairs.push(`${k_b64}:${v_b64}`);
						}
					}
				}
				const envPairsStr = envPairs.join(" ");
				const codeB64 = Buffer.from(code).toString("base64");

				return `run\t${msgId}\t${cwdB64}\t${silentVal}\t${storeHistVal}\t${envPairsStr}\t${codeB64}`;
			},
		});
	}

	static async start(options: KernelStartOptions): Promise<JuliaKernel> {
		const availability = await checkJuliaKernelAvailability(options.cwd, options.interpreter);
		if (!availability.ok) {
			throw new Error(availability.reason ?? "Julia kernel unavailable");
		}

		let runtime = availability.runtime;
		if (!runtime) {
			const { env: shellEnv } = (await Settings.init()).getShellConfig();
			runtime = options.interpreter
				? resolveExplicitJuliaRuntime(options.interpreter, options.cwd, filterEnv(shellEnv))
				: resolveJuliaRuntime(options.cwd, filterEnv(shellEnv));
		}
		const spawnEnv: Record<string, string> = {};
		for (const key in runtime.env) {
			const value = runtime.env[key];
			if (typeof value === "string") spawnEnv[key] = value;
		}
		for (const key in options.env) {
			const value = options.env[key];
			if (typeof value === "string") spawnEnv[key] = value;
		}

View on GitHub (pinned to 9690622007)

Solutions

1. Install Julia and ensure the `julia` binary is executable and on PATH for the process spawning the kernel.
2. Use the thrown reason: "not found on PATH" → install/PATH fix; "Tried: ..." list shows which binaries failed and why.
3. Pass `interpreter` as the resolved path to a real `julia` executable (not the juliaup shim) if shims cause probe failures.
4. Verify manually with `julia -e 'exit(0)'` in the target environment to reproduce and debug the probe.
5. Retry after installing — failed probes are not cached, so the next start re-probes and picks up a new install.

Example fix

// before
const kernel = await JuliaKernel.start({ cwd: projectDir }); // throws: not on PATH
// after
const kernel = await JuliaKernel.start({
  cwd: projectDir,
  interpreter: "/usr/local/bin/julia",
});

import { checkJuliaKernelAvailability } from ".../eval/jl/kernel";
const avail = await checkJuliaKernelAvailability(options.cwd, options.interpreter);
if (!avail.ok) throw new Error(`Cannot start Julia kernel: ${avail.reason}`);
const kernel = await JuliaKernel.start(options);

function canStartKernel(a: { ok: boolean; runtime?: unknown }): a is { ok: true; runtime: NonNullable<typeof a.runtime> } {
  return a.ok && a.runtime !== undefined;
}

let kernel;
try {
  kernel = await JuliaKernel.start({ cwd, interpreter });
} catch (e) {
  if (String(e).includes("Julia")) {
    // probe again after install, or surface install instructions
    throw new Error("Install Julia: https://julialang.org/ — original: " + e);
  }
  throw e;
}

When it happens

Trigger: Direct `JuliaKernel.start({ cwd, interpreter, ... })` when Julia is not on PATH, the explicit interpreter path is wrong, all enumerated runtimes fail the `julia -e 'exit(0)'` probe, or the availability probe was cancelled.

Common situations: Embedding/SDK users spawning a kernel directly without Julia installed; pointing `interpreter` at a `juliaia`/`juliaup` shim that doesn't behave as a plain binary; probing from a service account whose PATH lacks user-local julia installs; corrupt Julia installation failing to exit cleanly.

Related errors

• ${availability.reason ?? "Julia kernel unavailable"}
• imageUrls exposure "${name}" requires the ${name} binary on
• ${displayName} executable not found on PATH
• ssh binary not found on PATH
• Julia backend is unavailable in this session. Pass language:

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/13fd0cb31c740f4a. Report an issue: GitHub.