What causes "jj {} failed" in nikivdev/code?

Read the stderr lines printed just before the error to see jj's own message, then fix that condition.

jj {} failed

Error message

jj {} failed

What it means

jj_run_in executes a jj subcommand in the repo root, streaming its stderr; if the process exits non-zero it bails with the full argument list. The actual jj error text is already printed to stderr lines above the bail message.

Source

Thrown at src/ext.rs:381

fn jj_run_in(repo_root: &Path, args: &[&str]) -> Result<()> {
    let output = Command::new("jj")
        .current_dir(repo_root)
        .args(args)
        .output()
        .with_context(|| format!("failed to run jj {}", args.join(" ")))?;
    let stdout = String::from_utf8_lossy(&output.stdout);
    if !stdout.trim().is_empty() {
        print!("{}", stdout);
    }
    let stderr = String::from_utf8_lossy(&output.stderr);
    for line in stderr.lines() {
        if line.contains("Refused to snapshot") {
            continue;
        }
        eprintln!("{}", line);
    }
    if !output.status.success() {
        bail!("jj {} failed", args.join(" "));
    }
    Ok(())
}

fn jj_capture_in(repo_root: &Path, args: &[&str]) -> Result<String> {
    let output = Command::new("jj")
        .current_dir(repo_root)
        .args(args)
        .output()
        .with_context(|| format!("failed to run jj {}", args.join(" ")))?;
    if !output.status.success() {
        bail!("jj {} failed", args.join(" "));
    }
    Ok(String::from_utf8_lossy(&output.stdout).to_string())
}

fn git_capture_in(repo_root: &Path, args: &[&str]) -> Result<String> {
    let output = Command::new("git")

View on GitHub (pinned to a747e741ae)

Solutions

Read the stderr lines printed just before the error to see jj's own message, then fix that condition.
Re-run the same jj command manually in the source repo to reproduce and diagnose.
Resolve working-copy problems (conflicts, locks) in the source workspace and retry the import.

Example fix

// before: opaque failure
// error: jj workspace add ... failed
// after (shell): reproduce for the real error
cd <source> && jj workspace add --help  # or re-run the failing command verbatim

Defensive patterns

Strategy: retry

Validate before calling

let probe = std::process::Command::new("jj")
    .args(["--version"])
    .output()
    .map(|o| o.status.success())
    .unwrap_or(false);
if !probe { return Err(anyhow!("jj is unavailable; install jujutsu first")); }

Try / catch

for attempt in 0..2 {
    match import_external_path(source) {
        Err(e) if e.to_string().starts_with("jj ") && attempt == 0 => {
            eprintln!("jj failed ({e}); inspect stderr above, fixing state and retrying");
            continue;
        }
        r => { r?; break; }
    }
}

Prevention

Pin a compatible jj version in your environment.
Avoid running concurrent jj operations on the same workspace.
Always read the stderr lines the tool prints before the bail message.

When it happens

Trigger: Any jj invocation from prepare_source_workspace failing: workspace add refused, snapshot refused due to a dirty/locked working copy, invalid args, or jj missing/crashing.

Common situations: Source repo with conflicts or an inconsistent working copy; incompatible jj version; running while another jj process holds a lock.

Related errors

AI-assisted analysis of nikivdev/code@a747e741ae (2026-09-01). Data as JSON: /api/errors/fb1d539d664da24e. Report an issue: GitHub.