What causes "jj command failed" in xai-org/grok-build?

Run the same jj command manually in the cwd (`jj -R log`) to see the real error.

jj command failed

Error message

jj command failed

What it means

`jj_cli_inner` (behind `jj_cli`/`jj_cli_mut`) runs the Jujutsu (`jj`) CLI in a working directory — with `--ignore-working-copy` for read-only queries — and returns trimmed stdout. On non-zero exit the error message is the trimmed stderr; if jj wrote nothing to stderr this generic fallback "jj command failed" is used. This is the jj counterpart of the git_cli failure path.

Source

Thrown at crates/codegen/xai-grok-workspace/src/session/git.rs:172

    let stderr = String::from_utf8_lossy(&output.stderr).trim().to_string();
    if output.status.success() {
        let stdout = String::from_utf8_lossy(&output.stdout).trim().to_string();
        if !stderr.is_empty() {
            tracing::warn!(
                cwd = %cwd.display(),
                "jj_cli success with stderr warnings"
            );
        }
        tracing::debug!(exit_code = 0, stdout_len = stdout.len(), "jj_cli success");
        Ok(stdout)
    } else {
        let code = output.status.code();
        tracing::warn!(
            cwd = %cwd.display(),
            exit_code = ?code,
            "jj_cli FAILED"
        );
        Err(anyhow::anyhow!(
            "{}",
            if stderr.is_empty() {
                "jj command failed"
            } else {
                &stderr
            }
        ))
    }
}
/// Detect the VCS kind for a given path based on the discovered git root.
///
/// Checks for `.jj/` directory alongside `.git/` to identify colocated Jujutsu repos.
pub fn detect_vcs_kind(git_root: &Path) -> VcsKind {
    if git_root.join(".jj").is_dir() {
        VcsKind::JujutsuColocated
    } else {
        VcsKind::Git
    }

View on GitHub (pinned to bc7f02eddd)

Solutions

Run the same jj command manually in the cwd (`jj -R <cwd> log`) to see the real error.
Confirm the repo is jj-initialized or colocated (a `.jj/` directory exists) before calling jj commands.
Upgrade jj (`jj --version`) — older releases may not support `--ignore-working-copy`.
Run `jj workspace add`/re-init if the workspace metadata is missing or corrupt.

Defensive patterns

Strategy: try-catch

Validate before calling

// Only call jj commands on jj repos, and ensure jj is installed
fn jj_available(cwd: &Path) -> bool {
    cwd.join(".jj").is_dir()
        && std::process::Command::new("jj")
            .arg("--version")
            .output().map(|o| o.status.success()).unwrap_or(false)
}

Try / catch

match jj_cli(cwd, &["log", "-r", "@"]).await {
    Ok(out) => use_output(out),
    Err(e) if e.to_string() == "jj command failed" => {
        eprintln!("jj failed in {} with no stderr — run the command manually to see why", cwd.display());
    }
    Err(e) => eprintln!("jj: {e}"),
}

Prevention

Use `detect_vcs_kind` to route git vs jj instead of calling jj blindly in git-only repos.
Keep jj up to date — read-only helpers pass `--ignore-working-copy`, absent in old versions.
Check `.jj/` exists (colocated repo) before issuing jj queries.
Empty-stderr failures are logged via tracing::warn with cwd and exit code — enable debug logs when diagnosing.

When it happens

Trigger: Any jj invocation via `jj_cli`/`jj_cli_mut` that exits non-zero with empty stderr: no jj repo in cwd, jj version too old to support a flag like `--ignore-working-copy`, corrupted repo, or jj terminated by a signal leaving stderr empty.

Common situations: Calling jj commands in a plain git repo without `.jj/` (not colocated); ancient jj versions lacking `--ignore-working-copy`; workspace operations on repos with unresolved conflicts; jj not on PATH in the spawned environment.

Related errors

AI-assisted analysis of xai-org/grok-build@bc7f02eddd (2026-08-31). Data as JSON: /api/errors/b68baf7df0d61280. Report an issue: GitHub.