What causes "gen agent list failed: {}" in nikivdev/code?

Read the stderr suffix in the message — it contains gen's actual error.

gen agent list failed: {}

Error message

gen agent list failed: {}

What it means

fetch_gen_agent_entries runs `gen agent list` and, unlike list_gen_agents, includes the subprocess stderr in the error. When the command's exit status is non-zero it bails with 'gen agent list failed: <stderr>'. This is the richer variant of the gen-listing failure used when building agent entries.

Source

Thrown at src/agents.rs:805

        GenLocation::Repo(ref repo) => {
            let mut cmd = Command::new("bun");
            cmd.args([
                "run",
                "--cwd",
                &repo.join("packages/opencode").to_string_lossy(),
                "--conditions=browser",
                "src/index.ts",
                "agent",
                "list",
            ])
            .env("GEN_MODE", "1");
            apply_project_config_env(&mut cmd);
            cmd.output().context("failed to run gen agent list")?
        }
    };

    if !output.status.success() {
        bail!(
            "gen agent list failed: {}",
            String::from_utf8_lossy(&output.stderr)
        );
    }

    let stdout = String::from_utf8_lossy(&output.stdout);
    Ok(parse_gen_agent_list(&stdout))
}

fn parse_gen_agent_list(stdout: &str) -> Vec<AgentEntry> {
    let mut entries = Vec::new();
    for line in stdout.lines() {
        let line = line.trim();
        if line.is_empty() {
            continue;
        }
        if let Some((name, mode)) = parse_agent_list_line(line) {
            if mode == "primary" {

View on GitHub (pinned to a747e741ae)

Solutions

Read the stderr suffix in the message — it contains gen's actual error.
Run `gen agent list` manually in the resolved gen repo to reproduce.
Update/reinstall gen so the `agent list` subcommand works and its output format matches.
Fix any project config (flow.toml) env values that gen rejects.

Example fix

// terminal
$ f agents list
Error: gen agent list failed: error: unknown command 'agent'
// fix: update gen to a version supporting `agent list`
$ cd ~/gen && git pull && f install

Defensive patterns

Strategy: try-catch

Validate before calling

command -v gen >/dev/null || { echo "gen not installed"; exit 1; }
gen agent list >/dev/null 2>&1 || { echo "gen agent list broken"; exit 1; }

Type guard

fn gen_ok() -> bool {
    std::process::Command::new("gen").arg("agent").arg("list")
        .output().map(|o| o.status.success()).unwrap_or(false)
}

Try / catch

match fetch_gen_agent_entries() {
    Err(e) => {
        let msg = e.to_string();
        if let Some(stderr) = msg.strip_prefix("gen agent list failed: ") {
            eprintln!("gen reported: {stderr}");
        }
    }
    Ok(entries) => { /* use entries */ }
}

Prevention

Read the stderr suffix in the error — it names the real cause.
Keep gen's version aligned with flow's expected `agent list` output.
Run `gen agent list` manually when upgrading either tool.
Check project config env vars before invoking gen-dependent commands.

When it happens

Trigger: Calling build_agent_entries/list-flows that fetch gen agent entries when `gen agent list` exits non-zero — gen binary missing prerequisites, malformed gen config, or the subcommand emitting errors on stderr.

Common situations: Outdated gen version whose `agent list` output contract changed; project env vars breaking gen; permission errors reading gen's agent directory.

Related errors

AI-assisted analysis of nikivdev/code@a747e741ae (2026-09-01). Data as JSON: /api/errors/14afbae5f7a856b4. Report an issue: GitHub.