What causes "MCP attach workspace is empty" in astrid-runtime/astrid?

Pass an absolute workspace directory path in the registration

MCP attach workspace is empty

Error message

MCP attach workspace is empty

What it means

validate_workspace converts the workspace string of an attach registration into a canonical PathBuf for the gateway to operate in. An empty string carries no workspace, so it is rejected with this dedicated error before any path handling. The gateway requires an explicit, resolvable workspace directory.

Solutions

Pass an absolute workspace directory path in the registration
Set the workspace config/env variable before launching the client
Default the workspace to the current directory (canonicalized) if the caller intends cwd
Add a client-side preflight check that the workspace string is non-empty

Example fix

// before
workspace_abs: env::var("WORKSPACE").unwrap_or_default(),
// after
workspace_abs: std::fs::canonicalize(env::var("WORKSPACE").context("WORKSPACE must be set")?)?.display().to_string(),

Defensive patterns

Strategy: validation

Validate before calling

if workspace.trim().is_empty() { return Err("workspace must be a non-empty absolute path"); }

Type guard

fn has_workspace(reg: &AttachRegistration) -> bool { !reg.workspace_abs.is_empty() }

Prevention

Require an explicit workspace in config with a startup-time check
Fall back to std::env::current_dir() canonicalized instead of empty
Guard env-var interpolation with defaults

When it happens

Trigger: Attach registration's workspace_abs field is an empty string; workspace field lost during serialization or template substitution produced "".

Common situations: Config with an unset workspace variable interpolated to empty; client forgot to pass the workspace argument; CI environment where WORKSPACE env var is not set.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

AI-assisted analysis of astrid-runtime/astrid@affd8760f4 (2026-09-09). Data as JSON: /api/errors/61ad61b70fcc19e0. Report an issue: GitHub.

Appendix: source

Thrown at crates/astrid-cli/src/commands/mcp/gateway.rs:972

    }
    Ok(principal)
}

fn mint_hook_token() -> String {
    format!(
        "{}{}",
        Uuid::new_v4().as_simple(),
        Uuid::new_v4().as_simple()
    )
}

fn mint_boot_token() -> String {
    Uuid::new_v4().as_simple().to_string()
}

fn validate_workspace(value: &str) -> Result<PathBuf> {
    if value.is_empty() {
        anyhow::bail!("MCP attach workspace is empty");
    }
    let path = PathBuf::from(value);
    if !path.is_absolute() {
        anyhow::bail!("MCP attach workspace must be absolute: {value}");
    }
    std::fs::canonicalize(&path)
        .with_context(|| format!("failed to resolve MCP attach workspace {value}"))
}

fn set_socket_mode(path: &Path) -> Result<()> {
    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt;
        std::fs::set_permissions(path, std::fs::Permissions::from_mode(0o600))?;
    }
    Ok(())
}

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