BoundaryML/baml · error

No download URL for checksum asset

Error message

No download URL for checksum asset

What it means

Having found the checksum asset, get_playground_dist reads checksum_asset["browser_download_url"] as a string to know where to download it. If that field is missing or not a string, this error is returned. Like the main asset's download URL check, this guards against malformed asset objects.

Source

Thrown at engine/playground-server/src/server.rs:182

        .find(|a| a["name"].as_str() == Some(&web_panel_asset_name))
        .ok_or_else(|| anyhow::anyhow!("No asset named '{}' in release", web_panel_asset_name))?;
    let download_url = asset["browser_download_url"]
        .as_str()
        .ok_or_else(|| anyhow::anyhow!("No download URL for asset"))?;

    // Find the checksum asset
    let checksum_asset = assets
        .iter()
        .find(|a| a["name"].as_str() == Some(&checksum_asset_name))
        .ok_or_else(|| {
            anyhow::anyhow!(
                "No checksum asset named '{}' in release",
                checksum_asset_name
            )
        })?;
    let checksum_url = checksum_asset["browser_download_url"]
        .as_str()
        .ok_or_else(|| anyhow::anyhow!("No download URL for checksum asset"))?;

    tracing::info!(
        "Found assets - main: {}, checksum: {}",
        download_url,
        checksum_url
    );

    // Compute extraction directory using the provided version
    let home =
        dirs::home_dir().ok_or_else(|| anyhow::anyhow!("Could not determine home directory"))?;
    let extract_root: PathBuf = home
        .join(".baml/playground")
        .join(format!("web-panel-dist-{version}"));
    let dist_dir = extract_root.join("dist");

    // If already extracted, return the correct directory
    if dist_dir.exists() && dist_dir.read_dir()?.next().is_some() {
        tracing::info!("Web panel already extracted at: {}", dist_dir.display());

View on GitHub (pinned to bd85ce9dee)

Solutions

1. Inspect the checksum asset JSON and confirm browser_download_url exists; fix synthetic payloads if applicable.
2. Construct the download URL from the release/asset IDs as a fallback.
3. Update the parsing logic if the GitHub API response shape changed.

// preflight: confirm the checksum asset has a download URL
let v: serde_json::Value = reqwest::get(&api_url).await?.json().await?;
let ok = v["assets"].as_array().map_or(false, |a| {
    a.iter().any(|x| x["name"].as_str().map_or(false, |n| n.ends_with(".sha256"))
        && x["browser_download_url"].is_string())
});
if !ok { eprintln!("Checksum asset missing browser_download_url"); }

fn checksum_url<'a>(release: &'a serde_json::Value, name: &str) -> Option<&'a str> {
    release["assets"].as_array()?.iter()
        .find(|a| a["name"].as_str() == Some(name))?
        ["browser_download_url"].as_str()
}

match get_playground_dist().await {
    Err(e) if e.to_string().contains("No download URL for checksum asset") => {
        eprintln!("Malformed checksum asset payload — inspect the API response");
    }
    other => other?,
}

When it happens

Trigger: The matched checksum asset JSON has no string browser_download_url field — synthetic/mocked payloads or unexpected API response shape.

Common situations: Mocked GitHub responses for tests missing the field; intermediary proxies altering the JSON; GitHub API schema drift.

Understand the failure class

Background: "invalid response format", "malformed payload", "missing data field": when an API returns 200 but the response shape is wrong — this error's family across 23 libraries.

Related errors

• No assets in release metadata
• No download URL for asset
• Failed to parse JSON response: {e}
• `{BAML_JSON_JSON}` is declared by the stdlib
• Failed to deserialize value: {e}

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/67019a5be03c80a9. Report an issue: GitHub.