xai-org/grok-build · error

ACP response missing result field

Error message

ACP response missing result field

What it means

Raised by `ext_call` when the parsed ACP envelope contains neither an `error` nor a `result` field — a structurally valid response with no payload. The ACP extension contract requires one of the two; receiving neither means the agent sent an incomplete or protocol-violating reply.

Solutions

1. Check the agent's handler for the corresponding extension method and ensure it always sets either result or error.
2. Verify you are sending a request (with id), not a notification, so the agent replies with a full response.
3. Confirm agent and CLI agree on the same ACP extension protocol version.
4. Add a fallback in the caller to treat None result as an empty/default value if the method legitimately may return no payload.

Example fix

// before
let info: WorktreeInfo = ext_call(tx, "worktree/show", &params).await?;
// after
let info: Option<WorktreeInfo> = ext_call(tx, "worktree/show", &params).await
    .ok() // or change ext_call to map missing result to None for this method

fn has_payload(v: &serde_json::Value) -> bool {
    v.get("result").is_some() || v.get("error").is_some()
}

let info: Result<WorktreeInfo> = ext_call(tx, "worktree/show", &params).await;
match info {
    Ok(v) => use(v),
    Err(e) if e.to_string().contains("missing result field") => {
        // treat as empty/default result for methods that may legitimately return nothing
        use(WorktreeInfo::default());
    }
    Err(e) => return Err(e),
}

When it happens

Trigger: Agent implementation responds with an empty object or an envelope that omits both `result` and `error`; an intermediary drops the payload; agent acknowledges the method without producing a result (notification-style reply to a request).

Common situations: Bug in the agent's extension handler that returns early without setting a result; misconfigured agent that treats extension requests as notifications; protocol version mismatch where the request id is reused for a notification.

Related errors

• response parse error
• -32601
• -32601
• -32601
• -32602

AI-assisted analysis of xai-org/grok-build@bc7f02eddd (2026-08-31). Data as JSON: /api/errors/bfeec6852bd2a30a. Report an issue: GitHub.

Appendix: source

Thrown at crates/codegen/xai-grok-pager/src/worktree_cmd/mod.rs:150

}
async fn ext_call<T: serde::de::DeserializeOwned>(
    tx: &xai_acp_lib::AcpAgentTx,
    method: &str,
    params: &impl serde::Serialize,
) -> Result<T> {
    let req =
        ext_request(method, params).map_err(|e| anyhow::anyhow!("failed to build request: {e}"))?;
    let resp = acp_send(req, tx)
        .await
        .map_err(|e| anyhow::anyhow!("{e}"))?;
    let envelope: ExtEnvelope<T> = serde_json::from_str(resp.0.get())
        .map_err(|e| anyhow::anyhow!("response parse error: {e}"))?;
    if let Some(err) = envelope.error {
        bail!("ACP error: {err}");
    }
    envelope
        .result
        .ok_or_else(|| anyhow::anyhow!("ACP response missing result field"))
}
async fn cmd_list(
    tx: &xai_acp_lib::AcpAgentTx,
    repo: Option<String>,
    types: Vec<String>,
    json: bool,
    all: bool,
) -> Result<()> {
    let records: Vec<WorktreeRecord> = ext_call(
        tx,
        "x.ai/git/worktree/list",
        &serde_json::json!({
            "repo": repo,
            "type": types,
            "includeAll": all,
        }),
    )
    .await?;

View on GitHub (pinned to bc7f02eddd)