xai-org/x-algorithm · error · anyhow::Error

{e}

Error message

{e}

What it means

Returned by fetch_following_list_internal when serde_json fails to parse the Strato response body as StratoResponse<Vec<String>>. The warn log already prints the error and a 300-char response preview, which usually reveals whether the body is HTML (error page), truncated, or a different schema.

Source

Thrown at thunder/strato_client.rs:159

        match serde_json::from_str::<StratoResponse<Vec<String>>>(&text) {
            Ok(result) => {
                metrics::STRATO_REQUESTS
                    .with_label_values(&["fetch_following_list", "success"])
                    .inc();
                Ok(result.v)
            }
            Err(e) => {
                metrics::STRATO_REQUESTS
                    .with_label_values(&["fetch_following_list", "parse_error"])
                    .inc();
                warn!(
                    "Failed to parse following list response for {}: {}. Response preview: {}",
                    user_id,
                    e,
                    &text[..text.len().min(300)]
                );
                Err(anyhow!(e))
            }
        }
    }

    pub async fn fetch_user_metadata(&self, user_id: i64) -> Result<Option<UserMetadata>> {
        let start = std::time::Instant::now();

        let url = format!("{}/op/fetch/gizmoduck/composite.User", self.base_url);

        let payload = serde_json::json!([user_id, (serde_json::json!({}), ["profile", "counts"])]);

        let response = self
            .client
            .post(&url)
            .header("Content-Type", "application/json")
            .body(serde_json::to_string(&payload)?)
            .send()
            .await

View on GitHub (pinned to 24c60942c5)

Solutions

1. Inspect the warn log's response preview to identify what was actually returned
2. If HTML from a proxy, check the Strato endpoint URL/LB config and any required headers (auth, accept-encoding)
3. If the schema changed, update StratoResponse<Vec<String>> to match the current Strato API shape
4. Verify HTTP client decompression settings so gzip/br bodies are decoded before parsing

Example fix

// before
match serde_json::from_str::<StratoResponse<Vec<String>>>(&text) {
    Ok(result) => { ... }
    Err(e) => Err(anyhow!(e)),
}

// after
match serde_json::from_str::<StratoResponse<Vec<String>>>(&text) {
    Ok(result) => { ... }
    Err(e) => Err(anyhow::anyhow!(
        "strato parse failed for user {user_id}: {e}; body starts: {}",
        &text[..text.len().min(120)]
    )),
}

// sanity check body shape before parse: starts with '{' and contains "data" key

match serde_json::from_str::<StratoResponse<Vec<String>>>(&text) { Ok(r) => ..., Err(e) if text.trim_start().starts_with('<') => anyhow::bail!("proxy HTML page returned"), Err(e) => Err(anyhow!(e)) }

When it happens

Trigger: Calling fetch_following_list when Strato returns a 200 with an unexpected body: an HTML error/proxy page, a different response schema after an API change, or truncated/garbled payloads from network issues.

Common situations: A proxy or LB intercepting the request and returning HTML; Strato API version change altering the JSON shape; encoding/compression (gzip not decompressed) issues; partial responses on connection resets.

Related errors

• {metric_label} fetch failed after retries: {e}
• response.status().to_string()
• ttl=-1
• Strato error code {}: {}
• Post metadata is required

AI-assisted analysis of xai-org/x-algorithm@24c60942c5 (2026-08-28). Data as JSON: /api/errors/98a93c1483e4f3e5. Report an issue: GitHub.