What causes "generate-image: no image in response " in pbakaus/impeccable?

Re-run with a different, clearly safe prompt to rule out content-filter suppression.

generate-image: no image in response

Error message

generate-image: no image in response

What it means

The API call succeeded (2xx) but the JSON response contained no usable image: the `data[0].b64_json` field was missing or empty. generate-image cannot write an output file without it, so it reports "no image in response" and exits 1.

Source

Thrown at crates/context/src/generate_image.rs:369

        Ok(r) => {
            let st = r.status();
            (st, r.into_string().unwrap_or_default())
        }
        Err(ureq::Error::Status(code, r)) => (code, r.into_string().unwrap_or_default()),
        Err(e) => {
            io.err(&format!("TypeError: fetch failed: {}\n", e));
            return 1;
        }
    };
    if !(200..300).contains(&status) {
        let snippet: String = text.chars().take(300).collect();
        io.err(&format!("generate-image: API error {}: {}\n", status, snippet));
        return 1;
    }
    let json: Value = serde_json::from_str(&text).unwrap_or(Value::Null);
    let b64 = json.get("data").and_then(|d| d.get(0)).and_then(|d| d.get("b64_json")).and_then(|b| b.as_str()).filter(|s| !s.is_empty());
    let Some(b64) = b64 else {
        io.err("generate-image: no image in response\n");
        return 1;
    };
    let bytes = base64_decode(b64);
    let _ = std::fs::write(abs(&out), bytes);
    // best-effort embed + sidecar
    // JS-PARITY: generate-image.mjs#676 reports whether the embed actually
    // succeeded. The install-path-with-spaces half of #676 is a JS-only
    // subprocess concern (fileURLToPath vs URL.pathname); the engine embeds
    // in-process, so only the success tracking and message carry over here.
    let embedded;
    {
        let mut sub_io = Io::captured("", io.cwd.clone(), io.env.clone()).0;
        let ret = crate::embed_prompt::run(&[out.clone(), "--prompt".to_string(), prompt.clone()], &mut sub_io);
        embedded = ret == 0;
        if !embedded {
            io.err("generate-image: failed to embed prompt in the image\n");
        }
        let mut m = Map::new();

View on GitHub (pinned to 2bc2879276)

Solutions

Re-run with a different, clearly safe prompt to rule out content-filter suppression.
Verify you are using the supported model/endpoint whose response includes b64_json; adjust model/parameters if the API version changed.
Inspect the raw response (network log) to see whether data contains url instead of b64_json and adapt the workflow accordingly.
Check for proxy/gateway interference that strips or rewrites the JSON body.
Retry — occasionally transient API-side issues return empty payloads.

Example fix

// before
// response: {"data":[{"url":"https://..."}]} → no image in response
// after
// request the format that returns base64 (b64_json) for the model in use, then rerun:
impeccable generate-image --prompt "..." --out o.png

Defensive patterns

Strategy: fallback

Type guard

function hasB64Image(json) {
  return typeof json?.data?.[0]?.b64_json === "string" && json.data[0].b64_json.length > 0;
}
// if the raw response is available: if (!hasB64Image(parsed)) handleEmpty();

Try / catch

const r = spawnSync("impeccable", ["generate-image", ...], { encoding: "utf8" });
if (r.status !== 0 && r.stderr.includes("no image in response")) {
  // inspect response shape / adjust model or prompt, then retry once with a safe prompt
  retryWithSafePrompt();
}

Prevention

Pin the model/endpoint version whose responses include b64_json.
Avoid prompts likely to trip content filters when automation must succeed.
Log raw API responses in wrappers to diagnose schema changes quickly.
Beware proxies that rewrite JSON bodies.

When it happens

Trigger: The response JSON parses but `json["data"][0]["b64_json"]` is absent or an empty string — e.g. the API returned a URL instead of base64 (response_format mismatch), the request was content-filtered with an empty data array, or an unexpected schema from a different/updated endpoint.

Common situations: Model or API version changes that alter the response shape; prompts flagged by the safety system returning empty results; a gateway/interceptor (corporate proxy) rewriting the response; account settings returning URLs rather than b64 payloads.

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

AI-assisted analysis of pbakaus/impeccable@2bc2879276 (2026-09-08). Data as JSON: /api/errors/2f19e98ff6011a8a. Report an issue: GitHub.