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Adding AI Error Analysis to a macOS Menu Bar App with Gemini API

#ai #rust #tauri #gemini

When a monitored script fails, most tools just show you a red icon.
HiyokoBar does something better: it automatically sends the error output to Gemini AI and displays a diagnosis — no copy-pasting logs, no context switching.
Here's how I built it.

The Problem
Engineers spend a surprising amount of time doing this:

Script fails
Copy error output
Open browser
Paste into ChatGPT/Claude/Gemini
Read diagnosis
Switch back to terminal

This is 2026. The AI should come to you.

Architecture
Each monitor card in HiyokoBar has an analyze_errors toggle. When enabled:

Script runs via std::process::Command
Non-zero exit code detected
stdout + stderr sent to Gemini API
Response displayed as "AI Insight" panel in golden color

The entire flow is automatic. Zero user interaction required.

Implementation
The Gemini API Call
rustuse reqwest::Client;
use serde_json::json;

pub async fn analyze_error(
error_output: &str,
api_key: &str,
) -> Result> {
let prompt = format!(
"You are a senior engineer analyzing a script error. \
Provide a concise diagnosis (2-3 sentences max) and the most likely fix.\n\n\
Error output:\n{}",
error_output
);

let client = Client::new();
let response = client
    .post("https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash:generateContent")
    .header("X-goog-api-key", api_key)
    .json(&json!({
        "contents": [{
            "parts": [{"text": prompt}]
        }],
        "generationConfig": {
            "maxOutputTokens": 256,
            "temperature": 0.3
        }
    }))
    .send()
    .await?;

let data: serde_json::Value = response.json().await?;
let text = data["candidates"][0]["content"]["parts"][0]["text"]
    .as_str()
    .unwrap_or("Analysis unavailable")
    .to_string();

Ok(text)
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}
Key decisions:

gemini-2.5-flash for speed and cost efficiency
maxOutputTokens: 256 — engineers want diagnosis, not essays
temperature: 0.3 — factual, not creative

Triggering the Analysis
rustasync fn run_monitor(monitor: &Monitor, api_key: Option<&str>) -> MonitorResult {
let output = Command::new(&monitor.command)
.args(&monitor.args)
.output()
.await;

match output {
    Ok(out) if out.status.success() => MonitorResult::Success(
        String::from_utf8_lossy(&out.stdout).to_string()
    ),
    Ok(out) => {
        let error_text = format!(
            "stdout: {}\nstderr: {}",
            String::from_utf8_lossy(&out.stdout),
            String::from_utf8_lossy(&out.stderr)
        );

        // Only analyze if AI is enabled and key is available
        let insight = if monitor.analyze_errors {
            if let Some(key) = api_key {
                analyze_error(&error_text, key).await.ok()
            } else {
                None
            }
        } else {
            None
        };

        MonitorResult::Error { error_text, insight }
    }
    Err(e) => MonitorResult::Error {
        error_text: e.to_string(),
        insight: None,
    }
}
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}
The AI Insight UI
On the React side, the insight panel appears with a golden glow when an AI diagnosis is available:
tsx{result.insight && (
<motion.div
initial={{ opacity: 0, y: -8 }}
animate={{ opacity: 1, y: 0 }}
className="mt-2 p-3 rounded-lg border border-yellow-500/30 bg-yellow-500/10"

<div className="flex items-center gap-2 mb-1">
  <Sparkles className="w-3 h-3 text-yellow-400" />
  <span className="text-xs font-bold text-yellow-400">AI INSIGHT</span>
</div>
<p className="text-xs text-yellow-200/80">{result.insight}</p>


)}

Storing the API Key Securely
Never put API keys in config files. I use macOS Keychain via the keyring crate:
rustuse keyring::Entry;

pub fn save_gemini_key(key: &str) -> keyring::Result<()> {
Entry::new("hiyoko-bar", "gemini-api-key")?.set_password(key)
}

pub fn load_gemini_key() -> keyring::Result {
Entry::new("hiyoko-bar", "gemini-api-key")?.get_password()
}
The key lives in Keychain, never touches disk as plaintext.

Result
The AI Insight feature turns HiyokoBar from a "pretty dashboard" into an actual engineering tool. When your Docker container crashes at 2am, you want a diagnosis in your menu bar — not another tab to open.

HiyokoBar: https://hiyokoko.gumroad.com/l/hiyokobar

🇯🇵 日本語版: https://hiyokoko.gumroad.com/l/hiyokobar_jp

🐤 Launched on Product Hunt today — would love your support!
https://www.producthunt.com/products/hiyokobar

X: @hiyoyoko

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