---
id: 1768d9ab-0c21-4ec3-bb04-bd70366f6240
type: solution
title: "File-based logging for Rust TUI apps using tracing-appender"
tags: [sba-scout, rust, tracing, logging, tui, ratatui, solution]
importance: 0.6
confidence: 0.8
created: "2026-02-28T16:53:12.444250+00:00"
updated: "2026-02-28T16:53:58.777098+00:00"
relations:
  - target: bc4abc6e-57c1-4d6c-b414-213c1367be9b
    type: RELATED_TO
    direction: outgoing
    strength: 0.9
    edge_id: d07fb339-8eb5-40c8-b63c-fcce499f0fc3
  - target: 2cf3058c-85f4-481a-bbe7-17ebb9b9e908
    type: RELATED_TO
    direction: outgoing
    strength: 0.7
    edge_id: 8b24bed4-38a2-4a70-8b5e-de2782c897e0
---

# File Logging for Rust TUI Apps

**Project:** sba-scout (Rust) | **Commit:** `bf7c3f8`

## Problem

Writing to stdout/stderr corrupts ratatui TUI display. Any tracing output needs to go to a file instead.

## Solution

Use `tracing-appender` with `rolling::never()` for a fixed log file path.

### Dependencies

```toml
tracing = "0.1"
tracing-subscriber = { version = "0.3", features = ["env-filter"] }
tracing-appender = "0.2"
```

### Setup

```rust
use tracing_appender::rolling;
use tracing_subscriber::EnvFilter;

let file_appender = rolling::never("data", "sba-scout.log");
let (non_blocking, _guard) = tracing_appender::non_blocking(file_appender);

tracing_subscriber::fmt()
    .with_env_filter(EnvFilter::from_default_env())
    .with_writer(non_blocking)
    .init();

// _guard must stay alive for the duration of the app!
```

### Usage

- Set `RUST_LOG=debug` (or `info`, `error`, etc.) for verbose output
- Log is written to `data/sba-scout.log`
- Add `tracing::error!()` alongside UI notification sends to capture full error context in log

## Critical

The `WorkerGuard` returned by `non_blocking()` must be kept alive (stored in a variable that lives for the entire app scope). Dropping it early silently stops log output.