store: File-based logging for Rust TUI apps using tracing-appender

graph/solutions/file-based-logging-for-rust-tui-apps-using-tracing-appender-1768d9.md

@@ -0,0 +1,57 @@
+---
+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: "2026-02-28T16:53:12.444250+00:00"
+---
+
+# 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.