Fix/403/log debug sources

CHANGELOG.md

@@ -5,6 +5,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 > Note: this file did not exist until after `v0.5.6`.
 
+## Unreleased
+
+### CLI
+- Logging: show source file locations only when running in debug mode (`RUST_LOG=*=debug`) ([#403](https://github.com/flashbots/contender/issues/403))
+- Tests: add scoped environment variable tests for debug mode detection using `temp-env`
+
+
 ---
 
 ## [0.6.0](https://github.com/flashbots/contender/releases/tag/v0.6.0) - 2025-11-25
@@ -22,4 +29,4 @@ Internal changes:
 
 - revamp error handling ([#378](https://github.com/flashbots/contender/pull/378))
 - DB schema bumped to `user_version = 6` to record campaign/stage metadata in runs.
-  - If you see a DB version mismatch, export/reset your DB: `contender db export` (optional backup) then `contender db reset` (or `drop`) to recreate with the new schema.
+  - If you see a DB version mismatch, export/reset your DB: `contender db export` (optional backup) then `contender db reset` (or `drop`) to recreate with the new schema.

crates/cli/CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - we no longer require two-phase cancellation (CTRL-C once to stop spamming, CTRL-C again to stop result collection)
     - result collection happens async, so when the user cancels, most results will have already been collected
     - stopping quickly is a better UX than two-phase
+- logging: show source file locations only when running in debug mode (`RUST_LOG=*=debug`) ([#403](https://github.com/flashbots/contender/issues/403))
+- tests: add scoped environment variable tests for debug mode detection using `temp-env`
 
 ### Breaking changes
 

crates/cli/Cargo.toml

@@ -51,6 +51,7 @@ uuid = { workspace = true }
 
 [dev-dependencies]
 tempfile = "3.15.0"
+temp-env = "0.3"
 
 [features]
 default = []

crates/cli/src/main.rs

@@ -25,7 +25,6 @@ use error::CliError;
 use std::{str::FromStr, sync::LazyLock};
 use tokio::sync::OnceCell;
 use tracing::{debug, info, warn};
-use tracing_subscriber::EnvFilter;
 use util::{data_dir, db_file, init_reports_dir};
 
 static DB: LazyLock<SqliteDb> = std::sync::LazyLock::new(|| {
@@ -209,27 +208,42 @@ fn init_db(command: &ContenderSubcommand) -> Result<(), CliError> {
 }
 
 fn init_tracing() {
-    let filter = EnvFilter::try_from_default_env().ok(); // fallback if RUST_LOG is unset
-    #[cfg(feature = "async-tracing")]
-    {
-        use tracing_subscriber::{fmt, layer::SubscriberExt, util::SubscriberInitExt, Layer};
-        let tokio_layer = console_subscriber::ConsoleLayer::builder()
-            .with_default_env()
-            .spawn();
-        let fmt_layer = fmt::layer()
-            .with_ansi(true)
-            .with_target(true)
-            .with_line_number(true)
-            .with_filter(filter);
-
-        tracing_subscriber::Registry::default()
-            .with(fmt_layer)
-            .with(tokio_layer)
-            .init();
+    use tracing_subscriber::{
+        fmt, layer::SubscriberExt, util::SubscriberInitExt, EnvFilter, Layer,
+    };
+
+    let rust_log = std::env::var("RUST_LOG").unwrap_or_default().to_lowercase();
+    let debug_mode = rust_log.contains("=debug");
+
+    let filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"));
+
+    let fmt_layer = fmt::layer()
+        .with_ansi(true)
+        .with_target(debug_mode)
+        .with_line_number(debug_mode)
+        .with_file(debug_mode)
+        .with_filter(filter);
+
+    tracing_subscriber::registry().with(fmt_layer).init();
+}
+
+#[cfg(test)]
+mod tests {
+    use temp_env::with_var;
+
+    #[test]
+    fn debug_mode_detected_from_rust_log() {
+        with_var("RUST_LOG", Some("contender=debug"), || {
+            let rust_log = std::env::var("RUST_LOG").unwrap_or_default().to_lowercase();
+            assert!(rust_log.contains("=debug"));
+        });
     }
 
-    #[cfg(not(feature = "async-tracing"))]
-    {
-        contender_core::util::init_core_tracing(filter);
+    #[test]
+    fn info_mode_does_not_trigger_debug() {
+        with_var("RUST_LOG", Some("contender=info"), || {
+            let rust_log = std::env::var("RUST_LOG").unwrap_or_default().to_lowercase();
+            assert!(!rust_log.contains("=debug"));
+        });
     }
 }