refactor: remove magic string 'traces' and add Environment::traces_dir() method

- Add public const TRACES_DIR_NAME for the 'traces' subdirectory name
- Implement Environment::traces_dir() method to return traces directory path
- Replace all environment.data_dir().join('traces') calls with environment.traces_dir()
- Update test files to use TRACES_DIR_NAME constant instead of hardcoded 'traces' string

This centralizes the traces directory path logic in one place, making it easier
to maintain and change if needed. All linters, unit tests, and E2E tests pass.

Author: josecelano

src/application/commands/configure.rs

@@ -283,7 +283,7 @@ impl ConfigureCommand {
         };
 
         // Generate trace file with complete error chain
-        let traces_dir = environment.data_dir().join("traces");
+        let traces_dir = environment.traces_dir();
         let clock = Arc::new(SystemClock);
         let trace_writer = ConfigureTraceWriter::new(traces_dir, clock);
 

src/application/commands/provision.rs

@@ -488,7 +488,7 @@ impl ProvisionCommand {
         };
 
         // Generate trace file
-        let traces_dir = environment.data_dir().join("traces");
+        let traces_dir = environment.traces_dir();
         let clock = Arc::new(SystemClock);
         let writer = ProvisionTraceWriter::new(traces_dir, clock);
 

src/domain/environment/mod.rs

@@ -70,6 +70,9 @@ use crate::shared::{ssh::SshCredentials, Username};
 use serde::{Deserialize, Serialize};
 use std::path::PathBuf;
 
+/// Directory name for trace files within an environment's data directory
+pub const TRACES_DIR_NAME: &str = "traces";
+
 /// Environment configuration encapsulating all environment-specific settings
 ///
 /// This entity represents a complete environment configuration including naming,
@@ -348,6 +351,39 @@ impl<S> Environment<S> {
         self.data_dir.join("templates")
     }
 
+    /// Returns the traces directory for this environment
+    ///
+    /// The traces directory is located at `data/{env_name}/traces/`
+    /// and contains error trace files for failed operations.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use torrust_tracker_deploy::domain::{Environment, EnvironmentName};
+    /// use torrust_tracker_deploy::shared::{Username, ssh::SshCredentials};
+    /// use std::path::PathBuf;
+    ///
+    /// let env_name = EnvironmentName::new("production".to_string())?;
+    /// let ssh_username = Username::new("torrust".to_string())?;
+    /// let ssh_credentials = SshCredentials::new(
+    ///     PathBuf::from("keys/prod_rsa"),
+    ///     PathBuf::from("keys/prod_rsa.pub"),
+    ///     ssh_username,
+    /// );
+    /// let environment = Environment::new(env_name, ssh_credentials);
+    ///
+    /// assert_eq!(
+    ///     environment.traces_dir(),
+    ///     PathBuf::from("data/production/traces")
+    /// );
+    ///
+    /// # Ok::<(), Box<dyn std::error::Error>>(())
+    /// ```
+    #[must_use]
+    pub fn traces_dir(&self) -> PathBuf {
+        self.data_dir.join(TRACES_DIR_NAME)
+    }
+
     /// Returns the ansible build directory for this environment
     ///
     /// # Examples

src/infrastructure/trace/writer/commands/configure.rs

@@ -154,11 +154,12 @@ mod tests {
     /// Returns (writer, `temp_dir`, `traces_dir`)
     /// The `temp_dir` must be kept alive for the duration of the test
     fn create_test_writer() -> (ConfigureTraceWriter, TempDir, PathBuf) {
+        use crate::domain::environment::TRACES_DIR_NAME;
         use crate::testing::MockClock;
         use chrono::TimeZone;
 
         let temp_dir = TempDir::new().expect("Failed to create temp dir");
-        let traces_dir = temp_dir.path().join("traces");
+        let traces_dir = temp_dir.path().join(TRACES_DIR_NAME);
         let fixed_time = Utc.with_ymd_and_hms(2025, 10, 7, 12, 0, 0).unwrap();
         let clock = Arc::new(MockClock::new(fixed_time));
         let writer = ConfigureTraceWriter::new(traces_dir.clone(), clock);

src/infrastructure/trace/writer/commands/provision.rs

@@ -156,11 +156,12 @@ mod tests {
     /// Returns (writer, `temp_dir`, `traces_dir`)
     /// The `temp_dir` must be kept alive for the duration of the test
     fn create_test_writer() -> (ProvisionTraceWriter, TempDir, PathBuf) {
+        use crate::domain::environment::TRACES_DIR_NAME;
         use crate::testing::MockClock;
         use chrono::TimeZone;
 
         let temp_dir = TempDir::new().expect("Failed to create temp dir");
-        let traces_dir = temp_dir.path().join("traces");
+        let traces_dir = temp_dir.path().join(TRACES_DIR_NAME);
         let fixed_time = Utc.with_ymd_and_hms(2025, 10, 7, 12, 0, 0).unwrap();
         let clock = Arc::new(MockClock::new(fixed_time));
         let writer = ProvisionTraceWriter::new(traces_dir.clone(), clock);

src/infrastructure/trace/writer/common.rs

@@ -162,6 +162,7 @@ mod tests {
 
     // Test helpers - Arrange phase utilities
 
+    use crate::domain::environment::TRACES_DIR_NAME;
     use crate::testing::MockClock;
     use chrono::TimeZone;
     use std::sync::Arc;
@@ -171,8 +172,10 @@ mod tests {
     /// Returns (writer, `temp_dir`, `traces_dir`)
     /// The `temp_dir` must be kept alive for the duration of the test
     fn create_test_writer() -> (CommonTraceWriter, TempDir, PathBuf) {
+        use crate::domain::environment::TRACES_DIR_NAME;
+
         let temp_dir = TempDir::new().expect("Failed to create temp dir");
-        let traces_dir = temp_dir.path().join("traces");
+        let traces_dir = temp_dir.path().join(TRACES_DIR_NAME);
         let fixed_time = chrono::Utc.with_ymd_and_hms(2025, 10, 7, 12, 0, 0).unwrap();
         let clock = Arc::new(MockClock::new(fixed_time));
         let writer = CommonTraceWriter::new(traces_dir.clone(), clock);
@@ -389,7 +392,7 @@ mod tests {
             perms.set_mode(0o444); // Read-only
             fs::set_permissions(&readonly_dir, perms).expect("Failed to set permissions");
 
-            let traces_dir = readonly_dir.join("traces");
+            let traces_dir = readonly_dir.join(TRACES_DIR_NAME);
             let fixed_time = chrono::Utc.with_ymd_and_hms(2025, 10, 7, 12, 0, 0).unwrap();
             let clock = Arc::new(MockClock::new(fixed_time));
             let writer = CommonTraceWriter::new(traces_dir, clock);