WEB Manager Session + Generation Fence tests

src/api/config_store/atomic.rs

@@ -11,6 +11,8 @@ use nix::fcntl::{Flock, FlockArg, OFlag, openat, renameat};
 use nix::sys::stat::Mode;
 #[cfg(unix)]
 use nix::unistd::{UnlinkatFlags, fsync, unlinkat};
+#[cfg(unix)]
+use tracing::warn;
 
 use super::compute_source_revision;
 use crate::api::model::ApiFailure;
@@ -75,7 +77,7 @@ impl ConfigWriteLock {
     }
 }
 
-/// Replaces one config source through a durable same-directory rename.
+/// Replaces one config source through a same-directory rename after syncing file data.
 pub(in crate::api) async fn write_atomic(
     path: PathBuf,
     contents: String,
@@ -362,7 +364,15 @@ fn write_and_publish(
         anchored.name(),
     )
     .map_err(errno_to_io)?;
-    fsync(anchored.parent()).map_err(errno_to_io)?;
+    // Rename is the commit boundary. A later directory-sync error cannot be reported as an
+    // uncommitted mutation because mandatory in-process publication must still run.
+    if let Err(error) = fsync(anchored.parent()).map_err(errno_to_io) {
+        warn!(
+            path = %path.display(),
+            %error,
+            "Config rename committed but directory durability sync failed"
+        );
+    }
     Ok(committed_revision)
 }
 

src/api/config_store/tests.rs

@@ -346,13 +346,13 @@ async fn config_sidecar_lock_serializes_competing_revision_writers() {
     let second = second.await.unwrap();
 
     assert_ne!(first.is_ok(), second.is_ok());
-    let conflict = if let Err(error) = first {
-        error
-    } else {
-        second.unwrap_err()
+    let (winner_revision, conflict) = match (first, second) {
+        (Ok(revision), Err(error)) | (Err(error), Ok(revision)) => (revision, error),
+        _ => unreachable!("exactly one cooperative writer must commit"),
     };
     assert_eq!(conflict.code, "revision_conflict");
-    let persisted = tokio::fs::read_to_string(path).await.unwrap();
+    assert_eq!(winner_revision, current_revision(&path).await.unwrap());
+    let persisted = tokio::fs::read_to_string(&path).await.unwrap();
     assert!(persisted.contains("first.example") || persisted.contains("second.example"));
 }