fix(storage): RGA insert_str now correctly respects position parameter (#1593)

Author: chefsale

Cargo.lock

@@ -1,9 +1,12 @@
 [package]
 name = "calimero-dag"
+authors.workspace = true
 version.workspace = true
 edition.workspace = true
 repository.workspace = true
 license.workspace = true
+description.workspace = true
+publish = true
 
 [dependencies]
 async-trait.workspace = true

crates/dag/Cargo.toml

@@ -342,10 +342,13 @@ impl<S: StorageAdaptor> ReplicatedGrowableArray<S> {
                     break;
                 }
             } else {
-                // Sort by CharId (HLC timestamp) for deterministic order
-                candidates.sort_by_key(|(id, _)| *id);
+                // Sort by CharId in REVERSE order (latest timestamp first)
+                // This ensures sequential mid-document insertions are placed correctly:
+                // When inserting at position 6 in "Hello World", the new characters
+                // should come BEFORE 'W', not after it, even though they have the same left neighbor.
+                candidates.sort_by_key(|(id, _)| std::cmp::Reverse(*id));
 
-                // Take the character with lowest CharId (earliest timestamp)
+                // Take the character with highest CharId (latest timestamp)
                 let (next_id, next_char) = candidates[0];
                 ordered.push((*next_id, next_char.clone()));
                 current_left = *next_id;

crates/storage/src/collections/rga.rs

@@ -13,13 +13,12 @@ fn test_rga_basic_insert() {
     rga.insert(1, 'i').unwrap();
     assert_eq!(rga.get_text().unwrap(), "Hi");
 
-    // Insert at position 0 - both 'H' and '!' have left=root
-    // RGA orders by HLC timestamp: 'H' (earlier) comes before '!' (later)
+    // Insert at position 0 (before everything)
+    // Both 'H' and '!' have left=root, but '!' has later timestamp
+    // With REVERSED sort (latest first), '!' comes BEFORE 'H' - correct for sequential edits!
     rga.insert(0, '!').unwrap();
-    // '!' has left=root, later timestamp than 'H', so comes after 'H'
     let text = rga.get_text().unwrap();
-    assert!(text.starts_with('H')); // 'H' was first, has earliest timestamp
-    assert_eq!(text.len(), 3);
+    assert_eq!(text, "!Hi", "Insert at position 0 should prepend");
 }
 
 #[test]
@@ -71,6 +70,32 @@ fn test_rga_insert_str_middle() {
     assert_eq!(text.len(), 21); // "Hello" + " Beautiful" + " World"
 }
 
+#[test]
+fn test_rga_insert_str_position_bug() {
+    env::reset_for_testing();
+
+    let mut rga = ReplicatedGrowableArray::new();
+
+    // Insert "Hello World" as a single operation
+    rga.insert_str(0, "Hello World").unwrap();
+    assert_eq!(rga.get_text().unwrap(), "Hello World");
+
+    // Insert "Beautiful " at position 6 (after "Hello ", before "World")
+    // Position 6 should be right before 'W'
+    rga.insert_str(6, "Beautiful ").unwrap();
+    let result = rga.get_text().unwrap();
+
+    eprintln!("Result: '{}'", result);
+    eprintln!("Expected: 'Hello Beautiful World'");
+
+    // Expected: "Hello Beautiful World"
+    assert_eq!(
+        result, "Hello Beautiful World",
+        "insert_str at position 6 should insert before 'World', got: '{}'",
+        result
+    );
+}
+
 #[test]
 fn test_rga_delete_range() {
     env::reset_for_testing();

crates/storage/src/tests/rga.rs

@@ -1,6 +1,6 @@
 [package]
 name = "calimero-version"
-version = "0.10.0-rc.8"
+version = "0.10.0-rc.9"
 authors.workspace = true
 edition.workspace = true
 repository.workspace = true