chore: DiskTree Checkpoint Sidecar Publication (#555)

* implement disk tree checkpoint

Author: jiangzhe

docs/backlogs/000084-parallel-secondary-disk-tree-checkpoint-application.md

@@ -0,0 +1,44 @@
+# Backlog: Parallel secondary DiskTree checkpoint application
+
+## Summary
+
+Design and implement parallel application of secondary DiskTree checkpoint sidecar work.
+
+## Reference
+
+docs/tasks/000118-disk-tree-checkpoint-sidecar-publication.md; docs/rfcs/0014-dual-tree-secondary-index.md
+
+## Deferred From (Optional)
+
+docs/tasks/000118-disk-tree-checkpoint-sidecar-publication.md; docs/rfcs/0014-dual-tree-secondary-index.md Phase 2
+
+## Deferral Context (Optional)
+
+- Defer Reason: Parallel application needs mutable-file allocation, write staging, and deterministic root installation design beyond this local sidecar optimization pass.
+- Findings: Current sidecar application is sequential across secondary indexes because each writer borrows one MutableTableFile. DiskTree subtree rewrite is also sequential inside each root. Parallelism is plausible both across independent secondary indexes and across disjoint DiskTree subtrees.
+- Direction Hint: Design staged per-index and per-subtree rewrite outputs, then serialize root installation into MutableTableFile. Account for DiskTree's no-per-rewrite-GC policy and old-root readability.
+
+## Scope Hint
+
+Support parallelism across independent secondary indexes and, where feasible, across disjoint DiskTree subtree rewrites while preserving copy-on-write root publication semantics.
+
+## Acceptance Hint
+
+A future task proves parallel index-level and subtree-level DiskTree checkpoint application correctness, keeps old roots readable, preserves deterministic table-root publication, and includes performance evidence.
+
+## Notes (Optional)
+
+
+## Close Reason (Added When Closed)
+
+When a backlog item is moved to `docs/backlogs/closed/`, append:
+
+```md
+## Close Reason
+
+- Type: <implemented|stale|replaced|duplicate|wontfix|already-implemented|other>
+- Detail: <reason detail>
+- Closed By: <backlog close>
+- Reference: <task/issue/pr reference>
+- Closed At: <YYYY-MM-DD>
+```

docs/backlogs/next-id

@@ -1 +1 @@
-000084
+000085

docs/rfcs/0014-dual-tree-secondary-index.md

@@ -437,10 +437,10 @@ SAFETY:` comments, and run the repository lint gate. [D10], [C4], [C7]
     metadata.
   - Non-goals: changing foreground lookup or uniqueness behavior, changing
     catalog checkpointing, and independent MemTree flush.
-  - Task Doc: `docs/tasks/TBD.md`
-  - Task Issue: `#0`
-  - Phase Status: `pending`
-  - Implementation Summary: `pending`
+  - Task Doc: `docs/tasks/000118-disk-tree-checkpoint-sidecar-publication.md`
+  - Task Issue: `#554`
+  - Phase Status: done
+  - Implementation Summary: Implemented checkpoint sidecar publication for user-table secondary DiskTree roots. [Task Resolve Sync: docs/tasks/000118-disk-tree-checkpoint-sidecar-publication.md @ 2026-04-14]
 
 - **Phase 3: Recovery Source Migration**
   - Scope: use checkpointed DiskTree roots as a validated recovery source

docs/tasks/000118-disk-tree-checkpoint-sidecar-publication.md

@@ -1 +1 @@
-000118
+000119

docs/tasks/next-id

@@ -1483,6 +1483,34 @@ impl<'a> ColumnBlockIndex<'a> {
         )
     }
 
+    /// Loads validated delete deltas and authoritative row ids for one
+    /// persisted entry from one leaf-node read.
+    pub(crate) async fn load_delete_deltas_and_row_ids(
+        &self,
+        entry: &ColumnLeafEntry,
+    ) -> Result<(Vec<u32>, Vec<RowID>)> {
+        let node = self.read_node(entry.leaf_page_id).await?;
+        let view = self.read_entry_view(&node, entry)?;
+        let row_set = decode_logical_row_set(&view, self.file_kind(), entry.leaf_page_id)?;
+        let delete_set = self
+            .decode_logical_delete_set(&view, &row_set, entry.leaf_page_id)
+            .await?;
+        let delete_deltas = match delete_set {
+            LogicalDeleteSet::None { .. } => Vec::new(),
+            LogicalDeleteSet::Inline { row_id_deltas, .. } => row_id_deltas,
+            LogicalDeleteSet::External { row_id_deltas, .. } => {
+                row_id_deltas.ok_or(Error::InvalidState)?
+            }
+        };
+        let row_ids = decode_row_ids_from_row_set(
+            view.start_row_id,
+            &row_set,
+            self.file_kind(),
+            entry.leaf_page_id,
+        )?;
+        Ok((delete_deltas, row_ids))
+    }
+
     async fn decode_logical_delete_set(
         &self,
         view: &LeafEntryView<'_>,