fix(cluster,native): minor correctness fixes in applier and plan builders

- `metadata_group/applier.rs`: remove stale doc comment that described
  `apply_topology_change` as backward-compatible with old test wiring;
  the field is simply optional.
- `plan_builder/graph.rs`: correct `clamped_depth` parameter from
  `Option<u64>` to `Option<u32>` to match the wire field type.
- `plan_builder/vector.rs`: add explicit `u32` bounds check on
  `vector_id` with a structured `BadRequest` error rather than silently
  truncating the surrogate.

Author: farhan-syah

nodedb-cluster/src/metadata_group/applier.rs

@@ -114,8 +114,7 @@ impl CacheApplier {
     }
 
     /// Mutate the live topology handle (if attached) in response to
-    /// a committed `TopologyChange`. Silent no-op when no handle is
-    /// set — backward-compatible with older test wiring.
+    /// a committed `TopologyChange`. Optional; no-op when not configured.
     fn apply_topology_change(&self, change: &TopologyChange) {
         let Some(live) = &self.live_topology else {
             return;

nodedb/src/control/server/native/dispatch/plan_builder/graph.rs

@@ -14,7 +14,7 @@ use super::parse_direction;
 /// rejecting out-of-range values rather than forwarding them to the
 /// engine. Mirrors the pgwire ingress so no entry point can saturate
 /// traversal with an unbounded fan-out.
-fn clamped_depth(value: Option<u64>, default: usize, field: &str) -> crate::Result<usize> {
+fn clamped_depth(value: Option<u32>, default: usize, field: &str) -> crate::Result<usize> {
     let v = value.map(|v| v as usize).unwrap_or(default);
     if v > MAX_GRAPH_TRAVERSAL_DEPTH {
         return Err(crate::Error::BadRequest {

nodedb/src/control/server/native/dispatch/plan_builder/vector.rs

@@ -133,9 +133,14 @@ pub(crate) fn build_multi_search(
 }
 
 pub(crate) fn build_delete(fields: &TextFields, collection: &str) -> crate::Result<PhysicalPlan> {
-    let vector_id = fields.vector_id.ok_or_else(|| crate::Error::BadRequest {
+    let vector_id_wire = fields.vector_id.ok_or_else(|| crate::Error::BadRequest {
         detail: "missing 'vector_id'".to_string(),
     })?;
+    let vector_id: u32 = vector_id_wire
+        .try_into()
+        .map_err(|_| crate::Error::BadRequest {
+            detail: "vector_id exceeds 32-bit surrogate space".to_string(),
+        })?;
 
     Ok(PhysicalPlan::Vector(VectorOp::Delete {
         collection: collection.to_string(),