How to properly declare subjectTransforms for KeyValue buckets

[ricker-flow]

I want to create a KV bucket that is a subject transform of several streams. I created the following resource. The bucket appears in the cluster but it is not being populated.

apiVersion: jetstream.nats.io/v1beta2
kind: KeyValue
metadata:
  name: core-v2
spec:
  bucket: core-v2
  storage: file
  preventDelete: true
  description: A single key value store for all core data
  replicas: 2
  sources:
    - name: agreement
      subjectTransforms:
        - dest: node.>
          source: agreement.*.*.>
    - name: digital
      subjectTransforms:
        - dest: node.>
          source: digital.*.*.>
    - name: collection
      subjectTransforms:
        - dest: node.>
          source: collection.*.*.>

[jnmoyne]

Your transform doesn't look right.
Messages in KV's underlying streams must be using subjects for the format $KV.<bucket name>.<key> so your destination transform should reflect that, otherwise the messages will make it into the stream but you won't be able to see them through the KV API.

[ricker-flow]

Just FYI, I tried declaring it as a stream:

apiVersion: jetstream.nats.io/v1beta2
kind: Stream
metadata:
  name: KV_core-v2
spec:
  name: KV_core-v2
  storage: file
  preventDelete: true
  description: A single key value store for all core data
  replicas: 2
  sources:
    - name: agreement
      subjectTransforms:
        - dest: KV_core-v2.node.>
          source: agreement.*.*.>
    - name: digital
      subjectTransforms:
        - dest: KV_core-v2.node.>
          source: digital.*.*.>

Did not work. NATS assumes the sources are buckets.

> nats kv info core-v2
Handling connection for 4222
Information for Key-Value Store Bucket core-v2 created 2025-08-12T09:15:08-04:00

Configuration:

          Bucket Name: core-v2
         History Kept: 1
        Values Stored: 0
           Compressed: false
   Backing Store Kind: JetStream
          Description: A single key value store for all core data
          Bucket Size: 0 B
  Maximum Bucket Size: unlimited
   Maximum Value Size: unlimited
          Maximum Age: unlimited
     JetStream Stream: KV_core-v2
              Storage: File

Sources Information:

        Source Bucket: physical
            Last Seen: never
                  Lag: 0
        Source Bucket: service
            Last Seen: never
                  Lag: 0
        Source Bucket: predicate
            Last Seen: never
                  Lag: 0
...