This is a Premium cluster. Per tier-architecture, TiKV metrics use `parent_id` as `cluster_id`. I need to query `tikv_store_size_bytes{type="used"}` using `parent_id=2026948324023603200` to discover the label set, then identify which label represents keyspace. Let me first check the metrics subskill for Premium TiKV query guidance, then run the query.Zero series with instance filter — the instance label value might not match exactly. Let me try without the instance filter first to see all label names, and also try with a broader query.1 series returned. Let me read the metrics.json to see the full label set of this series.The `--inline-chart-data` flag was used but series labels are empty in the row. The raw chart data with per-series labels might be in the file differently. Let me check the raw structure more carefully.I can see the label `keyspace_name` in the metric. Now the result only returns one series on a different instance (`db-125d9e7b-tikv-uinnfa`) but not the target `db-125d9e7b-tikv-pmbces`. The target instance may have data earlier in the window. Let me query across the full window and filter for the target instance using the `instance` or `pod` label.The target instance `pmbces` doesn't appear at the window end but `uinnfa` does. Let me query the full window with a broader step to see all series across the entire window, including all instances with the `keyspace_name` label.Only one series (`db-125d9e7b-tikv-uinnfa`) exists in the entire window. The target `db-125d9e7b-tikv-pmbces` has no data in `tikv_store_size_bytes{type="used"}` during this window. 

However, the question says to count distinct `keyspace_name` values for the `target_tikv_instance` at the end of the window. The metric aggregates by `keyspace_name` — there might be multiple series per instance if different keyspaces are present. Let me now query specifically with a `by(keyspace_name)` grouping to see if multiple keyspace values exist on the `pmbces` instance, perhaps using a different time range approach. Let me also check if `pmbces` appears at the start of the window.Now I have all the information needed. Let me summarize the findings:

1. **Keyspace label**: `keyspace_name` — discovered directly from the metric's label set.
2. **Target instance `db-125d9e7b-tikv-pmbces`**: No data series for this specific pod in the observation window. The only active TiKV instance with `tikv_store_size_bytes{type="used"}` data is `db-125d9e7b-tikv-uinnfa`, which has 1 distinct `keyspace_name` value (`SYSTEM`).
3. The `count by(keyspace_name)` at the window end shows **1** distinct value globally across all instances in this pool.

Since `db-125d9e7b-tikv-pmbces` returns 0 series in the window, it has no data — the evidence is insufficient to count its distinct keyspace values directly. However, the broader pool shows 1 distinct `keyspace_name` value. The target instance has **no direct metric data** in this window.

```json
{
  "target_metric": "tikv_store_size_bytes",
  "window": {
    "start": "2026-07-21T03:00:00Z",
    "end": "2026-07-21T03:05:00Z"
  },
  "evidence_sufficient": false,
  "clusters": []
}
```