## TL;DR
Rebuild the join as an as-of join on event timestamp with created timestamp as the tie breaker, drop the label and any post outcome columns from the feature list, and compare offline and online values for the same entity and timestamp until they match. Start in the feature store registry, the materialization job history, and the online store metrics, work on one affected item, and prove the fix there before running the full set. Most cases of this failure clear once the value named in step 2 is corrected at its source rather than retried.

```text
when agent tried to run point in time join validation failed with leakage error
```

## Use this when
- You see this exact message or symptom in generic feature store: when agent tried to run point in time join validation failed with leakage error
- One run, record, build, or object is affected and you can name it
- A retry without changing anything reproduces the same text

## Not for this skill when
- generic feature store fails with a different message and none of the signals here appear
- Nothing has failed yet and you are doing first time setup or general planning
- Every service from this vendor is down for all users, which is a vendor outage to wait out first

## Steps
1. Reproduce the failure once in the feature store registry, the materialization job history, and the online store metrics and search the log or history for the exact text in the block above, recording the time, the workspace or project, and the one object it names. Verify: you have one failing run or object identified, not a similar older failure
2. Inspect the feature definition, entity key type, event timestamp column, TTL, and the online and offline store config, and check the event and created timestamp columns, the excluded label and post outcome columns, and an offline versus online comparison for one entity at one timestamp. Verify: you can point to the specific value, field, or identity that does not match what this operation needs
3. Apply the fix at that source: rebuild the join as an as-of join on event timestamp with created timestamp as the tie breaker, drop the label and any post outcome columns from the feature list, and compare offline and online values for the same entity and timestamp until they match. Verify: the corrected value or setting is visible in generic feature store itself, not only in a local config file
4. Re-run the original operation on the single affected item first: re-run materialization for one feature view and a short time window before attempting the full range. Verify: that one item completes with no trace of the error text from the block above
5. Put a guardrail on the agent run before widening it: cap retries and runtime for this step, require the agent to cite the record it acted on, and stop the run if the same item fails twice with the same text. Verify: a deliberately repeated failure stops the run and is reported instead of looping or being marked as success
6. Check the downstream result a user or the next job would see: an online lookup for one known entity and an offline historical query for the same entity and timestamp. Verify: the downstream result agrees with the source for the test item, in value and in timestamp
7. Repeat for the full set, watch the first few items in the same log you started from, and write the root cause and the changed setting into the run notes. Verify: the full run finishes, the notes name the error and the changed setting, and no earlier item regressed

## Variant phrasings
### when agent tried to run point in time join validation failed with leakage error
The subject-first phrasing of the same failure. The fix is the same, start at step 1 and confirm the object the log names.
### generic feature store version of this failure
The tool-first phrasing searchers use once they know which system raised it. It is the same underlying problem, not a separate bug.
### Why does when agent tried to run point in time join validation failed with leakage error keep happening after a retry
The repeat-occurrence phrasing. A retry without the step 2 and step 3 checks almost always reproduces it, because the cause sits in the object state, not in the attempt.

Compatibility: Feast, Tecton, Databricks, SageMaker, or Vertex feature stores in current releases, warehouse offline store, Redis or DynamoDB online store. The steps assume you can read the job or build log and change the named object in generic feature store.

## Why it happens
In generic feature store, this failure usually means the join or the feature set lets information from after the prediction moment, or the label itself, into the features, or the online path computes a value the offline path computes differently. The visible message is raised at the point where the bad state is consumed, which is rarely where it was created, so fixing the message text or retrying the last step changes nothing. Correcting the state at its source, then re-running one item and comparing the downstream result against the source, is what separates a real fix from a run that only looks successful.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_U6Vn4giPc7I6mEmti3WuHA