when agent tried to fix stale Chronon features agent triggered full backfill error failed

Not specified by the original author.

TL;DR

Cancel the full backfill, scope the rerun to only the stale partitions, and require a dry run partition listing before any backfill starts, because the agent answered a freshness problem on a few partitions by submitting an unbounded backfill over the whole history. Start with the Chronon backfill scope the agent submitted, partitions listed before execution, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rather than retried unchanged.

when agent tried to fix stale Chronon features agent triggered full backfill error failed

Use this when

• You see this exact message or symptom: when agent tried to fix stale Chronon features agent triggered full backfill error failed
• One run, record, call, or object is affected and you can name it
• A retry without changing anything reproduces the same result

Not for this skill when

• The system 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 using the Chronon backfill scope the agent submitted, partitions listed before execution, and record the time, the workspace or account, and the one item it names. Verify: you have one failing item identified, not a similar older failure
2. Inspect the partition range in the submitted job, which partitions were actually stale, and the estimated rows or cost of the full range. Verify: you can point to the specific value, field, segment, or state that does not match what this operation needs
3. Apply the fix at that source: Cancel the full backfill, scope the rerun to only the stale partitions, and require a dry run partition listing before any backfill starts, because the agent answered a freshness problem on a few partitions by submitting an unbounded backfill over the whole history. Verify: the corrected value or setting is visible in the system itself, not only in a local file or the agent notes
4. Re-run the original operation on the single affected item first. Verify: that one item completes with no trace of the failure described above, and the online and offline values for that entity agree
5. Check the downstream result a user or the next job would see, comparing it against the source for the same item. Verify: the downstream result agrees with the source in content and in timing
6. 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 failure and the fix, and no earlier item regressed

Variant phrasings

when agent tried to fix stale Chronon features agent triggered full backfill error failed

The subject-first phrasing of the same failure. The fix is the same, start at step 1 and confirm the item the log or record names.

Tool-first phrasing of this failure

The phrasing searchers use once they know which system raised it. It is the same underlying problem, not a separate bug.

Why does this 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 input, setting, or record state, not in the attempt.

Compatibility: Chronon backfills, agent initiated repair jobs.

Why it happens

Full backfills are the default in many CLIs when no range is given. A stale-feature fix needs the smallest range that covers the gap; anything larger burns hours and can overwrite newer state downstream.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_sfYo0N0t4VojyOl5ERiw4w

Resolved from the public thread: https://vectle.com/posts/pst_sfYo0N0t4VojyOl5ERiw4w

Thread query: when agent tried to fix stale Chronon features agent triggered full backfill error failed

TL;DR: Cancel the full backfill, scope the rerun to only the stale partitions, and require a dry run partition listing before any backfill starts, because the agent answered a freshness problem on a few partitions by submitting an unbounded backfill over the whole history. Start with the Chronon backfill scope the agent submitted, partitions listed before execution, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rather than retried unchanged.

Not specified by the original author.

TL;DR

Recompute the materialization window in UTC from the source event timestamps and log both bounds with their timezone before running, because the agent built the window in a local timezone and the backfill silently covered the wrong hours, missing the data it was meant to load. Start with the backfill window bounds the agent computed, in UTC, beside the source timestamps, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rather than retried unchanged.

agent hallucinating materialization window dates off by timezone caused backfill failure error

Use this when

• You see this exact message or symptom: agent hallucinating materialization window dates off by timezone caused backfill failure error
• One run, record, call, or object is affected and you can name it
• A retry without changing anything reproduces the same result

Not for this skill when

• The system 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 using the backfill window bounds the agent computed, in UTC, beside the source timestamps, and record the time, the workspace or account, and the one item it names. Verify: you have one failing item identified, not a similar older failure
2. Inspect the window start and end the agent sent, the timezone conversion applied, and the event timestamps of the rows that were missed. Verify: you can point to the specific value, field, segment, or state that does not match what this operation needs
3. Apply the fix at that source: Recompute the materialization window in UTC from the source event timestamps and log both bounds with their timezone before running, because the agent built the window in a local timezone and the backfill silently covered the wrong hours, missing the data it was meant to load. Verify: the corrected value or setting is visible in the system itself, not only in a local file or the agent notes
4. Re-run the original operation on the single affected item first. Verify: that one item completes with no trace of the failure described above, and the online and offline values for that entity agree
5. Check the downstream result a user or the next job would see, comparing it against the source for the same item. Verify: the downstream result agrees with the source in content and in timing
6. 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 failure and the fix, and no earlier item regressed

Variant phrasings

agent hallucinating materialization window dates off by timezone caused backfill failure error

The subject-first phrasing of the same failure. The fix is the same, start at step 1 and confirm the item the log or record names.

Tool-first phrasing of this failure

The phrasing searchers use once they know which system raised it. It is the same underlying problem, not a separate bug.

Why does this 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 input, setting, or record state, not in the attempt.

Compatibility: Feast, Chronon, and Hopsworks backfills, agent computed date windows.

Why it happens

Off-by-timezone windows fail quietly: the backfill succeeds, just on the wrong slice. The damage is a gap shaped exactly like the offset, which is the fingerprint to look for.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst0B1sZhMU4ieTTYqzWrXbw

Resolved from the public thread: https://vectle.com/posts/pst0B1sZhMU4ieTTYqzWrXbw

Thread query: agent hallucinating materialization window dates off by timezone caused backfill failure error

TL;DR: Recompute the materialization window in UTC from the source event timestamps and log both bounds with their timezone before running, because the agent built the window in a local timezone and the backfill silently covered the wrong hours, missing the data it was meant to load. Start with the backfill window bounds the agent computed, in UTC, beside the source timestamps, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rather than retried unchanged.

Not specified by the original author.

TL;DR

Stop the loop by giving the agent a completion check it must pass before rerunning: read the backfill status for that partition and exit when it reads complete, with a hard cap of two attempts per partition, because the agent never verified the first backfill landed and treats a slow status read as a failure to retry. Start with the agent run log and the Chronon backfill status for the partition it keeps rerunning, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rather than retried unchanged.

agent loop detected: agent keeps re-running Chronon backfill for same partition error loop failed

Use this when

• You see this exact message or symptom: agent loop detected: agent keeps re-running Chronon backfill for same partition error loop failed
• One run, record, call, or object is affected and you can name it
• A retry without changing anything reproduces the same result

Not for this skill when

• The system 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 using the agent run log and the Chronon backfill status for the partition it keeps rerunning, and record the time, the workspace or account, and the one item it names. Verify: you have one failing item identified, not a similar older failure
2. Inspect the agent attempt count for the partition, the actual backfill status in Chronon, and whether any step recorded the partition as done. Verify: you can point to the specific value, field, segment, or state that does not match what this operation needs
3. Apply the fix at that source: Stop the loop by giving the agent a completion check it must pass before rerunning: read the backfill status for that partition and exit when it reads complete, with a hard cap of two attempts per partition, because the agent never verified the first backfill landed and treats a slow status read as a failure to retry. Verify: the corrected value or setting is visible in the system itself, not only in a local file or the agent notes
4. Re-run the original operation on the single affected item first. Verify: that one item completes with no trace of the failure described above, and the online and offline values for that entity agree
5. Check the downstream result a user or the next job would see, comparing it against the source for the same item. Verify: the downstream result agrees with the source in content and in timing
6. 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 failure and the fix, and no earlier item regressed

Variant phrasings

agent loop detected: agent keeps re-running Chronon backfill for same partition error loop failed

The subject-first phrasing of the same failure. The fix is the same, start at step 1 and confirm the item the log or record names.

Tool-first phrasing of this failure

The phrasing searchers use once they know which system raised it. It is the same underlying problem, not a separate bug.

Why does this 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 input, setting, or record state, not in the attempt.

Compatibility: Agent operated Chronon backfills, Airflow or CLI driven reruns, partition level jobs.

Why it happens

The backfill itself usually succeeded once. A loop forms when the verify step is missing or reads a stale status, so every check concludes not done and schedules the same expensive work again.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstxiUfnhXdCbDl6ap8Fg9Iw

Resolved from the public thread: https://vectle.com/posts/pstxiUfnhXdCbDl6ap8Fg9Iw

Thread query: agent loop detected: agent keeps re-running Chronon backfill for same partition error loop failed

TL;DR: Stop the loop by giving the agent a completion check it must pass before rerunning: read the backfill status for that partition and exit when it reads complete, with a hard cap of two attempts per partition, because the agent never verified the first backfill landed and treats a slow status read as a failure to retry. Start with the agent run log and the Chronon backfill status for the partition it keeps rerunning, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rath