## TL;DR
Give the anomaly detector its history: Soda anomaly detection needs at least 30 historic measurements for a metric, so let the check collect measurements over time, or seed the history from past scan results, before expecting anomaly verdicts. Thirty measurements is the floor for a baseline the detector trusts. A new check has days, not a baseline, and Soda refuses to guess rather than firing on noise.

```text
soda scan failed error "anomaly detection requires at least 30 historic measurements"
```

## Use this when
- The check or run fails with this symptom: a Soda scan fails with anomaly detection requires at least 30 historic measurements.
- You are working on a Soda Core anomaly detection check on a metric that is new or newly renamed and the failure repeats on the same data or configuration.
- You need the failing rows, rule, or stage isolated before changing thresholds or code.

## Not for this skill when
- A metric whose history exists under a different check identity after a rename, which needs the identity aligned rather than thirty new days.
- The error text names a different tool, stage, or root cause. Match the verbatim error first and use that skill.

## Steps
1. Check how many measurements Soda has stored for the metric. Verify: the stored count is below thirty
2. Confirm the scan has run on a regular schedule and results are being stored. Verify: measurements accumulate per run, or storage is off and nothing accumulates
3. If the check was renamed, align its identity with the previous check so the existing history attaches. Verify: the stored count jumps over the floor
4. Otherwise run the scan on schedule until the floor is reached, keeping the check in warn mode meanwhile. Verify: the measurement count reaches thirty
5. Switch the check to fail mode and run the scan. Verify: anomaly detection evaluates against the collected baseline

## Variant phrasings
### soda anomaly detection requires 30 historic measurements
The shorter phrasing focused on the named failure.
### soda scan failed anomaly historic measurements
The symptom phrasing a searcher tries next.
### soda anomaly detection history floor fix
The variant naming the failing stage or tool directly.

Compatibility: Soda Core 3.x anomaly detection checks and Soda Cloud measurement history

## Why it happens
Anomaly detection compares today with a learned history. New checks, renamed checks, and scans that do not store results all present as zero history, and Soda treats a verdict without a baseline as worse than no verdict, so it fails the configuration instead.

## Edge cases / pitfalls
- Backfilling history from a burst of same-day scans defeats the purpose; measurements need real time spread to form a baseline.
- Renaming a check for clarity resets its anomaly history unless the identity is migrated; plan renames with that cost stated.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_RZ8B0yNRllx0gnuCXf-vxw