Source checks
When Backwork last fetched a policy, the hash of what it fetched, and the sampled accuracy audits measured for the policy's source
Every policy object in a v1 response has a source_check. It tells you where Backwork fetched the policy, when it last fetched it, a hash of what it fetched, and how accurate an audit found the records from that source.
"source_check": {
"source_url": "https://www.molinahealthcare.com/policies/botox.pdf",
"last_fetched_at": "2026-09-28T04:00:00.000Z",
"content_sha256": "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08",
"source_accuracy": [
{ "field": "overall", "sampled_at": "2026-09-15T00:00:00.000Z", "sample_size": 120, "accuracy": 0.9667, "ci_low": 0.917, "ci_high": 0.987, "method": "manual_review_v1" },
{ "field": "codes", "sampled_at": "2026-09-15T00:00:00.000Z", "sample_size": 120, "accuracy": 0.9333, "ci_low": 0.875, "ci_high": 0.966, "method": "manual_review_v1" }
]
}| Field | Meaning |
|---|---|
source_url | The URL Backwork fetches the policy from. |
last_fetched_at | When Backwork last fetched the policy. null when no fetch time is recorded. The payer may have changed the document since. |
content_sha256 | SHA-256 of the fetched content, as 64 lowercase hex characters. null when the loader did not record one. Compare it across responses to see whether the fetched content changed. |
source_accuracy | The latest audit of each field for the policy's source, overall first. null when the policy has no recorded source or the source has no audit yet. |
source_check itself is null only when the policy is no longer on record.
Sampled accuracy
Backwork audits a sample of the policy records from each source against the source documents. Each entry in source_accuracy is the most recent audit of one field:
| Field | Meaning |
|---|---|
field | overall for the record as a whole, or one field: title, effective_date, codes, link. |
sampled_at | When the audit drew its sample. |
sample_size | How many records the audit sampled. |
accuracy | The share of sampled records that matched the source, from 0 to 1. |
ci_low, ci_high | The 95% Wilson score confidence interval for accuracy. |
method | How the audit decided whether a record matched. |
The figures describe a sample of the source's records, not the policy in the response. Use the interval, not only the point estimate: with a small sample_size the interval is wide. Before you rely on a policy for a coverage, billing, or prior-auth decision, read its source.
The Backwork app and the public policy pages show the same data as Source checked September 28, 2026 and Sampled accuracy for this source: 97% (95% CI 92–99%, n=120, September 2026).
Code entries carry their own check, grounding. See Code sources.
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