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Runnable teaching lab · local only

# Claims-denial recommendation slice

Trace one bounded recommendation from an exact candidate through authorization, a simulated claims system of record, readback, telemetry, and recovery.

Node 22 · zero dependencies

    unzip lumyn-claims-denial-lab.zip
    cd lumyn-claims-denial-lab/labs/claims-denial
    npm test
    npm start

Then open `http://127.0.0.1:8787`.

01 · Build

## Bind the candidate

Inspect a deterministic adapter, candidate manifest, policy revision and simulated source record.

02 · Break

## Inject the failures

Exercise missing authority, drift, stale state, duplicate requests and a lost response after commit.

03 · Prove

## Read the effect back

Verify the operation in the source of record and inspect sanitized latency, cost, outcome and candidate traces.

Honest boundary

## A teaching fixture, not a billing product.

The data, identities, policy and recommender are synthetic. The API records a recommendation only; it cannot approve or submit a claim. This runnable candidate (`claims-denial-recommender-0.1.0`) is separate from the worked-case candidate `rec-0.4.3`; evidence never transfers between them. Its digest demonstrates drift detection for this narrow fixture, not a complete Mission 8 release binding. It does not prove payer-rule correctness, production readiness, security certification, customer value or job readiness.

Inspect the proof

## The public source and tests are part of the lesson.

Download the complete runnable lab or inspect its source files below. The original lab files are Apache-2.0 licensed and intentionally small enough to understand end to end.

Download complete lab (.zip) → Lab runbook → Service boundary → Simulated system of record → Failure and recovery tests → Runnable package manifest → Apache-2.0 license →

Field exercises

## Move from passing tests to an operating argument.

### Canary

Bound the cohort, denominator, verifier, observation window, cost ceiling, specialist capacity and stop conditions.

### Rollback

Preserve the previous candidate, policy, data contract and in-flight idempotency behavior.

### Incident

Distinguish a lost response from an uncommitted effect using readback and the operation trace.

### Transfer

Have another operator run, diagnose and recover the service without depending on the builder.