Review step misses cross-path format inconsistency

Problem

The review step evaluated a diff where two separate write paths populate the same column (beneficiary_country) with different formats (alpha-2 vs alpha-3 country codes). It gave a clean findings: [] and marked risk as "low", missing the data consistency bug entirely.

The root cause: the review agent inspected each changed file in isolation and concluded both paths were correct individually. It did not trace the actual runtime values flowing into the shared column from different sources - which would have required reading code outside the diff.

Suggested improvement

When the review step sees a new column being written from multiple code paths (multiple call sites to the same create method, or the same column set in different services/controllers), it should:

1. Identify all write paths to that column in the diff
2. Trace the data source for each path (even outside the diff) to check format consistency
3. Flag when the same logical field could arrive in different formats (e.g. alpha-2 vs alpha-3, string vs integer, different enum serializations)

This is a class of bug where each path looks correct in isolation but the combined data is inconsistent - a "format convergence" check.

Evidence

• Review step output: findings=[], risk_level=low, rationale="Straightforward additive change - a nullable string column populated at write time with no index, no backfill, and correct nil-safe extraction in both code paths."