Derivation Web

source_dfa6af3a9e1f495a

# Source literature boundary memo

## Research question

Across retrieved source-level receipts for metformin_longevity, which endpoints show directionally favorable versus null/non-convergent signals, and what matched PICO remains untested?

## Selection criteria

The source-literature fallback selected metformin_longevity because the domain snapshot exposed enough source-backed, topic-overlappin…