Function storage_key 

pub fn storage_key(repo: &str, base_sha: &str, head_sha: &str) -> String

The LEGACY localStorage key a review document was filed under, exposed to the page as pd_storage_key and consulted once per load to migrate old state. Pages now key state by review_id — a render-time fingerprint of the canonical diff content (see cli/src/render.rs and docs/PAGE.md) — so an identical regenerated diff keeps its comments. Carrying comments across a CHANGED diff remains export → import, where review::ReviewDocument::merge applies.