fn read_chunk_count(field_key: &str) -> Result<usize, StoreError>Expand description
Ok(0) means the :count entry genuinely doesn’t exist (field never
written under the chunked layout). Err means the read itself failed —
reagent P1: a prior version of this collapsed both into the same 0,
which muxbus_clear used to bound its per-field deletion loop
(for i in 0..count) — a transient read failure made that loop delete
NOTHING, while the field’s :count key was still deleted unconditionally
right after, so logout appeared to succeed while the real token chunks
were silently orphaned in the OS keychain. Callers must not treat Err
as “0 chunks.”