ChatDatabase gains a second AEAD key — the local vault key (setSensitiveKey /
lockSensitive) — and a sensitivity predicate. Rows of conversations the
predicate marks sensitive are encrypted under the vault key instead of the
seed-derived key, and are persisted only while the vault is unlocked (never
stored under the seed key). load() tries the seed key then the vault key, so a
sensitive row is WITHHELD whenever the vault key is absent — including on a
fresh instance that holds only the seed (the "fresh seed import can't read
sensitive conversations" guarantee); a wrong vault key withholds too, never
yields garbage. encrypt/decrypt are now key-parametrized; lock() also wipes the
vault key. Unit-tested end to end.
Phase B, step 3 (DB dual-key).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
DanSandClaude Opus 4.8
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