- password-vault: createVault takes { messengerRootHex } opt; unlockVault
surfaces messengerRoot (null on legacy vaults, so nothing regresses);
saveVault persists it; bindMessengerRoot mutates an unlocked state for a
later attach-mnemonic-to-existing-vault flow.
- main.js password-setup: when the user provides a mnemonic, ALSO compute
seedToPurposeRoot(seed, "messenger/0") and store it. Random-seed vaults
stay as-is (no mnemonic = no messenger root to store).
- main.js hermes-init: two modes now — { mnemonic } (unchanged) or
{ useVault: true } (uses vaultState.messengerRoot directly, no mnemonic).
Response includes source: "vault" | "mnemonic" for the panel to badge.
- main.js hermes-can-use-vault: cheap availability probe used by the panel
to decide whether to show the vault sign-in shortcut.
- hermes.js: nostrKeyFromRoot(root) accepts 32-byte Uint8Array or 64-char
hex; produces the same {sk, pkHex, npub} as nostrKeyFromMnemonic for the
same seed (unit-verified: derivation paths converge on f2c92519...67f4).
- Messages panel: "Sign in with password vault" button appears above the
mnemonic entry iff the vault is unlocked AND was set up from a mnemonic.
The mnemonic path stays as the always-available fallback — bind is
genuinely optional, not required.
