Hermes' WhatsApp bridge routinely surfaces the same person under either
a phone-format JID (60123456789@s.whatsapp.net) or a LID (…@lid),
and may flip between the two for a single human within the same
conversation. Before this change, build_session_key used the raw
identifier verbatim, so the bridge reshuffling an alias form produced
two distinct session keys for the same person — in two places:
1. DM chat_id — a user's DM sessions split in half, transcripts and
per-sender state diverge.
2. Group participant_id (with group_sessions_per_user enabled) — a
member's per-user session inside a group splits in half for the
same reason.
Add a canonicalizer that walks the bridge's lid-mapping-*.json files
and picks the shortest/numeric-preferred alias as the stable identity.
build_session_key now routes both the DM chat_id and the group
participant_id through this helper when the platform is WhatsApp.
All other platforms and chat types are untouched.
Expose canonical_whatsapp_identifier and normalize_whatsapp_identifier
as public helpers. Plugins that need per-sender behaviour (role-based
routing, per-contact authorization, policy gating) need the same
identity resolution Hermes uses internally; without a public helper,
each plugin would have to re-implement the walker against the bridge's
internal on-disk format. Keeping this alongside build_session_key
makes it authoritative and one refactor away if the bridge ever
changes shape.
_expand_whatsapp_aliases stays private — it's an implementation detail
of how the mapping files are walked, not a contract callers should
depend on.