Implement the M6 milestone: all live maps, journals, subscriptions,
activity and cache keys inside kap-server are now keyed by the full
SessionRef, while the /api/v1/ws wire stays byte-identical.
- Resolve bare session ids once at attach time through the v1 resolver,
pin the ref on the subscription, and address every broadcaster,
transcript, fs-watch, and replay operation by ref; ambiguous or
unavailable ids get a compatible ack error and no subscription.
- Re-key the transcript stores, op journals, event journals (now
per-runtime directories), snapshot caches, and the lifecycle tracked
map by sessionRefKey; bare-id lookups answer only on a unique match.
- Route internal session events by an internal runtimeId payload field
(never projected onto the wire) with resolver fallback; keep the
active-state queue append synchronous to preserve frame ordering.
- Add multi-runtime isolation tests (same sessionId on two runtimes
never crosses transcript/prompt/journal streams) and a repeatable
black-box comparison harness that diffs a base-commit server against
this build over REST, WS, and export scenarios.
- Widen node-sdk PlanInfo.path to string|null to match the engine type
and fix the stale resolver-fallback comment in the broadcaster.
