RLM parent lineage options are not forwarded during session replacement

[Bruce-anle]

Summary

In the v0.7.2 source, rlmParentNodeId and rlmParentAgent are explicit session creation options, but the replacement createRuntime(...) calls do not forward those fields through sessionOptions.

This is a source-level observation only. I have not performed a runtime reproduction, so this does not establish a user-visible lineage failure or that every replacement path should preserve incoming lineage values.

Source observation

• The fields are defined in AgentSessionCreationOptions and forwarded by the session factory here.
• Replacement call sites omit sessionOptions containing these fields: switchSession, newSession, fork paths, and importFromJsonl.

Open question / expected semantics

Could maintainers clarify which layer should own lineage for each path?

• newSession may intentionally establish new lineage.
• switchSession and JSONL import may treat the target session or its header as authoritative.
• A fork may derive new parent relationships.

Given those differences, should any path forward the explicit options, reconstruct lineage from persisted metadata, or leave the values unset? What test boundary would best encode the intended behavior? No fix is proposed pending that guidance.

Additional context

Adjacent merged work: #584, #589, and #596.

Related but separate: #1467 covers host handlers after replacement.