LMXF-specification/PLANS.md

LXMF Specification Investigation Plan

Each investigation must include:

1. Question being answered.
2. Upstream files inspected.
3. Exact version or commit.
4. Relevant classes/functions/constants.
5. Observed behavior.
6. Whether behavior is normative, inferred, or unresolved.
7. Test vectors needed.
8. SPEC.md sections affected.
9. Open questions.