Why: The further-objective docs are now the system's next big-phase
target; the plan pins the two-tree-one-net product on top of the
generic platform with two hard invariants - downstream-only domain
logic and always-degradable-to-generic-agent when the plugin is off.
Evidence: docs-only change; milestone mapping verified against
further-objective 10 (W1-W16), readiness claims verified against the
pinned worktrees (EXT-1 symbols in surface.txt, v0.1.0 tags, RDM repo
seed facts as recorded in vision doc 13).
Impact: Adds one proposal; no code changes.
Refs: docs/proposals/2026-10-07-agent-stack-n1q1i1-plans.md
weichen
b8eaa1676f