Merge pull request 'nisse-review marks a reply that settles its thread; the PR's author resolves it' (#169) from review-settled into main

docs/Development-Plan.md

@@ -707,6 +707,14 @@ of earlier points, replies on threads, the round cap and its reset, `stop` and
   to the model to make again (on #166 it didn't, and looped to the turn cap).
   Each reply carries its point's key, so a run re-done after a crash answers
   nothing twice.
+- **Settled threads:** each `reply` says whether it settles its thread (a
+  concession, or an answer or deferral accepted; never while waiting on a
+  change). A settled reply carries `<!-- nisse-review: settled -->`. Being
+  read-only (R3), the reviewer can't resolve the thread, so the PR's author
+  does: nisse-dev resolves every comment on that thread's line when it next
+  watches the PR and takes the settled reply as no point to answer (nor one
+  posted top-level, which has no thread to resolve);
+  `scripts/resolve_settled.py` does the same for PRs made by hand.
 - **Sign-off:** `sign_off` posts a short review when there is nothing to raise;
   while it stays happy, a later review offers `still_happy`, which posts nothing
   (operator: no repeated LGTMs).