Work>work: selectable runs, log pre-chosen, merge tab no longer shows another task's merge

docs/RUNS-AND-MERGE.md

@@ -57,6 +57,17 @@ follows is:
 Merging does not happen on its own. `m` in `Work>work` asks first and shows the branch and the
 base branch before anything runs.
 
+### "Why is a task that only added a file being merged and rebased?"
+
+Because that file is a commit, and the commit is on the task's branch, not on `main`. Merging is
+the only step that puts it there. The rebase is not a rewrite of your work: it moves the task's
+branch onto the current tip of `main` so the checks run against what would actually land. When
+`main` has not moved since the branch was cut, the rebase does nothing at all and the log shows
+it as a single step.
+
+A documentation change and a five-hundred-line refactor go through the same gate. What differs
+is only what the review and the checks find.
+
 ## Working without the Board
 
 `Work>work` is self-contained now:
@@ -65,8 +76,8 @@ base branch before anything runs.
 |---|---|
 | `n` / `p` | next / previous task in the project — the header shows `task 3 of 13` |
 | `o` | pick a task from a list |
-| `↑` / `↓` | choose a run in the runs tab |
-| `Enter` | open that run's log |
+| `↑` / `↓` | choose a run in the runs tab (the chosen one is marked `▸`) |
+| `Enter` | open that run's log — the newest run is already chosen when a task opens |
 | `[` / `]` | switch tabs: runs, change, facts, review, log, merge |
 | `m` | merge this task — asks first |
 | `t` | open a tool pane (Lazygit, Hunk, Yazi, Neovim, fzf, shell, ocr) |