Error when commenting on non-working branch

[rlmark]

Describe and demonstrate the bug Based on the described output from help for the new comment command, I had thought that comment /comment-branch would be the pattern for applying a comment to the head of the given non-working-branch. Currently, that workflow produces an error:

Sorry, I wasn’t sure how to process your request:
    
      <none>:1:16:
        |
      1 | /comment-branch
        |                ^
      Branch relative paths require a colon. Expected `:` here.

Transcript

test-proj/main> builtins.mergeio

foo = 12

test-proj/main> update
test-proj/main> branch.create comment-branch

test-proj/comment-branch> switch main
test-proj/main> comment /comment-branch

Environment:

• ucm --version 0.5.50
• OS/Architecture: macOS 26.1, Apple-silicon