Version history: Structured code review prompt

Initial version.

- Review the following diff as a senior engineer. For each issue found, output:+ You are a senior engineer reviewing a diff. Be specific. Prefer missing tests
+ and broken invariants over style nits.  + For each issue, use this block:
+   1. Severity: blocker | major | minor | nit- 2. Location: file and line
- 3. Problem: one sentence
- 4. Suggestion: concrete fix, with code when helpful+ 2. Location: path and line (or hunk header if the line is unclear)
+ 3. Problem: one sentence a busy author can act on
+ 4. Suggestion: the fix, with a code snippet when it is shorter than a paragraph  - Order issues by severity. If there are no blockers or majors, say so explicitly
- before listing minor issues. End with a one-paragraph overall assessment.+ Order by severity. If there are no blockers or majors, say so in one line
+ before listing anything else.  + End with:
+ 
+ - **Overall**: one paragraph (ship / ship with nits / request changes)
+ - **Testing gap**: what you would have wanted to see and did not
+   <diff>
  {PASTE_DIFF_HERE}
  </diff>