separate new vs previous PR comments in review flow

Split PR comments by the latest commit date so Claude knows which
comments are new (actionable) and which are older (context only).

- get_pr_review_comments now accepts an optional cutoff date parameter
- When provided, returns {new_comments, previous_comments} instead of flat lists
- start_review_task passes the latest commit date as cutoff
- The PRD generation prompt clearly labels new comments as actionable
  and previous comments as background context only
- The reply-to-comments flow (no cutoff) still gets the flat format

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: robertherber

scripts/eternity-loop.sh

@@ -770,15 +770,19 @@ get_ci_failure_details() {
 }
 
 # Fetch all non-resolved, non-outdated PR comments for review context
+# Optional 3rd arg: cutoff date (ISO 8601). When provided, comments are split into
+#   "new" (after cutoff — actionable) and "previous" (before cutoff — context only).
 get_pr_review_comments() {
   local work_dir="$1"
   local pr_number="$2"
+  local cutoff_date="${3:-}"
   local tmpdir
   tmpdir=$(mktemp -d)
 
   cd "$work_dir"
 
   log_err "  [comments] Fetching review comments for PR #$pr_number..."
+  [ -n "$cutoff_date" ] && log_err "  [comments] Cutoff date: $cutoff_date"
 
   # Get review comments via GraphQL - only unresolved, non-outdated threads
   local repo_nwo
@@ -865,17 +869,44 @@ get_pr_review_comments() {
   log_err "  [comments] Review bodies with text: $rv_count"
   log_err "  [comments] Total comments collected: $((rc_count + ic_count + rv_count))"
 
-  # Combine into a single JSON object
+  # Combine and split by cutoff date if provided
   python3 -c "
-import json
+import json, sys
+
 rc = json.load(open('$tmpdir/review_comments.json'))
 ic = json.load(open('$tmpdir/issue_comments.json'))
 rv = json.load(open('$tmpdir/reviews.json'))
-print(json.dumps({
-  'review_comments': rc,
-  'issue_comments': ic,
-  'reviews': rv
-}, indent=2))
+
+cutoff = '$cutoff_date'
+
+if cutoff:
+    def split_by_cutoff(items):
+        new = [c for c in items if (c.get('created_at') or '') > cutoff]
+        previous = [c for c in items if (c.get('created_at') or '') <= cutoff]
+        return new, previous
+
+    rc_new, rc_prev = split_by_cutoff(rc)
+    ic_new, ic_prev = split_by_cutoff(ic)
+    rv_new, rv_prev = split_by_cutoff(rv)
+
+    print(json.dumps({
+        'new_comments': {
+            'review_comments': rc_new,
+            'issue_comments': ic_new,
+            'reviews': rv_new
+        },
+        'previous_comments': {
+            'review_comments': rc_prev,
+            'issue_comments': ic_prev,
+            'reviews': rv_prev
+        }
+    }, indent=2))
+else:
+    print(json.dumps({
+        'review_comments': rc,
+        'issue_comments': ic,
+        'reviews': rv
+    }, indent=2))
 "
 
   rm -rf "$tmpdir"
@@ -1004,13 +1035,7 @@ start_review_task() {
 
   mkdir -p "$ralph_dir"
 
-  # Collect all non-outdated PR comments
-  log_err "[start-review] Collecting PR comments..."
-  local comments
-  comments=$(get_pr_review_comments "$work_dir" "$pr_number")
-  log_err "[start-review] PR comments collected."
-
-  # Clean working tree and check out the branch
+  # Clean working tree and check out the branch first (need commit date for cutoff)
   clean_working_tree "$work_dir"
   log_err "[start-review] Checking out branch $branch_name..."
   if ! git checkout "$branch_name" 2>/dev/null; then
@@ -1022,6 +1047,18 @@ start_review_task() {
   fi
   git pull origin "$branch_name" --ff-only 2>/dev/null || true
   log_err "[start-review] On branch: $(git branch --show-current), latest commit: $(git log -1 --format='%h %s')"
+
+  # Get the latest commit date as cutoff for splitting comments
+  local latest_commit_date
+  latest_commit_date=$(TZ=UTC git log -1 --format="%ad" --date=format-local:'%Y-%m-%dT%H:%M:%SZ' 2>/dev/null) || true
+  log_err "[start-review] Latest commit date (cutoff): $latest_commit_date"
+
+  # Collect PR comments, split by cutoff date
+  log_err "[start-review] Collecting PR comments..."
+  local comments
+  comments=$(get_pr_review_comments "$work_dir" "$pr_number" "$latest_commit_date")
+  log_err "[start-review] PR comments collected."
+
   log_err "[start-review] Invoking Claude to generate review prd.json..."
 
   claude --dangerously-skip-permissions --print -p "$(read_prompt create-review-prd.md)
@@ -1035,9 +1072,16 @@ project: \"$issue_id: $issue_title (review feedback)\"
 - Title: $issue_title
 - URL: $issue_url
 
-## PR #$pr_number Review Comments
+## PR #$pr_number — NEW Review Comments (after latest commit $latest_commit_date)
+These are the comments that need to be addressed. Create user stories for these.
+
+$(echo "$comments" | python3 -c "import json,sys; d=json.load(sys.stdin); print(json.dumps(d.get('new_comments', d), indent=2))")
+
+## PR #$pr_number — Previous Comments (before latest commit, for context only)
+These comments were posted before the latest commit. They may have already been addressed.
+Do NOT create user stories for these — they are provided only as background context.
 
-$comments
+$(echo "$comments" | python3 -c "import json,sys; d=json.load(sys.stdin); print(json.dumps(d.get('previous_comments', {}), indent=2))")
 
 $RALPH_SKILL_GUIDELINES" 2>&1 | tee /dev/stderr || true