handle case where new release happens runs and check last diff repo commit rather than just last week

the latter is to handle the case where we run this flow multiple times a day or in the same week and there arent any new changes. Previously it would still use the current weeks diff results rather than reporting that there are no changes

Author: LFDanLu

.github/workflows/weekly-api-diff.yml

@@ -34,7 +34,7 @@ jobs:
         run: yarn build:api-published
 
       - name: Generate diff
-        run: yarn compare:apis --isCI > /tmp/diff-current.txt || true
+        run: yarn --silent compare:apis --isCI > /tmp/diff-current.txt || true
 
       # Check out snapshots repo so we can read the previous diff and commit the new one
       - uses: actions/checkout@v4
@@ -49,16 +49,20 @@ jobs:
           TODAY=$(date +%Y-%m-%d)
           echo "TODAY=$TODAY" >> $GITHUB_ENV
 
-          cp /tmp/diff-current.txt snapshots/diffs/$TODAY.txt
-
-          PREV=$(ls -t snapshots/diffs/*.txt 2>/dev/null | sed -n '2p')
+          # Compare against most recent existing diff BEFORE writing the diff
+          # so that we dont report a diff if we run before a week passes and nothing has changed
+          PREV=$(ls -t snapshots/diffs/*.txt 2>/dev/null | head -1)
           if [ -n "$PREV" ]; then
-            diff "$PREV" snapshots/diffs/$TODAY.txt > /tmp/weekly-delta.txt || true
+            diff "$PREV" /tmp/diff-current.txt > /tmp/weekly-delta.txt || true
           else
             echo "(first run — no previous diff to compare against)" > /tmp/weekly-delta.txt
           fi
 
-          if [ -s /tmp/diff-current.txt ]; then
+          # Only commit if there are pending API changes and they differ from last week.
+          # If diff-current is empty (release landed), skip commit so the previous
+          # non-empty diff stays as the baseline for next week's comparison.
+          if [ -s /tmp/diff-current.txt ] && [ -s /tmp/weekly-delta.txt ]; then
+            cp /tmp/diff-current.txt snapshots/diffs/$TODAY.txt
             cd snapshots
             git config user.email "github-actions@github.com"
             git config user.name "GitHub Actions"
@@ -89,9 +93,10 @@ jobs:
           workspace = os.environ['GITHUB_WORKSPACE']
           diff_url = f"https://github.com/{snapshots_repo}/blob/main/diffs/{today}.txt"
 
-          diff_size = os.path.getsize('/tmp/diff-current.txt')
+          vs_release_size = os.path.getsize('/tmp/diff-current.txt')
+          vs_last_week_size = os.path.getsize('/tmp/weekly-delta.txt') if os.path.exists('/tmp/weekly-delta.txt') else 0
 
-          if diff_size == 0:
+          if vs_release_size == 0 or vs_last_week_size == 0:
             message = f"📊 Weekly API Diff — {today}\n\nNo API changes vs release baseline this week — either nothing new has landed on main yet, or all pending changes were included in a release."
           else:
             delta = open('/tmp/weekly-delta.txt').read()[:4000]