Make NEWS.md release-link footer idempotent

Seed available_footnotes from the existing release-tag link defs in the
file before overlaying freshly fetched URLs, so gems whose Octokit
fetches are skipped this run keep their URLs instead of being stranded
at their old positions. With every used ref backed by a footnote, the
reject step can drop all release-tag defs unconditionally and re-emit
them in body-ref order, eliminating the back-and-forth reordering
between consecutive scheduled bot runs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hsbt

tool/update-NEWS-github-release.rb

@@ -339,8 +339,16 @@ def update_news_md(results)
     i += 1
   end
 
-  # All footnote definitions we can emit from this run, indexed by ref name
+  # All footnote definitions we can emit, indexed by ref name. Seed from existing
+  # release-tag defs in the file so gems skipped this run (e.g. transient API
+  # failures) keep their URLs, then overlay freshly fetched URLs.
+  release_ref_pattern = %r{^\[([^\]]+)\]:\s+(https://github\.com/[^/]+/[^/]+/releases/tag/.*)}
   available_footnotes = {}
+  new_lines.each do |line|
+    if (m = line.match(release_ref_pattern))
+      available_footnotes[m[1]] = "[#{m[1]}]: #{m[2]}"
+    end
+  end
   results.each do |r|
     r[:footnote_links].each do |fl|
       available_footnotes[fl[:ref]] = "[#{fl[:ref]}]: #{fl[:url]}"
@@ -349,18 +357,10 @@ def update_news_md(results)
 
   # Refs the regenerated body actually uses (e.g. `][gem-vX.Y.Z]`)
   used_refs = new_lines.join.scan(/\]\[([^\]]+)\]/).flatten.uniq
-  used_set = used_refs.to_set
 
-  # Drop existing GitHub release-tag link defs that are either orphaned (no
-  # body reference) or about to be re-emitted from this run's results. Defs
-  # still referenced by gems we couldn't refresh are preserved in place.
-  release_ref_pattern = %r{^\[([^\]]+)\]:\s+https://github\.com/[^/]+/[^/]+/releases/tag/}
-  new_lines.reject! do |line|
-    if (m = line.match(release_ref_pattern))
-      ref = m[1]
-      !used_set.include?(ref) || available_footnotes.key?(ref)
-    end
-  end
+  # Drop all existing GitHub release-tag link defs; the used subset is
+  # re-emitted below in body-ref order so the footer is deterministic.
+  new_lines.reject! { |line| line.match?(release_ref_pattern) }
 
   # Trim trailing blank lines so the appended footer block is clean
   new_lines.pop while new_lines.last == "\n"