Put the whole unfurl, lookups included, under one deadline

The deadline in Opengraph::Fetch started after the lookup of the pasted
host, and an unfurl looks up more hosts outside any fetch: the canonical
URL's, and the image's, once to check its content type and again to
validate it. Each of those waits as long as the resolver takes to give
up. Move the deadline up to UnfurlLinksController, around everything the
link leads to; Opengraph::Fetch keeps its per-operation timeouts and
makes no retries.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bj8KnxpTf9sj2Ysa8aLAVa

app/controllers/unfurl_links_controller.rb

@@ -1,8 +1,9 @@
 class UnfurlLinksController < ApplicationController
-  def create
-    opengraph = Opengraph::Metadata.from_url(url_param)
+  # The pasted link decides which hosts an unfurl looks up and fetches from, and how quickly they answer.
+  DEADLINE = 10.seconds
 
-    if opengraph.valid?
+  def create
+    if opengraph = unfurl(url_param)
       render json: opengraph
     else
       head :no_content
@@ -13,4 +14,14 @@ class UnfurlLinksController < ApplicationController
     def url_param
       params.require(:url)
     end
+
+    # One deadline for everything the link leads to: DNS lookups, redirects, the page, the image check.
+    def unfurl(url)
+      Timeout.timeout(DEADLINE) do
+        Opengraph::Metadata.from_url(url).then { |opengraph| opengraph if opengraph.valid? }
+      end
+    rescue Timeout::Error
+      Rails.logger.warn "Gave up unfurling #{url} after #{DEADLINE.inspect}"
+      nil
+    end
 end