Build the download address from the plugin header, not from the forge

The v1.4.0 release went out and the feed came back readable, with this in it:

  "browser_download_url":
    "http://57.129.89.117:25001/kw/woocommerce-email-discount-manager/..."

That field is filled from the forge's own configured root URL, which is not
necessarily the address the outside world reaches it on. A shop handed that
would be downloading plugin code over plain HTTP from a raw IP on a
non-standard port, bypassing the Cloudflare tunnel in front of gitea.nolimit.dk
and breaking the day that address changes.

parse_release() now rebuilds both the package and the release-page address from
the repository address in the plugin header, which is the one place that
already had to be right for any of this to work. tests/smoke.php pins it with
the exact response the live feed returned.

The release check had the same bug from the other end, and a worse version of
it: it verified the address the API reported rather than the one the plugin
builds, so it was a green check on a URL no shop ever uses. It now downloads
the package the plugin would download and opens the zip to confirm it is the
plugin and not an error page with a 200 on it.

And it only runs on the forge named in "Update URI". The other one is a mirror;
requiring a mirror to be anonymously readable failed the GitHub half of the
v1.4.0 release for a repository that is private on purpose.

ci/update-smoke.sh is the check none of the above can stand in for: install the
previous version into a throwaway shop and let WordPress find, download and
install the new one by itself. Every piece can be individually correct and the
update still not arrive.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

ci/publish-release.sh

@@ -113,8 +113,25 @@ print(json.dumps({
 fi
 
 ci_step "the feed, read the way a shop reads it"
-# Deliberately no token on any request below. A "check" that sends credentials
-# the shops do not have is the false positive that hides exactly this bug.
+
+# Only the forge named in "Update URI" actually serves shops. This script runs
+# on both, and the other one is a mirror — requiring a mirror to be anonymously
+# readable would fail every release for a repository that is private on purpose.
+# (It did, on the first v1.4.0 run: GitHub is private and is not the feed.)
+update_uri=$(sed -n -E 's/^[[:space:]]*\*[[:space:]]*Update URI:[[:space:]]*(.*)/\1/p' "$PLUGIN_MAIN" | head -1 | tr -d '[:space:]')
+feed_host=$(printf '%s' "$update_uri" | sed -E 's|^[a-z]+://([^/]+).*|\1|')
+this_host=$(printf '%s' "${GITHUB_SERVER_URL:-}" | sed -E 's|^[a-z]+://([^/]+).*|\1|')
+
+if [ -z "$update_uri" ]; then
+  echo "The plugin header has no Update URI, so there is no feed to check."
+  exit 0
+fi
+
+if [ "$feed_host" != "$this_host" ]; then
+  echo "  $this_host is a mirror; shops read $feed_host. Nothing to verify here."
+  exit 0
+fi
+
 feed=$(curl -fsS --max-time 30 "$release_api" 2>/dev/null || true)
 
 if [ -z "$feed" ]; then
@@ -126,16 +143,35 @@ if [ -z "$feed" ]; then
   exit 1
 fi
 
-package=$(printf '%s' "$feed" | tr ',' '\n' | sed -n -E 's/.*"browser_download_url":[[:space:]]*"([^"]*\.zip)".*/\1/p' | head -1)
-if [ -z "$package" ]; then
+printf '%s' "$feed" | grep -q '"browser_download_url"' || {
   echo
   ci_fail "The release is readable, but it has no zip attached. WordPress would be offered an update it cannot download."
   exit 1
-fi
+}
 
-code=$(curl -s -o /dev/null -w '%{http_code}' -L --max-time 60 "$package")
+# Checked at the address the PLUGIN builds, not the one the API reports.
+#
+# A forge fills browser_download_url from its own configured root URL, which is
+# not necessarily the address the outside world reaches it on: gitea.nolimit.dk
+# returns http://57.129.89.117:25001/... there, a plain-HTTP raw IP that
+# bypasses the Cloudflare tunnel. Verifying that address would be verifying a
+# URL no shop ever uses — a green check on the wrong thing, which is worse than
+# no check.
+package="$update_uri/releases/download/$TAG/$PLUGIN_SLUG.zip"
+code=$(curl -s -o /tmp/wpci-feed.zip -w '%{http_code}' -L --max-time 120 "$package")
 echo "  $package -> HTTP $code"
-[ "$code" = 200 ] || { ci_fail "The package URL is not anonymously downloadable."; exit 1; }
+[ "$code" = 200 ] || { ci_fail "The package URL the plugin will use is not anonymously downloadable."; exit 1; }
+
+# And it has to be the plugin, not an error page with a 200 on it.
+python3 -c '
+import sys, zipfile
+names = zipfile.ZipFile("/tmp/wpci-feed.zip").namelist()
+main = sys.argv[1] + "/" + sys.argv[2]
+if main not in names:
+    sys.exit("The downloaded zip does not contain " + main)
+print("  it is the plugin: %d entries, %s present" % (len(names), main))
+' "$PLUGIN_SLUG" "$PLUGIN_MAIN"
+rm -f /tmp/wpci-feed.zip
 
 echo
 echo "Published $TAG. A shop running this plugin will be offered it within twelve hours,"