diff --git a/.github/workflows/open-gitea-pr.yml b/.github/workflows/open-gitea-pr.yml
new file mode 100644
index 0000000..42a2d4d
--- /dev/null
+++ b/.github/workflows/open-gitea-pr.yml
@@ -0,0 +1,66 @@
+name: Open Gitea PR on merge to main
+
+# When main changes on GitHub (i.e. after a PR is merged here), push those
+# commits to a branch on Gitea and open a pull request there, so the same
+# change can be reviewed and landed on the Gitea side. One-way: GitHub -> Gitea.
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  open-gitea-pr:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
+        with:
+          fetch-depth: 0
+
+      - name: Push main to Gitea and open a pull request
+        env:
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+          GITEA_HOST: git.zambazosmedia.group
+          GITEA_USER: nomad
+          GITEA_REPO: Commonwealth-Online/Commonwealth-Online-Server
+          SYNC_BRANCH: sync/from-github
+        run: |
+          set -euo pipefail
+          if [ -z "${GITEA_TOKEN:-}" ]; then
+            echo "::error::Missing GITEA_TOKEN secret. Add a Gitea access token as a"
+            echo "::error::repository secret named GITEA_TOKEN (Settings -> Secrets and"
+            echo "::error::variables -> Actions -> New repository secret)."
+            exit 1
+          fi
+
+          git config user.name  "github-sync"
+          git config user.email "github-sync@users.noreply.github.com"
+
+          # Mirror the current main onto a dedicated Gitea branch. Force is safe:
+          # this branch is owned by the automation and only ever tracks GitHub main.
+          git remote add gitea "https://${GITEA_USER}:${GITEA_TOKEN}@${GITEA_HOST}/${GITEA_REPO}.git"
+          git push -f gitea "HEAD:refs/heads/${SYNC_BRANCH}"
+
+          # Open a PR on Gitea: sync/from-github -> main. If one is already open,
+          # the push above has already updated it, so a 409 is success too.
+          http_code=$(curl -sS -o /tmp/gitea_pr.json -w "%{http_code}" -X POST \
+            "https://${GITEA_HOST}/api/v1/repos/${GITEA_REPO}/pulls" \
+            -H "Authorization: token ${GITEA_TOKEN}" \
+            -H "Content-Type: application/json" \
+            -d "{\"title\":\"Sync from GitHub main\",\"head\":\"${SYNC_BRANCH}\",\"base\":\"main\",\"body\":\"Automated: GitHub main was updated. Review and merge to land it on Gitea.\"}")
+
+          echo "Gitea pulls API returned HTTP ${http_code}"
+          cat /tmp/gitea_pr.json || true
+          echo
+
+          if [ "${http_code}" = "201" ]; then
+            echo "Opened a new Gitea pull request."
+          elif [ "${http_code}" = "409" ] || grep -qiE "already exist|issue_exist" /tmp/gitea_pr.json; then
+            echo "A Gitea PR from ${SYNC_BRANCH} is already open; it now has the latest commits."
+          else
+            echo "::warning::Unexpected Gitea response (${http_code}). The branch was pushed;"
+            echo "::warning::open the PR manually on Gitea if it did not appear."
+          fi