From 1bead05d19f0e475908240a80a6050d80105def6 Mon Sep 17 00:00:00 2001
From: Javanaut <javanaut@refulgent.de>
Date: Thu, 16 Apr 2026 19:36:40 +0200
Subject: [PATCH] ff

---
 tools/merge_dev_into_main.sh | 50 ++++++++++++++++++++++++------------
 1 file changed, 33 insertions(+), 17 deletions(-)

diff --git a/tools/merge_dev_into_main.sh b/tools/merge_dev_into_main.sh
index 3cf4ff6..e540635 100755
--- a/tools/merge_dev_into_main.sh
+++ b/tools/merge_dev_into_main.sh
@@ -189,7 +189,27 @@ branch_divergence_counts() {
     printf '%s %s\n' "${remote_only}" "${local_only}"
 }
 
-require_branch_contains_remote() {
+fast_forward_branch_to_remote() {
+    local branch="$1"
+    local remote_ref="refs/remotes/${ORIGIN_REMOTE}/${branch}"
+    local current_head=""
+
+    current_head="$(git rev-parse --abbrev-ref HEAD)"
+
+    printf "Fast-forwarding local branch '%s' to '%s/%s'...\n" \
+        "${branch}" \
+        "${ORIGIN_REMOTE}" \
+        "${branch}"
+
+    if [ "${current_head}" = "${branch}" ]; then
+        git merge --ff-only "${remote_ref}" >/dev/null
+        return 0
+    fi
+
+    git branch -f "${branch}" "${remote_ref}" >/dev/null
+}
+
+sync_release_source_branch() {
     local branch="$1"
     local remote_only=""
     local local_only=""
@@ -201,7 +221,7 @@ require_branch_contains_remote() {
     fi
 
     if [ "${remote_only}" -ne 0 ]; then
-        fail "Local branch '${branch}' is behind '${ORIGIN_REMOTE}/${branch}' by ${remote_only} commit(s). Pull or rebase first."
+        fast_forward_branch_to_remote "${branch}"
     fi
 
     if [ "${local_only}" -ne 0 ]; then
@@ -213,26 +233,24 @@ require_branch_contains_remote() {
     fi
 }
 
-require_branch_matches_remote_exactly() {
+sync_release_target_branch() {
     local branch="$1"
     local remote_only=""
     local local_only=""
 
     read -r remote_only local_only < <(branch_divergence_counts "${branch}")
 
-    if [ "${remote_only}" -eq 0 ] && [ "${local_only}" -eq 0 ]; then
-        return 0
-    fi
-
     if [ "${remote_only}" -ne 0 ] && [ "${local_only}" -ne 0 ]; then
         fail "Local branch '${branch}' has diverged from '${ORIGIN_REMOTE}/${branch}' (${local_only} local-only commit(s), ${remote_only} remote-only commit(s)). Reconcile the branches first."
     fi
 
-    if [ "${remote_only}" -ne 0 ]; then
-        fail "Local branch '${branch}' is behind '${ORIGIN_REMOTE}/${branch}' by ${remote_only} commit(s). Pull or rebase first."
+    if [ "${local_only}" -ne 0 ]; then
+        fail "Local branch '${branch}' is ahead of '${ORIGIN_REMOTE}/${branch}' by ${local_only} commit(s). Push or reconcile first so the release starts from the published ${branch} tip."
     fi
 
-    fail "Local branch '${branch}' is ahead of '${ORIGIN_REMOTE}/${branch}' by ${local_only} commit(s). Push first so the release starts from the published ${branch} tip."
+    if [ "${remote_only}" -ne 0 ]; then
+        fast_forward_branch_to_remote "${branch}"
+    fi
 }
 
 resolve_release_version() {
@@ -295,9 +313,7 @@ print_release_plan() {
 
     printf 'Dry run only. Planned steps:\n'
     printf '1. Ensure current branch is %s and the worktree is clean.\n' "${DEV_BRANCH}"
-    printf '2. Fetch %s and verify local %s contains %s/%s while local %s exactly matches %s/%s.\n' \
-        "${ORIGIN_REMOTE}" \
-        "${DEV_BRANCH}" \
+    printf '2. Fetch %s, fast-forward local %s and %s from %s when safe, and fail on divergence or unpublished local %s commits.\n' \
         "${ORIGIN_REMOTE}" \
         "${DEV_BRANCH}" \
         "${MAIN_BRANCH}" \
@@ -350,8 +366,8 @@ require_repo_state
 require_dev_checkout
 require_clean_worktree
 fetch_remote_state
-require_branch_contains_remote "${DEV_BRANCH}"
-require_branch_matches_remote_exactly "${MAIN_BRANCH}"
+sync_release_source_branch "${DEV_BRANCH}"
+sync_release_target_branch "${MAIN_BRANCH}"
 
 RELEASE_VERSION="$(resolve_release_version)"
 RELEASE_TAG="v${RELEASE_VERSION}"
@@ -387,8 +403,8 @@ fi
 run_pre_release_tests
 require_clean_worktree
 fetch_remote_state
-require_branch_contains_remote "${DEV_BRANCH}"
-require_branch_matches_remote_exactly "${MAIN_BRANCH}"
+sync_release_source_branch "${DEV_BRANCH}"
+sync_release_target_branch "${MAIN_BRANCH}"
 require_release_tag_available "${RELEASE_VERSION}"
 
 git switch "${MAIN_BRANCH}" >/dev/null