diff --git a/scripts/release.sh b/scripts/release.sh
index f3c85df..0b2c91b 100755
--- a/scripts/release.sh
+++ b/scripts/release.sh
@@ -36,6 +36,25 @@ check_prerequisites() {
         log_error "GitHub CLI not authenticated. Run 'gh auth login' first"
         exit 1
     fi
+
+    # Refuse to guess which [Unreleased] section is the real one. Release-note
+    # extraction stops at the first heading, so a duplicate means one section can
+    # never ship — and it stays invisible until someone reads the whole file.
+    local unreleased_headings
+    unreleased_headings=$(grep -c '^## \[Unreleased\]' CHANGELOG.md 2>/dev/null || true)
+    if [ "${unreleased_headings:-0}" -gt 1 ]; then
+        log_error "CHANGELOG.md has $unreleased_headings '## [Unreleased]' headings; there must be at most one"
+        echo ""
+        grep -n '^## \[Unreleased\]' CHANGELOG.md
+        echo ""
+        echo "Merge them into the topmost one, or retitle the stale section with the"
+        echo "version it actually shipped in, then re-run."
+        echo ""
+        echo "Most likely cause: a release took the commit-subject fallback, which"
+        echo "leaves an empty [Unreleased] in place, and a later curated one was added"
+        echo "above it. The empty section is the one to drop."
+        exit 1
+    fi
 }
 
 # Get core library version
@@ -186,6 +205,26 @@ update_versions() {
     log_info "All version files updated to $new_version"
 }
 
+# Print the body of the "## [Unreleased]" section — everything between that
+# heading and the next "## [" heading.
+unreleased_body() {
+    awk '/^## \[Unreleased\]/ { inside = 1; next }
+         inside && /^## \[/    { inside = 0 }
+         inside                { print }' CHANGELOG.md 2>/dev/null || true
+}
+
+# Retitle "## [Unreleased]" as the release heading, leaving its content alone.
+# Only the first match is rewritten; main() has already refused to proceed if
+# there is more than one.
+promote_unreleased() {
+    local heading=$1
+
+    awk -v heading="$heading" '
+        /^## \[Unreleased\]/ && !promoted { print heading; promoted = 1; next }
+        { print }' CHANGELOG.md > CHANGELOG.md.tmp
+    mv CHANGELOG.md.tmp CHANGELOG.md
+}
+
 # Generate changelog
 generate_changelog() {
     local new_version=$1
@@ -193,6 +232,19 @@ generate_changelog() {
 
     log_step "Generating changelog for v$new_version"
 
+    # Prefer what a human wrote. The file declares Keep a Changelog, whose whole
+    # workflow is to maintain [Unreleased] and promote it on release — so a
+    # curated section is the release notes, and regenerating over it throws away
+    # the only description of the change anyone will read
+    # (livetemplate/livetemplate#511).
+    if [ -n "$(unreleased_body | tr -d '[:space:]')" ]; then
+        log_info "Promoting the curated [Unreleased] section to v$new_version"
+        promote_unreleased "## [v$new_version] - $(date +%Y-%m-%d)"
+        return
+    fi
+
+    log_warn "No curated [Unreleased] content; falling back to a commit-subject list"
+
     if [ -n "$prev_tag" ]; then
         {
             echo "# Changelog"
@@ -682,4 +734,8 @@ main() {
     echo "  • Update examples to use new version"
 }
 
-main "$@"
+# Sourced with RELEASE_SH_LIB=1 by scripts/test_release_changelog.sh, which
+# exercises the changelog functions without running a release.
+if [ -z "${RELEASE_SH_LIB:-}" ]; then
+    main "$@"
+fi
diff --git a/scripts/test_release_changelog.sh b/scripts/test_release_changelog.sh
new file mode 100755
index 0000000..293c35b
--- /dev/null
+++ b/scripts/test_release_changelog.sh
@@ -0,0 +1,169 @@
+#!/usr/bin/env bash
+# Tests the changelog handling in release.sh: a curated [Unreleased] section is
+# promoted to the release heading, and the commit-subject fallback is used only
+# when there is nothing curated to promote.
+#
+# Sources release.sh with RELEASE_SH_LIB=1 so the functions are defined without
+# main() running.
+
+set -e
+
+PROJECT_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+TMPDIR=$(mktemp -d)
+
+failures=0
+
+pass() { echo "  ✓ $1"; }
+fail() { echo "  ✗ $1"; echo "$2" | sed 's/^/      /'; failures=$((failures + 1)); }
+
+# Source before installing the cleanup trap: release.sh registers its own EXIT
+# trap at top level, which would otherwise replace ours and leak TMPDIR.
+# shellcheck source=/dev/null
+RELEASE_SH_LIB=1 source "$PROJECT_ROOT/scripts/release.sh"
+trap 'rm -rf "$TMPDIR"' EXIT
+
+header() {
+    cat <<'EOF'
+# Changelog
+
+All notable changes to @livetemplate/client will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+EOF
+}
+
+echo "🔥 Testing release.sh changelog handling..."
+cd "$TMPDIR"
+
+echo ""
+echo "1️⃣  Curated [Unreleased] is promoted, content preserved verbatim"
+{
+    header
+    echo "## [Unreleased]"
+    echo ""
+    echo "### Fixed"
+    echo ""
+    echo "- **Something a human wrote.** With detail worth keeping."
+    echo ""
+    echo "## [v0.1.0] - 2026-01-01"
+    echo ""
+    echo "- older"
+} > CHANGELOG.md
+generate_changelog "9.9.9" >/dev/null 2>&1
+
+if grep -q '^## \[v9.9.9\] - ' CHANGELOG.md; then
+    pass "release heading written"
+else
+    fail "release heading missing" "$(head -12 CHANGELOG.md)"
+fi
+if ! grep -q '^## \[Unreleased\]' CHANGELOG.md; then
+    pass "[Unreleased] heading consumed, not left stranded"
+else
+    fail "[Unreleased] survived the promotion" "$(grep -n 'Unreleased' CHANGELOG.md)"
+fi
+if grep -q 'Something a human wrote' CHANGELOG.md; then
+    pass "curated prose preserved"
+else
+    fail "curated prose lost" "$(cat CHANGELOG.md)"
+fi
+# The regression that motivated this: a commit-subject dump appearing instead of,
+# or above, the curated text.
+if ! grep -qE '^- .* \([0-9a-f]{7,}\)$' CHANGELOG.md; then
+    pass "no raw commit-subject dump"
+else
+    fail "raw commit dump present despite curated content" "$(grep -nE '^- .* \([0-9a-f]{7,}\)$' CHANGELOG.md)"
+fi
+if [ "$(grep -c '^## \[v9.9.9\]' CHANGELOG.md)" = "1" ] && grep -q '^## \[v0.1.0\]' CHANGELOG.md; then
+    pass "prior releases still present, exactly one new heading"
+else
+    fail "history damaged" "$(grep -n '^## \[' CHANGELOG.md)"
+fi
+
+# Which branch generate_changelog took. Asserted on the decision rather than the
+# resulting file: the fallback's output differs per repo (and with whether any
+# tag exists), but the choice between promoting and regenerating does not.
+# Captured into a variable rather than piped into `grep -q`: release.sh brings
+# `set -o pipefail` in with it, and grep -q exits on first match, so the closed
+# pipe can make generate_changelog exit non-zero and fail the whole pipeline —
+# intermittently, depending on which finishes first.
+took_fallback() {
+    local out
+    out=$(generate_changelog "9.9.9" 2>&1)
+    [[ "$out" == *"falling back"* ]]
+}
+
+echo ""
+echo "2️⃣  Empty [Unreleased] falls through to the commit-subject fallback"
+{
+    header
+    echo "## [Unreleased]"
+    echo ""
+    echo "## [v0.1.0] - 2026-01-01"
+    echo ""
+    echo "- older"
+} > CHANGELOG.md
+if took_fallback; then
+    pass "empty section not promoted to a contentless release heading"
+else
+    fail "promoted an empty [Unreleased]" "$(head -12 CHANGELOG.md)"
+fi
+
+echo ""
+echo "3️⃣  Whitespace-only [Unreleased] counts as empty"
+{
+    header
+    echo "## [Unreleased]"
+    echo ""
+    echo "   "
+    echo ""
+    echo "## [v0.1.0] - 2026-01-01"
+} > CHANGELOG.md
+if took_fallback; then
+    pass "whitespace-only section treated as empty"
+else
+    fail "whitespace-only section was promoted" "$(head -12 CHANGELOG.md)"
+fi
+
+echo ""
+echo "3️⃣ b  A curated section does NOT take the fallback"
+{
+    header
+    echo "## [Unreleased]"
+    echo ""
+    echo "- real content"
+    echo ""
+    echo "## [v0.1.0] - 2026-01-01"
+} > CHANGELOG.md
+if ! took_fallback; then
+    pass "promotion chosen over regeneration"
+else
+    fail "regenerated over curated content" "$(head -12 CHANGELOG.md)"
+fi
+
+echo ""
+echo "4️⃣  unreleased_body reads only its own section"
+{
+    header
+    echo "## [Unreleased]"
+    echo ""
+    echo "MINE"
+    echo ""
+    echo "## [v0.1.0] - 2026-01-01"
+    echo ""
+    echo "NOT-MINE"
+} > CHANGELOG.md
+body=$(unreleased_body)
+if echo "$body" | grep -q 'MINE' && ! echo "$body" | grep -q 'NOT-MINE'; then
+    pass "stops at the next version heading"
+else
+    fail "section boundary wrong" "$body"
+fi
+
+echo ""
+if [ "$failures" -ne 0 ]; then
+    echo "❌ $failures check(s) failed"
+    exit 1
+fi
+echo "✅ All changelog checks passed"