chore: add release note generator

scripts/generate-release-note.sh

@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+repo_root="$(cd -- "$script_dir/.." && pwd)"
+prompt_file="${RELEASE_PROMPT_FILE:-"$repo_root/scripts/release-prompt.txt"}"
+
+if ! command -v codex >/dev/null 2>&1; then
+    echo "generate-release-note.sh: codex CLI is required but was not found in PATH." >&2
+    exit 127
+fi
+
+if [[ ! -f "$prompt_file" ]]; then
+    echo "generate-release-note.sh: prompt file not found: $prompt_file" >&2
+    exit 1
+fi
+
+commit_messages="$(cat)"
+
+if [[ -z "${commit_messages//[[:space:]]/}" ]]; then
+    echo "generate-release-note.sh: expected commit messages on stdin." >&2
+    echo "Example: git log --oneline -n 20 | ./scripts/generate-release-note.sh" >&2
+    exit 1
+fi
+
+prompt_tmp="$(mktemp)"
+output_tmp="$(mktemp)"
+log_tmp="$(mktemp)"
+
+cleanup() {
+    rm -f "$prompt_tmp" "$output_tmp" "$log_tmp"
+}
+trap cleanup EXIT
+
+while IFS= read -r line || [[ -n "$line" ]]; do
+    if [[ "$line" == *"<PASTE_COMMIT_MESSAGES_HERE>"* ]]; then
+        printf '%s\n' "${line//<PASTE_COMMIT_MESSAGES_HERE>/$commit_messages}"
+    else
+        printf '%s\n' "$line"
+    fi
+done < "$prompt_file" > "$prompt_tmp"
+
+if ! codex \
+    --ask-for-approval never \
+    exec \
+    --cd "$repo_root" \
+    --ephemeral \
+    --sandbox read-only \
+    --color never \
+    --output-last-message "$output_tmp" \
+    - < "$prompt_tmp" > "$log_tmp" 2>&1; then
+    cat "$log_tmp" >&2
+    exit 1
+fi
+
+cat "$output_tmp"