chore: import upstream snapshot with attribution

scripts/release/lib/changes.ts

@@ -0,0 +1,66 @@
+import { spawnSync } from "child_process";
+import { ROOT } from "./config.js";
+
+export function getLastReleaseTag(): string | null {
+  const result = spawnSync(
+    "git",
+    ["tag", "--list", "v*", "--sort=-v:refname"],
+    { cwd: ROOT, encoding: "utf8" },
+  );
+  const tags = result.stdout.trim().split("\n").filter(Boolean);
+
+  for (const tag of tags) {
+    if (/^v\d+\.\d+\.\d+$/.test(tag)) {
+      return tag;
+    }
+  }
+
+  return null;
+}
+
+export interface Commit {
+  hash: string;
+  subject: string;
+}
+
+export function getCommitsSinceLastRelease(): Commit[] {
+  const lastTag = getLastReleaseTag();
+  const range = lastTag ? `${lastTag}..HEAD` : "HEAD";
+
+  const result = spawnSync(
+    "git",
+    ["log", range, "--oneline", "--no-merges", "--format=%H %s"],
+    { cwd: ROOT, encoding: "utf8" },
+  );
+
+  return result.stdout
+    .trim()
+    .split("\n")
+    .filter(Boolean)
+    .map((line) => {
+      const spaceIdx = line.indexOf(" ");
+      return {
+        hash: line.slice(0, spaceIdx),
+        subject: line.slice(spaceIdx + 1),
+      };
+    });
+}
+
+export interface ChangesSummary {
+  lastTag: string | null;
+  commitCount: number;
+  commits: Commit[];
+  oneline: string;
+}
+
+export function getChangesSummary(): ChangesSummary {
+  const lastTag = getLastReleaseTag();
+  const commits = getCommitsSinceLastRelease();
+
+  return {
+    lastTag,
+    commitCount: commits.length,
+    commits,
+    oneline: commits.map((c) => `- ${c.subject}`).join("\n"),
+  };
+}