Function createWorktreePool

packages/shared/worktree-pool.ts:58–164

(
  config: WorktreePoolConfig,
  initial?: PoolEntry,
  initialPending?: Promise<PoolEntry>,
)

}

export function createWorktreePool(
  config: WorktreePoolConfig,
  initial?: PoolEntry,
  initialPending?: Promise<PoolEntry>,
): WorktreePool {
  const pool = new Map<string, PoolEntry>();
  const pending = new Map<string, Promise<PoolEntry>>();
  // FETCH_HEAD is shared per-repo state: a creation's PR-head fetch must not
  // run while another creation (or the seeded background warmup) is between
  // its own fetch and `git worktree add`. Serialize all creations through
  // this chain.
  let creationChain: Promise<unknown> = Promise.resolve();
  if (initial) pool.set(initial.prUrl, initial);

  // Seeded background warmup: the initial entry starts ready:false while the
  // caller builds its checkout (fetch/clone) off the request path. ensure()
  // awaits the in-flight warmup instead of starting a duplicate creation.
  // On failure the entry is KEPT as ready:false — resolve() stays undefined so
  // consumers never receive a path that was never created; same-repo ensure()
  // can retry creation once the failed warmup is cleared from pending.
  if (initial && initialPending) {
    const tracked = initialPending.then(
      (entry) => {
        pool.set(initial.prUrl, entry);
        return entry;
      },
      (err) => {
        pending.delete(initial.prUrl);
        throw err;
      },
    );
    pending.set(initial.prUrl, tracked);
    creationChain = tracked.catch(() => {});
    tracked
      .then(() => pending.delete(initial.prUrl))
      .catch(() => {}); // warmup may complete with nobody awaiting it
  }

  return {
    get(prUrl) { return pool.get(prUrl); },
    has(prUrl) { return pool.has(prUrl); },
    resolve(prUrl) {
      const entry = pool.get(prUrl);
      return entry?.ready ? entry.path : undefined;
    },

    async ensure(runtime, metadata) {
      const existing = pool.get(metadata.url);
      if (existing?.ready) return existing;

      const inflight = pending.get(metadata.url);
      if (inflight) return inflight;

      if (!config.isSameRepo) {
        throw new Error("Cross-repo pool cannot create worktrees for other PRs");
      }

      const create = async (): Promise<PoolEntry> => {