Add Brotli pre-compression cache for /octokit/release

[Copilot]

The /octokit/release proxy endpoint returned uncompressed JSON with no content-encoding negotiation. This adds br pre-compression with Accept-Encoding-aware responses.

Changes

• Dual cache via shared promise: Replaces the simple unknown cache with a promise-based lock (releaseFetchPromise) that deduplicates concurrent cold-cache requests. On resolution, caches both the raw JSON string and a Brotli-compressed Buffer.
• Async Brotli compression: Uses promisify(brotliCompress) to compress the serialized response without blocking the event loop.
• Content negotiation: Checks Accept-Encoding on each request — returns Content-Encoding: br + compressed buffer when br is present, plain JSON string otherwise.
• Vary: Accept-Encoding: Added so downstream caches key correctly on encoding.
• Timer safety: Stores the expiry timer handle and guards reset/clear with a promise identity check to prevent stale timers from evicting an active cache.

GET /octokit/release
Accept-Encoding: br
→ 200  Content-Encoding: br  (pre-compressed Buffer, ~10s TTL)

GET /octokit/release
→ 200  application/json; charset=utf-8  (plain JSON string, same cache)

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
ehtt-editor	Ready	Preview, Comment	Mar 3, 2026 8:21am