sgc-electron-delta-updater

# Electron 增量自动更新 为现有 Electron 应用交付可验证的增量更新链路；以用户实际安装包、公开更新源和安装结果为准，而不是以 CI 成功为准。 ## Triggers ### Activate when - 用户说“给这个 Electron App 加增量自动更新”或“检查更新一直转圈”。 - 用户提到 macOS Sparkle、appcast、DMG、blockmap、签名、公证或 delta 更新包。 - User asks to “add a delta updater”, “ship Sparkle updates”, or “verify an Electron update release”. ### Do not activate when - 用户只想修改版本号、更新日志或普通下载页；使用版本管理或发布工作流。 - 用户要做网页热更新、PWA 缓存更新或移动端 OTA；使用相应平台的更新机制。 ## Workflow (MANDATORY) **You MUST follow these steps in order.** ### Step 0: Establish the update contract - Identify target platforms, package format, current updater library, update feed, signing owner, release channel, and rollback expectation. - Treat macOS delta-only behavior as an explicit product promise only when complete archives are intentionally excluded. - Separate four states: check, download/stage, install handoff, and post-restart verification. - Read [references/electron-macos-delta.md](references/electron-macos-delta.md) for macOS Sparkle work and [references/release-verification.md](references/release-verification.md) before modifying a release pipeline. ### Step 1: Make checks bounded and recoverable - Use one in-flight check per update service. - Pass an `AbortSignal` through every network layer, including appcast fetches. - On timeout, abort the request, wait for stale updater state and connections to settle, then allow a later retry. - Configure the updater's own network session; do not assume it inherits a developer shell prox...