chore: retry and cache the Electron zip download during CI builds

.circleci/src/pipeline/@pipeline.yml

@@ -329,11 +329,29 @@ commands:
   build-and-persist:
     description: Save entire folder as artifact for other jobs to run without reinstalling
     steps:
+      - run:
+          name: Generate Electron version key
+          command: node -p "require('./package.json').devDependencies.electron" > electron_version
+      - restore_cache:
+          name: Restore Electron download cache
+          keys:
+            - v{{ checksum ".circleci/cache-version.txt" }}-{{ checksum "platform_key"
+              }}-electron-download-cache-{{ checksum "electron_version" }}
       - run:
           name: Build packages
           command: |
             source ./scripts/ensure-node.sh
+            # @packages/electron forwards this to @electron/get, whose default
+            # cache root is platform-specific — pinning it keeps a single
+            # save_cache path valid on every executor
+            export electron_config_cache="$HOME/.electron-cache"
             yarn build
+      - save_cache:
+          name: Save Electron download cache
+          key: v{{ checksum ".circleci/cache-version.txt" }}-{{ checksum "platform_key"
+            }}-electron-download-cache-{{ checksum "electron_version" }}
+          paths:
+            - ~/.electron-cache
       - run:
           name: Sync Cloud Validations
           command: |

packages/electron/package.json

@@ -23,6 +23,7 @@
   },
   "devDependencies": {
     "@electron/fuses": "1.8.0",
+    "@electron/get": "^4.0.1",
     "@electron/packager": "18.3.6",
     "@vitest/coverage-v8": "^3.2.4",
     "eslint": "^9.31.0",

packages/electron/src/install.ts

@@ -135,6 +135,35 @@ interface PkgElectronAppOptions {
   overwrite: boolean
   electronVersion: string
   icon: string
+  electronZipDir?: string
+}
+
+// @electron/packager would fetch this through @electron/get, which never
+// retries and re-fetches SHASUMS256.txt even on cache hits. Calling it here
+// lets us retry; electronZipDir then points the packager at the result.
+async function downloadElectronZipWithRetries (options: { version: string, platform: string, arch: string }): Promise<string> {
+  // required dynamically for the same mksnapshot reason as @electron/packager below
+  const e = 'electron'
+  const { downloadArtifact } = require(`@${e}/get`)
+  const retryDelaysMs = [2000, 4000, 8000, 16000, 32000]
+
+  // same env var the `electron` package's own installer honors, so CI can point
+  // both at one cacheable directory. Undefined falls back to the platform default.
+  const cacheRoot = process.env.electron_config_cache
+
+  for (let attempt = 0; ; attempt++) {
+    try {
+      return await downloadArtifact({ artifactName: 'electron', cacheRoot, ...options })
+    } catch (err) {
+      const delayMs = retryDelaysMs[attempt]
+
+      if (delayMs === undefined) throw err
+
+      debug('electron zip download failed %o', { attempt, err })
+      console.log(`Electron download failed (${(err as Error).message}), retrying in ${delayMs / 1000}s (attempt ${attempt + 1} of ${retryDelaysMs.length})`)
+      await new Promise((resolve) => setTimeout(resolve, delayMs))
+    }
+  }
 }
 
 async function pkgElectronApp (
@@ -180,6 +209,14 @@ async function pkgElectronApp (
     ...options,
   }
 
+  const zipPath = await downloadElectronZipWithRetries({
+    version: resolvedOptions.electronVersion,
+    platform: resolvedOptions.platform,
+    arch: resolvedOptions.arch,
+  })
+
+  resolvedOptions.electronZipDir = path.dirname(zipPath)
+
   debug('packager options %j', resolvedOptions)
   const [appPath] = await pkgr(resolvedOptions)