feat(desktop): mirror each release to a stable bucket prefix

packages/desktop/scripts/stage-release.ts

@@ -11,13 +11,22 @@
 // setFeedURL). electron-updater resolves the prefixed name with
 // `new URL(name, base)`, so no client change is needed.
 //
+// Each release is also mirrored to a stable prefix, so a download link can be
+// written down once and keep working. That is for humans only: the manifests
+// name <version>/ and an installed build never resolves anything else.
+//
 // Produces, for base https://…/codev:
 //   <out>/latest-mac.yml            -> …/codev/latest-mac.yml
 //   <out>/<version>/<artifacts>     -> …/codev/<version>/…
+//                                   -> …/codev/latest/…   (copied in-bucket)
 import { $ } from "bun"
 import { copyFile, mkdir, readdir, readFile, stat, writeFile } from "node:fs/promises"
 import { join } from "node:path"
 
+// A folder named "latest" beside the latest*.yml files. Confusable on a
+// listing, but it is the name a download link is expected to have.
+const STABLE_PREFIX = "latest"
+
 const distDir = argValue("--dist") ?? join(import.meta.dir, "..", "dist")
 const outDir = argValue("--out") ?? join(distDir, "release")
 
@@ -84,14 +93,36 @@ const upload = (from: string, to: string) =>
     ? $`mc cp ${from} ${target}/${to}`
     : Promise.resolve(console.log(`  mc cp ${from} <alias>/<bucket>/codev/${to}`))
 
+// Both sides are already in the bucket, so mc issues a server-side copy and no
+// bytes travel through here — the mirror costs storage, not another upload.
+const mirror = (from: string, to: string) =>
+  target
+    ? $`mc cp ${target}/${from} ${target}/${to}`
+    : Promise.resolve(console.log(`  mc cp <alias>/<bucket>/codev/${from} <alias>/<bucket>/codev/${to}`))
+
+// Every manifest of a release carries the same version, and the loop below
+// uploads a version folder whole — so without deduping, four channel files mean
+// uploading every artifact four times.
+const versions = new Set<string>()
+for (const manifest of manifests)
+  versions.add(/^version:\s*(\S+)\s*$/m.exec(await readFile(join(outDir, manifest), "utf8"))![1]!)
+
 if (!target) console.log("\nCODEV_UPDATE_TARGET is unset; run these where the storage credentials live:")
 // Artifacts first, manifests last: a client that reads the manifest must find
 // every file it names already in place.
-for (const manifest of manifests) {
-  const version = /^version:\s*(\S+)\s*$/m.exec(await readFile(join(outDir, manifest), "utf8"))![1]!
+for (const version of versions)
   for (const file of await readdir(join(outDir, version)))
     await upload(join(outDir, version, file), `${version}/${file}`)
-}
+
+// Then the stable prefix. Nothing reads it — the manifests name <version>/ and
+// that is all an installed build ever resolves — it exists so a download link
+// can be written down once, in the docs or an email, and keep working.
+// Blockmaps are left out: they only mean anything beside the artifact a
+// manifest names, which is the versioned copy.
+for (const version of versions)
+  for (const file of await readdir(join(outDir, version)))
+    if (!file.endsWith(".blockmap")) await mirror(`${version}/${file}`, `${STABLE_PREFIX}/${file}`)
+
 for (const manifest of manifests) await upload(join(outDir, manifest), manifest)
 
 function argValue(flag: string) {