feat: initial commit

docs/updates/bundle-archive-v1.md

@@ -0,0 +1,32 @@
+# Bundle Archive v1
+
+Downloaded updates are bundle archives rather than installer executables.
+
+Archive requirements:
+
+- top-level `bundle.json`
+- payload files stored relative to the install root
+- no absolute paths
+- no `..` path traversal
+- provider checksum must match the downloaded archive before staging
+
+`bundle.json`:
+
+```json
+{
+  "schemaVersion": 1,
+  "entrypoint": "MyApp.exe",
+  "files": [
+    { "path": "MyApp.exe", "mode": "0755" },
+    { "path": "resources/config.json", "mode": "0644" }
+  ]
+}
+```
+
+Install roots:
+
+- macOS: the `.app` bundle directory
+- Windows: the directory containing the running `.exe`
+- Linux: the directory containing the running binary
+
+The helper-mode apply flow stages the archive, validates `bundle.json`, backs up existing files, copies payload files into the install root, and relaunches the app using `entrypoint`.