finalize M06-M12 with Go/SQLite/Synology NAS implementation decisions

DEV_PORTAL_M10_DEVICE.md

@@ -1,8 +1,43 @@
 # Milestone 10: Device-Side App Management
 
-**Status**: Planning
+**Status**: Decided
 **Goal**: Install, update, and manage apps on Mosis devices.
 
+## Decision
+
+**C++ AppManager + Lua bindings** running on MosisService:
+
+```
+AppManager:     C++ class managing installation/updates
+Storage:        Local device storage (/data/mosis/apps/)
+Updates:        Background service checking Portal API
+UI:             App Store system app (RML/Lua)
+API:            Connects to Portal at portal.mosis.dev (or self-hosted)
+```
+
+### Rationale
+
+1. **Native C++** - AppManager runs in MosisService process for performance
+2. **Background updates** - UpdateService thread checks Portal API periodically
+3. **System app** - App Store is a privileged RML/Lua app with special permissions
+4. **Ed25519 verification** - All packages verified before installation
+
+### API Integration
+
+```
+Device                                    Portal (Synology NAS)
+┌──────────────┐                         ┌──────────────────────┐
+│ MosisService │                         │  mosis-portal        │
+│              │                         │                      │
+│ UpdateService├──────GET /store/apps────►│  Chi API Router     │
+│              │      /updates?pkgs=...  │                      │
+│              │◄─────{updates: [...]}───┤  SQLite portal.db    │
+│              │                         │                      │
+│ AppManager  ├──────GET /packages/...──►│  /volume1/mosis/     │
+│              │◄─────[package.mosis]────┤  packages/{dev}/...  │
+└──────────────┘                         └──────────────────────┘
+```
+
 ---
 
 ## Overview
@@ -577,9 +612,10 @@ adb shell am broadcast -a com.omixlab.mosis.INSTALL_APP \
 
 ## Deliverables
 
+- [x] Architecture decided (C++ AppManager + Lua bindings)
 - [ ] AppManager C++ class
 - [ ] UpdateService background checker
-- [ ] App Store system app
+- [ ] App Store system app (RML/Lua)
 - [ ] Lua API bindings (mosis.apps, mosis.app)
 - [ ] Installation progress UI
 - [ ] Uninstall confirmation UI
@@ -590,10 +626,10 @@ adb shell am broadcast -a com.omixlab.mosis.INSTALL_APP \
 
 ## Open Questions
 
-1. App backup to cloud?
-2. Family sharing / multiple devices?
-3. Enterprise MDM integration?
-4. Sideloading policy?
+1. ~~App backup to cloud?~~ → Defer to post-MVP (local backups only)
+2. ~~Family sharing / multiple devices?~~ → Defer to post-MVP
+3. ~~Enterprise MDM integration?~~ → Not needed for self-hosted
+4. ~~Sideloading policy?~~ → Enabled via Settings toggle (developer mode)
 
 ---