# Sandbox Implementation Milestones

Based on SANDBOX.md design document. Implementation order optimized for dependencies.

---

## Milestone 1: Core Sandbox Foundation ✅

**Status**: Complete
**Goal**: Create isolated Lua environments with resource limits.
**Estimated Files**: 3 new files

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| LuaSandbox class | `src/main/cpp/sandbox/lua_sandbox.h` | Main sandbox container |
| Custom allocator | `src/main/cpp/sandbox/lua_sandbox.cpp` | Per-app memory tracking/limits |
| Instruction hook | `src/main/cpp/sandbox/lua_sandbox.cpp` | CPU limit enforcement |
| Globals removal | `src/main/cpp/sandbox/lua_sandbox.cpp` | Remove os, io, debug, etc. |
| Bytecode prevention | `src/main/cpp/sandbox/lua_sandbox.cpp` | Text-only loading mode |
| Metatable protection | `src/main/cpp/sandbox/lua_sandbox.cpp` | Freeze _G and string metatable |

### Implementation Tasks

1. Create `LuaSandbox` class with:
   - `lua_State* m_L` - isolated state
   - `SandboxLimits m_limits` - memory/CPU/stack limits
   - `SandboxContext m_context` - app_id, permissions, etc.
   - Custom allocator that tracks `m_memory_used`

2. Implement `RemoveDangerousGlobals()`:
   - Remove: `os`, `io`, `debug`, `package`, `require`, `ffi`, `jit`
   - Remove: `dofile`, `loadfile`, `load`, `loadstring`
   - Remove: `rawget`, `rawset`, `rawequal`, `rawlen`
   - Remove: `collectgarbage`, `newproxy`
   - Remove: `string.dump`

3. Implement instruction hook:
   - `lua_sethook(L, InstructionHook, LUA_MASKCOUNT, 1000)`
   - Throw error when limit exceeded

4. Implement `ProtectBuiltinTables()`:
   - Set `__metatable` on string metatable
   - Freeze `_G` with `__newindex` error

### Dependencies

- Lua library already linked (via RmlUi)

### Test Criteria

```cpp
TEST(LuaSandbox, DangerousGlobalsRemoved);
TEST(LuaSandbox, BytecodeRejected);
TEST(LuaSandbox, MemoryLimitEnforced);
TEST(LuaSandbox, CPULimitEnforced);
TEST(LuaSandbox, MetatableProtected);
```

---

## Milestone 2: Permission System ✅

**Status**: Complete
**Goal**: Gate API access based on app permissions.
**Estimated Files**: 2 new files

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| PermissionGate | `src/main/cpp/sandbox/permission_gate.h` | Permission checking |
| User gesture tracking | `src/main/cpp/sandbox/permission_gate.cpp` | Recent tap/click detection |
| Permission categories | `src/main/cpp/sandbox/permission_gate.cpp` | Normal/Dangerous/Signature |

### Implementation Tasks

1. Define permission categories:
   ```cpp
   enum class PermissionCategory { Normal, Dangerous, Signature };
   ```

2. Create `PermissionGate` class:
   - `bool Check(lua_State* L, const std::string& permission)`
   - `int RequirePermission(lua_State* L, const char* perm)` - throws Lua error

3. Implement user gesture tracking:
   - `void RecordUserGesture()` - called on touch down
   - `bool HasRecentUserGesture(int ms)` - check within time window

4. Define permission manifest parsing:
   - Read `manifest.json` from app package
   - Extract `permissions` array

### Dependencies

- Milestone 1 (LuaSandbox)

### Test Criteria

```cpp
TEST(PermissionGate, NormalPermissionAutoGranted);
TEST(PermissionGate, DangerousPermissionRequiresGrant);
TEST(PermissionGate, SignaturePermissionSystemOnly);
TEST(PermissionGate, UserGestureRequired);
```

---

## Milestone 3: Audit Logging & Rate Limiting ✅

**Status**: Complete
**Goal**: Track security events and prevent API abuse.
**Estimated Files**: 2 new files

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| AuditLog | `src/main/cpp/sandbox/audit_log.h/cpp` | Security event logging |
| RateLimiter | `src/main/cpp/sandbox/rate_limiter.h/cpp` | Token bucket rate limiting |

### Implementation Tasks

1. Create `AuditLog` class:
   ```cpp
   enum class AuditEvent {
       AppStart, AppStop, PermissionCheck, PermissionDenied,
       NetworkRequest, FileAccess, SandboxViolation, ResourceLimitHit
   };
   ```

2. Implement thread-safe logging:
   - Ring buffer with max entries
   - Log critical events to Android logcat

3. Create `RateLimiter` class:
   - Token bucket algorithm
   - Per-operation limits: `network.request`, `storage.write`, etc.
   - `bool Check(const std::string& app_id, const std::string& operation)`

### Dependencies

- Milestone 1 (LuaSandbox)

### Test Criteria

```cpp
TEST(AuditLog, LogsSecurityEvents);
TEST(AuditLog, ThreadSafe);
TEST(RateLimiter, EnforcesLimits);
TEST(RateLimiter, RefillsOverTime);
```

---

## Milestone 4: Safe Path & Require ✅

**Status**: Complete
**Goal**: Secure file access within app sandbox.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| Path validation | `src/main/cpp/sandbox/path_sandbox.h/cpp` | Canonical path checking |
| Safe require | `src/main/cpp/sandbox/path_sandbox.cpp` | Module loader from app/scripts/ |

### Implementation Tasks

1. Implement `ValidatePath()`:
   - Reject `..` traversal
   - Reject absolute paths
   - Canonicalize and verify prefix match

2. Implement `SafeRequire()`:
   - Validate module name (alphanumeric + underscore)
   - Load from `app_path/scripts/name.lua`
   - Cache in registry `__loaded`
   - Text-only mode (`"t"`)

3. Register as global `require`:
   ```cpp
   lua_pushcfunction(L, SafeRequire);
   lua_setglobal(L, "require");
   ```

### Dependencies

- Milestone 1 (LuaSandbox)

### Test Criteria

```cpp
TEST(PathSandbox, RejectsTraversal);
TEST(PathSandbox, RejectsAbsolutePaths);
TEST(SafeRequire, LoadsFromScriptsDir);
TEST(SafeRequire, CachesModules);
```

---

## Milestone 5: Timer & Callback System ✅

**Status**: Complete
**Goal**: Safe timer APIs managed by kernel.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| TimerManager | `src/main/cpp/sandbox/timer_manager.h/cpp` | setTimeout/setInterval |

### Implementation Tasks

1. Create `TimerManager` class:
   - Priority queue of pending timers
   - Per-app timer limits (max 100)
   - Minimum 10ms granularity

2. Implement Lua APIs:
   ```lua
   setTimeout(callback, ms) -> id
   clearTimeout(id)
   setInterval(callback, ms) -> id
   clearInterval(id)
   ```

3. Integrate with kernel main loop:
   - Check and fire timers each frame
   - Reset instruction count before callback

4. Implement cleanup:
   - `ClearAppTimers(app_id)` on app stop

### Dependencies

- Milestone 1 (LuaSandbox)
- Milestone 3 (RateLimiter)

### Test Criteria

```cpp
TEST(TimerManager, FiresTimeout);
TEST(TimerManager, FiresInterval);
TEST(TimerManager, LimitsPerApp);
TEST(TimerManager, CleansUpOnStop);
```

---

## Milestone 6: JSON & Crypto APIs ✅

**Status**: Complete
**Goal**: Safe data parsing and cryptographic primitives.
**Estimated Files**: 2 new files

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| JSON API | `src/main/cpp/sandbox/json_api.cpp` | Safe encode/decode |
| Crypto API | `src/main/cpp/sandbox/crypto_api.cpp` | Hash, random, HMAC |

### Implementation Tasks

1. Implement `json.decode()`:
   - Depth limit (32)
   - String length limit (1 MB)
   - Array/object size limits

2. Implement `json.encode()`:
   - Cycle detection
   - Output size limit

3. Implement crypto APIs:
   - `crypto.randomBytes(n)` - CSPRNG
   - `crypto.hash("sha256", data)`
   - `crypto.hmac("sha256", key, data)`
   - Remove `math.randomseed`, replace `math.random` with per-app RNG

### Dependencies

- Milestone 1 (LuaSandbox)
- nlohmann-json (already in vcpkg)

### Test Criteria

```cpp
TEST(JsonApi, DecodesValid);
TEST(JsonApi, RejectsDeepNesting);
TEST(JsonApi, RejectsTooLarge);
TEST(CryptoApi, RandomBytesSecure);
TEST(CryptoApi, HashCorrect);
```

---

## Milestone 7: Virtual Filesystem ✅

**Status**: Complete
**Goal**: Per-app isolated storage with quotas.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| VirtualFS | `src/main/cpp/sandbox/virtual_fs.h/cpp` | App storage API |

### Implementation Tasks

1. Define virtual path mapping:
   ```
   /data/   → /data/data/com.omixlab.mosis/apps/<app_id>/data/
   /cache/  → /data/data/com.omixlab.mosis/apps/<app_id>/cache/
   /temp/   → (session-only, cleared on stop)
   /shared/ → requires storage.shared permission
   ```

2. Implement Lua file API:
   ```lua
   fs.read(path) -> string
   fs.write(path, data) -> bool
   fs.append(path, data) -> bool
   fs.delete(path) -> bool
   fs.exists(path) -> bool
   fs.list(dir) -> table
   fs.mkdir(path) -> bool
   fs.stat(path) -> {size, modified, isDir}
   ```

3. Enforce limits:
   - Per-app quota (50 MB default)
   - Max file size (10 MB)
   - Max path depth (10)

4. Cleanup `/temp/` on app stop.

### Dependencies

- Milestone 1 (LuaSandbox)
- Milestone 2 (PermissionGate)
- Milestone 4 (Path validation)

### Test Criteria

```cpp
TEST(VirtualFS, ReadsWritesInAppDir);
TEST(VirtualFS, BlocksTraversal);
TEST(VirtualFS, EnforcesQuota);
TEST(VirtualFS, CleansUpTemp);
```

---

## Milestone 8: SQLite Database ✅

**Status**: Complete
**Goal**: Per-app SQLite with injection prevention.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| DatabaseManager | `src/main/cpp/sandbox/database_manager.h/cpp` | SQLite sandbox |

### Implementation Tasks

1. Create per-app database:
   - Location: `/data/data/com.omixlab.mosis/apps/<app_id>/db/app.db`
   - Max database size: 50 MB

2. Implement SQLite authorizer:
   ```cpp
   sqlite3_set_authorizer(db, Authorizer, sandbox);
   // Block: ATTACH, DETACH, dangerous PRAGMAs, load_extension
   ```

3. Implement Lua API:
   ```lua
   local db = database.open("mydata")
   db:execute("CREATE TABLE IF NOT EXISTS items (id INTEGER PRIMARY KEY, name TEXT)")
   db:execute("INSERT INTO items (name) VALUES (?)", {"Item 1"})
   local rows = db:query("SELECT * FROM items WHERE id > ?", {0})
   db:close()
   ```

4. Enforce prepared statements only (no raw SQL interpolation).

### Dependencies

- Milestone 1 (LuaSandbox)
- Milestone 2 (PermissionGate)
- SQLite3 (add to vcpkg)

### Test Criteria

```cpp
TEST(Database, CreatesTables);
TEST(Database, PreparedStatements);
TEST(Database, BlocksAttach);
TEST(Database, BlocksDangerousPragma);
```

---

## Milestone 9: Network - HTTP

**Goal**: Secure HTTP requests with domain filtering.
**Estimated Files**: 2 new files

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| HttpRequestValidator | `src/main/cpp/sandbox/http_validator.h/cpp` | URL/domain validation |
| NetworkManager | `src/main/cpp/sandbox/network_manager.h/cpp` | HTTP client wrapper |

### Implementation Tasks

1. Implement URL parsing and validation:
   - Require HTTPS
   - Block private IPs, localhost, metadata IPs
   - Domain whitelist from manifest

2. Implement Lua HTTP API:
   ```lua
   local response = network.request({
       url = "https://api.example.com/data",
       method = "POST",
       headers = {...},
       body = "...",
       timeout = 30000
   })
   ```

3. Integrate with Android HttpURLConnection or libcurl.

4. Enforce limits:
   - Request body: 10 MB
   - Response body: 50 MB
   - Timeout: 60s
   - Concurrent requests: 6

### Dependencies

- Milestone 1 (LuaSandbox)
- Milestone 2 (PermissionGate)
- Milestone 3 (RateLimiter, AuditLog)

### Test Criteria

```cpp
TEST(HttpValidator, BlocksPrivateIP);
TEST(HttpValidator, BlocksLocalhost);
TEST(HttpValidator, RequiresHttps);
TEST(HttpValidator, EnforcesDomainWhitelist);
TEST(NetworkManager, MakesRequest);
```

---

## Milestone 10: Network - WebSocket

**Goal**: Secure WebSocket connections.
**Estimated Files**: 1 new file (extends NetworkManager)

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| WebSocketManager | `src/main/cpp/sandbox/websocket_manager.h/cpp` | WS connections |

### Implementation Tasks

1. Implement connection management:
   - Max 5 connections per app
   - Idle timeout: 5 minutes
   - Message size limit: 1 MB

2. Implement Lua WebSocket API:
   ```lua
   local ws = network.websocket("wss://api.example.com/ws")
   ws:on("open", function() ... end)
   ws:on("message", function(data) ... end)
   ws:on("close", function(code, reason) ... end)
   ws:send(data)
   ws:close()
   ```

3. Use same URL validation as HTTP.

4. Cleanup connections on app stop.

### Dependencies

- Milestone 9 (HttpRequestValidator)

### Test Criteria

```cpp
TEST(WebSocketManager, Connects);
TEST(WebSocketManager, LimitsPerApp);
TEST(WebSocketManager, CleansUpOnStop);
```

---

## Milestone 11: Virtual Hardware - Camera

**Goal**: Camera access with mandatory indicators.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| CameraInterface | `src/main/cpp/sandbox/camera_interface.h/cpp` | Camera API |

### Implementation Tasks

1. Implement session management:
   - `startSession(options)` - requires permission + user gesture
   - `capturePhoto()` - returns frame data
   - `stopSession()`

2. Mandatory recording indicator:
   - Show in system UI (cannot be hidden by app)

3. Implement Lua API:
   ```lua
   local session = camera.start({facing = "back", resolution = "720p"})
   session:on("frame", function(data) ... end)
   local photo = session:capture()
   session:stop()
   ```

4. Rate limit: 1 session at a time, max 30 fps.

### Dependencies

- Milestone 2 (PermissionGate + user gesture)
- Milestone 3 (AuditLog)
- Game engine camera bridge (future)

### Test Criteria

```cpp
TEST(CameraInterface, RequiresPermission);
TEST(CameraInterface, RequiresUserGesture);
TEST(CameraInterface, ShowsIndicator);
TEST(CameraInterface, StopsOnAppStop);
```

---

## Milestone 12: Virtual Hardware - Microphone

**Goal**: Audio recording with mandatory indicators.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| MicrophoneInterface | `src/main/cpp/sandbox/microphone_interface.h/cpp` | Mic API |

### Implementation Tasks

1. Implement recording session:
   - `startRecording(options)` - requires permission + user gesture
   - `stopRecording()` - returns audio data

2. Mandatory recording indicator (same as camera).

3. Implement Lua API:
   ```lua
   local recording = microphone.start({sampleRate = 44100, channels = 1})
   recording:on("data", function(samples) ... end)
   local audio = recording:stop()
   ```

4. Rate limit: 1 recording at a time.

### Dependencies

- Milestone 2 (PermissionGate + user gesture)
- Milestone 3 (AuditLog)

### Test Criteria

```cpp
TEST(MicrophoneInterface, RequiresPermission);
TEST(MicrophoneInterface, RequiresUserGesture);
TEST(MicrophoneInterface, ShowsIndicator);
```

---

## Milestone 13: Virtual Hardware - Audio Output

**Goal**: Safe audio playback.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| AudioOutputInterface | `src/main/cpp/sandbox/audio_output.h/cpp` | Speaker API |

### Implementation Tasks

1. Implement playback:
   - `play(audioData, options)`
   - `stop()`
   - `setVolume(0.0-1.0)`

2. System volume limit (app cannot exceed system volume).

3. Implement Lua API:
   ```lua
   local player = audio.play(soundData, {loop = false, volume = 0.8})
   player:on("ended", function() ... end)
   player:stop()
   ```

4. Concurrent sound limit: 10 per app.

### Dependencies

- Milestone 1 (LuaSandbox)

### Test Criteria

```cpp
TEST(AudioOutput, PlaysSound);
TEST(AudioOutput, RespectsVolumeLimit);
TEST(AudioOutput, LimitsConcurrent);
```

---

## Milestone 14: Virtual Hardware - Location

**Goal**: Location with privacy controls.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| LocationInterface | `src/main/cpp/sandbox/location_interface.h/cpp` | GPS API |

### Implementation Tasks

1. Two permission levels:
   - `location.coarse` - city-level (1km accuracy)
   - `location.fine` - precise GPS

2. Implement Lua API:
   ```lua
   location.getCurrentPosition(function(pos)
       print(pos.latitude, pos.longitude, pos.accuracy)
   end)

   local watch = location.watchPosition(function(pos) ... end, {
       enableHighAccuracy = true,
       timeout = 30000
   })
   watch:stop()
   ```

3. Rate limit: 1 request per second.

4. Reduce precision for coarse permission.

### Dependencies

- Milestone 2 (PermissionGate)
- Milestone 3 (RateLimiter)

### Test Criteria

```cpp
TEST(LocationInterface, RequiresPermission);
TEST(LocationInterface, CoarseReducesPrecision);
TEST(LocationInterface, RateLimits);
```

---

## Milestone 15: Virtual Hardware - Sensors

**Goal**: Motion sensors with fingerprinting prevention.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| SensorInterface | `src/main/cpp/sandbox/sensor_interface.h/cpp` | Accelerometer, gyro, etc. |

### Implementation Tasks

1. Supported sensors:
   - Accelerometer (requires `sensors.motion`)
   - Gyroscope (requires `sensors.motion`)
   - Magnetometer (requires `sensors.motion`)
   - Proximity (auto-granted)
   - Ambient light (auto-granted)

2. Implement Lua API:
   ```lua
   local sub = sensors.subscribe("accelerometer", function(data)
       print(data.x, data.y, data.z, data.timestamp)
   end, {frequency = 60})
   sub:stop()
   ```

3. Reduce precision to prevent fingerprinting:
   - Round values to 2 decimal places
   - Limit update frequency to 60 Hz

### Dependencies

- Milestone 2 (PermissionGate)

### Test Criteria

```cpp
TEST(SensorInterface, RequiresPermission);
TEST(SensorInterface, ReducesPrecision);
TEST(SensorInterface, LimitsFrequency);
```

---

## Milestone 16: Virtual Hardware - Bluetooth

**Goal**: Bluetooth discovery and pairing.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| BluetoothInterface | `src/main/cpp/sandbox/bluetooth_interface.h/cpp` | BT API |

### Implementation Tasks

1. Discovery with user consent:
   - `startDiscovery()` requires user confirmation
   - Return device name/address only (no full UUID list)

2. Implement Lua API:
   ```lua
   bluetooth.startDiscovery(function(devices)
       for _, device in ipairs(devices) do
           print(device.name, device.address)
       end
   end, {timeout = 30})

   bluetooth.connect(address, function(connection)
       connection:send(data)
   end)
   ```

3. Limit: 5 connections per app.

### Dependencies

- Milestone 2 (PermissionGate + user gesture)

### Test Criteria

```cpp
TEST(BluetoothInterface, RequiresPermission);
TEST(BluetoothInterface, RequiresUserConsent);
```

---

## Milestone 17: Virtual Hardware - Contacts

**Goal**: Contact access with granular permissions.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| ContactsInterface | `src/main/cpp/sandbox/contacts_interface.h/cpp` | Contacts API |

### Implementation Tasks

1. Separate read/write permissions:
   - `contacts.read` - query contacts
   - `contacts.write` - add/modify contacts

2. Implement Lua API:
   ```lua
   local contacts = contacts.query({search = "John"})
   for _, c in ipairs(contacts) do
       print(c.name, c.phone, c.email)
   end

   contacts.add({name = "New Contact", phone = "555-1234"})
   ```

3. Limit fields returned (no raw account data).

### Dependencies

- Milestone 2 (PermissionGate)

### Test Criteria

```cpp
TEST(ContactsInterface, RequiresReadPermission);
TEST(ContactsInterface, RequiresWritePermission);
```

---

## Milestone 18: Inter-App Communication

**Goal**: Kernel-mediated message passing.
**Estimated Files**: 1 new file

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| MessageBus | `src/main/cpp/sandbox/message_bus.h/cpp` | App-to-app messaging |

### Implementation Tasks

1. Implement intent system:
   - Manifest declares received intents
   - Sender must have required permissions

2. Implement Lua API:
   ```lua
   -- Sending
   intents.send({
       action = "share",
       type = "text/plain",
       data = "Hello world"
   })

   -- Receiving (in manifest + handler)
   intents.on("share", function(intent)
       print(intent.from, intent.data)
   end)
   ```

3. Validate sender/receiver at runtime.

### Dependencies

- Milestone 2 (PermissionGate)
- Milestone 3 (AuditLog)

### Test Criteria

```cpp
TEST(MessageBus, SendsToRegisteredReceiver);
TEST(MessageBus, BlocksUnregisteredAction);
```

---

## Milestone 19: Security Testing Suite

**Goal**: Comprehensive test coverage.
**Estimated Files**: 3 new files

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| Unit tests | `tests/test_sandbox_security.cpp` | Core sandbox tests |
| Integration tests | `tests/test_sandbox_integration.cpp` | Full system tests |
| Fuzzer | `tests/fuzz_sandbox.cpp` | Random input testing |

### Implementation Tasks

1. Write unit tests for all milestones (see individual test criteria).

2. Write integration tests:
   - Full app lifecycle
   - Permission flow
   - Resource cleanup

3. Implement fuzzer:
   - Generate random Lua code
   - Verify no crashes
   - Verify sandbox integrity after each run

4. Security audit checklist (from SANDBOX.md).

### Dependencies

- All previous milestones

---

## Milestone 20: Kernel Integration

**Goal**: Wire sandbox into existing kernel.
**Estimated Files**: Modify existing files

### Deliverables

| Component | File | Description |
|-----------|------|-------------|
| App lifecycle | `src/main/cpp/kernel.cpp` | App start/stop |
| Sandbox manager | `src/main/cpp/kernel.cpp` | Multi-app management |

### Implementation Tasks

1. Replace global `lua_State` with `LuaSandboxManager`:
   - Create sandbox per app
   - Route events to correct sandbox

2. Integrate with RmlUi:
   - Bridge RmlUi document events to sandbox
   - Replace `Rml::Lua::Interpreter` with sandboxed states

3. Wire up resource cleanup on app stop.

### Dependencies

- Milestones 1-18

---

## Summary

| Phase | Milestones | Description |
|-------|------------|-------------|
| **Foundation** | 1-4 | Core sandbox, permissions, logging, paths |
| **Core APIs** | 5-8 | Timers, JSON, crypto, filesystem, database |
| **Network** | 9-10 | HTTP and WebSocket |
| **Hardware** | 11-17 | Camera, mic, audio, location, sensors, BT, contacts |
| **System** | 18-20 | IPC, testing, integration |

### Recommended Order

1. **Milestone 1** - Must be first (foundation)
2. **Milestone 2** - Permissions (needed by everything)
3. **Milestone 3** - Audit/rate limiting (needed by APIs)
4. **Milestone 4** - Path security (needed by fs/require)
5. **Milestone 5-6** - Timers, JSON (high value)
6. **Milestone 7-8** - Storage, database (app data)
7. **Milestone 9-10** - Network (app connectivity)
8. **Milestones 11-17** - Hardware (as needed)
9. **Milestone 18** - IPC (multi-app)
10. **Milestone 19-20** - Testing & integration

### Quick Start

Begin with **Milestone 1** to establish the core sandbox. This is the foundation everything else builds on.