meatbag/handoffs/session_handoff.md

# Project Meatbag: Session Handoff

**Date**: June 27, 2026  
**Ecosystem**: WhetForge  
**Goal**: Scaffolding and Implementing the MVP for **Meatbag**, a multiplatform "Human Latency Optimization Tool" for server-driven UI (SDUI).

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## 1. What We Did This Session
We initiated the project from scratch, structured it as a Kotlin Multiplatform Gradle project, and developed a stateful routing backend and a stateless Compose Multiplatform client. The session focused on achieving a successful end-to-end ping-pong loop:
1. An agent submits an `ApprovalRequest` via HTTP POST to the backend.
2. The backend determines the target device and attention tier based on user context rules, then suspends the request.
3. The backend notifies the target device via WebSockets.
4. The client simulates haptics (or alerts) based on the `AttentionTier`, parses the JSON UI primitive, and inflates the UI dynamically.
5. The human taps "Yes" / interacts, sending a response to the backend.
6. The backend resumes the suspended agent request and returns the response.

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## 2. Core Project Architecture
The project directory is structured as a multi-module Kotlin project:

* **`:common` (Kotlin Multiplatform)**
  * [UiPrimitive.kt](file:///Users/blindmouse/meatbag/common/src/commonMain/kotlin/meatbag/common/UiPrimitive.kt): Declares the sealed hierarchy representing JSON UI elements (`UiPrimitive` with sub-types `ApprovalRequest`, `ActionList`, `TextInput`), the `AttentionTier` enum (`SILENT_HAPTIC`, `BACKGROUND_NOTIFICATION`, `OVERRIDE_SCREEN`), and common payload envelopes (`WebSocketPayload`, `ApprovalResponse`). Includes polymorphic serialization helpers.
  * [UiPrimitiveTest.kt](file:///Users/blindmouse/meatbag/common/src/commonTest/kotlin/meatbag/common/UiPrimitiveTest.kt): Verifies correct serialization and parsing with class discriminators.

* **`:backend` (Ktor/JVM)**
  * [Application.kt](file:///Users/blindmouse/meatbag/backend/src/main/kotlin/meatbag/backend/Application.kt): Scaffolds Ktor Netty, sets up CORS/WebSockets/ContentNegotiation plugins, exposes client-facing WebSocket (`/ws/connect`), response handler (`/api/respond`), agent request (`/api/request`), and diagnostic endpoints. Includes context-aware urgency auto-detection.
  * [DeviceRegistry.kt](file:///Users/blindmouse/meatbag/backend/src/main/kotlin/meatbag/backend/DeviceRegistry.kt): Registers connected active client devices dynamically.
  * [RoutingEngine.kt](file:///Users/blindmouse/meatbag/backend/src/main/kotlin/meatbag/backend/RoutingEngine.kt): Implements attention-based routing (e.g. routes urgent/silent haptics to Wear OS if active, otherwise falls back to phone/desktop) and holds coroutine suspend contexts via `CompletableDeferred` pending user callbacks.
  * [RoutingEngineTest.kt](file:///Users/blindmouse/meatbag/backend/src/test/kotlin/meatbag/backend/RoutingEngineTest.kt): Fully verifies WebSocket connections, payload transmission, attention tier routing, and callback resume resolution under Ktor's `testApplication` engine.

* **`:client` (Compose Multiplatform / Desktop target)**
  * [ComponentRegistry.kt](file:///Users/blindmouse/meatbag/client/src/commonMain/kotlin/meatbag/client/ComponentRegistry.kt): dynamic Compose renderer converting `UiPrimitive` polymorphically into premium, dark cyberpunk UI components using Unidirectional Data Flow (UDF) callbacks.
  * [MeatbagClient.kt](file:///Users/blindmouse/meatbag/client/src/commonMain/kotlin/meatbag/client/MeatbagClient.kt): Manages WebSocket connections and POST responses. Decodes payloads and triggers simulated attention effects (vibrations, sound chimes, or display takeover overlays).
  * [Main.kt](file:///Users/blindmouse/meatbag/client/src/desktopMain/kotlin/meatbag/client/Main.kt): Cyberpunk glassmorphic client simulator. Displays connection logs and simulates haptic profiles (Smartwatch vs. Phone vs. Desktop) and injects local offline mock payloads for isolated UI debugging.

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## 3. Configuration & Dependency Fixes Applied
During compilation and verification, several compatibility fixes were successfully applied:
1. **Plugin Portal Registration**: Configured `gradlePluginPortal()` in `settings.gradle.kts` to allow resolution of the Ktor and Kotlin JVM plugins.
2. **Kotlin Compiler Version Alignment**: Managed Kotlin compiler plugin versions centrally in the root `build.gradle.kts` and applied them cleanly inside sub-modules to prevent classloader duplicate classpath conflicts.
3. **Obsolete Property Removal**: Removed the obsolete `kotlin.mpp.enableGranularSourceSetsMetadata=true` from `gradle.properties` to fix Kotlin Gradle compiler configuration errors.
4. **Client Test Classpath**: Added Ktor Client content negotiation and websocket JVM targets to `:backend` test dependencies so that Ktor's test client works flawlessly during JUnit runs.
5. **Client Simulator Fixes**:
   * Fixed window size dimensions to use `Dp` units (`1280.dp`, `800.dp`).
   * Resolved Ktor 2.x `Frame.Text` read extension function resolution by importing `io.ktor.websocket.readText`.
   * Refactored client `log` helpers to be non-suspending (using flow `tryEmit` instead of `emit`), and introduced a public `injectMockEvent` helper to safely feed mock events from the simulator UI without coroutine thread blocks.

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## 4. Current Status
* **Compilation Status**: `BUILD SUCCESSFUL` for all modules and targets.
* **Testing Status**: Common serialization and backend integration routing tests pass successfully.
* **Active Subagents**: Cleaned up and terminated all background subagent processes.

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## 5. Next Steps
1. **Develop Android/Wear OS Platform Code**: Implement physical haptic motor triggers (`Vibrator` and `VibratorManager`) in `wearMain` and push banner notifications in `androidMain`.
2. **Persistence Layer**: Implement a database (e.g., SQLite via SQLDelight or PostgreSQL) to persist user rule-sets and past agent requests.
3. **Authentication**: Secure endpoints using API keys for CLI agents and OAuth/Device Tokens for clients.