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: 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: Verifies correct serialization and parsing with class discriminators.

• :backend (Ktor/JVM)

  • 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: Registers connected active client devices dynamically.
  • 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: 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: dynamic Compose renderer converting UiPrimitive polymorphically into premium, dark cyberpunk UI components using Unidirectional Data Flow (UDF) callbacks.
  • MeatbagClient.kt: Manages WebSocket connections and POST responses. Decodes payloads and triggers simulated attention effects (vibrations, sound chimes, or display takeover overlays).
  • 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.