Epic: Unified Authoring Architecture

[mikewolfd]

Motivation

Today, studio and chat are separate worlds: studio calls Project methods directly, chat creates its own McpBridge with its own Project instance, and the user imports results between them. This architecture unifies them into a single workspace where one Project instance is shared between the user (canvas) and the AI (MCP tools), with a proposal layer (ProposalManager) for reviewing AI changes before committing them.

Three motivations drive this:

1. Shared undo/redo — one history stack, both actors contributing
2. Convergence — chat and canvas are the same workspace, AI sees user edits in real-time
3. Stack simplification — collapse the separate Project instances, make MCP the universal AI surface with full spec coverage

Architecture Overview

The critical inversion: studio creates the MCP infrastructure (wrapping its own Project), and chat connects to it — reversing the current flow where chat creates McpBridge with its own Project.

Studio
+-- Project (single instance, source of truth)
|     +-- CommandPipeline (with recording middleware, actor-tagged)
+-- ProposalManager (controls middleware, dependency analysis via WASM, merge/reject)
+-- MCP Server (full tool coverage, brackets tool calls with beginEntry/endEntry)
|     +-- InMemoryTransport -> MCP Client A (ChatSession)
|     +-- InMemoryTransport -> MCP Client B (inline actions)
+-- ChatSession (conversation state, AI adapter, extended ToolContext)
+-- Canvas (renders project.state, calls project.* for user actions — never blocked)
+-- Chat Panel (renders conversation + changeset merge review UI)

What Gets Deleted

• McpBridge class — deleted entirely
• Chat's separate Project instance — gone
• Import/export dance between chat and studio — gone
• Separate chat entry point (main-chat.tsx, chat/, chat-v2/) — consolidated into integrated panel

Delivery Phases

Phase 1: Foundation — Engine + Core (E1-E3, C1-C11)

Push spec-level logic and structural queries down the stack. Prerequisites for everything else.

• Phase 1: Foundation — Engine + Core (E1-E3, C1-C11) #10

Phase 2: Studio-Core + MCP Tools (S1-S18) + Theme/Component Coverage

Each studio-core addition ships with its MCP tool. Theme and component full coverage in parallel.

• Phase 2: Studio-Core + MCP Tools (S1-S18) + Theme/Component Coverage #11

Phase 3: New Document Types + Remaining Tools

Locale, ontology, references, migration, mapping, bind fine-grained, shape composition, publish, composition, changelog, response, audit.

• Phase 3: New Document Types + Remaining MCP Tools #12

Phase 4A: ProposalManager (Changeset Semantics)

Middleware-based recording, restoreState(), ProposalManager class, Rust dependency analysis, changeset MCP tools. Can start as soon as Phase 1 core middleware is in place.

• Phase 4A: ProposalManager (Changeset Semantics) #13

Phase 4B: Chat Integration in Studio

ChatSession refactor, adapter update, studio chat panel, inline canvas AI actions, interview-to-scaffold flow. Can start after Phase 2 MCP coverage.

• Phase 4B: Chat Integration in Studio #14

Phase 4C: Convergence — Changeset Review UI

Where Track A (ProposalManager) meets Track B (chat panel). Dependency-grouped accept/reject, user overlay awareness, conflict diagnostics.

• Phase 4C: Convergence — Changeset Review UI #15

Spec Reference

thoughts/specs/2026-03-24-unified-authoring-architecture.md