# v3.1.0 — Actor Compiler + Full LLM Integration (M2) — Overview

**Released:** v3.1.0  
**Milestone:** M2 — Actor Compiler + Full LLM Integration  
**Theme:** Introduce the Actor system, compile YAML-defined actors into executable LangGraph graphs, and wire full LLM integration through MCP adapter, tool router, skill registry, and validation runner.

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## Overview

v3.1.0 builds on the v3.0.0 foundation by introducing the **Actor system** —
declarative YAML definitions for AI agents compiled into LangGraph `StateGraph`
structures at runtime. It also delivers MCP adapter (external tool server
connectivity), tool router (provider normalization), skill registry (reusable
tool collections), and validation runner (pre-apply quality gates).

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## Goals

1. Define a declarative YAML format for actors (`llm`, `tool`, `graph`).
2. Compile GRAPH-type actors into executable LangGraph `StateGraph` structures.
3. Connect to external MCP tool servers for tool discovery and invocation.
4. Route LLM tool calls across OpenAI, Anthropic, and LangChain formats.
5. Manage reusable tool collections via the skill registry.
6. Enforce validation gates before plan apply via the validation runner.

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## Feature Index

| Feature | Description | Documentation |
|---------|-------------|---------------|
| **Actor YAML** | Declarative defs: llm, tool, graph types | [Actor Format](actor-yaml.md) |
| **Actor Compiler** | Compile to LangGraph StateGraph | [Actor Format](actor-yaml.md) |
| **MCP Adapter** | External MCP tool server connectivity | [Integration](integration.md) |
| **Tool Router** | Normalize across OpenAI/Anthropic/LC formats | [Integration](integration.md) |
| **Skill Registry** | Persistent, composable tool collections | [Skills](skills.md) |
| **Validation Runner** | Pre-apply required/informational gates | [Skills](skills.md) |

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## Architecture Notes

### Actor System Design

Follows the **Actor Abstraction Definition** (see [ADR-031](../../adr/ADR-031-actor-abstraction-definition.md)):
- **Declarative** — defined in YAML, not code.
- **Composable** — GRAPH actors embed other actors as subgraphs.
- **Compiled** — validated and compiled to LangGraph at load time.
- **Namespaced** — `namespace/name` format required.

### LangGraph Integration

See [ADR-022](../../adr/ADR-022-langchain-langgraph-integration.md). The compiler
takes GRAPH actors through an 8-step pipeline, producing LangGraph `StateGraph` structures.

### MCP & Skills

MCP adapter implements Model Context Protocol (see [ADR-029](../../adr/ADR-029-model-context-protocol.md)). Skill registry implements the Skill Abstraction Definition (see [ADR-030](../../adr/ADR-030-skill-abstraction-definition.md) and [ADR-012](../../adr/ADR-012-skill-system.md)).

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## See Also

- [Actor Format & Compiler](actor-yaml.md)
- [MCP + Tool Router](integration.md)
- [Skills + Validation Runner](skills.md)
- [Quick Start Guide](quickstart.md) — common workflows
