# ADR 0007: hive-addons Plugin Architecture

**Status**: Implemented
**Date**: 2026-02-04
**Memory ID**: 20260204190741-1a2fba44

## Context

We need a plugin/addon system for hive-mcp to enable:
1. Community contributions without core bloat
2. Separating optional features (connectors, generators, importers)
3. Safe experimentation with new capabilities

## Decision

### Separation of Concerns
- **hive-mcp (core)**: Protocols, loading mechanism, core features
- **hive-addons (separate repo)**: Implementations, community contributions

### IAddon Protocol (in core)
```clojure
(defprotocol IAddon
  (addon-id [this])
  (addon-type [this])      ; :connector, :generator, :importer
  (capabilities [this])
  (initialize! [this config])
  (tools [this]))          ; Returns MCP tool definitions
```

### Loading Syntax (deps.edn + Doom hybrid)
```clojure
{:addons
 {hive-agi/slack
  {:git/url "https://github.com/hive-agi/hive-addons"
   :git/sha "a1b2c3d"
   :addon/root "connectors/slack"}

  local/my-addon
  {:local/root "~/PP/my-addon"}}}
```

### Addon Types
- **connectors**: Bidirectional sync (Slack, GitHub, Notion)
- **generators**: Output creation (diagrams, presentations)
- **importers**: Input parsing (PDF, docs)
- **mcp-bridge**: Proxy to foreign MCP servers (NEW)

## NIH Research Summary

| System | Registry | Isolation | Key Insight |
|--------|----------|-----------|-------------|
| Polylith | deps.edn | In-process | Components + Bases pattern |
| Doom Emacs | MELPA + straight.el | In-process | Recipe DSL is expressive |
| Terraform | Registry | Subprocess (gRPC) | Protocol versioning |
| Babashka Pods | N/A | Subprocess (bencode) | Any language, lightweight |

## Recommendations

1. **Registry**: deps.edn native (git/local/mvn), hive-registry later
2. **Dependencies**: tools.deps breadth-first + peer-dep metadata
3. **Isolation**: In-process for Clojure, Babashka pods for polyglot
4. **Loading**: Dynamic hot-reload, lazy opt-in

## Future: hive-registry
MELPA-like registry for discovery and versioning.