nexus-context MCP server — expose agent memory and personas as MCP tools

[canoo]

Problem

Project memory written to ~/.config/nexus/agent-memory/<project>/ is read by tools that happen to load NEXUS steering files. Tools without steering file support, or tools mid-session, cannot query this memory. Writing back from a tool session to agent-memory requires manual file operations.

Research shows developers are using Obsidian and similar 'second brain' setups as a manual long-term memory bridge between AI tools (r/hermesagent, April 2026). NEXUS should automate this.

Solution

A second MCP server — nexus-context — that runs locally alongside nexus-ollama and exposes agent memory and personas as queryable MCP tools. Any tool with MCP support gets real-time, bidirectional project context.

MCP tools exposed

nexus_get_context(project?)      → returns relevant agent-memory for current project
nexus_log_decision(what, why)    → writes a decision entry back to agent-memory
nexus_get_persona(name)          → returns full instructions for a named persona
nexus_list_personas()            → returns available specialist agents with descriptions
nexus_get_session_summary()      → returns summary of current session context

How it works

1. nexus sync automatically adds nexus-context to each installed tool's MCP config
2. Any tool with MCP support (Claude Code, Cursor, Windsurf, Cline, Continue.dev) can call these tools
3. Context is shared in real-time — a decision logged from Claude Code is immediately available when you switch to Cursor
4. No file-polling, no steering-file dependency

Config entry written by nexus sync

{
  "mcpServers": {
    "nexus-context": {
      "command": "node",
      "args": ["~/.config/nexus/tools/mcp/context-server.mjs"]
    }
  }
}

Dependencies

Requires #81 (nexus sync, to auto-add to tool MCP configs) and the agent-memory directory convention already established in NEXUS.md.