nexus/migrations/20260101000018_create_chat_mcp.sql

-- Migration 018: Create Chat & MCP Registry tables
-- AI assistant with full MCP (Model Context Protocol) server registry

-- ==================== MCP SERVER REGISTRY ====================

-- MCP Server definitions
CREATE TABLE mcp_servers (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

    name VARCHAR(100) NOT NULL UNIQUE,
    description TEXT,

    -- Connection config
    transport_type VARCHAR(20) NOT NULL,  -- 'stdio', 'sse', 'websocket'
    command VARCHAR(500),                  -- for stdio: command to run
    args JSONB NOT NULL DEFAULT '[]',      -- command arguments
    env JSONB NOT NULL DEFAULT '{}',       -- environment variables
    url VARCHAR(500),                      -- for sse/websocket

    is_active BOOLEAN NOT NULL DEFAULT TRUE,

    -- Rate limiting
    rate_limit_per_minute INTEGER CHECK (rate_limit_per_minute > 0),
    rate_limit_per_hour INTEGER CHECK (rate_limit_per_hour > 0)
);

-- Tools provided by MCP servers
CREATE TABLE mcp_tools (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

    server_id UUID NOT NULL REFERENCES mcp_servers(id) ON DELETE CASCADE,

    name VARCHAR(100) NOT NULL,
    description TEXT,
    input_schema JSONB NOT NULL DEFAULT '{}',

    is_active BOOLEAN NOT NULL DEFAULT TRUE,

    UNIQUE (server_id, name)
);

-- Role-based permissions for MCP tools
CREATE TABLE mcp_tool_permissions (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

    tool_id UUID NOT NULL REFERENCES mcp_tools(id) ON DELETE CASCADE,
    role team_role NOT NULL,

    UNIQUE (tool_id, role)
);

-- Per-user tool permissions (override role-based)
CREATE TABLE mcp_tool_user_permissions (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

    tool_id UUID NOT NULL REFERENCES mcp_tools(id) ON DELETE CASCADE,
    team_profile_id UUID NOT NULL REFERENCES team_profiles(id) ON DELETE CASCADE,

    is_allowed BOOLEAN NOT NULL,  -- explicit allow/deny

    UNIQUE (tool_id, team_profile_id)
);

-- ==================== CHAT (AI ASSISTANT) ====================

-- Chat conversations (AI assistant)
CREATE TABLE chat_conversations (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

    team_profile_id UUID NOT NULL REFERENCES team_profiles(id) ON DELETE CASCADE,
    title VARCHAR(255) NOT NULL,
    is_active BOOLEAN NOT NULL DEFAULT TRUE
);

-- Chat messages with tool call tracking
CREATE TABLE chat_messages (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

    conversation_id UUID NOT NULL REFERENCES chat_conversations(id) ON DELETE CASCADE,

    role VARCHAR(20) NOT NULL CHECK (role IN ('user', 'assistant', 'tool')),
    content TEXT,

    -- For tool calls/results
    tool_calls JSONB NOT NULL DEFAULT '[]',
    tool_results JSONB NOT NULL DEFAULT '[]'
);

-- ==================== MCP TOOL EXECUTION LOG ====================

-- Tool execution log (for auditing, rate limiting, debugging)
CREATE TABLE mcp_tool_executions (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

    tool_id UUID NOT NULL REFERENCES mcp_tools(id) ON DELETE CASCADE,
    team_profile_id UUID NOT NULL REFERENCES team_profiles(id) ON DELETE CASCADE,
    chat_message_id UUID REFERENCES chat_messages(id) ON DELETE SET NULL,

    -- Execution details
    input JSONB NOT NULL,
    output JSONB,
    error TEXT,

    started_at TIMESTAMPTZ NOT NULL,
    completed_at TIMESTAMPTZ,
    duration_ms INTEGER CHECK (duration_ms >= 0),

    status VARCHAR(20) NOT NULL CHECK (status IN ('pending', 'running', 'success', 'error'))
);

-- ==================== INDEXES ====================

-- MCP server queries
CREATE INDEX idx_mcp_servers_active ON mcp_servers(is_active);

-- MCP tool queries
CREATE INDEX idx_mcp_tools_server ON mcp_tools(server_id);
CREATE INDEX idx_mcp_tools_active ON mcp_tools(is_active);

-- Permission lookups
CREATE INDEX idx_mcp_tool_permissions_tool ON mcp_tool_permissions(tool_id);
CREATE INDEX idx_mcp_tool_permissions_role ON mcp_tool_permissions(role);
CREATE INDEX idx_mcp_tool_user_permissions_tool ON mcp_tool_user_permissions(tool_id);
CREATE INDEX idx_mcp_tool_user_permissions_user ON mcp_tool_user_permissions(team_profile_id);

-- Chat queries
CREATE INDEX idx_chat_conversations_user ON chat_conversations(team_profile_id);
CREATE INDEX idx_chat_conversations_active ON chat_conversations(team_profile_id, is_active);
CREATE INDEX idx_chat_messages_conversation ON chat_messages(conversation_id);
CREATE INDEX idx_chat_messages_conversation_created ON chat_messages(conversation_id, created_at DESC);

-- Rate limiting queries
CREATE INDEX idx_mcp_tool_executions_rate_limit
    ON mcp_tool_executions (tool_id, team_profile_id, created_at DESC);
CREATE INDEX idx_mcp_tool_executions_status ON mcp_tool_executions(status);
CREATE INDEX idx_mcp_tool_executions_started ON mcp_tool_executions(started_at DESC);