-- Migration 111: Create message_reactions table (v0.502 CH1-01)
CREATE TABLE IF NOT EXISTS message_reactions (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    message_id UUID NOT NULL REFERENCES messages(id) ON DELETE CASCADE,
    emoji VARCHAR(50) NOT NULL,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    CONSTRAINT uq_message_reactions_user_message_emoji UNIQUE (user_id, message_id, emoji)
);
CREATE INDEX idx_message_reactions_message_id ON message_reactions(message_id);