-- Seen tracking: private per-user state
CREATE TABLE particle_seen (
    particle_id TEXT NOT NULL REFERENCES particles(id) ON DELETE CASCADE,
    email VARCHAR(255) NOT NULL,
    seen_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    PRIMARY KEY (particle_id, email)
);

-- Ack tracking: public, visible to others
CREATE TABLE particle_acks (
    particle_id TEXT NOT NULL REFERENCES particles(id) ON DELETE CASCADE,
    email VARCHAR(255) NOT NULL,
    acked_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    PRIMARY KEY (particle_id, email)
);

-- Index for bulk "which particles has this user seen?"
CREATE INDEX idx_particle_seen_email ON particle_seen(email, particle_id);

-- Index for "who acked this particle?"
CREATE INDEX idx_particle_acks_particle ON particle_acks(particle_id);