-- §5 / §10.3 / §15.6 / §15.7: the freshness cursors and the watch model.
--
-- Two cursor families per §15.7: per-event read state lives on notifications
-- (added in 006); per-scope freshness lives on pr_seen and branch_chat_seen.
-- They serve different jobs and are reconciled by the visit-advances-cursor
-- reconciler in §15.7.

CREATE TABLE pr_seen (
    id                      INTEGER PRIMARY KEY AUTOINCREMENT,
    user_id                 INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    rfc_slug                TEXT NOT NULL,
    pr_number               INTEGER NOT NULL,
    last_seen_commit_sha    TEXT,
    last_seen_message_id    INTEGER REFERENCES thread_messages(id) ON DELETE SET NULL,
    seen_at                 TEXT NOT NULL DEFAULT (datetime('now')),
    UNIQUE (user_id, rfc_slug, pr_number)
);

CREATE TABLE branch_chat_seen (
    id                      INTEGER PRIMARY KEY AUTOINCREMENT,
    user_id                 INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    rfc_slug                TEXT NOT NULL,
    branch_name             TEXT NOT NULL,
    last_seen_message_id    INTEGER REFERENCES thread_messages(id) ON DELETE SET NULL,
    seen_at                 TEXT NOT NULL DEFAULT (datetime('now')),
    UNIQUE (user_id, rfc_slug, branch_name)
);

-- §15.6: the watch model. Three states; auto-rules upgrade but never
-- downgrade; explicit settings exempt from the 90-day decay. Per-RFC
-- mute lives here as state='muted'.
CREATE TABLE watches (
    id                      INTEGER PRIMARY KEY AUTOINCREMENT,
    user_id                 INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    rfc_slug                TEXT NOT NULL,
    state                   TEXT NOT NULL CHECK (state IN ('watching', 'following', 'muted')),
    set_by                  TEXT NOT NULL CHECK (set_by IN ('auto', 'explicit')),
    set_at                  TEXT NOT NULL DEFAULT (datetime('now')),
    last_participation_at   TEXT,            -- 90-day decay key per §15.6
    UNIQUE (user_id, rfc_slug)
);

CREATE INDEX idx_watches_user ON watches (user_id);
CREATE INDEX idx_watches_rfc ON watches (rfc_slug);
CREATE INDEX idx_watches_decay ON watches (state, last_participation_at);