Build reusable bot framework

config/migrations/0003_outbound_messages.sql

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+CREATE TABLE IF NOT EXISTS outbound_messages (
+    id UUID PRIMARY KEY,
+    user_uuid UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    channel VARCHAR(50) NOT NULL,
+    payload JSONB NOT NULL,
+    available_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    status VARCHAR(20) NOT NULL DEFAULT 'pending',
+    attempts INTEGER NOT NULL DEFAULT 0,
+    max_attempts INTEGER NOT NULL DEFAULT 3,
+    leased_by VARCHAR(255),
+    lease_until TIMESTAMPTZ,
+    last_error TEXT,
+    idempotency_key VARCHAR(255) NOT NULL UNIQUE,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    delivered_at TIMESTAMPTZ,
+    cancelled_at TIMESTAMPTZ,
+    CONSTRAINT outbound_messages_status_check
+        CHECK (status IN ('pending', 'delivering', 'delivered', 'failed', 'cancelled')),
+    CONSTRAINT outbound_messages_attempts_check
+        CHECK (attempts >= 0 AND max_attempts > 0)
+);
+
+CREATE INDEX IF NOT EXISTS outbound_messages_claim_idx
+    ON outbound_messages (channel, available_at, created_at)
+    WHERE status = 'pending';
+
+CREATE INDEX IF NOT EXISTS outbound_messages_expired_lease_idx
+    ON outbound_messages (lease_until)
+    WHERE status = 'delivering';
+
+CREATE INDEX IF NOT EXISTS outbound_messages_user_idx
+    ON outbound_messages (user_uuid, created_at DESC);