The Excel & Google Sheets Breaking Point

                  ┌────────────────────────────────────────┐
                  │    The Shared Spreadsheet Concurrency Barrier   │
                  └───────────────────┬────────────────────┘
                                      │
         ┌────────────────────────────┼────────────────────────────┐
         ▼                            ▼                            ▼
[Accidental Overwrite]      [Data Exfiltration]          [Concurrency Lag]
Row 842 deleted by clerk;   Staff downloads entire       5 users editing; browser
₹4.2L dispatch missed!      client base in 1-click.      spins for 2 minutes.

-- PostgreSQL Row-Level Security (RLS) Policy Example
-- Ensures sales reps can only see their own assigned leads,
-- while operations managers see all records, and exports are restricted.

ALTER TABLE leads ENABLE ROW LEVEL SECURITY;

-- 1. Sales Reps Policy: Can only view and edit leads assigned to their User ID
CREATE POLICY sales_rep_own_leads ON leads
  FOR ALL
  TO authenticated
  USING (
    assigned_rep_id = auth.uid() 
    AND (SELECT role FROM user_profiles WHERE id = auth.uid()) = 'sales_rep'
  );

-- 2. Operations Director Policy: Full read and update visibility
CREATE POLICY director_full_access ON leads
  FOR ALL
  TO authenticated
  USING (
    (SELECT role FROM user_profiles WHERE id = auth.uid()) IN ('director', 'ops_head')
  );

-- 3. Audit Logging Trigger: Automatically logs every change with timestamp and IP
CREATE OR REPLACE FUNCTION log_lead_update()
RETURNS TRIGGER AS $
BEGIN
  INSERT INTO audit_logs (table_name, record_id, changed_by, old_data, new_data, updated_at)
  VALUES ('leads', NEW.id, auth.uid(), to_jsonb(OLD), to_jsonb(NEW), NOW());
  RETURN NEW;
END;
$ LANGUAGE plpgsql;

CREATE TRIGGER trigger_audit_lead
AFTER UPDATE ON leads
FOR EACH ROW EXECUTE FUNCTION log_lead_update();