Keys: the most important decision

[Key] prevents duplicates. When you call TryAdd, Curiosity checks the key:

• Key exists → update the existing node
• Key is new → create a new node

Run the same connector twice, same source data → identical graph. That's idempotency.

[Key] public string Id { get; set; }  // ✓  source ID — stable across runs

[Key] public Guid Id { get; set; }    // ✗  Guid.NewGuid() — new node on every run

Rules:

• Use the source system's own ID
• Never use row order, sequence numbers, or random values
• Avoid composite keys — pick one stable identifier

No source ID? Build a deterministic one from stable fields:

// Hash a canonical string — brittle under schema changes, but better than random
string key = $"{row.Author}::{row.Title.ToLowerInvariant()}::{row.Date:yyyy-MM-dd}";

If at all possible, add a proper ID to the source instead.

Idempotency test: run the connector twice with no source changes. Node and edge counts must be identical.