A trace from request to response is half a trace. The other half is from outcome back to the rule that allowed it. Most platforms have one direction; few have both. Why bidirectional matters for debugging, for audit, and for AI agent decisions, and the pattern that makes it work.
The four 'as code' methodologies aren't competing, they layer. IaC builds the foundation. Config-as-code parameterizes it. PaC enforces what's allowed. DaC is the surface a non-engineer reads. Walking through the layers, with concrete examples from Terraform up to the form a business owner sees.
Multi-tenant from day one is roughly 2x the cost of the single-tenant version. The hidden costs aren't in the code, they're in auth, audit, query routing, observability, support tiering, and billing. Often the cheaper move is to start single-tenant and earn your way in.
