Prompt injection defenses are maturing (but still not bulletproof).

Defenses improved but aren't magic—implement defense-in-depth.

What changed
Model-level defenses improved but aren't perfect
Best practices documented and widely available
Architectural patterns for defense-in-depth established
Who it affects
Security teams
Production AI builders
Anyone handling user-generated content
What to do now
Separate system instructions from user content architecturally
Validate and sanitize all user inputs
Implement output verification for sensitive operations
Monitor for unusual behavior patterns