Understanding the THSP Protocol: A Deep Dive

The THSP (Truth-Harm-Scope-Purpose) Protocol is the core decision validation framework powering Sentinel. In this post, we'll explore how each gate works and why the four-gate design is essential for robust AI safety.

Why Four Gates?

Traditional AI safety approaches often focus on a single dimension (usually harm prevention). But this creates blind spots:

The THSP Protocol addresses this by requiring ALL four gates to pass.

Gate 1: TRUTH

The Truth Gate validates factual accuracy. It asks: "Is this factually correct?"

This gate prevents:

Implementation uses a combination of:

Gate 2: HARM

The Harm Gate assesses potential for damage. It asks: "Could this cause damage?"

This gate evaluates:

Pattern matching identifies 2000+ harmful patterns across categories.

Gate 3: SCOPE

The Scope Gate enforces boundaries. It asks: "Is this within authorized limits?"

This gate ensures agents don't:

Scope is configurable per-agent, allowing precise access control.

Gate 4: PURPOSE

The Purpose Gate is unique to THSP v2. It asks: "Does this serve genuine benefit?"

This is the key insight: **the absence of harm is not sufficient**.

An action that:

...should still be blocked. This prevents:

Gate Interaction

Gates are evaluated in parallel for performance, but all must pass:

Decision → [TRUTH] ──┐

│

→ [HARM] ───┼──→ ALL PASS? → ALLOW

│

→ [SCOPE] ──┤

│

→ [PURPOSE]─┘

If any gate fails, the action is blocked with an explanation of which gate failed and why.

Configuring THSP

Each gate can be configured with different sensitivity levels:

const config = {

truth: { threshold: 0.85, requireSources: true },

harm: { categories: ['physical', 'financial'], threshold: 0.90 },

scope: { allowedActions: ['read', 'write'], maxCost: 100 },

purpose: { requireExplicit: true, minBenefit: 0.7 }

}

Conclusion

The THSP Protocol provides comprehensive decision validation by requiring four independent checks. This defense-in-depth approach catches threats that single-dimension systems miss.

For implementation details, see our [documentation](/docs/thsp-protocol).

The Sentinel Team