Humanbound website
DG

Co-Founder & co-CEO, Tech & Product, Humanbound

Demetris Gerogiannis

Humanbound cover for "One Link Away: What 1,350 Runs Taught Us About Prompt Guardrails," a controlled study of 9 models. A terminal window for a pricing agent on SKU-4471 shows three tool calls: a clean competitor listing, a fetch of "this week's offer," and a final fetch that leaks the £118.40 unit cost disguised as 1x1x8.4.

One Link Away: What 1,350 Runs Taught Us About Prompt Guardrails

We gave nine models a pricing agent's job and a competitor page one link away from a trap. Four leaked a confidential unit cost on every run. Here is what 1,350 runs say about how much a system-prompt guardrail actually buys you.

DG
Demetris Gerogiannis
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Infographic titled 'The Humanbound Firewall: A Multi-Tier Defense for AI Agents' on a dark chalkboard-style background with white and orange text. The layout is divided into five sections. Top-left, 'Why Single-Layer Guardrails Fail' highlights three problems: The Context Gap, Multi-turn Blindness, and The Novelty Lag, each with hand-drawn icons. Below it, 'The 4-Tier Defensive Stack' shows a layered pyramid diagram with four tiers: Tier 0 (Sanitization), Tier 1 (Generic Attack Detection using ensemble detectors like DeBERTa), Tier 2 (Domain-Specific Classifiers with normal traffic and adversarial pattern models plus a streaming LLM), and Tier 3 (The LLM Judge). Arrows show data flowing upward through the tiers. Top-right, 'The Continuous Test-and-Defend Loop' illustrates a cycle where the humanbound CLI/SDK engine runs adversarial tests producing transcripts, which become labeled training data. Below it, 'The Feedback Loop' shows how that data refreshes the Tier 2 classifier inside humanbound-firewall, which protects the live agent in production. Bottom-right, 'Open Source vs. Managed Platform' contrasts the Apache-2.0 licensed open-source firewall (offering transparency and auditability) with the managed platform for CISOs (providing continuous testing, posture scoring, compliance evidence, and cross-deployment intelligence). A NotebookLM logo appears in the bottom-right corner.

Why we open-sourced humanbound-firewall

We released humanbound-firewall under Apache-2.0. A multi-tier runtime defense for AI agents, with each layer inspectable, escalating on uncertainty, and trainable on your own adversarial test data.

DG
Demetris Gerogiannis
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You're Still Alt-Tabbing to a Security Tool

AI agent security won't be adopted through better dashboards. It'll be adopted when it disappears into existing workflows. Embed adversarial testing into your terminal via MCP - security becomes a conversation, not a context switch.

DG
Demetris Gerogiannis
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