Title: ThumbGate Enterprise — Dialogflow CX guardrail architecture

Draw a clean left-to-right architecture diagram of a pre-action safety gate in
front of Dialogflow CX fulfillment, all inside the customer's Google Cloud tenant.

Nodes (left to right):
1. "Caller" (a person on a phone/chat) — small user icon.
2. "Dialogflow CX" (Google conversational agent) — box.
3. "ThumbGate gate" — a shield/gate box labelled "Cloud Run · customer GCP tenant".
   This is the focal element; emphasize it.
4. A decision diamond "allow?".
5. On the ALLOW branch: "Existing fulfillment (BigQuery / CRM / billing)" — database/box.
6. On the BLOCK branch: "Safe response — no side-effect" — box with a stop/shield accent.
7. Below the gate, a dashed optional link to "Vertex AI / Gemini (in-tenant, no data egress)".

Flows:
- Caller -> Dialogflow CX (solid).
- Dialogflow CX -> ThumbGate gate, labelled "fulfillment webhook" (solid).
- ThumbGate gate -> decision diamond.
- Diamond -> Existing fulfillment, labelled "allow" (green accent).
- Diamond -> Safe response, labelled "block" (red accent).
- Existing fulfillment -> back to Dialogflow CX (response).
- Safe response -> back to Dialogflow CX (response).
- ThumbGate gate ..dashed.. Vertex AI / Gemini, labelled "optional scoring".

Style: modern, minimal, GCP-blue accents; the gate is the hero; one tagline at the
bottom: "Block the bad action before the side-effect runs." No clutter.
