Overview
TaurusX Engines are the AI model layer — the part of the system that actually generates responses. Rather than exposing raw API access to a specific vendor, TaurusX wraps all AI models behind a unified Engine Abstraction Layer.
This means that when you use TaurusX, you are using a TaurusX engine — not a named external model. The kernel chooses which model to use based on context, plan tier, and message complexity, and that choice is completely transparent to the surface.
Engine Abstraction Layer
The Engine Abstraction Layer (EAL) is the kernel subsystem that manages all AI model calls. Every surface — mobile chat, Continuum, TX Terminal, CLI — routes all AI requests through the EAL. No surface calls a model provider directly.
The EAL provides:
- Model-agnostic interface — one API surface regardless of which model is underneath
- Automatic fallback — if the selected engine is unavailable, the EAL reroutes to the next available engine
- Consistent billing — all engine calls are metered in TaurusX Cycles regardless of underlying model cost
- Plan enforcement — the EAL checks plan tier before dispatching; free users cannot call enterprise engines
- Prompt injection — the EAL injects the active tone, state, and accessibility flags into every prompt automatically
Available Engines
| TX Engine Name | Character | Best For | Plan Required |
|---|---|---|---|
| TX-Flash | Fastest, most concise | Quick answers, status checks, one-liners | Free |
| TX-Haiku | Fast, balanced, efficient | Everyday chat, learning, casual interaction | Free |
| TX-Sonnet | Smart, capable, nuanced | Technical work, code review, planning | Pro |
| TX-Opus | Most capable, highest reasoning | Complex analysis, multi-step strategy, research | Pro |
| TX-Enterprise | Enterprise-grade, highest context | Long documents, enterprise workflows, audit | Enterprise |
| TX-Kids | Safe, age-adapted, filtered | Kids Mode chat, Homework Helper, Vault queries | Free (Kids only) |
Routing Engine
The Routing Engine is the decision layer that sits in front of the EAL. For every incoming message, it determines which TX Engine to invoke based on:
| Factor | How it influences engine selection |
|---|---|
| Message complexity | Short factual questions → TX-Flash; deep analysis → TX-Opus |
| Active state | Technical or Executive state prefers TX-Sonnet or TX-Opus |
| User plan | Free plan caps at TX-Haiku; Pro unlocks TX-Sonnet and TX-Opus |
| Explicit directive | <engine:tx-opus> in message forces a specific engine |
| Meta-Agent active | Planning tasks always use TX-Opus regardless of plan (governed by meta-agent cycles) |
| Kids Mode | All requests in Kids Mode are routed to TX-Kids; no override |
Engine Selection
By default, TaurusX selects the best engine for each message automatically. You do not need to choose. However, you can direct the Routing Engine explicitly using an inline directive:
<engine:tx-opus>Forces TX-Opus for this message and the remainder of the session<engine:tx-flash>Forces TX-Flash — maximum speed, minimum tokens<engine:auto>Returns to automatic selection (default)Inline directives are stripped from the message before it reaches the engine. The model never sees the directive — only the cleaned message and the injected system context.
Plan Tiers & Access
| Plan | Engines Available | Daily Task Limit | API Tier |
|---|---|---|---|
| Free | TX-Flash, TX-Haiku | 20 tasks/day | free |
| Pro | TX-Flash, TX-Haiku, TX-Sonnet, TX-Opus | 200 tasks/day | pro |
| Enterprise | All engines including TX-Enterprise | Unlimited | enterprise |
| Kids (Free) | TX-Kids only | 10 sessions/day | free |
Billing is metered in Cycles — TaurusX's internal unit of AI consumption. Each engine has a different Cycle cost per token. The current Cycle balance is shown in the Continuum dashboard and in the Capability Panel.