model-first-reasoning

# Model-First Reasoning (MFR)

A rigorous methodology that REQUIRES constructing an explicit problem MODEL before any reasoning or implementation. The model becomes a frozen contract that governs all downstream work.

> Based on Kumar & Rana (2025), "Model-First Reasoning LLM Agents: Reducing Hallucinations through Explicit Problem Modeling" (arXiv:2512.14474)

## Why MFR Works

**Hallucination is not merely the generation of false statements—it is a symptom of reasoning performed without a clearly defined model of the problem space.**

Reasoning does not create structure; it operates on structure. When that structure is implicit or unstable, reasoning becomes unreliable. MFR provides "soft symbolic grounding"—enough structure to stabilize reasoning without imposing rigid formalism.

## Core Principle

**Phase 1 produces the MODEL. Phase 2 reasons/implements ONLY within the model.**

This prevents the common failure mode where reasoning introduces ad-hoc decisions, missing constraints, or invented behavior not grounded in the problem definition.

## Non-Negotiable Rules

1. **Phase 1 (Model)** produces NO code, no solution steps—only the formal model
2. **Phase 2 (Implement)** may NOT introduce new entities, state, actions, or constraints
3. If you need something not in the model: output exactly `MODEL INCOMPLETE` + what to add, then STOP
4. No invented APIs or dependencies. If not provided, either ask (unknowns) or create a stub clearly marked `STUB`

## The Model as Contract

After creating the model, run a **MODEL AUDIT** before coding:

### Audit Checks

| Check | Description |
|-------|-------------|
| **Coverage** | Every user requirement is represented in exactly one of: a constraint, the goal/acceptance criteria, or an action precondition/effect |
| **Operability** | Every operation your plan would require is present as an action |
| **Consistency** | Constraints don't contradict each other; action effects don't violate invariants |
| **Testability** | Every