# 📐 L2 Spec — Phase Change Material — Stefan moving-boundary problem Mismatch-Only Spec
**ID:** `L2-202-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-202`](/artifact/l1/L1-202)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.48 · **Delta tier:** 5
> **⛓ On-chain block:** 41554038
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 32 – 1024 |
| W | px | 32 – 1024 |
| Snr db | dB | 0 – 40 |
| N sensors | — | 4 – 256 |
| K solid error | — | 0.0 – 0.1 |
| K liquid error | — | 0.0 – 0.1 |
| Supercool error | — | 0.0 – 5.0 |
| Latent heat error | — | 0.0 – 0.1 |
## 2. Tolerance (ε)
**Type:** `fn`
```
16.0 + 0.25*SNR_dB - 20.0*latent_heat_error - 25.0*k_liquid_error - 25.0*k_solid_error - 0.5*supercool_error
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.48 |
| Delta tier | 5 |
## 4. Fingerprint
`81d2791beb57a834016bccfd866eeec3a8c99fccc11a388019f56f50c4890a82`
## 5. On-chain Registration
- **Chain hash:** `0x255da686de74a5c34d911a85bc16584f883fe0fd73864862799e659623404adf`
- **Chain tx hash:** `0x7c9c9538c63da4b7da6984ed6baa5100f2556d656ed9b26404c2add2806402eb`
- **Chain block:** `41554038`
---
## File Mapping
This bundle consists of: `L2-202-001.md`, `L2-202-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-202-001.md` | Source of truth — edit this | Human or LLM |
| `L2-202-001.json` | Structured metadata for the registry | LLM regenerates from the sections above |
**Prompt for your LLM after editing this Markdown:**
> Read the attached Markdown. Regenerate the sibling `.json` so every field matches.
> Preserve the schema documented in the rows above.
> Output each file in its own fenced code block tagged with the filename.
> Output only the JSON object.
_This Markdown was auto-synthesized from the catalog row for `L2-202-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._