# zenfro_v2 — Grammar of Time on the v1 weather backbone

Cascade miner generator. Evolves `zenfro_v1` (weather-heavy aurora blend) with
**Grammar of Time (GoT)** and forecast-friendly seasonality upgrades.

## Why this prior

Cascade holds Toto2 fixed and trains it from scratch on your corpus. Eval is
forecast skill on held-out windows: **4096-step context → next 64 steps**
(CRPS + MASE). Winning synthetic priors (Chronos-2, TempoPFN, CauKer) compose
temporal primitives rather than sampling one ARIMA family.

| Layer | What |
|---|---|
| Stems (v1) | weather (~34%), trend/seasonal, AR2, integrated, RFF-GP, … |
| GoT (~22%) | compose ⊕, splice ‖, nested ⋉, causal ▷ |
| Seasonality | coupled calendar pairs (24↔168, 7↔52, …) + amp/phase drift |
| Clean mode | low-noise seasonal rows for sharp periodic reconstruction |

## Grammar of Time

```
Series     → Production | Stem
Production → Compose | Splice | Nested | Causal
Compose    → Stem ⊕ Stem [⊕ Stem]     # additive / multiplicative phrase
Splice     → Stem ‖ Stem              # clause = change of generating law
Nested     → Envelope ⋉ Carrier       # slow modulates fast
Causal     → Driver ▷ Response        # lagged temporal chain
```

GoT stems are cheap (seasonal+AR, RFF, integrated, AR2, diurnal-weatherish) so
compositions stay wall-safe under the token budget.

## Layout

```
zenfro_v2/
  generator.py      # Generator(DataGenerator)
  config.json       # active mixture + GoT knobs
  requirements.txt  # numpy + numba
  README.md
```

## Quick checks

```bash
cascade verify ./mywork/zenfro_v2
cascade score ./mywork/zenfro_v2 --pool-dir <held-out>
```

## Config knobs

| key | role |
|---|---|
| `family_weights` | mixture over stems + GoT |
| `got_depth` | stems stacked in compose (2–4) |
| `got_mul_frac` | multiplicative vs additive compose |
| `got_splice_cuts` | clause boundaries in splice |
| `got_nest_ratio` | slow/fast scale span |
| `got_causal_lag_frac` | max lag as fraction of L |
| `sa_clean_*` | clean low-noise seasonal mode |
| `tr_*` / `gr_*` | trend / growth excursion |

## Contract

- Deterministic at a fixed seed
- NumPy + numba only, code-only (no shipped weights)
- Full-context series (`min_length = max_length = 4096`)