# Mode playtest notes — engine (GR-E03 / GR-E04)

**Date:** 2026-08-08  
**Workplan:** [GROUND-WP-0003](../workplans/GROUND-WP-0003-playtest-semi-and-coalitions.md)  
**Source:** [GROUND-RPT-0003](../reports/260807-clay-borg-attack-and-modes.md) (clay-borg attack-value panel + full-mode playouts)  
**Variant:** `ground-darvo-r0` (baseline)

These notes close the **engine** half of WP-0003 (“human table *or* full
engine playout”). They are not a substitute for human felt-play if we want
table texture later; they do answer “do the modes score to the end, and
what does ATTACK do?”

---

## Runs covered

| Task | Mode | Seats | Evidence |
|------|------|------:|----------|
| T01 | MODE_SEMI | 2p | attack-value cells; modes playable to scoring |
| T02 | MODE_SEMI | 3–4p (and 6p) | same panel |
| T03 | MODE_COALITION | 2p | same |
| T04 | MODE_COALITION | 3–4p (and 6p) | same |
| — | MODE_COOP | all | control cells |

**Identical-play differentiation (seed 1, 4p, 37 commands):**

| Mode | Winners |
|------|---------|
| SHARED GROUND | all four (mastery 4) |
| COMMON PROBLEM (semi) | **P3** (top personal) |
| BONDED COALITIONS | **P1+P2** (best Bond network) |

Encoding of Modes.csv behaves as three distinct games.

**Driver note (clay-borg):** GR-E03/E04 were previously unplayed because
`cb-play` forced SHARED GROUND — fixed on their side; not a modes defect.

---

## Outcomes checklist

### Shared total vs threshold / personal scores

- Group success rates under “never attack” competent-ish policy (wins per
  200 games, 2/3/4/6 seats):
  - SHARED: 132 / 165 / 190 / 200  
  - SEMI (seat-0 among winners framing differs; personal race present): lower individual “among winners” counts  
  - COALITION: high “among winners” when not attacking (network still intact)
- Exact seed-by-seed personal score tables were not shipped in RPT-0003;
  mode differentiation and ATTACK value are the load-bearing results.

### Stress / DARVO

- Under competent non-attacking play on baseline r0: **DARVO armed 0 times**
  in the RPT-0003 competent aggregate (500 games cited).
- Later CB-EV-0031: peak Stress *held* never exceeds start **2** when policies
  never select ATTACK — Stress only falls. Inbound pressure is ATTACK-only
  for those policies.

### ATTACK value (all three modes)

| mode | never | sometimes | always |
|------|------:|----------:|-------:|
| SHARED | 132/165/190/200 | identical | 0 |
| SEMI | 59/52/48/44 | 59/52/48/**34** | 0 |
| COALITION | 131/134/132/116 | **59/52/48/34** | 0 |

*(2/3/4/6 seats.)* ATTACK never improves outcomes; in coalitions it roughly
halves “among winners.” E04 attacking numbers match E03 when Bonds break
(GR-A07 + network scoring).

### Underdetermined rules exposed?

- **No new U-items** from mode scoring itself.
- **Design gap (not rules ambiguity):** ATTACK/DARVO irrelevant under
  competent baseline play — tracked experimentally via WP-0006 (H1,
  reject) → WP-0007 (H2 scoped stress, in flight).

---

## Follow-ups

| Item | Where |
|------|--------|
| Restore inbound Stress without flat table tax | H2 `h2-scoped-problem-stress` |
| Human felt-play of semi/coalition (optional) | residual note below; not blocking |
| Opening-action economy (INVESTIGATE first) | clay-borg offer; deferred |

**Residual (optional, not a new workplan unless scheduled):** one human
2p semi and one 3–4p coalition session for “feels like one game” texture.
Engine checklist for T01–T04 is satisfied.