clay-borg/evidence/CB-EV-0033-boards-and-modes.md

# CB-EV-0033 — the four boards and the three modes, measured

date: 2026-08-08
produced by: [CB-WP-0047](../workplans/CB-WP-0047-all-four-boards-and-all-three-modes.md),
[CB-WP-0049](../workplans/CB-WP-0049-a-seat-that-plays-its-own-objective.md)
instrument: `games/ground/examples/scenario-panel.rs` (`make panels`)
reported to ground-game as: `reports/260808-clay-borg-boards-and-modes.md`

## What was run

4 scenarios × 3 modes × 3 seat bands × 2 policies, **100 games per cell**,
seeds 0..100, every seat filled by the same bot.

| policy | what it is |
|---|---|
| `greedy` | `GreedyPolicy`, which **never reads `state.mode`** |
| `objective` | `ObjectivePolicy`, which plays its seat's own objective, read off `GroundState::score` |

**Every cell asserts `games == 100` and `played == 100`** — a game that
ran is not a game that was played (CB-REV-0003 #2), and a short column is
a sample nobody chose (CB-REV-0002 #1).

**Both policies are proven blind** to what their seat cannot see
([ADR-0023](../decisions/ADR-0023-a-policy-is-bound-by-what-its-seat-can-see.md)):
vary only face-down Problems and other seats' hands, and neither changes
its move. The control is proven against a deliberate peeker first.

## 1 — SCN_01 and SCN_02 are the same board

Identical suit and value at **every** priority. Every cell matches
exactly, in both policies, at all three seat bands.

Not a defect — a reskin is a legitimate design choice — but **"four
scenarios" buys three boards**, and a panel that treated them as four
independent samples would be counting one of them twice. Pinned by
`which_scenarios_are_mechanically_distinct`, so a future divergence is a
decision rather than a drift.

## 2 — SCN_04 is the hard board at 2 players

| board | 2p group success (greedy, /100) |
|---|---|
| SCN_01 / SCN_02 | 67 |
| SCN_03 | 73 |
| **SCN_04** | **52** |

**The 2p deals are identical in every respect except one.** All four
scenarios deal Surface + priorities 1–2, all four give values 2+2+2 = 6
available against a threshold of 5, and all four start at Stress 2 over
five rounds. The single difference is the **suit multiset**:

| board | 2p suits |
|---|---|
| SCN_01 / SCN_02 | Repair, Clarify, Boundary |
| SCN_03 | Boundary, Clarify, Repair |
| **SCN_04** | **Repair, Clarify, Repair** |

SCN_04 is the only deck that needs **two of one suit** in the 2p deal.
Because every other parameter is held fixed by the edition itself, this
is close to a controlled comparison — but **the causal claim is not
measured**: nothing here demonstrates that the second Repair is what
costs the 15 points. The falsifier is a deck with a doubled suit that
does *not* lose group success.

## 3 — every board is a formality at 6 players

100/100 group success in all twelve 6p cells, both policies, every mode.
Consistent with F17's shape. Reported, not acted on.

## 4 — the modes change who wins, not whether the group succeeds

`greedy` vs `objective`, group success:

**Unchanged in 34 of 36 cells.** SCN_03 at 4p moves 99 → 100 in all three
modes, which is the SOLVE-by-card-value refinement and not a mode effect
(it moves under SHARED GROUND too).

Winning **seats** per game, BONDED COALITIONS:

| board | 4p greedy | 4p objective |
|---|---|---|
| SCN_01 / SCN_02 | 2.04 | **2.98** |
| SCN_03 | 2.12 | **3.29** |
| SCN_04 | 2.05 | **3.01** |

COMMON PROBLEM at 6p: 1.10 → 1.17. Everything else flat.

**The control that makes this mean anything:** under SHARED GROUND the
two policies agree at all but ≤2 decision points across twelve boards. A
moving column is therefore mode-awareness and not simply a different bot.

### Where the modes *can* differ

**SOLVE always claims for the actor**, so a seat maximising its own score
and one maximising the group's want the same SOLVE in nearly every
position. That is a fact about GROUND's action set and it bounds how far
apart any two policies can get. The two real divergences:

- **SUPPORT regulates someone else** — worth less when the beneficiary is
  a rival, worth *more* when a Bond merges them into my coalition and my
  score is the coalition's sum;
- **SOLVE's value is the card's value**, which greedy ignores entirely.

### The seat-band pattern, and one untested explanation

2p: nothing moves in any mode. 4p: the largest effect. 6p: **nothing**
under BONDED COALITIONS.

**Sensitivity:** vary only the seat band and the effect appears and
disappears with every other parameter held. A candidate explanation is
that **two relation slots per seat cap network growth**, so at 6p the
incentive exists and cannot be acted on. **Untested.** The falsifier is a
run with a third relation slot: if coalition size at 6p then moves the
way it does at 4p, the cap is the cause.

## What this does not establish

- **No policy models a rival playing their objective.** A competitive
  mode in which nobody anticipates an opponent is a weak test of that
  mode. F27 stays `reported`, not resolved.
- **No felt play.** Every number here is bots.
- **Bond-scoped joint SOLVE remains untested** (CB-EV-0032 criterion 4,
  unchanged): these policies read the mode, not the module.