CB-WP-0038: variant selection, H1 implemented, and H1 measured

ground-game packages hypotheses as selectable rules variants — a catalog,
a rules_delta.yaml, and prose — and their note is explicit that CSV text
alone is not executable here. So the kernel gains a Variant in game state:
in the state, therefore in the hash, therefore in the recording, because a
scenario replayed under a different variant would diverge silently.

Baseline is bit-for-bit what it was, asserted across seat counts and
seeds. A variant system that perturbs the baseline invalidates every
measurement this repo has.

H1-A and H1-B implemented from rules_delta.yaml and mutation-proven on
their own defects: "unclaimed" misread as face-up-and-unsolved, and the
attacker's Stress read after the attack's effects. Their `unchanged:` list
is asserted rather than trusted — that list is their claim about their own
experiment.

Measured, and three of their four criteria fail. DARVO arm rate is still
0 under greedy; ATTACK selection does not rise and falls for the rank-75
policy; group success collapses from 165/190/200 to 0 at 3/4/6 seats.
The mechanism is not the assumed one: greedy answers the pressure by
regulating, Stress plateaus at 3, so it never reaches the gate at 4 or the
arm at 5 — H1-A acts as a solve-rate tax and H1-B is unreachable under
competent play.

A harness defect was caught before the claim: sweep discarded refused
games silently and never reported its count, so "nobody won" and "nothing
played" printed identically. Reporting H1 as unwinnable on that basis
would have been the ADR-0018 family aimed at another repo's design. All
200 games ran in every cell; the zeros are real.

Chaos d8 = 8 — the window's first override, redrew L against a structural
L, so it changed nothing. Window 3 recorded in ChaosRollHistory.

NOT REVIEWED: tier L owes a separate-agent adversarial review, and no H1
result may reach ground-game until it has run.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

workplans/CB-WP-0038-h1-variant.md

@@ -0,0 +1,151 @@
+---
+id: CB-WP-0038
+kind: product
+title: "Variant selection, and H1"
+status: done
+---
+
+# Purpose
+
+```
+structural tier  L   (a new capability port: the kernel gains a selectable
+                      rules variant, so what the engine plays is no longer
+                      a constant)
+chaos            d8 = 8  → OVERRIDE, redraw = L
+declared tier    L
+```
+
+**Declaration 10 of chaos window 3**, and **the window's first 8**.
+The redraw returned the structural tier, so **the override changed
+nothing** — recorded in [`ChaosRollHistory.md`](../specs/ChaosRollHistory.md)
+because a roll that changes nothing is exactly the observation ADR-0017's
+retirement condition needs.
+
+> **Tier L owes a separate-agent adversarial review** (InnerLoop Step 2),
+> and it has **not** been done. The maintainer asked for implementation
+> directly, so the code proceeds — but **no H1 result may go to
+> `ground-game` until that review has run.** Measurement that reaches the
+> game's owner is exactly what the review exists to check.
+
+## What ground-game built, and what it asks of us
+
+`ground-game` has packaged hypothesis **H1** as a *selectable rules
+variant*, not a patch:
+
+- `editions/catalog.yaml` — `variant_id → path`, `default_variant: ground-darvo-r0`
+- `editions/experiments/h1-problem-stress/` — `VARIANT.md` (prose),
+  `rules_delta.yaml` (machine-readable), overridden `Actions.csv` and
+  `Rules_Text.csv`
+- design note `history/260807-attack-darvo-stress-design.md` with success
+  criteria
+
+Their note is explicit about our side:
+
+> *"clay-borg **hardcodes** much of the rules kernel and **vendors**
+> selected CSVs. H1-A/B are **rules-kernel changes**, not Problem table
+> changes. CSV text alone is not executable in the current engine."*
+
+**They are right, and F25 is the same observation from our side.**
+
+## The two deltas
+
+| id | phase | rule |
+|---|---|---|
+| **H1-A** | round end | if **any** Problem in play is unclaimed (face-up unsolved, hidden, **or Denied**), **each player +1 Stress** — *before* the clamp that arms DARVO |
+| **H1-B** | attack resolution | an Attack that resolves **and is not cancelled**, by an attacker whose Stress was **≥ 4 before that Attack's effects**, gives the attacker **−1 Stress**, after target and relation effects, then clamp |
+
+**H1-B applies to the DARVO extra Attack too**, because it shares the
+resolution path.
+
+## Task: selection
+
+```task
+id: CB-WP-0038-T01
+status: done
+priority: high
+```
+
+A variant is chosen, not compiled in.
+
+**Controls:**
+- **the variant is part of game state and reaches the recording.** A
+  scenario replayed under the wrong variant would diverge silently, and
+  the recording is the artifact everything else rests on;
+- **baseline is the default**, and every existing scenario replays
+  byte-identically — this is the load-bearing control, because a variant
+  system that perturbs the baseline invalidates every measurement we have;
+- the catalog is **vendored with a digest**, like every other borrowed
+  file.
+
+**Done 2026-08-08.** `Variant` in `GroundState`, `#[serde(default)]` so
+every scenario written before variants existed loads as baseline — which
+is what it was. Set beside `mode`, before the hash, so a recording replays
+under the variant it was played under. `--variant` on `cb-play`.
+
+**`baseline_is_bit_for_bit_what_it_was`** compares state hashes across
+2/3/6 seats and eight seeds. Selecting the baseline explicitly must equal
+not selecting anything, or every measurement this repo has is invalid.
+
+## Task: the deltas in the kernel
+
+```task
+id: CB-WP-0038-T02
+status: done
+priority: high
+```
+
+**Controls:**
+- **each delta fails on its own**, by mutation;
+- **`rules_delta.yaml`'s `unchanged:` list is asserted, not trusted** —
+  deal and thresholds, SOLVE legality, Support, GROUND modes, the DARVO
+  stage table, starting Stress 2, two relation slots. That list is
+  ground-game's claim about their own experiment, and it is checkable;
+- **"unclaimed" includes Denied and hidden**, which is the clause a
+  careless reading drops.
+
+**Done 2026-08-08.** Both mutation-proven on their own defect:
+
+| mutation | what went red |
+|---|---|
+| "unclaimed" read as *face-up and unsolved* | *"every player takes the pressure, not just some"* |
+| attacker Stress read after the attack's effects, and soothing a cancelled Attack | *"a cancelled Attack still soothed the attacker"* |
+
+**H1-A lands before the DARVO arm check**, per the delta's own ordering;
+applying it after would leave the pressure unable to arm anything for a
+round, which is the opposite of the hypothesis.
+
+**`h1_changes_nothing_it_said_it_would_not`** asserts ground-game's
+`unchanged:` list across all five seat counts — deal, thresholds, starting
+Stress 2, relation slots, mode, deck. That list is their claim about their
+own experiment, and taking it on faith is the habit CB-WP-0037 ended.
+
+## Task: re-run the panel
+
+```task
+id: CB-WP-0038-T03
+status: done
+priority: high
+```
+
+Their §3.2 criteria, on the same harness as RPT-0003.
+
+**Controls:**
+- **baseline and H1 measured by the same instrument in the same run**, or
+  the comparison is between two harnesses rather than two rule sets;
+- **a single policy's numbers are not a fact about the game**
+  (RetrospectiveAnalysis §4.1) — the panel is plural or there is no result;
+- **report what fails to move.** H1 under-delivering is a result their
+  §6 has a branch for, and reporting only the confirming half is how a
+  measurement becomes advocacy.
+
+**Done 2026-08-08, and the result is largely negative.** See
+[CB-EV-0030](../evidence/CB-EV-0030-h1-measured.md).
+
+**A harness defect was caught first, and it mattered.** The first run
+showed `won`, `atk` and `darvo` all exactly `0` at 3+ seats under H1 —
+which is the signature of games being *discarded*, not lost, because
+`sweep` had `let Ok(g) = play(..) else { continue }` and never reported
+its game count. **Reporting "H1 makes the game unwinnable" when the truth
+might have been "our harness threw every H1 game away" would have been the
+ADR-0018 family aimed at another repo's design decision.** Instrumented:
+all 200 games ran in every cell. The zeros are real.