feat(genome): uniform crossover for hypothesis genomes

Aggiunge `uniform_crossover` che eredita ogni campo da p1 o p2
con probabilita' 0.5, popola `parent_ids=[p1.id, p2.id]` e incrementa
la generazione. Deterministico dato lo stesso `random.Random` seed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/multi_swarm/genome/crossover.py

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+from __future__ import annotations
+
+import random
+from typing import Any
+
+from .hypothesis import HypothesisAgentGenome, ModelTier
+
+
+def uniform_crossover(
+    p1: HypothesisAgentGenome,
+    p2: HypothesisAgentGenome,
+    rng: random.Random,
+) -> HypothesisAgentGenome:
+    """Per ogni campo, eredita da p1 (prob 0.5) o p2."""
+
+    def pick(field: str) -> Any:
+        return getattr(p1 if rng.random() < 0.5 else p2, field)
+
+    tier_pick: ModelTier = pick("model_tier")
+    feature_pick: list[str] = pick("feature_access")
+
+    payload: dict[str, Any] = {
+        "system_prompt": pick("system_prompt"),
+        "feature_access": list(feature_pick),
+        "temperature": pick("temperature"),
+        "top_p": pick("top_p"),
+        "model_tier": tier_pick.value,
+        "lookback_window": pick("lookback_window"),
+        "cognitive_style": pick("cognitive_style"),
+        "parent_ids": [p1.id, p2.id],
+        "generation": max(p1.generation, p2.generation) + 1,
+    }
+    return HypothesisAgentGenome.from_dict(payload)

tests/unit/test_genome_crossover.py

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+import random
+
+from multi_swarm.genome.crossover import uniform_crossover
+from multi_swarm.genome.hypothesis import HypothesisAgentGenome, ModelTier
+
+
+def make(name: str) -> HypothesisAgentGenome:
+    return HypothesisAgentGenome(
+        system_prompt=f"prompt-{name}",
+        feature_access=["close"] if name == "A" else ["close", "volume"],
+        temperature=0.7 if name == "A" else 1.1,
+        top_p=0.9,
+        model_tier=ModelTier.C,
+        lookback_window=100 if name == "A" else 300,
+        cognitive_style="physicist" if name == "A" else "biologist",
+    )
+
+
+def test_crossover_lineage() -> None:
+    p1 = make("A")
+    p2 = make("B")
+    rng = random.Random(0)
+    child = uniform_crossover(p1, p2, rng)
+    assert sorted(child.parent_ids[-2:]) == sorted([p1.id, p2.id])
+    assert child.generation == max(p1.generation, p2.generation) + 1
+
+
+def test_crossover_inherits_each_field_from_one_parent() -> None:
+    p1 = make("A")
+    p2 = make("B")
+    rng = random.Random(0)
+    child = uniform_crossover(p1, p2, rng)
+    assert child.system_prompt in (p1.system_prompt, p2.system_prompt)
+    assert child.temperature in (p1.temperature, p2.temperature)
+    assert child.lookback_window in (p1.lookback_window, p2.lookback_window)
+    assert child.cognitive_style in (p1.cognitive_style, p2.cognitive_style)
+
+
+def test_crossover_deterministic_with_same_seed() -> None:
+    p1 = make("A")
+    p2 = make("B")
+    c1 = uniform_crossover(p1, p2, random.Random(42))
+    c2 = uniform_crossover(p1, p2, random.Random(42))
+    assert c1.to_dict() == c2.to_dict()