island-select

Goal:

• Select the next island strategy and parent hypothesis set for one evolution round.

Inputs:

• islands/ISLANDS.json
• current viable hypotheses/<id>/HYPOTHESIS.json frontier
• iteration_count
• numeric island-selection settings from state/RESOLVED_RUN_CONFIG.json

Outputs:

• deterministic SelectionResult
• selection strategy
• selected parent hypotheses
• when consumed by routing, updated state/STRATEGY_PLAN.json signals

Context Loading:

• Open skills/shared-references/schema-index.md.
• Read packages/agent_contracts/state.py and confirm the exact IslandStateContract shape used inside islands/ISLANDS.json.
• Read packages/agent_contracts/hypothesis.py for the exact HypothesisContract shape.
• Read packages/agent_contracts/resolved_config.py for the island numeric settings.
• When the result is persisted into routing state, also read packages/agent_contracts/strategy_plan.py.

Execution Contract:

• This skill is deterministic and must not call an LLM.
• Use from tools import select_island_hypotheses as the stable invocation surface.
• The exported helper is implemented in packages/agent_mechanics/island_select.py.
• The helper signature is select_island_hypotheses(islands, hypotheses, iteration_count, ucb_exploration_constant=..., softmax_temperature=..., stagnation_epsilon=...) -> SelectionResult.
• The helper is the canonical implementation of UCB island selection, stagnation-triggered multi-island fallback, and Elo-softmax parent sampling.
• islands/ISLANDS.json is the only canonical persisted island source for this skill. Do not read, repair from, or write state/ISLANDS.json.
• If islands/ISLANDS.json is missing, invalid, or uses deprecated item keys such as island_id, reward, stagnation_count, or last_updated, stop and report an invalid canonical island artifact instead of selecting parents.

Execution Steps:

1. Open skills/shared-references/schema-index.md, then read packages/agent_contracts/state.py, packages/agent_contracts/hypothesis.py, and packages/agent_contracts/resolved_config.py.
2. Load island state from islands/ISLANDS.json and the current viable hypotheses from their canonical HYPOTHESIS.json artifacts. Reject state/ISLANDS.json as a non-canonical legacy path.
3. Read iteration_count and the island numeric settings from state/RESOLVED_RUN_CONFIG.json.
4. Call tools.select_island_hypotheses(...) with the canonical inputs.
5. Return the SelectionResult to the caller. When used by routing, persist:

• signals.selection_strategy
• signals.selected_parent_ids
• signals.selected_island_ids

1. Validate any updated state/STRATEGY_PLAN.json artifact before declaring completion.

Artifact Rules:

• Do not replace the helper with ad hoc manual parent choice when the canonical artifacts are available.
• When routing persists the result, the selected parent set becomes the only valid parent set for the next child hypothesis in that round.
• islands/ISLANDS.json remains the canonical source of island reward and visit statistics; this skill reads it but does not mutate it.
• Canonical island items must use id, decayed_reward, decayed_visits, and visit_count. Deprecated aliases are not accepted as selection inputs.

Completion Rule:

• This skill is complete only when the deterministic selection result has been produced and any caller-owned routing artifact has been updated consistently with that result.