Ensure example_id exists in init_state (default to 0)

[willccbb]

Motivation

• Prevent missing example_id from causing downstream errors by ensuring init_state always supplies a valid example_id when inputs omit it.

Description

• Add a guard in Environment.init_state to set state_input["example_id"] = 0 when example_id is not present before constructing the State (file: verifiers/envs/environment.py).

Testing

• Ran uv run pytest tests/test_environment.py -k init_state which passed (2 passed, 28 deselected).
• Ran uv run ruff check verifiers/envs/environment.py which completed with all checks passing.

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Codex Task

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Note

Low Risk
Small, localized defaulting change in state initialization; main risk is minor behavior change for callers that relied on absent example_id.

Overview
Ensures Environment.init_state always populates state_input["example_id"] by defaulting to 0 when the input row omits it, preventing downstream code from failing on missing IDs.

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[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[cursor]

All missing example_ids silently collapse to same value

Medium Severity

When example_id is missing from the input, it defaults to the constant 0 for every item. If init_state is called for multiple inputs that all lack example_id (e.g., when bypassing the dataset pipeline that assigns unique IDs via _ensure_example_id), all those items silently share example_id = 0. This can cause incorrect grouping or tracking downstream, since example_id is expected to uniquely identify examples — as emphasized by _ensure_example_id and EnvGroup logic that explicitly ensures uniqueness. A per-call unique value or an incrementing counter would avoid silent collisions.

 

[cursor]

Missing documentation update for new default behavior

Low Severity

This PR modifies the behavior of init_state — a method documented in docs/reference.md (line 306) — by making example_id effectively optional with a default of 0. The docs currently list example_id as "Required" in RolloutInput (line 120). Per the documentation update rule, changes to core user-facing functionality described in docs/ need corresponding documentation updates to reflect the new defaulting behavior.

 

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