arena/environments/redaction_pressure/README.md

# redaction-pressure v0.2

A one-turn Verifiers v1 environment. The model returns regex rules; the scanner runs
them against later records from the same deterministic corpus stream.

## Reward contract

- **Recall (0.35):** a labelled secret counts only when every original character in
  its span is gone. Partial edits earn zero span recall.
- **Precision (0.35):** source characters belonging to fully removed secret spans,
  divided by all removed source characters. Partial damage stays in the denominator.
- **Clean gate (0.30):** every secret fully removed, every non-secret character and
  decoy preserved, and no validation or timeout errors.
- **Validity:** malformed JSON, bad entries, more than 24 rules, unsafe replacements,
  invalid regexes, excessive matches, timeouts, or an exhausted episode budget multiply
  every reward by zero.

Replacement is intentionally limited to `"[REDACTED]"` or `""`. That prevents a rule
from matching a complete secret and then leaking it through a capture expansion.

## Splits

`train` and `dev` have separate, deterministic public seed ranges. `private_eval` derives
seeds with HMAC from `REDACTION_PRESSURE_PRIVATE_SEED`, which must contain at least 32
characters. The secret is never task data; traces carry its SHA-256 commitment and reveal
the derived task seed only in the completed trace so the episode can be reproduced by an
authorized evaluator.

Never present public `dev` scores as private evaluation.

## Trace identity

Each task records the environment, corpus, and reward-schema versions, split commitment,
and a SHA-256 digest of the behavior-bearing installed Python sources. Scoring repeats
the identity under `trace.info.environment` and records validation failures under
`trace.info.redaction_errors`.

## Checks

From the Arena repository root:

```bash
uv sync --project environments/redaction_pressure
uv run --project environments/redaction_pressure \
  python -m unittest discover -s environments/redaction_pressure/tests -v
uv run --with regex python probe.py
```

Arena's environments are independently published libraries, so their generated
`uv.lock` files are intentionally not committed. The runtime contract above is pinned in
this environment's `pyproject.toml` and exercised on Python 3.11 and 3.12 in CI.

The committed tests demonstrate oracle 1.0 and inaction 0.0, reject the historical
first-character exploit across all 64 public development tasks, exercise parser and
rule validation, prove deterministic/private split behavior, and interrupt hostile
regexes under the shared episode budget.