Module overlap 

Does this session’s diff touch the files its own contract executes?

The outcome contract is the automated trust boundary, and its derivation is already well hardened: OutcomeContract::validate rejects assertion-less checks, toolchain-only no-ops and placeholder names; strip_exit_masking_pipes blocks pipelines that always exit 0; and the derivation prompt encodes a dogfooded anti-hacking rule about -k filters and bespoke reproduction snippets.

What remains is that the agent can edit the test files the contract runs. coder::policy addresses that deliberately and correctly:

“Deliberately scoped to what is mechanically decidable. conftest.py, pyproject.toml, tox.ini, and setup.cfg are NOT denied: editing them is often the actual task, and no matcher can separate ‘add a fixture’ from ‘change how tests run’.”

This module does not change that. Denying test-adjacent edits would break the many sessions where editing tests is the task. But denial is not the only option: disclosure is mechanically decidable and was simply absent. If check run_failing_test runs pytest tests/test_x.py and the diff modifies tests/test_x.py, that is a fact computable from data already in hand — and it was never computed, let alone surfaced at the approval gate.

Why the extraction errs toward flagging

Pulling paths out of a shell command is a heuristic; there is no parse that is both general and exact. So it follows policy.rs’s established posture — conservative token matching, biased toward reporting — because the costs are wildly asymmetric: a false positive costs one line of disclosure that a human dismisses in a second, while a false negative silently restores the status quo this exists to fix.

Structs

CheckOverlap

One check whose command references paths the session’s diff also touched.

Functions

contract_overlap

Which of changed_paths each contract check executes.

disclosure

One-line disclosure for the approval surface. None when nothing overlaps.

referenced_paths

Path-like tokens referenced by a check’s command.