Issue #937 — Making Review Dispatches Read-Only at the Repository Boundary

The Problem

A code review needs to read the checkout and may need to post findings on GitHub, but it should not edit the PR files it is reviewing. Review dispatches already selected a read-oriented role, yet caller-supplied write grants could restore write:src/ or write:docs/. Codex GitHub-write dispatches also used a writable workspace sandbox.

What This PR Shipped

Review permission resolution now strips every write:* capability after all defaults and explicit grants are merged. Codex review jobs retain the network capability needed for GitHub review submission while using a read-only workspace sandbox. Non-review dispatch behavior is unchanged.

What This Achieved on the Path to Autonomy

The review boundary is now enforced by dispatch policy and harness sandbox selection, reducing the chance that an evaluator mutates the artifact it was asked to assess.

Strategic Note: The Goal at the End of This PR

Keep review, implementation, and publication capabilities distinct so every automated action has the smallest filesystem authority needed for its job.