[FEATURE] Add @claude review stop to unsubscribe a PR from push-triggered reviews

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When @claude review subscribes a PR to push-triggered reviews, there is no way to unsubscribe without merging or closing the PR. This creates runaway cost on active PRs with frequent pushes. This becomes punitive on large monorepos or large PRs, and risks a bad first experience with Claude Code Review.

The only options currently available are:

• Stop pushing (impractical during active review iteration)
• Hit the org spend cap (blunt instrument that affects all repos)
• Close and reopen the PR (disruptive, loses review context)

Prior Issues: this has been requested before _but was closed by the stale bot without implementation_:

• #38442 — "[FEATURE] Add @claude stop command to opt a PR out of automatic subsequent push reviews" (closed as stale 2026-04-27)
• #38444 — Duplicate of above (closed as stale)

Proposed Solution

Add @claude review stop (or @claude unsubscribe) as a top-level PR comment command that:

1. Removes the PR's push-triggered review subscription
2. Posts a confirmation comment (e.g., "Unsubscribed from push-triggered reviews. Use @claude review or @claude review once to start a new review.")
3. Does not cancel any currently-running review

The PR can be re-subscribed later with @claude review if needed, or receive one-off further review via @claude review once.

Alternative Solutions

• @claude review pause / @claude review resume — More granular but adds complexity.
• Per-review cost cap in admin settings — e.g., "skip review if estimated cost exceeds $X". Less disruptive than a monthly spend cap.
• Exponential backoff on re-reviews — After N reviews on the same PR, require manual @claude review once to continue. Prevents runaway cost by default.
• Warning on subscribe — When @claude review subscribes a PR, post a cost estimate (e.g., "This PR will be re-reviewed on each push. Estimated cost per review: ~$20. Use @claude review once for a single review instead.").

Priority

High - Significant impact on productivity

Feature Category

Other

Use Case Example

New Claude Enterprise customer connects Claude GitHub App
Account admin configures Claude Code Review against one or more repositories, conservatively selecting Manual review setting. No REVIEW.md or Review spend limits in place yet.
Engineers encouraged to try Claude Code Review by @mentioning Claude with @claude review or @claude review once.
Account admin, after checking initial costs incurred by Claude Code, realizes cost impact of @claude review upon an large PR receiving multiple pushes under active review.
Account admin intervenes or alerts an engineer to stop continued review with @claude review stop. PR review continues to final approval / merge without incurring ongoing review cost.

Additional Context

As an aside, it would be helpful to indicate the incurred token and/or $ cost of each Claude Code Review in the review output itself. This would provide a better feedback loop for tuning REVIEW.md.