Problem

crit in git mode reviews the current local branch/stack against its base. That works well for simple branches, but it gets awkward in stacked-diff workflows.

In a stacked PR setup (for example Sapling stacks, ghstack-like workflows, or multiple dependent PRs on one local stack), running crit shows the whole stacked diff instead of just the PR I want to review. That makes it hard to review one PR in isolation while still testing it locally on top of its dependencies.

Example

Suppose I have:

• PR A: base change
• PR B: depends on A
• PR C: depends on B

Locally, my working stack contains all three. If I want to review just PR B in crit, crit currently shows the full stacked diff instead of the PR-scoped slice.

The current workaround is to:

• review explicit files with crit <file...>, or
• manually reshape/rebase the local stack first

Both are inconvenient, especially when PR comments are tied to a specific GitHub PR.

Requested feature

Add support for reviewing a specific PR directly, for example:

crit --pr 295

or

crit pr 295

and ideally also support PR URLs:

crit --pr https://github.com/owner/repo/pull/295

Desired behavior

When a PR is specified, crit should scope the review to that PR’s diff only, not the entire local stack.

This is especially important for stacked-diff scenarios where:

• the local checkout intentionally contains multiple dependent commits/PRs
• I want to test locally on top of dependencies
• but I only want to review the files/hunks that belong to one PR

Possible implementation ideas

Any of these would help:

• resolve the PR’s base/head and review only that diff range
• support explicit commit-range review in git mode
• integrate PR-scoped review with existing GitHub PR sync (crit pull / crit push)

Why this would help

This would make crit much easier to use in modern stacked-review workflows, especially with Sapling or other dependent-PR setups, where "current branch diff" is not the same thing as "the PR I want to review".