pr-review-toolkit: Agents hallucinate unsupported gh pr diff --stat flag

[bbarry]

Summary

When using /pr-review-toolkit:review-pr, agents frequently execute gh pr diff <number> --stat which fails because --stat is not a supported flag for gh pr diff.

Observed Behavior

During PR reviews, agents generate commands like:

gh pr diff 123 --stat 2>&1

This fails because gh pr diff only supports --color, --name-only, --patch, and --web. There is no --stat flag (confirmed on gh 2.86.0 and checked release notes through 2.87.2).

Root Cause

The commands/review-pr.md file instructs agents to identify changed files (line 33: git diff --name-only) but provides no guidance on how to get a diffstat summary. Agents infer they should use gh pr diff --stat by analogy with git diff --stat (which is valid), but the gh CLI does not support this flag.

This is an LLM hallucination — the flag looks plausible because git diff --stat works, so the model assumes the same flag exists on gh pr diff.

Suggested Fix

Add explicit guidance in commands/review-pr.md step 3 ("Identify Changed Files") specifying valid commands for getting diff statistics:

- Run `git diff --stat` for a diffstat summary (do NOT use `gh pr diff --stat` — the `--stat` flag is not supported by `gh pr diff`)
- Run `gh pr diff <number> --name-only` for changed file names only

Alternatively, a note in the agent files (agents/code-reviewer.md, etc.) reminding agents that gh pr diff only supports --color, --name-only, --patch, and --web would also help.

Environment

• Claude Code version: 1.0.33
• gh CLI version: 2.86.0 (also verified against 2.87.x release notes)
• Plugin source: claude-plugins-official marketplace