claude-code - 💡(How to fix) Fix code-review skill posts comments with literal \n instead of newlines (intermittent)

Summary

The `code-review` skill intermittently posts PR comments where newlines appear as literal `\n` (backslash + n) characters rather than being rendered as actual newlines, making the review unreadable in the GitHub UI.

Reproduction

The skill is invoked via `anthropics/claude-code-action@v1` workflow:

```yaml

• uses: anthropics/claude-code-action@v1 with: plugin_marketplaces: 'https://github.com/anthropics/claude-code.git' plugins: 'code-review@claude-code-plugins' prompt: '/code-review:code-review --comment ${{ github.repository }}/pull/${{ github.event.pull_request.number }}' claude_args: '--model claude-sonnet-4-6' ```

Real example from a private repo (PR #449, comment id 4402885550). Initial body retrieved via `gh api`:

```

Code review\n\n1件の問題が見つかりました。\n\n### CLAUDE.md 違反: 依存ライブラリ管理ワークフローの迂回\n\n対象ファイル: `services/ctfd/...` (line 1)\n\n...

```

`\n` is stored as 2 literal characters (backslash + n), not as the newline control character.

Frequency: ~1 in 8 PRs in the same repo (12%). The other 7 reviews had proper newlines. Self-recovery: A subsequent push triggered re-execution and the comment was updated to proper newlines (about 11 minutes later).

Root Cause Analysis

Tracing the comment-posting code paths:

The vulnerable path: the skill prompt §7 instructs:

If `--comment` argument IS provided and NO issues were found, post a summary comment using `gh pr comment` and stop.

When the LLM generates something like:

```bash gh pr comment 449 -b "## Code review\n\n1件..." ```

bash does not interpret `\n` inside double quotes as a newline — it passes the 2 literal characters to `gh`, which forwards them to the GitHub API, which stores them as-is.

Proposed Fix

Update the `code-review` skill prompt §7 to mandate `--body-file` with a temp file (or heredoc):

If `--comment` argument IS provided and NO issues were found, post a summary comment using `gh pr comment` and stop. Always pass the body via a temporary file with `--body-file` to ensure newlines are preserved:

```bash cat > /tmp/review.md <<'EOF'

Code review

No issues found. Checked for bugs and CLAUDE.md compliance. EOF gh pr comment <PR> --body-file /tmp/review.md ```

Do not use `-b "..."` with escape sequences (`\n`, `\t`, etc.) as bash will not interpret them inside double quotes.

The same change should apply anywhere else in the skill (or sibling skills) where `gh pr comment` / `gh issue comment` is suggested.

Why this is the right place to fix

• The action's TypeScript entrypoints already use Octokit (which handles JSON encoding correctly)
• The vulnerable path is only the skill's instruction → fixing the prompt fixes all consumers
• Downstream consumers cannot easily work around this without forking the skill
• A post-process workaround (e.g. `PATCH /comments` after detecting literal `\n`) is fragile and adds maintenance burden

Acceptance Criteria

• `code-review` skill prompt updated to mandate `--body-file` for any `gh pr comment` / `gh issue comment` invocation
• Manual test: trigger the skill on a PR and verify the resulting comment renders newlines correctly

Environment

• Action: `anthropics/claude-code-action@v1`
• Skill: `code-review@claude-code-plugins` (from `anthropics/claude-code`)
• Model: `claude-sonnet-4-6`