feat: add GitHub CLI authentication requirements and guidelines

.claude/rules/github-cli.md

@@ -0,0 +1,46 @@
+# GitHub CLI (gh) Requirements
+
+## CRITICAL: gh CLI Authentication is Mandatory
+
+When any task requires GitHub operations (PRs, issues, releases, checks, etc.), you MUST use the `gh` CLI.
+
+**If `gh` CLI is not authenticated or not available, you MUST:**
+
+1. **STOP immediately** — do NOT attempt any fallback (WebFetch, curl, API calls, etc.)
+2. **Tell the user** that `gh` CLI authentication is required
+3. **Prompt the user** to run `gh auth login` before continuing
+4. **Wait** — do not proceed until the user confirms authentication
+
+## Prohibited Fallbacks
+
+The following fallbacks are **STRICTLY FORBIDDEN** when `gh` is unavailable or unauthenticated:
+
+- Using `WebFetch` to scrape GitHub URLs
+- Using `curl` against the GitHub API directly
+- Using `WebSearch` to find PR/issue information
+- Any other workaround that bypasses `gh` CLI
+
+## Required Check
+
+Before any `gh` command, if you are unsure about authentication status, run:
+
+```bash
+gh auth status
+```
+
+If the output indicates the user is not logged in, **STOP and prompt**:
+
+> `gh` CLI is not authenticated. Please run `gh auth login` and try again.
+
+## Example Correct Behavior
+
+```
+# gh not authenticated → STOP
+User: Please review PR #123
+Assistant: gh CLI is not authenticated. Please run `gh auth login` first, then retry.
+[Session stops — no fallback attempted]
+```
+
+## Why This Rule Exists
+
+Falling back to WebFetch or other HTTP-based access when `gh` is unavailable silently bypasses authentication and can expose unintended behavior. Stopping and prompting ensures credentials are properly configured before any GitHub interaction.

AGENTS.md

@@ -24,6 +24,8 @@ GROWI is a team collaboration wiki platform using Markdown, featuring hierarchic
 | **coding-style** | Coding conventions, naming, exports, immutability, comments |
 | **security** | Security checklist, secret management, OWASP vulnerability prevention |
 | **performance** | Model selection, context management, build troubleshooting |
+| **github-cli** | **CRITICAL**: gh CLI auth required; stop immediately if unauthenticated |
+
 | **testing** | Test commands, pnpm vitest usage |
 
 ### On-Demand Skills