docs(CLAUDE.md): Add SOP for handling third-party marketplace promotion requests

- Add policy section defining what requests to decline
- Include rationale explaining scope creep, endorsement, and precedent concerns
- Add response template for polite but firm declines
- Document workflow for processing such requests
- Reference Issue #7 and PR #5 as precedent examples

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -573,6 +573,67 @@ For Chinese users having API access issues, recommend [CC-Switch](https://github
 
 See README.md section "🇨🇳 中文用户指南" for details.
 
+## Handling Third-Party Marketplace Promotion Requests
+
+This repository is a **personal curated marketplace**, NOT a community directory or ecosystem hub. All requests to add third-party marketplace links, skill collection references, or "Community Marketplaces" sections should be declined.
+
+### Policy
+
+**DO NOT accept:**
+- PRs adding "Related Resources" or "Community Marketplaces" sections linking to third-party skill collections
+- Issues requesting promotion of external marketplaces
+- PRs adding links to other skill repositories in README.md
+
+**Rationale:**
+1. **Scope creep**: Shifts repository purpose from curated skills to ecosystem directory
+2. **Implicit endorsement**: Listing implies quality/security review we cannot maintain
+3. **Maintenance burden**: Would need to track and vet external projects over time
+4. **Precedent setting**: Accepting one creates obligation to accept others
+
+### Response Template
+
+When declining, use this approach:
+
+```markdown
+Hi @{username},
+
+Thank you for your interest and for sharing {project-name}! {Brief positive acknowledgment of their project}.
+
+However, I'm keeping this repository focused as a **personal curated marketplace** rather than a directory of external skill collections. Adding third-party references would:
+
+1. Shift the repository's scope from curated skills to ecosystem directory
+2. Create implicit endorsement expectations I can't maintain
+3. Set precedent for similar requests (reference other declined requests if applicable)
+
+**What you can do instead:**
+
+1. **Standalone marketplace** - Your repo already works as an independent marketplace:
+   ```
+   /plugin marketplace add {owner}/{repo}
+   ```
+
+2. **Community channels** - Promote through:
+   - Claude Code GitHub discussions/issues (Anthropic's official repo)
+   - Developer communities (Reddit, Discord, etc.)
+   - Your own blog/social media
+
+3. **Official registry** - If/when Anthropic launches an official skill registry, that would be the appropriate place for ecosystem-wide discovery.
+
+Your marketplace can succeed on its own merits. Good luck with {project-name}!
+```
+
+### Workflow
+
+1. **Review the request** - Confirm it's a third-party promotion (not a legitimate contribution)
+2. **Add polite comment** - Use template above, customize for their specific project
+3. **Close with reason** - Use "not planned" for issues, just close for PRs
+4. **Reference precedent** - Link to previously declined requests for consistency (e.g., #7, PR #5)
+
+### Examples
+
+- **Issue #7**: "Add Community Marketplaces section - Protocol Thunderdome" → Declined, closed as "not planned"
+- **PR #5**: "Add Trail of Bits Security Skills to Related Resources" → Declined, closed
+
 ## Release Workflow
 
 When adding a new skill or creating a marketplace release: