feat(marketplace): command consolidation + 8 new plugins (v8.1.0 → v9.0.0) [BREAKING]

Phase 1b: Rename all ~94 commands across 12 plugins to /<noun> <action>
sub-command pattern. Git-flow consolidated from 8→5 commands (commit
variants absorbed into --push/--merge/--sync flags). Dispatch files,
name: frontmatter, and cross-reference updates for all plugins.

Phase 2: Design documents for 8 new plugins in docs/designs/.

Phase 3: Scaffold 8 new plugins — saas-api-platform, saas-db-migrate,
saas-react-platform, saas-test-pilot, data-seed, ops-release-manager,
ops-deploy-pipeline, debug-mcp. Each with plugin.json, commands, agents,
skills, README, and claude-md-integration. Marketplace grows from 12→20.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/debug-mcp/skills/mcp-protocol.md

@@ -0,0 +1,131 @@
+# MCP Protocol Skill
+
+Model Context Protocol (MCP) specification reference for debugging and development.
+
+## Protocol Overview
+
+MCP uses JSON-RPC 2.0 over stdio (standard input/output) for communication between Claude Code and MCP servers.
+
+### Transport Types
+
+| Transport | Description | Use Case |
+|-----------|-------------|----------|
+| **stdio** | JSON-RPC over stdin/stdout | Default for Claude Code |
+| **SSE** | Server-Sent Events over HTTP | Remote servers |
+
+## Tool Definitions
+
+Tools are the primary way MCP servers expose functionality.
+
+### Tool Registration
+
+```python
+@mcp.tool()
+def list_issues(state: str = "open", labels: list[str] = None) -> str:
+    """List issues from the repository.
+
+    Args:
+        state: Issue state filter (open, closed, all)
+        labels: Filter by label names
+    """
+    # implementation
+```
+
+### Tool Schema (JSON)
+
+```json
+{
+  "name": "list_issues",
+  "description": "List issues from the repository",
+  "inputSchema": {
+    "type": "object",
+    "properties": {
+      "state": {
+        "type": "string",
+        "enum": ["open", "closed", "all"],
+        "default": "open",
+        "description": "Issue state filter"
+      },
+      "labels": {
+        "type": "array",
+        "items": { "type": "string" },
+        "description": "Filter by label names"
+      }
+    },
+    "required": []
+  }
+}
+```
+
+## Resource Definitions
+
+Resources expose data that can be read by the client.
+
+```python
+@mcp.resource("config://settings")
+def get_settings() -> str:
+    """Return current configuration."""
+    return json.dumps(config)
+```
+
+## Prompt Definitions
+
+Prompts provide reusable prompt templates.
+
+```python
+@mcp.prompt()
+def analyze_issue(issue_number: int) -> str:
+    """Generate a prompt to analyze a specific issue."""
+    return f"Analyze issue #{issue_number} and suggest solutions."
+```
+
+## JSON-RPC Message Format
+
+### Request
+
+```json
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "method": "tools/call",
+  "params": {
+    "name": "list_issues",
+    "arguments": {"state": "open"}
+  }
+}
+```
+
+### Response (Success)
+
+```json
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "result": {
+    "content": [{"type": "text", "text": "..."}]
+  }
+}
+```
+
+### Response (Error)
+
+```json
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "error": {
+    "code": -32600,
+    "message": "Invalid Request"
+  }
+}
+```
+
+## Error Codes
+
+| Code | Meaning |
+|------|---------|
+| -32700 | Parse error (invalid JSON) |
+| -32600 | Invalid request |
+| -32601 | Method not found |
+| -32602 | Invalid params |
+| -32603 | Internal error |