[Plugin] Add experimental next-dev Claude Code plugin

[gaojude]

Summary

Adds a new next-dev plugin to the Next.js Claude Code marketplace at .claude-plugin/plugins/next-dev/. It wires the dev server's MCP endpoint into Claude Code so agents editing Next.js code get real-time Turbopack compilation feedback instead of discovering all errors at the final pnpm build.

Two skill-scoped hooks fire while the /next-dev <port> skill is active:

• UserPromptSubmit → pings the dev server, then calls pause_compilation. Intermediate edits within a turn no longer trigger HMR. Silent no-op if the port file is missing or the server is unreachable.
• Stop → calls compile_and_resume (drains all buffered tasks in one batch), then get_compilation_issues. If issues are found, returns decision: block with formatted errors, forcing the agent to fix them. stop_hook_active is checked to prevent infinite loops.

State files (.claude/port, .claude/dismissed-issues.json) are project-local via $CLAUDE_PROJECT_DIR. Hook scripts and skill scripts are plugin-local via ${CLAUDE_PLUGIN_ROOT}.

The agent can also dismiss non-actionable errors (node_modules resolution failures, Turbopack empty-module stubs) for the rest of the session via dismiss-errors.mjs.

Status: experimental

This plugin depends on MCP tools that are not yet in stable Next.js:

MCP tool	PR	Status
get_compilation_issues	#92062	Landed
pause_compilation / compile_and_resume	#92410	Open

The activation script verifies the tools are present at localhost:<port>/_next/mcp and refuses to enable hooks otherwise — installing against an unsupported Next.js version produces a clear error rather than broken hooks. The plugin is marked experimental in plugin.json, the marketplace entry, the plugins index, and the README.

Files

.claude-plugin/
├── marketplace.json                                  (next-dev entry added)
└── plugins/
    ├── README.md                                     (next-dev row added)
    └── next-dev/
        ├── .claude-plugin/plugin.json
        ├── README.md
        ├── hooks/
        │   ├── enter-manual-compile.mjs
        │   ├── stop-compile-check.mjs
        │   └── mcp-client.mjs
        └── skills/next-dev/
            ├── SKILL.md
            └── scripts/
                ├── activate.mjs
                ├── get-errors.mjs
                └── dismiss-errors.mjs

Test plan

• Install via /plugin marketplace add vercel/next.js + /plugin install next-dev@nextjs against a Next.js dev server built from Add manual compile mode to pause Turbopack scheduling during batched edits #92410
• /next-dev 3000 activates cleanly; activation fails with a clear message when tools are missing
• UserPromptSubmit hook pauses compilation and is a silent no-op when the server is down
• Stop hook compiles in one batch, blocks on errors, and exits 0 on stop_hook_active=true
• Dismiss flow hides node_modules / turbopack-stub errors and resets on next activation

[vercel]

Suggested change

	lines.push(
	`${issues.length} issue(s). Fix them or dismiss non-actionable ones with: node "./scripts/dismiss-errors.mjs"`
	const pluginRoot = process.env.CLAUDE_PLUGIN_ROOT || '.'
	lines.push(
	`${issues.length} issue(s). Fix them or dismiss non-actionable ones with: node "${pluginRoot}/skills/next-dev/scripts/dismiss-errors.mjs"`

Stop hook message contains wrong path to dismiss-errors.mjs, causing the agent to receive a non-working command when compilation errors block it.

[vercel]

Stop hook missing stop_hook_active check allows infinite blocking loop when compilation errors can't be fixed