feat(plugins): add official OpenSpec plugin for spec-driven development

Add kimi-openspec official plugin that integrates Fission-AI OpenSpec CLI
into Kimi Code via MCP stdio transport.

Features:
- 11 OpenSpec tools: init, new_change, list, show, status, validate,
  archive, update, instructions, read_file, refresh_cache
- Built-in openspec_kickoff prompt for spec-driven workflow initialization
- In-memory cache of openspec/ directory for fast listing operations
- Direct file reading via read_file to bypass CLI subprocess overhead
- Auto-installs @fission-ai/openspec via npx --yes

The plugin is registered in plugins/marketplace.json as an official plugin.

Closes discussion #927

Author: qer

plugins/marketplace.json

@@ -10,6 +10,15 @@
       "keywords": ["data", "mcp"],
       "source": "./official/kimi-datasource"
     },
+    {
+      "id": "kimi-openspec",
+      "tier": "official",
+      "displayName": "OpenSpec",
+      "version": "1.0.0",
+      "description": "Official OpenSpec plugin for spec-driven development — manage change proposals, specifications, tasks, and archives.",
+      "keywords": ["openspec", "spec-driven", "sdd", "mcp"],
+      "source": "./official/kimi-openspec"
+    },
     {
       "id": "superpowers",
       "tier": "curated",

plugins/official/kimi-openspec/SKILL.md

@@ -0,0 +1,167 @@
+# kimi-openspec
+
+Official OpenSpec plugin for Kimi Code — enables spec-driven development (SDD) workflows.
+
+## Overview
+
+This plugin integrates [OpenSpec](https://github.com/Fission-AI/OpenSpec) into Kimi Code, allowing AI assistants to manage structured change proposals, specifications, and tasks before writing code.
+
+## What is OpenSpec?
+
+OpenSpec is a lightweight, open-source spec-driven development framework that helps AI coding assistants follow instructions more effectively. It works with 30+ tools including Kimi Code, Claude Code, Cursor, GitHub Copilot, and more.
+
+### Core Workflow
+
+```
+/opsx:new → /opsx:continue → /opsx:apply → /opsx:verify → /opsx:archive
+```
+
+### Key Concepts
+
+- **Proposals** — Structured change requests with technical designs
+- **Specifications** — Living documentation that captures functional requirements
+- **Task Checklists** — Implementation tasks with AI guidance
+- **Archives** — Completed changes preserved for reference
+
+## Installation
+
+This plugin is bundled with Kimi Code as an official plugin. To enable it:
+
+```bash
+kimi plugin install kimi-openspec
+```
+
+Or add it to your Kimi Code configuration.
+
+## Prerequisites
+
+- Node.js 18+ (for running `npx`)
+- The plugin automatically installs `@fission-ai/openspec` via `npx --yes`
+
+## Tools
+
+### `openspec_init`
+
+Initialize OpenSpec in your project.
+
+**Parameters:**
+- `tools` (string, optional): AI tools to configure. Default: `"claude"`. Options: `"all"`, `"none"`, or comma-separated list (e.g. `"claude,cursor,codex"`).
+- `force` (boolean, optional): Auto-cleanup legacy files without prompting.
+
+### `openspec_new_change`
+
+Create a new change directory with proposal, design, tasks, and spec scaffolding.
+
+**Parameters:**
+- `name` (string, required): Name of the change (kebab-case recommended).
+- `description` (string, optional): Description to add to README.md.
+
+### `openspec_list`
+
+List all OpenSpec changes or specs.
+
+**Parameters:**
+- `specs` (boolean, optional): List specs instead of changes.
+
+### `openspec_show`
+
+Show details of a specific change or spec.
+
+**Parameters:**
+- `itemName` (string, required): Name of the item to show.
+- `type` (string, optional): Item type — `"change"` or `"spec"`.
+
+### `openspec_status`
+
+Display artifact completion status for a change.
+
+**Parameters:**
+- `changeName` (string, required): Change name to show status for.
+
+### `openspec_validate`
+
+Validate a change proposal or spec.
+
+**Parameters:**
+- `itemName` (string, optional): Name of the change to validate.
+- `all` (boolean, optional): Validate all changes and specs.
+- `strict` (boolean, optional): Enable strict validation mode.
+
+### `openspec_archive`
+
+Archive a completed change and merge its spec updates back into the main specs directory.
+
+**Parameters:**
+- `changeName` (string, required): Name of the change to archive.
+- `skipSpecs` (boolean, optional): Skip spec updates during archive.
+
+### `openspec_update`
+
+Update OpenSpec instruction files to the latest version.
+
+### `openspec_instructions`
+
+Output enriched instructions for an artifact or apply phase.
+
+**Parameters:**
+- `artifact` (string, required): Artifact name (e.g. `"design.md"`, `"tasks.md"`) or `"apply"`.
+- `changeName` (string, optional): Change name.
+
+### `openspec_read_file`
+
+Read any OpenSpec artifact directly by file type. Much faster than `show` — use this when you need file contents.
+
+**Parameters:**
+- `name` (string, required): Change or spec name.
+- `fileType` (string, required): File to read. Options: `proposal.md`, `design.md`, `tasks.md`, `spec.md`, `review.md`, `plan.md`, `.openspec.yaml`.
+- `type` (string, optional): Item type — `"change"` or `"spec"`. If omitted, prefers changes.
+
+### `openspec_refresh_cache`
+
+Force refresh the cached directory listing. Use if changes were made outside OpenSpec tools.
+
+## Prompts
+
+### `openspec_kickoff`
+
+A pre-built prompt that steers the AI into a strict spec-driven workflow from the first turn. Automatically injected when supported by the AI assistant.
+
+## Usage Example
+
+```
+User: I want to add a dark mode feature to this application.
+AI: I'll help you add a dark mode feature using OpenSpec for structured planning.
+
+[AI uses openspec_init if not already initialized]
+[AI uses openspec_new_change to create "add-dark-mode" change]
+[AI uses openspec_read_file to review proposal.md and tasks.md]
+[AI implements tasks sequentially]
+[AI uses openspec_validate to verify]
+[AI uses openspec_archive when complete]
+```
+
+## Architecture
+
+This plugin is an MCP (Model Context Protocol) server that:
+
+1. Wraps the `@fission-ai/openspec` CLI commands
+2. Maintains an in-memory cache of `openspec/changes/` and `openspec/specs/` directories for fast listing
+3. Provides direct file reading via `openspec_read_file` to bypass CLI subprocess overhead
+4. Exposes a built-in `openspec_kickoff` prompt for spec-driven workflow initialization
+
+## Cache
+
+The plugin maintains an in-memory cache of the OpenSpec directory structure:
+- Cache is built on server startup
+- Cache is refreshed after any mutating operation (`init`, `new_change`, `archive`, `update`)
+- Manual refresh available via `openspec_refresh_cache`
+
+## Error Handling
+
+- If OpenSpec CLI is not installed, the plugin will attempt to install it automatically via `npx --yes`
+- If the project is not initialized, list operations will suggest running `openspec_init`
+- File read operations return clear error messages with available files list
+
+## License
+
+MIT — see LICENSE file.