Add support for MCP(sse/streamableHttp) in export mode

[mokeyish]

closes #6473，#6448, #6437,#6323,#6154

💻 变更类型 | Change Type

• [x] feat
• [ ] fix
• [ ] refactor
• [ ] perf
• [ ] style
• [ ] test
• [ ] docs
• [ ] ci
• [ ] chore
• [x] build

🔀 变更说明 | Description of Change

📝 补充信息 | Additional Information

Summary by CodeRabbit

Summary by CodeRabbit

• New Features

  • Added support for both server and client modes, allowing configuration and tool data to be managed via local storage or file system based on build mode.
  • Introduced new build configuration options, including toggles for features like GPT-4, custom config, balance query, and more, all controllable via environment variables.
  • Added global compile-time constant to indicate export mode, improving environment-specific behavior.
  • Implemented a comprehensive MCP client and server management system with lifecycle controls, tool mapping, and configuration persistence.
  • Enabled dynamic delegation of MCP actions to client or server modules based on build mode.

• Improvements

  • Enhanced type safety and clarity in handling server configurations and tool lists.
  • Improved client lookup logic for tool execution, providing better fallback mechanisms.
  • Optimized initialization for access store in export mode to avoid unnecessary network requests.
  • Updated client creation to dynamically select transport type based on server config and build mode.
  • Simplified tools state management and rendering with clearer typing and type guards.

• Bug Fixes

  • Refined checks for server configuration types to ensure correct extraction and usage of user configurations.

[vercel[bot]]

@mokeyish is attempting to deploy a commit to the NextChat Team on Vercel.

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[coderabbitai[bot]]

"""

Walkthrough

This update introduces dual client/server mode support for MCP-related logic, governed by a new global EXPORT_MODE constant. It refactors server configuration types, enhances type safety for tool schemas, expands build configuration options, and adapts client/server behaviors to use localStorage or filesystem as appropriate. Type guards and conditional logic are added throughout.

Changes

File(s)	Change Summary
app/components/mcp-market.tsx	Refined type handling for the tools state, updated modal rendering logic, and improved server config checks using new type guards for better type safety and clarity. Added imports for ToolSchema and isServerStdioConfig.
app/config/build.ts	Extended getBuildConfig to include new properties (feature toggles, URLs, flags) sourced from environment variables, enriching the build configuration.
app/mcp/actions.ts	Replaced entire implementation with a dynamic import that conditionally loads either client or server-specific MCP actions module based on EXPORT_MODE. Removed all previous functions and internal logic.
app/mcp/actions.base.ts	Added comprehensive MCP client/server management module with functions for initializing, adding, pausing, resuming, removing, restarting clients, managing tools, and executing MCP actions. Supports config loading/saving via file or localStorage depending on mode, with logging and error handling.
app/mcp/actions.client.ts	New module re-exporting all exports from actions.base for client-side usage.
app/mcp/actions.server.ts	New server-side module re-exporting all exports from actions.base with "use server" directive for server context.
app/mcp/client.ts	Modified createClient to dynamically select between SSE and stdio transports using type guards and dynamic imports. Throws error if stdio transport is requested in export mode.
app/mcp/types.ts	Refactored server config to discriminated union of ServerStdioConfig, ServerSseConfig, and ServerSteamableConfig with type guards. Added ToolSchema interface and changed tools array type accordingly. Extended McpRequestMessage and McpConfigData interfaces with new properties.
app/store/access.ts	Modified fetch logic in useAccessStore to initialize state from client config in export mode before returning early, avoiding unnecessary network requests.
app/typing.ts	Declared global constant EXPORT_MODE: boolean for compile-time usage throughout the app.
next.config.mjs	Injected EXPORT_MODE as a compile-time constant into webpack build via DefinePlugin for conditional bundling logic.

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant MCPMarketPage
    participant MCPClient
    participant ConfigStore
    participant LocalStorage
    participant FileSystem

    User->>MCPMarketPage: Open MCP Market
    MCPMarketPage->>ConfigStore: Load MCP Config
    alt EXPORT_MODE enabled
        ConfigStore->>LocalStorage: Read MCP Config
        LocalStorage-->>ConfigStore: Config Data (possibly merged)
    else Not EXPORT_MODE
        ConfigStore->>FileSystem: Read MCP Config
        FileSystem-->>ConfigStore: Config Data
    end
    MCPMarketPage->>MCPClient: List Tools (with config)
    MCPClient->>MCPMarketPage: Tools List
    MCPMarketPage-->>User: Render Tools Modal

Assessment against linked issues

Objective	Addressed	Explanation
Support MCP SSE transport (#6473)	✅	Introduced ServerSseConfig type, isServerSseConfig guard, and SSE transport in client creation to support SSE.

Suggested labels

enhancement, planned

Suggested reviewers

• Dogtiti

Poem

A toggle for export, a config anew,
With type guards and unions, the logic grew.
Now tools are more clear,
And configs appear
From disk or from storage, depending on view!

🐇✨ """

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📥 Commits

Reviewing files that changed from the base of the PR and between 62d32f317d071efeadf12147570c83c75361e1af and 2f20905544d62224a0edd3cc85a446da4f6eda5c.

⛔ Files ignored due to path filters (1)

• yarn.lock is excluded by !**/yarn.lock, !**/*.lock

📒 Files selected for processing (3)

• app/mcp/client.ts (1 hunks)
• app/mcp/types.ts (3 hunks)
• package.json (1 hunks)

✅ Files skipped from review due to trivial changes (1)

• package.json

🚧 Files skipped from review as they are similar to previous changes (1)

• app/mcp/client.ts

🔇 Additional comments (5)

app/mcp/types.ts (5)

11-11: LGTM: Added optional name parameter

The addition of an optional name property to the McpRequestMessage params object allows for more flexible parameter identification when making tool calls.

---

69-77: Good improvement to type safety

Replacing the previous generic typing with a more specific ToolSchema interface improves type safety and makes the code more self-documenting. Having explicit fields for name, description, and inputSchema makes the expected structure clearer while still allowing for extensibility with the index signature.

---

117-122: Type guards correctly implement null checks

The type guards properly check for null before checking for object type, addressing the potential issue where typeof null === "object" would return true and could lead to runtime errors.

---

124-149: Good use of discriminated union for server configs

Refactoring the ServerConfig into a discriminated union with distinct types (ServerStdioConfig, ServerSseConfig, ServerSteamableConfig) improves type safety and makes the different configuration options explicit. This aligns well with the PR objective to support different modes in the MCP implementation.

---

152-152: LGTM: Added enableMcp flag

The addition of an optional enableMcp flag to McpConfigData allows for toggling MCP functionality, which is essential for the dual client/server mode support described in the PR objectives.

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[madaochina-dev]

我想支持stido模式该如何改代码

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

---

I want to support sido mode how to change the code

[mokeyish]

stdio 必须有后台进程，帮忙调用系统命令。纯前端只能 sse 和 streamableHttp。

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

---

stdio must have a background process to help call system commands. Pure front-end can only sse and streamableHttp.

[HsnVahedi]

Hi @mokeyish @madaochina-dev @marcusschiesser @shoito Thanks for your time and effort maintaining NextChat. I have a suggestion for you:

Why not using https://github.com/modelcontextprotocol/use-mcp hook to provide mcp client functionality?

Let me know if I can contribute to NextChat. I'd be more than happy to create a pull request and integrate use-mcp hook into nextChat.