MCP
Model Context Protocol (MCP) connects Veyyon to external tools and data as an MCP client
(consumes configured servers). Editor embedding uses ACP (veyyon acp), a different protocol.
Responsibility
- Discover MCP servers from the operator’s user and profile config files
- Connect over stdio or HTTP (streamable HTTP / SSE-style transports)
- Register tools as namespaced names (
mcp__<server>_<tool>, e.g.mcp__filesystem_delete) - Handle OAuth for remote servers and persist credentials per profile
Implementation (TypeScript)
| Module | Role |
|---|---|
packages/coding-agent/src/mcp/ | Config load, manager, OAuth, tool wiring |
packages/coding-agent/src/discovery/builtin.ts | Profile-scoped mcp.json / .mcp.json discovery |
packages/coding-agent/src/modes/terminal/controllers/mcp-command-controller.ts | /mcp TUI command dispatch, add, remove, enable, test, reconnect and reload |
packages/coding-agent/src/modes/terminal/controllers/mcp-oauth-login.ts | /mcp OAuth browser login, reauthorization and stored client credentials |
packages/coding-agent/src/modes/terminal/controllers/mcp-smithery-commands.ts | /mcp smithery-search, smithery-login and smithery-logout |
packages/coding-agent/src/modes/terminal/controllers/mcp-server-reports.ts | /mcp list, resources, prompts and notifications reports |
packages/coding-agent/src/modes/terminal/controllers/mcp-command-output.ts | /mcp help text, connection status block and error hints |
Primary config files:
- User:
~/.veyyon/profiles/default/agent/mcp.json(profile-scoped when using--profile)
There is no project scope. A checked-out working tree is untrusted input, so
<cwd>/.veyyon/mcp.json, a repo-root mcp.json/.mcp.json, and the foreign
.cursor/mcp.json and .vscode/mcp.json are not read.
Veyyon also ingests MCP definitions from other tools’ USER-level configs
(~/.claude, ~/.codex, ~/.gemini, ~/.cursor) when discovery is enabled.
A config file that exists but does not parse is REPORTED, never skipped: the
native provider raises Failed to parse JSON in <path> through the capability
warning channel, which MCPManager.discoverAndConnect puts on its status stream
and /mcp list and the boot health zone render. Before that, a mistyped comma in
mcp.json produced a session with every configured server missing and no line
anywhere saying why.
Engineering detail:
docs/handbook/src/reference/mcp-config.md,
docs/internal/mcp-runtime-lifecycle.md,
docs/internal/mcp-protocol-transports.md.