6.1 KiB
6.1 KiB
Test Plan: MCP Server Lifecycle
Feature description
MCP (Model Context Protocol) servers are external tools that run as subprocesses communicating via stdio. Loki manages their lifecycle through McpFactory (start/share via Weak dedup) and McpRuntime (per-scope active server handles). Servers are started/stopped during scope transitions (role/session/agent enter/exit).
Behaviors to test
MCP config loading
- mcp.json parsed correctly from functions directory
- Server specs include command, args, env, cwd
- Vault secrets interpolated in mcp.json
- Missing secrets reported as warnings
- McpServersConfig stored on AppState.mcp_config
McpFactory
- acquire() spawns new server when none active (requires real subprocess)
- acquire() returns existing handle via Weak upgrade (requires real subprocess)
- acquire() spawns fresh when Weak is dead (requires real subprocess)
- Multiple acquire() calls for same spec share handle (requires real subprocess)
- Different specs get different handles (via key inequality)
- McpServerKey built correctly from spec (sorted args/env)
McpRuntime
- insert() adds server handle by name (requires Arc)
- get() retrieves handle by name (requires Arc)
- server_names() returns all active names
- is_empty() correct for empty/non-empty
- search() finds tools by keyword (BM25 ranking) (requires live server)
- describe() returns tool input schema (requires live server)
- invoke() calls tool on server and returns result (requires live server)
spawn_mcp_server
- Builds Command from spec (command, args, env, cwd) (integration test)
- Creates TokioChildProcess transport (integration test)
- Completes rmcp handshake (serve) (integration test)
- Returns Arc (integration test)
- Log file created when log_path provided (integration test)
rebuild_tool_scope (MCP integration)
- Empty enabled_mcp_servers → no servers acquired
- "all" → all configured servers acquired (requires real subprocess)
- Comma-separated list → only listed servers acquired (requires real subprocess)
- Mapping resolution: alias → actual server key(s) (requires real subprocess)
- MCP meta functions appended for each started server (requires real subprocess)
- Old ToolScope dropped (releasing old server handles) (requires real subprocess)
- Loading spinner shown during acquisition (UI test)
- AbortSignal properly threaded through (integration test)
Server lifecycle during scope transitions
- Enter role with MCP: servers start (integration test)
- Exit role: servers stop (handle dropped) (integration test)
- Enter role A (MCP-X) → exit → enter role B (MCP-Y): X stops, Y starts (integration test)
- Enter role with MCP → exit to no MCP: servers stop, global MCP restored (integration test)
- Start REPL with global MCP → enter agent with different MCP: agent MCP takes over (integration test)
- Exit agent: agent MCP stops, global MCP restored (integration test)
MCP tool invocation chain
- LLM calls mcp__search_ → search results returned (integration test)
- LLM calls mcp__describe_ tool_name → schema returned (integration test)
- LLM calls mcp__invoke_ tool args → tool executed (integration test)
- Server not found → "MCP server not found in runtime" error (tested via McpRuntime.get)
- Tool not found → appropriate error (requires live server)
MCP support flag
- mcp_server_support=false → no MCP servers started
- mcp_server_support=false + agent with MCP → error (blocks) (requires agent init)
- mcp_server_support=false + role with MCP → warning, continues (requires role init)
- .set mcp_server_support true → MCP servers start (requires live server)
MCP in child agents
- Child agent MCP servers acquired via factory (integration test)
- Child agent MCP runtime populated (integration test)
- Child agent MCP tool invocations work (integration test)
- Child agent exit drops MCP handles (integration test)
Context switching scenarios (comprehensive)
- No MCP → role with MCP → exit role → no MCP (integration test)
- Global MCP-A → role MCP-B → exit role → global MCP-A (integration test)
- Global MCP-A → agent MCP-B → exit agent → global MCP-A (integration test)
- Role MCP-A → session MCP-B (overrides) → exit session (integration test)
- Agent MCP → child agent MCP → child exits → parent MCP intact (integration test)
- .set enabled_mcp_servers X → .set enabled_mcp_servers Y: X released, Y acquired (integration test)
- .set enabled_mcp_servers null → all released (integration test)
Additional behaviors tested (not in original plan)
- McpServerKey equality: same spec → equal keys
- McpServerKey inequality: different names → different keys
- McpServerKey inequality: different commands → different keys
- McpServerKey env coercion: Bool/Int → String
- McpFactory default has empty active map
- McpServer::is_remote() true for Http/Sse, false for Stdio
- McpServer::validate() all cross-field conflicts (6 cases)
- McpServersConfig: empty servers map, multiple servers, cwd field
- McpRegistry: default state, config accessor
- McpRegistry: resolve with whitespace trimming
- McpRegistry: resolve all-nonexistent returns empty
- rebuild_tool_scope: no mcp_config yields empty runtime
- rebuild_tool_scope: preserves tool_tracker across rebuild
- rebuild_tool_scope: REPL mode appends user interaction functions
- rebuild_tool_scope: CMD mode excludes user interaction functions
- MCP meta function name prefix constants are correct
- ToolScope default: empty functions, runtime, tracker
Old code reference
src/mcp/mod.rs— McpRegistry, init, reinit, start/stopsrc/config/mcp_factory.rs— McpFactory, acquire, McpServerKeysrc/config/tool_scope.rs— ToolScope, McpRuntimesrc/config/request_context.rs— rebuild_tool_scope, bootstrap_tools