1package agent
2
3import (
4 "cmp"
5 "context"
6 "encoding/json"
7 "errors"
8 "fmt"
9 "io"
10 "log/slog"
11 "maps"
12 "net/http"
13 "os/exec"
14 "strings"
15 "sync"
16 "time"
17
18 "github.com/charmbracelet/crush/internal/config"
19 "github.com/charmbracelet/crush/internal/csync"
20 "github.com/charmbracelet/crush/internal/home"
21 "github.com/charmbracelet/crush/internal/llm/tools"
22 "github.com/charmbracelet/crush/internal/permission"
23 "github.com/charmbracelet/crush/internal/pubsub"
24 "github.com/charmbracelet/crush/internal/version"
25 "github.com/modelcontextprotocol/go-sdk/mcp"
26)
27
28// MCPState represents the current state of an MCP client
29type MCPState int
30
31const (
32 MCPStateDisabled MCPState = iota
33 MCPStateStarting
34 MCPStateConnected
35 MCPStateError
36)
37
38func (s MCPState) String() string {
39 switch s {
40 case MCPStateDisabled:
41 return "disabled"
42 case MCPStateStarting:
43 return "starting"
44 case MCPStateConnected:
45 return "connected"
46 case MCPStateError:
47 return "error"
48 default:
49 return "unknown"
50 }
51}
52
53// MCPEventType represents the type of MCP event
54type MCPEventType string
55
56const (
57 MCPEventToolsListChanged MCPEventType = "tools_list_changed"
58 MCPEventPromptsListChanged MCPEventType = "prompts_list_changed"
59)
60
61// MCPEvent represents an event in the MCP system
62type MCPEvent struct {
63 Type MCPEventType
64 Name string
65 State MCPState
66 Error error
67 Counts MCPCounts
68}
69
70// MCPCounts number of available tools, prompts, etc.
71type MCPCounts struct {
72 Tools int
73 Prompts int
74}
75
76// MCPClientInfo holds information about an MCP client's state
77type MCPClientInfo struct {
78 Name string
79 State MCPState
80 Error error
81 Client *mcp.ClientSession
82 Counts MCPCounts
83 ConnectedAt time.Time
84}
85
86var (
87 mcpToolsOnce sync.Once
88 mcpTools = csync.NewMap[string, tools.BaseTool]()
89 mcpClient2Tools = csync.NewMap[string, []tools.BaseTool]()
90 mcpClients = csync.NewMap[string, *mcp.ClientSession]()
91 mcpStates = csync.NewMap[string, MCPClientInfo]()
92 mcpBroker = pubsub.NewBroker[MCPEvent]()
93 mcpPrompts = csync.NewMap[string, *mcp.Prompt]()
94 mcpClient2Prompts = csync.NewMap[string, []*mcp.Prompt]()
95)
96
97type McpTool struct {
98 mcpName string
99 tool *mcp.Tool
100 permissions permission.Service
101 workingDir string
102}
103
104func (b *McpTool) Name() string {
105 return fmt.Sprintf("mcp_%s_%s", b.mcpName, b.tool.Name)
106}
107
108func (b *McpTool) Info() tools.ToolInfo {
109 input := b.tool.InputSchema.(map[string]any)
110 required, _ := input["required"].([]string)
111 parameters, _ := input["properties"].(map[string]any)
112 return tools.ToolInfo{
113 Name: fmt.Sprintf("mcp_%s_%s", b.mcpName, b.tool.Name),
114 Description: b.tool.Description,
115 Parameters: parameters,
116 Required: required,
117 }
118}
119
120func runTool(ctx context.Context, name, toolName string, input string) (tools.ToolResponse, error) {
121 var args map[string]any
122 if err := json.Unmarshal([]byte(input), &args); err != nil {
123 return tools.NewTextErrorResponse(fmt.Sprintf("error parsing parameters: %s", err)), nil
124 }
125
126 c, err := getOrRenewClient(ctx, name)
127 if err != nil {
128 return tools.NewTextErrorResponse(err.Error()), nil
129 }
130 result, err := c.CallTool(ctx, &mcp.CallToolParams{
131 Name: toolName,
132 Arguments: args,
133 })
134 if err != nil {
135 return tools.NewTextErrorResponse(err.Error()), nil
136 }
137
138 output := make([]string, 0, len(result.Content))
139 for _, v := range result.Content {
140 if vv, ok := v.(*mcp.TextContent); ok {
141 output = append(output, vv.Text)
142 } else {
143 output = append(output, fmt.Sprintf("%v", v))
144 }
145 }
146 return tools.NewTextResponse(strings.Join(output, "\n")), nil
147}
148
149func getOrRenewClient(ctx context.Context, name string) (*mcp.ClientSession, error) {
150 sess, ok := mcpClients.Get(name)
151 if !ok {
152 return nil, fmt.Errorf("mcp '%s' not available", name)
153 }
154
155 cfg := config.Get()
156 m := cfg.MCP[name]
157 state, _ := mcpStates.Get(name)
158
159 timeout := mcpTimeout(m)
160 pingCtx, cancel := context.WithTimeout(ctx, timeout)
161 defer cancel()
162 err := sess.Ping(pingCtx, nil)
163 if err == nil {
164 return sess, nil
165 }
166 updateMCPState(name, MCPStateError, maybeTimeoutErr(err, timeout), nil, state.Counts)
167
168 sess, err = createMCPSession(ctx, name, m, cfg.Resolver())
169 if err != nil {
170 return nil, err
171 }
172
173 updateMCPState(name, MCPStateConnected, nil, sess, state.Counts)
174 mcpClients.Set(name, sess)
175 return sess, nil
176}
177
178func (b *McpTool) Run(ctx context.Context, params tools.ToolCall) (tools.ToolResponse, error) {
179 sessionID, messageID := tools.GetContextValues(ctx)
180 if sessionID == "" || messageID == "" {
181 return tools.ToolResponse{}, fmt.Errorf("session ID and message ID are required for creating a new file")
182 }
183 permissionDescription := fmt.Sprintf("execute %s with the following parameters:", b.Info().Name)
184 p := b.permissions.Request(
185 permission.CreatePermissionRequest{
186 SessionID: sessionID,
187 ToolCallID: params.ID,
188 Path: b.workingDir,
189 ToolName: b.Info().Name,
190 Action: "execute",
191 Description: permissionDescription,
192 Params: params.Input,
193 },
194 )
195 if !p {
196 return tools.ToolResponse{}, permission.ErrorPermissionDenied
197 }
198
199 return runTool(ctx, b.mcpName, b.tool.Name, params.Input)
200}
201
202func getTools(ctx context.Context, name string, permissions permission.Service, c *mcp.ClientSession, workingDir string) ([]tools.BaseTool, error) {
203 if c.InitializeResult().Capabilities.Tools == nil {
204 return nil, nil
205 }
206 result, err := c.ListTools(ctx, &mcp.ListToolsParams{})
207 if err != nil {
208 return nil, err
209 }
210 mcpTools := make([]tools.BaseTool, 0, len(result.Tools))
211 for _, tool := range result.Tools {
212 mcpTools = append(mcpTools, &McpTool{
213 mcpName: name,
214 tool: tool,
215 permissions: permissions,
216 workingDir: workingDir,
217 })
218 }
219 return mcpTools, nil
220}
221
222// SubscribeMCPEvents returns a channel for MCP events
223func SubscribeMCPEvents(ctx context.Context) <-chan pubsub.Event[MCPEvent] {
224 return mcpBroker.Subscribe(ctx)
225}
226
227// GetMCPStates returns the current state of all MCP clients
228func GetMCPStates() map[string]MCPClientInfo {
229 return maps.Collect(mcpStates.Seq2())
230}
231
232// GetMCPState returns the state of a specific MCP client
233func GetMCPState(name string) (MCPClientInfo, bool) {
234 return mcpStates.Get(name)
235}
236
237// updateMCPState updates the state of an MCP client and publishes an event
238func updateMCPState(name string, state MCPState, err error, client *mcp.ClientSession, counts MCPCounts) {
239 info := MCPClientInfo{
240 Name: name,
241 State: state,
242 Error: err,
243 Client: client,
244 Counts: counts,
245 }
246 switch state {
247 case MCPStateConnected:
248 info.ConnectedAt = time.Now()
249 case MCPStateError:
250 updateMcpTools(name, nil)
251 updateMcpPrompts(name, nil)
252 mcpClients.Del(name)
253 }
254 mcpStates.Set(name, info)
255}
256
257// CloseMCPClients closes all MCP clients. This should be called during application shutdown.
258func CloseMCPClients() error {
259 var errs []error
260 for name, c := range mcpClients.Seq2() {
261 if err := c.Close(); err != nil &&
262 !errors.Is(err, io.EOF) &&
263 !errors.Is(err, context.Canceled) &&
264 err.Error() != "signal: killed" {
265 errs = append(errs, fmt.Errorf("close mcp: %s: %w", name, err))
266 }
267 }
268 mcpBroker.Shutdown()
269 return errors.Join(errs...)
270}
271
272func doGetMCPTools(ctx context.Context, permissions permission.Service, cfg *config.Config) {
273 var wg sync.WaitGroup
274 // Initialize states for all configured MCPs
275 for name, m := range cfg.MCP {
276 if m.Disabled {
277 updateMCPState(name, MCPStateDisabled, nil, nil, MCPCounts{})
278 slog.Debug("skipping disabled mcp", "name", name)
279 continue
280 }
281
282 // Set initial starting state
283 updateMCPState(name, MCPStateStarting, nil, nil, MCPCounts{})
284
285 wg.Add(1)
286 go func(name string, m config.MCPConfig) {
287 defer func() {
288 wg.Done()
289 if r := recover(); r != nil {
290 var err error
291 switch v := r.(type) {
292 case error:
293 err = v
294 case string:
295 err = fmt.Errorf("panic: %s", v)
296 default:
297 err = fmt.Errorf("panic: %v", v)
298 }
299 updateMCPState(name, MCPStateError, err, nil, MCPCounts{})
300 slog.Error("panic in mcp client initialization", "error", err, "name", name)
301 }
302 }()
303
304 ctx, cancel := context.WithTimeout(ctx, mcpTimeout(m))
305 defer cancel()
306
307 c, err := createMCPSession(ctx, name, m, cfg.Resolver())
308 if err != nil {
309 return
310 }
311
312 mcpClients.Set(name, c)
313
314 tools, err := getTools(ctx, name, permissions, c, cfg.WorkingDir())
315 if err != nil {
316 slog.Error("error listing tools", "error", err)
317 updateMCPState(name, MCPStateError, err, nil, MCPCounts{})
318 c.Close()
319 return
320 }
321
322 prompts, err := getPrompts(ctx, c)
323 if err != nil {
324 slog.Error("error listing prompts", "error", err)
325 updateMCPState(name, MCPStateError, err, nil, MCPCounts{})
326 c.Close()
327 return
328 }
329
330 updateMcpTools(name, tools)
331 updateMcpPrompts(name, prompts)
332 mcpClients.Set(name, c)
333 counts := MCPCounts{
334 Tools: len(tools),
335 Prompts: len(prompts),
336 }
337 updateMCPState(name, MCPStateConnected, nil, c, counts)
338 }(name, m)
339 }
340 wg.Wait()
341}
342
343// updateMcpTools updates the global mcpTools and mcpClient2Tools maps
344func updateMcpTools(mcpName string, tools []tools.BaseTool) {
345 if len(tools) == 0 {
346 mcpClient2Tools.Del(mcpName)
347 } else {
348 mcpClient2Tools.Set(mcpName, tools)
349 }
350 for _, tools := range mcpClient2Tools.Seq2() {
351 for _, t := range tools {
352 mcpTools.Set(t.Name(), t)
353 }
354 }
355}
356
357func createMCPSession(ctx context.Context, name string, m config.MCPConfig, resolver config.VariableResolver) (*mcp.ClientSession, error) {
358 timeout := mcpTimeout(m)
359 mcpCtx, cancel := context.WithCancel(ctx)
360 cancelTimer := time.AfterFunc(timeout, cancel)
361
362 transport, err := createMCPTransport(mcpCtx, m, resolver)
363 if err != nil {
364 updateMCPState(name, MCPStateError, err, nil, MCPCounts{})
365 slog.Error("error creating mcp client", "error", err, "name", name)
366 return nil, err
367 }
368
369 client := mcp.NewClient(
370 &mcp.Implementation{
371 Name: "crush",
372 Version: version.Version,
373 Title: "Crush",
374 },
375 &mcp.ClientOptions{
376 ToolListChangedHandler: func(context.Context, *mcp.ToolListChangedRequest) {
377 mcpBroker.Publish(pubsub.UpdatedEvent, MCPEvent{
378 Type: MCPEventToolsListChanged,
379 Name: name,
380 })
381 },
382 PromptListChangedHandler: func(context.Context, *mcp.PromptListChangedRequest) {
383 mcpBroker.Publish(pubsub.UpdatedEvent, MCPEvent{
384 Type: MCPEventPromptsListChanged,
385 Name: name,
386 })
387 },
388 KeepAlive: time.Minute * 10,
389 },
390 )
391
392 session, err := client.Connect(mcpCtx, transport, nil)
393 if err != nil {
394 updateMCPState(name, MCPStateError, maybeTimeoutErr(err, timeout), nil, MCPCounts{})
395 slog.Error("error starting mcp client", "error", err, "name", name)
396 cancel()
397 return nil, err
398 }
399
400 cancelTimer.Stop()
401 slog.Info("Initialized mcp client", "name", name)
402 return session, nil
403}
404
405func maybeTimeoutErr(err error, timeout time.Duration) error {
406 if errors.Is(err, context.Canceled) {
407 return fmt.Errorf("timed out after %s", timeout)
408 }
409 return err
410}
411
412func createMCPTransport(ctx context.Context, m config.MCPConfig, resolver config.VariableResolver) (mcp.Transport, error) {
413 switch m.Type {
414 case config.MCPStdio:
415 command, err := resolver.ResolveValue(m.Command)
416 if err != nil {
417 return nil, fmt.Errorf("invalid mcp command: %w", err)
418 }
419 if strings.TrimSpace(command) == "" {
420 return nil, fmt.Errorf("mcp stdio config requires a non-empty 'command' field")
421 }
422 cmd := exec.CommandContext(ctx, home.Long(command), m.Args...)
423 cmd.Env = m.ResolvedEnv()
424 return &mcp.CommandTransport{
425 Command: cmd,
426 }, nil
427 case config.MCPHttp:
428 if strings.TrimSpace(m.URL) == "" {
429 return nil, fmt.Errorf("mcp http config requires a non-empty 'url' field")
430 }
431 client := &http.Client{
432 Transport: &headerRoundTripper{
433 headers: m.ResolvedHeaders(),
434 },
435 }
436 return &mcp.StreamableClientTransport{
437 Endpoint: m.URL,
438 HTTPClient: client,
439 }, nil
440 case config.MCPSSE:
441 if strings.TrimSpace(m.URL) == "" {
442 return nil, fmt.Errorf("mcp sse config requires a non-empty 'url' field")
443 }
444 client := &http.Client{
445 Transport: &headerRoundTripper{
446 headers: m.ResolvedHeaders(),
447 },
448 }
449 return &mcp.SSEClientTransport{
450 Endpoint: m.URL,
451 HTTPClient: client,
452 }, nil
453 default:
454 return nil, fmt.Errorf("unsupported mcp type: %s", m.Type)
455 }
456}
457
458type headerRoundTripper struct {
459 headers map[string]string
460}
461
462func (rt headerRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
463 for k, v := range rt.headers {
464 req.Header.Set(k, v)
465 }
466 return http.DefaultTransport.RoundTrip(req)
467}
468
469func mcpTimeout(m config.MCPConfig) time.Duration {
470 return time.Duration(cmp.Or(m.Timeout, 15)) * time.Second
471}
472
473func getPrompts(ctx context.Context, c *mcp.ClientSession) ([]*mcp.Prompt, error) {
474 if c.InitializeResult().Capabilities.Prompts == nil {
475 return nil, nil
476 }
477 result, err := c.ListPrompts(ctx, &mcp.ListPromptsParams{})
478 if err != nil {
479 return nil, err
480 }
481 return result.Prompts, nil
482}
483
484// updateMcpPrompts updates the global mcpPrompts and mcpClient2Prompts maps.
485func updateMcpPrompts(mcpName string, prompts []*mcp.Prompt) {
486 if len(prompts) == 0 {
487 mcpClient2Prompts.Del(mcpName)
488 } else {
489 mcpClient2Prompts.Set(mcpName, prompts)
490 }
491 for clientName, prompts := range mcpClient2Prompts.Seq2() {
492 for _, p := range prompts {
493 key := clientName + ":" + p.Name
494 mcpPrompts.Set(key, p)
495 }
496 }
497}
498
499// GetMCPPrompts returns all available MCP prompts.
500func GetMCPPrompts() map[string]*mcp.Prompt {
501 return maps.Collect(mcpPrompts.Seq2())
502}
503
504// GetMCPPrompt returns a specific MCP prompt by name.
505func GetMCPPrompt(name string) (*mcp.Prompt, bool) {
506 return mcpPrompts.Get(name)
507}
508
509// GetMCPPromptsByClient returns all prompts for a specific MCP client.
510func GetMCPPromptsByClient(clientName string) ([]*mcp.Prompt, bool) {
511 return mcpClient2Prompts.Get(clientName)
512}
513
514// GetMCPPromptContent retrieves the content of an MCP prompt with the given arguments.
515func GetMCPPromptContent(ctx context.Context, clientName, promptName string, args map[string]string) (*mcp.GetPromptResult, error) {
516 c, err := getOrRenewClient(ctx, clientName)
517 if err != nil {
518 return nil, err
519 }
520
521 return c.GetPrompt(ctx, &mcp.GetPromptParams{
522 Name: promptName,
523 Arguments: args,
524 })
525}