Split mcp/server.go (962L) into server, handlers_prompt, handlers_tool

server.go (223L): core lifecycle and routing
handlers_prompt.go (420L): prompt CRUD handlers
handlers_tool.go (335L): tool handlers and schema builders

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 335 insertions, 0 deletions

diff --git a/internal/mcp/handlers_tool.go b/internal/mcp/handlers_tool.go
new file mode 100644
index 0000000..759de9e
--- /dev/null
+++ b/internal/mcp/handlers_tool.go
@@ -0,0 +1,335 @@
+// Summary: MCP tool-related handler methods for listing tools, calling tools,
+// and JSON Schema definitions for tool inputs.
+package mcp
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+// handleToolsList processes the tools/list request.
+// Returns available tools for prompt management operations.
+func (s *Server) handleToolsList(req Request) {
+	s.mu.RLock()
+	if !s.initialized {
+		s.mu.RUnlock()
+		s.sendError(req.ID, ErrCodeInvalidRequest, "Server not initialized")
+		return
+	}
+	s.mu.RUnlock()
+
+	// Define 3 tools for prompt management
+	tools := []Tool{
+		s.makeCreatePromptTool(),
+		s.makeUpdatePromptTool(),
+		s.makeDeletePromptTool(),
+	}
+
+	result := ListToolsResult{
+		Tools:      tools,
+		NextCursor: "", // No pagination needed for 3 tools
+	}
+
+	s.sendResponse(req.ID, result)
+}
+
+// makeCreatePromptTool returns the JSON Schema definition for create_prompt tool.
+func (s *Server) makeCreatePromptTool() Tool {
+	return Tool{
+		Name:        "create_prompt",
+		Description: "Creates a new custom prompt template that can be invoked via the MCP prompts capability. The prompt is saved to user.jsonl and becomes immediately available for use.",
+		InputSchema: s.buildCreatePromptSchema(),
+	}
+}
+
+// buildCreatePromptSchema constructs the JSON Schema for create_prompt tool inputs.
+func (s *Server) buildCreatePromptSchema() map[string]interface{} {
+	return map[string]interface{}{
+		"type": "object",
+		"properties": map[string]interface{}{
+			"name": map[string]interface{}{
+				"type":        "string",
+				"description": "Unique identifier for the prompt (lowercase, underscores allowed)",
+			},
+			"title": map[string]interface{}{
+				"type":        "string",
+				"description": "Human-readable display name for the prompt",
+			},
+			"description": map[string]interface{}{
+				"type":        "string",
+				"description": "Detailed explanation of what the prompt does",
+			},
+			"arguments": buildArgumentArraySchema(),
+			"messages":  buildMessageArraySchema(),
+			"tags": map[string]interface{}{
+				"type":        "array",
+				"description": "Optional tags for categorizing the prompt",
+				"items":       map[string]interface{}{"type": "string"},
+			},
+		},
+		"required": []string{"name", "title", "messages"},
+	}
+}
+
+// makeUpdatePromptTool returns the JSON Schema definition for update_prompt tool.
+func (s *Server) makeUpdatePromptTool() Tool {
+	return Tool{
+		Name:        "update_prompt",
+		Description: "Updates an existing custom prompt template. Only custom prompts (stored in user.jsonl) can be updated; built-in prompts cannot be modified.",
+		InputSchema: s.buildUpdatePromptSchema(),
+	}
+}
+
+// buildUpdatePromptSchema constructs the JSON Schema for update_prompt tool inputs.
+func (s *Server) buildUpdatePromptSchema() map[string]interface{} {
+	return map[string]interface{}{
+		"type": "object",
+		"properties": map[string]interface{}{
+			"name": map[string]interface{}{
+				"type":        "string",
+				"description": "Name of the existing prompt to update",
+			},
+			"title": map[string]interface{}{
+				"type":        "string",
+				"description": "New display name (optional, only if changing)",
+			},
+			"description": map[string]interface{}{
+				"type":        "string",
+				"description": "New description (optional, only if changing)",
+			},
+			"arguments": buildArgumentArraySchema(),
+			"messages":  buildMessageArraySchema(),
+			"tags": map[string]interface{}{
+				"type":        "array",
+				"description": "New tags array (optional, replaces existing if provided)",
+				"items":       map[string]interface{}{"type": "string"},
+			},
+		},
+		"required": []string{"name"},
+	}
+}
+
+// makeDeletePromptTool returns the JSON Schema definition for delete_prompt tool.
+func (s *Server) makeDeletePromptTool() Tool {
+	return Tool{
+		Name:        "delete_prompt",
+		Description: "Deletes a custom prompt template. Only custom prompts (stored in user.jsonl) can be deleted; built-in prompts cannot be removed.",
+		InputSchema: map[string]interface{}{
+			"type": "object",
+			"properties": map[string]interface{}{
+				"name": map[string]interface{}{
+					"type":        "string",
+					"description": "Name of the prompt to delete",
+				},
+			},
+			"required": []string{"name"},
+		},
+	}
+}
+
+// handleToolsCall processes the tools/call request.
+// Dispatches to appropriate tool wrapper based on tool name.
+func (s *Server) handleToolsCall(req Request) {
+	s.mu.RLock()
+	if !s.initialized {
+		s.mu.RUnlock()
+		s.sendError(req.ID, ErrCodeInvalidRequest, "Server not initialized")
+		return
+	}
+	s.mu.RUnlock()
+
+	var params CallToolRequest
+	if err := json.Unmarshal(req.Params, &params); err != nil {
+		s.sendError(req.ID, ErrCodeInvalidParams, "Invalid tools/call params")
+		return
+	}
+
+	// Dispatch to appropriate tool wrapper
+	switch params.Name {
+	case "create_prompt":
+		s.callCreatePromptTool(req.ID, params.Arguments)
+	case "update_prompt":
+		s.callUpdatePromptTool(req.ID, params.Arguments)
+	case "delete_prompt":
+		s.callDeletePromptTool(req.ID, params.Arguments)
+	default:
+		s.sendToolError(req.ID, fmt.Sprintf("Unknown tool: %s", params.Name))
+	}
+}
+
+// callCreatePromptTool executes the create_prompt tool.
+// Converts map arguments to CreatePromptRequest and delegates to store.Create.
+func (s *Server) callCreatePromptTool(id any, args map[string]interface{}) {
+	// Convert map to CreatePromptRequest
+	params, err := convertToCreatePromptRequest(args)
+	if err != nil {
+		s.sendToolError(id, fmt.Sprintf("Invalid arguments: %v", err))
+		return
+	}
+
+	// Validate required fields
+	if err := validateCreateParams(params); err != nil {
+		s.sendToolError(id, err.Error())
+		return
+	}
+
+	// Build prompt and create
+	prompt := buildPromptFromCreateParams(params)
+	if err := s.store.Create(prompt); err != nil {
+		s.logger.Printf("create prompt error: %v", err)
+		s.sendToolError(id, fmt.Sprintf("Failed to create prompt: %v", err))
+		return
+	}
+
+	s.logger.Printf("created prompt via tool: %s", params.Name)
+
+	// Sync to slash commands if enabled
+	if s.syncer != nil {
+		if err := s.syncer.SyncCreate(prompt); err != nil {
+			s.logger.Printf("slash command sync failed: %v", err)
+		}
+	}
+
+	s.sendToolSuccess(id, fmt.Sprintf("Successfully created prompt: %s", params.Name))
+
+	// Notify clients that the prompt list has changed
+	s.sendPromptsListChangedNotification()
+}
+
+// callUpdatePromptTool executes the update_prompt tool.
+// Converts map arguments to UpdatePromptRequest and delegates to store.Update.
+func (s *Server) callUpdatePromptTool(id any, args map[string]interface{}) {
+	// Convert map to UpdatePromptRequest
+	params, err := convertToUpdatePromptRequest(args)
+	if err != nil {
+		s.sendToolError(id, fmt.Sprintf("Invalid arguments: %v", err))
+		return
+	}
+
+	if params.Name == "" {
+		s.sendToolError(id, "Prompt name is required")
+		return
+	}
+
+	// Get existing prompt
+	existing, err := s.store.Get(params.Name)
+	if err != nil {
+		s.logger.Printf("get prompt error: %v", err)
+		s.sendToolError(id, fmt.Sprintf("Prompt not found: %s", params.Name))
+		return
+	}
+
+	// Apply updates
+	applyPromptUpdates(existing, params)
+
+	if err := s.store.Update(existing); err != nil {
+		s.logger.Printf("update prompt error: %v", err)
+		s.sendToolError(id, fmt.Sprintf("Failed to update prompt: %v", err))
+		return
+	}
+
+	s.logger.Printf("updated prompt via tool: %s", params.Name)
+
+	// Sync to slash commands if enabled
+	if s.syncer != nil {
+		if err := s.syncer.SyncUpdate(existing); err != nil {
+			s.logger.Printf("slash command sync failed: %v", err)
+		}
+	}
+
+	s.sendToolSuccess(id, fmt.Sprintf("Successfully updated prompt: %s", params.Name))
+
+	// Notify clients that the prompt list has changed
+	s.sendPromptsListChangedNotification()
+}
+
+// callDeletePromptTool executes the delete_prompt tool.
+// Extracts name from arguments and delegates to store.Delete.
+func (s *Server) callDeletePromptTool(id any, args map[string]interface{}) {
+	// Extract name from arguments
+	name, ok := args["name"].(string)
+	if !ok || name == "" {
+		s.sendToolError(id, "Prompt name is required")
+		return
+	}
+
+	if err := s.store.Delete(name); err != nil {
+		s.logger.Printf("delete prompt error: %v", err)
+		s.sendToolError(id, fmt.Sprintf("Failed to delete prompt: %v", err))
+		return
+	}
+
+	s.logger.Printf("deleted prompt via tool: %s", name)
+
+	// Delete slash command file if enabled
+	if s.syncer != nil {
+		if err := s.syncer.Delete(name); err != nil {
+			s.logger.Printf("slash command sync delete failed: %v", err)
+		}
+	}
+
+	s.sendToolSuccess(id, fmt.Sprintf("Successfully deleted prompt: %s", name))
+
+	// Notify clients that the prompt list has changed
+	s.sendPromptsListChangedNotification()
+}
+
+// buildArgumentArraySchema creates the JSON Schema for prompt arguments array.
+func buildArgumentArraySchema() map[string]interface{} {
+	return map[string]interface{}{
+		"type":        "array",
+		"description": "Template variables that can be substituted when invoking the prompt",
+		"items": map[string]interface{}{
+			"type": "object",
+			"properties": map[string]interface{}{
+				"name": map[string]interface{}{
+					"type":        "string",
+					"description": "Argument name (used in {{name}} placeholders)",
+				},
+				"description": map[string]interface{}{
+					"type":        "string",
+					"description": "Description of the argument's purpose",
+				},
+				"required": map[string]interface{}{
+					"type":        "boolean",
+					"description": "Whether this argument must be provided",
+				},
+			},
+			"required": []string{"name"},
+		},
+	}
+}
+
+// buildMessageArraySchema creates the JSON Schema for prompt messages array.
+func buildMessageArraySchema() map[string]interface{} {
+	return map[string]interface{}{
+		"type":        "array",
+		"description": "Array of message objects (role + content) that form the prompt",
+		"items": map[string]interface{}{
+			"type": "object",
+			"properties": map[string]interface{}{
+				"role": map[string]interface{}{
+					"type":        "string",
+					"description": "Message role: 'user' or 'assistant'",
+					"enum":        []string{"user", "assistant"},
+				},
+				"content": map[string]interface{}{
+					"type": "object",
+					"properties": map[string]interface{}{
+						"type": map[string]interface{}{
+							"type":        "string",
+							"description": "Content type (currently only 'text' is supported)",
+							"enum":        []string{"text"},
+						},
+						"text": map[string]interface{}{
+							"type":        "string",
+							"description": "The message text (can include {{arg}} placeholders)",
+						},
+					},
+					"required": []string{"type", "text"},
+				},
+			},
+			"required": []string{"role", "content"},
+		},
+	}
+}