Add service layer and MCP server with read tools

Slice 1: internal/service is the one capability layer both the HTTP API and the MCP server call (AGENT.md 1.7); /api/repos and /api/repo route through it. Slice 2: internal/mcp serves an MCP server over Streamable HTTP at /mcp (go-sdk v1.8.0) with read tools list_repos and get_repo as thin adapters over the service, plus a round-trip test. Enabled air polling so hot reload works across the Docker-on-Windows bind mount. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-09-19 17:18:40 -04:00
parent dfa45de40c
commit 2d7f814a23
8 changed files with 300 additions and 8 deletions
@@ -0,0 +1,63 @@
+// Package mcp exposes GitManager's capabilities to Claude as an MCP server over
+// Streamable HTTP (AGENT.md §8.1). The tool handlers are THIN ADAPTERS over the
+// shared service layer (§1.7) — no Git/forge logic lives here. Read tools only
+// for now; acting/destructive tools arrive with the service methods that back
+// them, carrying the §1.4 confirmation contract.
+package mcp
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	mcpsdk "github.com/modelcontextprotocol/go-sdk/mcp"
+
+	"gitmanager/internal/repos"
+	"gitmanager/internal/service"
+)
+
+// getRepoInput is the argument schema for the get_repo tool.
+type getRepoInput struct {
+	Path string `json:"path" jsonschema:"absolute filesystem path of the repository, exactly as returned by list_repos"`
+}
+
+// NewServer builds the MCP server and registers the (currently read-only) tools.
+func NewServer(svc *service.Service, version string) *mcpsdk.Server {
+	s := mcpsdk.NewServer(&mcpsdk.Implementation{
+		Name:        "gitmanager",
+		Title:       "GitManager",
+		Version:     version,
+		Description: "Discover and inspect the user's local Git repositories.",
+	}, nil)
+
+	// list_repos — no arguments (empty struct = object schema with no properties).
+	mcpsdk.AddTool(s, &mcpsdk.Tool{
+		Name:        "list_repos",
+		Description: "List every Git repository GitManager has discovered, each with its current branch, dirty/clean state, ahead/behind counts, and remote names.",
+	}, func(_ context.Context, _ *mcpsdk.CallToolRequest, _ struct{}) (*mcpsdk.CallToolResult, []repos.State, error) {
+		return nil, svc.ListRepos(), nil
+	})
+
+	// get_repo — details for one already-discovered repository.
+	mcpsdk.AddTool(s, &mcpsdk.Tool{
+		Name:        "get_repo",
+		Description: "Get details for one repository: its local branches (with upstreams), recent commits, and remote URLs. The path must be one returned by list_repos.",
+	}, func(ctx context.Context, _ *mcpsdk.CallToolRequest, in getRepoInput) (*mcpsdk.CallToolResult, repos.Detail, error) {
+		detail, ok := svc.RepoDetail(ctx, in.Path)
+		if !ok {
+			return nil, repos.Detail{}, fmt.Errorf("unknown repository %q — call list_repos for valid paths", in.Path)
+		}
+		return nil, detail, nil
+	})
+
+	return s
+}
+
+// Handler serves the MCP server over Streamable HTTP. Mount it at /mcp. Like the
+// rest of the app it is localhost-bound and unauthenticated (§8.1) — the same
+// server instance backs every session.
+func Handler(s *mcpsdk.Server) http.Handler {
+	return mcpsdk.NewStreamableHTTPHandler(func(*http.Request) *mcpsdk.Server {
+		return s
+	}, nil)
+}