Slice 3: activity feed and active project (SSE + MCP tools)

Add internal/activity (thread-safe active project + bounded event feed with subscriber fan-out). Service exposes active-project/activity methods and takes the feed. New MCP tools get_active_project/set_active_project/get_activity and HTTP endpoints GET/POST /api/active-project, /api/activity, and /events (SSE). New <activity-feed> component updates live via EventSource; <repo-list> sets the active project on selection. Verified end-to-end in the running app: user actions push live events and set the active project (actor=user), all readable by Claude over MCP.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

cmd/server/main.go

@@ -5,6 +5,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"net/http"
 	"os"
 	"os/signal"
@@ -14,6 +15,7 @@ import (
 	"github.com/labstack/echo/v4"
 	"github.com/labstack/echo/v4/middleware"
 
+	"gitmanager/internal/activity"
 	"gitmanager/internal/config"
 	"gitmanager/internal/git"
 	"gitmanager/internal/logging"
@@ -51,8 +53,11 @@ func main() {
 	go scanner.Run(scanCtx)
 	log.Info("scanner started", "roots", cfg.RepoRoots, "interval", cfg.ScanInterval.String(), "fetch", cfg.ScanFetchEnabled)
 
+	// Coordination state: active project + activity feed (§8.2).
+	feed := activity.New(log, 200)
+
 	// The one service layer both the HTTP API and the MCP server call (§1.7).
-	svc := service.New(g, scanner.Index)
+	svc := service.New(g, scanner.Index, feed)
 
 	tmpl, err := render.New("web/templates")
 	if err != nil {
@@ -95,7 +100,65 @@ func main() {
 		return c.JSON(http.StatusOK, detail)
 	})
 
-	// MCP server — Claude connects here as a custom connector (§8.1). Same
+	// Active project + activity (§8.2).
+	e.GET("/api/active-project", func(c echo.Context) error {
+		return c.JSON(http.StatusOK, map[string]string{"path": svc.ActiveProject()})
+	})
+	e.POST("/api/active-project", func(c echo.Context) error {
+		var body struct {
+			Path string `json:"path"`
+		}
+		if err := c.Bind(&body); err != nil {
+			return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid body"})
+		}
+		// A user action in the UI (actor=user) — distinct from Claude's own switches.
+		if _, _, err := svc.SetActiveProject(activity.ActorUser, body.Path); err != nil {
+			return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
+		}
+		return c.JSON(http.StatusOK, map[string]string{"path": svc.ActiveProject()})
+	})
+	e.GET("/api/activity", func(c echo.Context) error {
+		return c.JSON(http.StatusOK, svc.Activity(0))
+	})
+
+	// SSE stream of activity events for live UI (§8.2).
+	e.GET("/events", func(c echo.Context) error {
+		w := c.Response()
+		w.Header().Set("Content-Type", "text/event-stream")
+		w.Header().Set("Cache-Control", "no-cache")
+		w.Header().Set("Connection", "keep-alive")
+		w.WriteHeader(http.StatusOK)
+		w.Flush()
+
+		ch, unsub := svc.SubscribeActivity()
+		defer unsub()
+
+		keepalive := time.NewTicker(25 * time.Second)
+		defer keepalive.Stop()
+
+		for {
+			select {
+			case <-c.Request().Context().Done():
+				return nil
+			case <-keepalive.C:
+				if _, err := w.Write([]byte(": ping\n\n")); err != nil {
+					return nil
+				}
+				w.Flush()
+			case ev := <-ch:
+				data, err := json.Marshal(ev)
+				if err != nil {
+					continue
+				}
+				if _, err := w.Write([]byte("event: activity\ndata: " + string(data) + "\n\n")); err != nil {
+					return nil
+				}
+				w.Flush()
+			}
+		}
+	})
+
+	// MCP server — Claude connects via the local stdio bridge (§8.1). Same
 	// service layer as the HTTP API (§1.7); localhost-bound like everything else.
 	mcpSrv := mcpserver.NewServer(svc, "0.1.0")
 	e.Any("/mcp", echo.WrapHandler(mcpserver.Handler(mcpSrv)))