feat: add slog structured logging

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

internal/api/logging_middleware.go

@@ -0,0 +1,52 @@
+package api
+
+import (
+	"log/slog"
+	"net/http"
+	"time"
+
+	"github.com/gin-gonic/gin"
+)
+
+// requestLogger returns a Gin middleware that logs each request via slog.
+// Requests to /healthz are skipped to avoid health-check noise.
+func requestLogger(lg *slog.Logger) gin.HandlerFunc {
+	if lg == nil {
+		lg = slog.Default()
+	}
+	return func(c *gin.Context) {
+		if c.FullPath() == "/healthz" || c.Request.URL.Path == "/healthz" {
+			c.Next()
+			return
+		}
+
+		start := time.Now()
+		c.Next()
+
+		status := c.Writer.Status()
+		path := c.FullPath()
+		if path == "" {
+			path = c.Request.URL.Path
+		}
+
+		attrs := []any{
+			"method", c.Request.Method,
+			"path", path,
+			"status", status,
+			"latency_ms", time.Since(start).Milliseconds(),
+			"client_ip", c.ClientIP(),
+		}
+		if len(c.Errors) > 0 {
+			attrs = append(attrs, "error", c.Errors.String())
+		}
+
+		switch {
+		case status >= http.StatusInternalServerError:
+			lg.Error("http request completed", attrs...)
+		case status >= http.StatusBadRequest:
+			lg.Warn("http request completed", attrs...)
+		default:
+			lg.Info("http request completed", attrs...)
+		}
+	}
+}

internal/api/router.go

@@ -1,6 +1,7 @@
 package api
 
 import (
+	"log/slog"
 	"net/http"
 
 	"codespace/internal/service"
@@ -9,10 +10,11 @@ import (
 )
 
 // NewRouter builds a Gin engine with all API routes registered.
-func NewRouter(workspaces *service.WorkspaceService, files *service.FileService, processes *service.ProcessService) *gin.Engine {
-	//gin.SetMode(gin.ReleaseMode)
+func NewRouter(workspaces *service.WorkspaceService, files *service.FileService, processes *service.ProcessService, lg *slog.Logger) *gin.Engine {
+	gin.SetMode(gin.ReleaseMode)
 	r := gin.New()
 	r.Use(gin.Recovery())
+	r.Use(requestLogger(lg))
 
 	wsHandler := &workspaceHandler{svc: workspaces}
 	fileHandler := &fileHandler{svc: files}

internal/api/router_test.go

@@ -17,10 +17,10 @@ func setupTestRouter(t *testing.T) http.Handler {
 	root := t.TempDir()
 	wsMgr := workspace.NewLocalManager(root)
 	procMgr := process.NewManager("")
-	wsSvc := service.NewWorkspaceService(wsMgr, procMgr)
+	wsSvc := service.NewWorkspaceService(wsMgr, procMgr, nil)
 	fileSvc := service.NewFileService(wsMgr)
-	procSvc := service.NewProcessService(wsMgr, procMgr)
-	return NewRouter(wsSvc, fileSvc, procSvc)
+	procSvc := service.NewProcessService(wsMgr, procMgr, nil)
+	return NewRouter(wsSvc, fileSvc, procSvc, nil)
 }
 
 func TestHealthz(t *testing.T) {

internal/service/process_service.go

@@ -1,6 +1,8 @@
 package service
 
 import (
+	"log/slog"
+
 	"codespace/internal/process"
 	"codespace/internal/workspace"
 )
@@ -9,11 +11,16 @@ import (
 type ProcessService struct {
 	workspaces workspace.Manager
 	processes  process.Manager
+	logger     *slog.Logger
 }
 
 // NewProcessService creates a ProcessService.
-func NewProcessService(workspaces workspace.Manager, processes process.Manager) *ProcessService {
-	return &ProcessService{workspaces: workspaces, processes: processes}
+// If lg is nil, slog.Default() is used.
+func NewProcessService(workspaces workspace.Manager, processes process.Manager, lg *slog.Logger) *ProcessService {
+	if lg == nil {
+		lg = slog.Default()
+	}
+	return &ProcessService{workspaces: workspaces, processes: processes, logger: lg}
 }
 
 // Start starts an OpenCode process for the given workspace.
@@ -22,12 +29,23 @@ func (s *ProcessService) Start(workspaceID string) error {
 	if err != nil {
 		return err
 	}
-	return s.processes.Start(workspaceID, ws.Root)
+	if err := s.processes.Start(workspaceID, ws.Root); err != nil {
+		s.logger.Error("process start failed", "workspace_id", workspaceID, "error", err)
+		return err
+	}
+	status := s.processes.Status(workspaceID)
+	s.logger.Info("process started", "workspace_id", workspaceID, "pid", status.PID)
+	return nil
 }
 
 // Stop stops the OpenCode process for the given workspace.
 func (s *ProcessService) Stop(workspaceID string) error {
-	return s.processes.Stop(workspaceID)
+	if err := s.processes.Stop(workspaceID); err != nil {
+		s.logger.Error("process stop failed", "workspace_id", workspaceID, "error", err)
+		return err
+	}
+	s.logger.Info("process stopped", "workspace_id", workspaceID)
+	return nil
 }
 
 // Restart restarts the OpenCode process for the given workspace.
@@ -36,7 +54,13 @@ func (s *ProcessService) Restart(workspaceID string) error {
 	if err != nil {
 		return err
 	}
-	return s.processes.Restart(workspaceID, ws.Root)
+	if err := s.processes.Restart(workspaceID, ws.Root); err != nil {
+		s.logger.Error("process restart failed", "workspace_id", workspaceID, "error", err)
+		return err
+	}
+	status := s.processes.Status(workspaceID)
+	s.logger.Info("process restarted", "workspace_id", workspaceID, "pid", status.PID)
+	return nil
 }
 
 // Status returns the process status for the given workspace.

internal/service/workspace_service.go

@@ -1,6 +1,8 @@
 package service
 
 import (
+	"log/slog"
+
 	"codespace/internal/process"
 	"codespace/internal/workspace"
 )
@@ -9,16 +11,26 @@ import (
 type WorkspaceService struct {
 	workspaces workspace.Manager
 	processes  process.Manager
+	logger     *slog.Logger
 }
 
 // NewWorkspaceService creates a WorkspaceService.
-func NewWorkspaceService(workspaces workspace.Manager, processes process.Manager) *WorkspaceService {
-	return &WorkspaceService{workspaces: workspaces, processes: processes}
+// If lg is nil, slog.Default() is used.
+func NewWorkspaceService(workspaces workspace.Manager, processes process.Manager, lg *slog.Logger) *WorkspaceService {
+	if lg == nil {
+		lg = slog.Default()
+	}
+	return &WorkspaceService{workspaces: workspaces, processes: processes, logger: lg}
 }
 
 // Create creates a new workspace.
 func (s *WorkspaceService) Create(id string) (*workspace.Workspace, error) {
-	return s.workspaces.Create(id)
+	ws, err := s.workspaces.Create(id)
+	if err != nil {
+		return nil, err
+	}
+	s.logger.Info("workspace created", "workspace_id", id)
+	return ws, nil
 }
 
 // Get retrieves a workspace by id.
@@ -30,7 +42,13 @@ func (s *WorkspaceService) Get(id string) (*workspace.Workspace, error) {
 func (s *WorkspaceService) Delete(id string) error {
 	status := s.processes.Status(id)
 	if status.Running {
-		_ = s.processes.Stop(id)
+		if err := s.processes.Stop(id); err != nil {
+			s.logger.Error("failed to stop workspace process before delete", "workspace_id", id, "error", err)
+		}
 	}
-	return s.workspaces.Delete(id)
+	if err := s.workspaces.Delete(id); err != nil {
+		return err
+	}
+	s.logger.Info("workspace deleted", "workspace_id", id)
+	return nil
 }