feat(mcp): CallerResolver (AuthSession -> project.Caller bridge)

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

internal/mcp/caller.go

@@ -0,0 +1,37 @@
+package mcp
+
+import (
+	"context"
+
+	"github.com/google/uuid"
+
+	"github.com/yan1h/agent-coding-workflow/internal/infra/errs"
+	"github.com/yan1h/agent-coding-workflow/internal/project"
+	"github.com/yan1h/agent-coding-workflow/internal/user"
+)
+
+// CallerResolver 把 MCP AuthSession 转成 project.Caller。
+type CallerResolver struct {
+	users user.Service
+}
+
+func NewCallerResolver(users user.Service) *CallerResolver {
+	return &CallerResolver{users: users}
+}
+
+func (r *CallerResolver) Resolve(ctx context.Context) (project.Caller, error) {
+	sess, ok := FromContext(ctx)
+	if !ok {
+		return project.Caller{}, errs.New(errs.CodeInternal,
+			"mcp: AuthSession missing from context (middleware order bug)")
+	}
+	uid, err := uuid.Parse(sess.UserID)
+	if err != nil {
+		return project.Caller{}, errs.Wrap(err, errs.CodeInternal, "parse user_id from auth session")
+	}
+	u, err := r.users.Get(ctx, uid)
+	if err != nil {
+		return project.Caller{}, err
+	}
+	return project.Caller{UserID: uid, IsAdmin: u.IsAdmin}, nil
+}