Major changes: logic add to panel, local variables, panel histor, users management...

internal/datasource/user.go

@@ -0,0 +1,27 @@
+package datasource
+
+import "context"
+
+// userKey is the unexported context key under which the end-user identity is
+// stored. Using a private type prevents collisions with other packages.
+type userKey struct{}
+
+// WithUser returns a copy of ctx carrying the end-user identity associated with
+// the request (e.g. the authenticated web client). Data sources may use this to
+// attribute operations to the actual user rather than the server process — for
+// example EPICS Channel Access access-security rules match on the client
+// username. An empty user is treated as "no client identity".
+func WithUser(ctx context.Context, user string) context.Context {
+	if user == "" {
+		return ctx
+	}
+	return context.WithValue(ctx, userKey{}, user)
+}
+
+// UserFrom returns the end-user identity stored in ctx by WithUser. The boolean
+// is false when no (non-empty) identity is present, in which case callers
+// should fall back to the server's own identity.
+func UserFrom(ctx context.Context) (string, bool) {
+	u, ok := ctx.Value(userKey{}).(string)
+	return u, ok && u != ""
+}