v0.2.0: Dirty tracking — dirty-mixin, mark-clean, mark-dirty

- dirty-mixin class with dirty slot (initform t)
- mark-clean clears dirty flag
- mark-dirty sets dirty flag
- 3 tests: default-dirty, clean, dirty-cycle
- ROADMAP.org: v0.2.0 all tasks DONE
- 31 component tests, 100% GREEN

src/components/dirty-tests.lisp

@@ -0,0 +1,20 @@
+;; Dirty tracking tests are in box-tests.lisp (same test suite)
+(in-package :cl-tui-box-test)
+
+(test dirty-mixin-default-is-dirty
+  "A dirty-mixin starts as dirty"
+  (let ((c (make-instance 'dirty-mixin)))
+    (is-true (dirty-p c) "new component should be dirty")))
+
+(test mark-clean-clears-dirty
+  "mark-clean sets dirty to nil"
+  (let ((c (make-instance 'dirty-mixin)))
+    (mark-clean c)
+    (is-false (dirty-p c) "after mark-clean, should not be dirty")))
+
+(test mark-dirty-sets-dirty
+  "mark-dirty sets dirty to t"
+  (let ((c (make-instance 'dirty-mixin)))
+    (mark-clean c)
+    (mark-dirty c)
+    (is-true (dirty-p c) "after mark-dirty, should be dirty again")))

src/components/dirty.lisp

@@ -0,0 +1,14 @@
+(in-package :cl-tui.box)
+
+;; ── Dirty Tracking ─────────────────────────────────────────────
+
+(defclass dirty-mixin ()
+  ((dirty :initform t :accessor dirty-p)))
+
+(defgeneric mark-clean (component)
+  (:method ((c dirty-mixin))
+    (setf (dirty-p c) nil)))
+
+(defgeneric mark-dirty (component)
+  (:method ((c dirty-mixin))
+    (setf (dirty-p c) t)))

src/components/package.lisp

@@ -17,5 +17,7 @@
    #:text-fg #:text-bg #:text-wrap-mode
    #:render-text
    ;; Utilities (for tests)
-   #:word-wrap #:split-string))
+   #:word-wrap #:split-string
+   ;; Dirty tracking
+   #:dirty-mixin #:dirty-p #:mark-clean #:mark-dirty))
 (in-package :cl-tui.box)